Ch 11 Animal Form and Function
Terms in this set (233)
cells are organized in the following ways:
3. organ system
Tissues are groups of similar cells performing a common function
4 general categories of tissues
epithelial tissue (outer skin layers and internal protectve coverings)
connective tissue (bone, cartilage, blood)
An organ is a group of different kinds of tissues functioning together to perform a particular activity
An organ systemis two or more organs working together to accomplish a particular task.
two groups animals can be loosely grouped upon how body temperature is maintained
Ectotherms are animals that obtain body heat from their environment. Since their temperatures often vary with the temperature of their environment, they are sometimes referred to as poikilotherms ("changing temperature"). Examples include most invertebrates, amphibians, reptiles, and fish. Because many of these animals may feel cold to the touch they are called "cold-blooded" animals, but many land-dwelling ectotherms can exceed ambient temperatures by basking in the sun.
Endotherms are animals that generate their own body heat. They are also referred to as homeotherms because they maintain a constant internal temperature or as "warm-blooded" because their temperature is relatively warm compared to ectotherms.
4 mechanisms that animals use to regulate their body temperatures
1. cooling by evaporation
2. warming by metabolism
3. adjusting surface area to regulate temperature
4. concurrent exchange
cooling by evaporation
Many animals lose heat by sweating. Since changing from a liquid to gaseous state requires energy (an endergonic reaction), body heat is removed when water vaporizes. Evaporative heat loss also occurs from the respiratory tract, a cooling process employed when animals pant.
Warming by metabolism
Muscle contraction and other metabolic activities generate heat. For example, shivering warms animals from the heat generated by muscle contractions and by metabolizing fat.
explain how metabolizing fat can help to warm up the body
heat is generated by metabolizing fat (in some animals in specialized fat deposits called brown fat). In the this process, oxidative phosphorylation in mitochondria is decoupled from electron transport chain when the permeability of the inner mitochondrial membrane to H+ is increased. This neutralizes the proton gradient, and, as a result, heat is generated instead of ATP.
adjusting surface are to regulate temperature
The extremities of bodies (arms, hands, feet, ears) add considerable surface area to the body. By changing the volume of blood that flows to these areas by vasodilation or vasoconstriction (increasing or decreasing the diameter of blood vessels), heat can be lost or conserved. In hot environments, for example, elephants and jackrabbits increase blood flow to their large ears to reduce body temperature. In contrast, animals in cold environments reduce blood flow to their ears, hands, and feet to conserve heat.
conserves body heat when a blood vessel with blood flowing toward and extremityis adjacent to a blood vessel with returning from the extremity. Heat conduction from the warm blood to the returning cold blood is redirected to internal parts of the body before reaching the extremity. This occurs, for example. in the legs of wading birds
behavioral, physiologycal, and anatomical adaptation examples to increase ability to survive in particular environment
-hibernation in winter
-hair, feathers, or blubber
-move from sun to shade or restrict activity to nights
Four mechanisms of gas exchange (respiration) in animals
1. direct with environment
explain direct with environment
Direct with environment. Some animals are small enough to allow gas exchange directly with the outside environment. Many of these animals, such as the Platyhelminthes (flatworms), typically have large surface areas, and every cell either is exposed to the outside environment or is close enough that gases are available by diffusion through adjacent cells. In larger animals, such as the Annelida (segmented worms), gas exchange through the skin is augmented by a distribution system (a circulatory system) just inside the skin.
Gills. Gills are evaginated structures, or outgrowths from the body, that create a large surface area over which gas exchange occurs. Inside the gills, a circulatory system removes the oxygen and delivers waste CO2. In some animals, such as polychaete worms (Annelida), the gills are external and unprotected. In other animals, the gills are internal and protected. In fish, for example, water enters the mouth, passes over the gills, and exits through the gill cover, or operculum. Countercurrent exchange between the opposing movements of water and the underlying blood through blood vessels maximizes the diffusion of O2 into the blood and CO2 into the water.
Tracheae. Insects have chitin-lined tubes, or tracheae, that permeate their bodies. Oxygen enters (or CO2 exits) the tracheae through openings called spiracles; diffusion occurs across moistened tracheal endings.
lungs (definition and two types of lungs)
Lungs are invaginated structures, or cavities within the body of the animal. Book lungs, occurring in many spiders, are stacks of flattened membranes enclosed in an internal chamber.
steps of gas exchange in humans (10)
1. nose, pharynx, larynx
3. bronchi, bronchioles
5. diffussion between alveolar chambers and blood
'6. bulk flow of O2
7. diffusion between blood and cells
8. bulk flow of CO2
9. bulk flow of air inot and out of the lungs (mechanics of respiration)
10. control of respiration
air enters the nose and passes through_
nasal cavity, pharynx, larynx
The larynx ("voice box") contains the vocal cords.
After passing through the larynx, air enters the trachea, a cartilage-lined tube. When the animal is swallowing, a special flap called the epiglottis covers the trachea, preventing the entrance of solid and liquid material
trachea leads to _, explain them
The trachea branches into two bronchi (singular, bronchus), which enter the lungs and then branch repeatedly, forming narrower tubes called bronchioles.
bronchioles lead to _.
Each bronchiole branch ends in a small sac called an alveolus (plural, alveoli). Each alveolus is densely surrounded by blood-carrying capillaries.
what happens at alveolus
Diffusion between alveolar chambers and blood. Gas exchange occurs by diffusion across the moist, sac membranes of the alveoli. Oxygen diffuses into the moisture covering the membrane, through the alveolar wall, through the blood capillary wall, into the blood, and into red blood cells. Carbon dioxide diffuses in the opposite direction.
explain bulk flow of O2
.The circulatory system transports O2 throughout the body within red blood cells. Red blood cells contain hemoglobin, iron-containing proteins to which O2 bonds.
explain diffusion between blood and cells
Blood capillaries permeate the body. Oxygen diffuses out of the red blood cells, across blood capillary walls, into interstitial fluids (the fluids surrounding the cells), and across cell membranes. Carbon dioxide diffuses in the opposite direction
explain bulk flow of CO2
Most CO2 is transported as dissolved bicarbonate ions (HCO3-) in the plasma, the liquid portion of the blood.
CO2 reaction and how transported
The formation of HCO3-, however, occurs in the red blood cells, where the formation of carbonic acid (H2CO3) is catalyzed by the enzyme carbonic anhydrase, as follows: CO2 + H2O --> H2CO3 (carbonic acid)--> H+ + HCO3^- (bicarbonate)
Following their formation in the red blood cells, HCO3- ions diffuse back into the plasma. Some CO2, however, does not become HCO3-; instead, it mixes directly with the plasma (as CO2 gas) or binds with the amino groups of the hemoglobin molecules inside red blood cells.
explain Bulk flow of air into and out of the lungs (mechanics of respiration)
Air is moved into and out of the lungs by changing their volume. The volume of the lungs is increased by the contraction of the diaphragm (a muscle under the lungs) and the intercostal muscles (muscles between the ribs). When the lung volume increases, the air pressure within the lungs decreases. This causes a pressure difference between the air in the lungs and the air outside the body. As a result, air rushes into the lungs by bulk flow. When the diaphragm and intercostal muscles relax, the volume of the lungs decreases, raising the pressure on the air, causing the air to rush out.
what is the main controller of respiration?
Chemoreceptors in the carotid arteries (arteries that supply blood to the brain) monitor the pH of the blood. When a body is active, CO2 production increases. When the CO2 that enters the plasma is converted to HCO3- and H+, the blood pH drops (becomes more acidic). In response, the chemoreceptors send nerve impulses to the diaphragm and intercostal muscles to increase respiratory rate. This results in a faster turnover in gas exchange, which, in turn, returns blood pH to normal. The regulation of the respiratory rate in this manner is an example of how homeostasis is maintained by negative feedback.
two types of circulatory systems
open circulatory system
closed circulatory system
open circulatory system
Open circulatory systemspump blood into an internal cavity called a hemocoel (or cavities called sinuses), which bathe tissues with an oxygen- and nutrient-carrying fluid called hemolymph.The hemolymph returns to the pumping mechanism of the system, a heart, through holes called ostia. Open circulatory systems occur in insects and most mollusks.
closed circulatory systems
In closed circulatory systems, the nutrient-, oxygen-, and waste-carrying fluid, blood, is confined to vessels. Closed circulatory systems are found among members of the phylum Annelida (earthworms, for example), certain mollusks (octopuses and squids), and vertebrates.
flow of blood in vessels
heart-->arteries-->arterioles-->capillaries-->venules-->veins-->heart--> pulmonary arteries-->pulmonary arteroles-->pulmonary veins-->pulmonary venules-->heart
oxygenated pathway through heart
lungs-->left pulmonary veins-->left atrium-->left AV valve (bicuspid or mitral)-->left ventricle-->aortic semilunar valve-->aorta-->aortic arch-->descending aorta-->body
(veins usually have deoxygenated blood but they have oxygenated blood at pulmonary veins)
deoxygenated pathway through heart
body-->inferior vena cava and superior vena cava-->right atrium-->right tricuspid AV valve-->right ventricle-->pulmonary semilunar valve-->pulmonary trunk-->right and left pumonary artery-->lungs
(arteries usually have oxygenated blood; the only exception are pulmonary arteries that have deoxygenated blood)
when AV valves and semilular valves close?
When the ventricles contract, the AV valve closes and prevents blood moving backward into the atrium. When the ventricles relax, the semilunar valve prevents backflow from the pulmonary artery back into the ventricles.
The blood pathway between the right side of the heart, to the lungs, and back to the left side of the heart is called the pulmonary circuit
The circulation pathway throughout the body (between the left and right sides of the heart) is the systemic circuit.
cardiac or heart cycle
The cardiac or heart cycle refers to the rhythmic contraction and relaxation of heart muscles.
who regulates the cardiac cycle?
The process is regulated by specialized tissues in the heart called autorhythmic cells, which are self-excitable and able to initiate contractions without external stimulation by nerve cells.
cardiac circle pathway (summary)
SA node-->AV node-->bundle of His-->purkinje fibers
cardicac cycle in detail way
1. The SA (sinoatrial) node, or pacemaker, located in the upper wall of the right atrium, spontaneously initiates the cycle by simultaneously contracting both atria and also by sending a delayed impulse that stimulates the AV (atrioventricular) node.
2. The AV node in the lower wall of the right atrium sends an impulse through the bundle of His, nodal tissue that passes down between both ventricles and then branches into the ventricles through the Purkinje fibers.This impulse results in the contraction of the ventricles.
3. When the ventricles contract (the systole phase), blood is forced through the pulmonary arteries and aorta. Also, the AV valves are forced to close. When the ventricles relax (the diastole phase), backflow into the ventricles causes the semilunar valves to close. The closing of AV valves, followed by the closing of the semilunar valves, produces the characteristic "lub-dup" sounds of the heart.
Hydrostatic pressure created by the heart forces blood to move through the arteries
what happens to pressure when blood reaches capillaries?
As blood reaches the capillaries, however, blood pressure drops dramatically and approaches zero in the venules.
how blood continues moving through veins?
Blood continues to move through the veins, not because of the contractions of the heart, but because of the movements of adjacent skeletal muscles which squeeze the blood vessels. Blood moves in the direction of the heart because valves in the veins prevent backflow.
how wastes and excess intersitial fluid gets back to circulatory system?
Wastes and excess interstitial fluids enter the circulatory system when they diffuse into capillaries. However, not all of the interstitial fluids enter the capillaries. Instead, some interstitial fluids and wastes are returned to the circulatory system by way of the lymphatic system, a second network of capillaries and veins
fluid in lymphatic veins is called_
how lymph moves?
moves slowly through lymphatic vessels by the contraction of adjacent muscles. Valves in the lymphatic veins prevent backflow.
where lymph returns to circulatory system?
Lymph returns to the blood circulatory system through two ducts located in the shoulder region.
besides returning interstitial fluid to circulatory system, what is another function of lymph system?
In addition to returning fluids to the circulatory system, the lymphatic system functions as a filter. Lymph nodes, enlarged bodies throughout the lymphatic system, act as cleaning filters and as immune response centers that defend against infection
Four components of blood?
red blood cells or erythrocytes
white blood cells or leukocytes
erythrocytes function and structure
Red blood cells, or erythrocytes, transport oxygen (attached to hemoglobin) and catalyze the conversion of CO2 and H2O to H2CO3. Mature red blood cells lack a nucleus, thereby maximizing hemoglobin content and thus their ability to transport O2.
white blood cells role
White blood cells, or leukocytes, consist of five major groups of disease-fighting cells that defend the body against infection.
The five classes of leukocytes are and what is their respective abundances?
neutrophils (40% - 75%)
eosinophils (1% - 6%)
basophils (less than 1%)
Granulocytes have visible granules or grains inside the cells that have different cell functions. Types of granulocytes include basophils, neutrophils, and eosinophils.
Agranulocytes are free of visible grains under the microscope and include lymphocytes and monocytes.
what is the most common leukocyte?
-first responders to sites of inflammation
-attracted to cytokines and in turn attract additional white blood cells once they arrive at the site of tissue damage
-can phagocytize bacteria
-elevated during inflammation
responsible for allergic and asthmatic responses
-large amounts of eosinophils indicate an allergic response or parasitic infection
-related to mast cells are similarly involved in allergic responses and parasite infections and often are responsible for the release of histamine, which stimulates blood vessels dilation
large immune cells that can differentiate into macrophages and dendritic cells
-Macrophage: their main role is to phagotize dead cells and pathogens
-if pathogen is ingested, its antigens are then presented on the surface of the macrophage to simulate other immune cells to mount a specific immune response to the invading pathogen. secrete cytokines
-dendritic cells are found in areas of the contact with external environment is more common (skin, intestine, and mucous membranes). They are more focused on processing antigens and presenting them to other immune cells and therefore are an important link to innate and adaptive immune systems
Two types of lymphoctes
produces antigen-specific antibodies
Helper T (CD4+) cells activate other immune cells
Cytotoxic T (CD8+) cells and natural killer T (NKT) cells destroy cells marked for destruction
Memory T cells remain after an infection so a response can be mounted more quickly if infected again
which protein activates the specific immunity of T cells?
If infection with an organism that display this antigen occurs, the antigen form the pathogen will be presented by a major histocompatibility protein complex (MHC) on the surface of an antigen-presenting cell, indicating that the corresponding T-cell should perform its function
What cells respond to MHC I?
Cytotoxic T cells (MHC I comes from cells infected with viruss or developing tumors and signal Tc to destroy those cells)
Who respond to MHC II?
T helper cells recognize and respond to antigens presented by MHC II complexes, which will release cytokines to simulate the immune response
why T cells are called like this?
They develop in bone marrow, but travel via bloodstream to Thymus where they mature (reason of the name). Once mature, they are released to lymph
B lymphocytes, like T cells, can also form _
Platelets are cell fragments that are involved in blood clotting. Platelets release factors that are involved in the conversion of the major clotting agent, fibrinogen, into its active form, fibrin. Threads of fibrin protein form a network that stops blood flow.
Plasma is the liquid portion of the blood that contains various dissolved substances.
blood clothing is an example of what kind of feedback mechanism?
brief description of the sequence of events
1. platelets adhere to the walls of the damaged blood vessels and release various substances that initiate a cascade of reactions, some of which attract additional platelets
2. additional platelets arrive that, in turn, release substances that attract still more platelets (positive feedback)
3. fibrinogen, dissolved in the blood, is converted into its active and solid form, fibrin
4. threads of fibrin protein bind to platelets together to form a network that stops blood flow
5. platelets contract, pulling fibrin fibers together to tighten the plug
main overall function of excretory systems?
help maintain homeostasis in organisms by regulating water balance and by removing harmful substances
Osmoregulation is the absorption and excretion of water and dissolved substances (solutes) so that proper water balance (and osmotic pressure) is maintained between the organism and its surroundings
two examples of osmoregulation
fresh water fish
.The body of a marine fish is hypoosmotic with its environment—that is, it is less salty than the surrounding water. Thus, water is constantly lost by osmosis. In order to maintain their proper internal environment, marine fish constantly drink, rarely urinate, and secrete accumulated salts (that they acquire when they drink) out through their gills.
fresh water fish
The body of a fresh water fish is hyperosmotic, or saltier than the surrounding water. Thus, water constantly diffuses into the fish. In response, fresh water fish rarely drink, constantly urinate, and absorb salts (that they lose in their urine) through their gills.
what are some toxic substances removed from blood?
by-products of cellular metabolism, such as nitrogen products of protein breakdown
Various excretory mechanisms have evolved in animals for the purpose of osmoregulation and for the removal of toxic substances (5).
1. contractile vacuole
2. flame cells (protonephridia)
3. nephridia (metanephridia)
4. malpighian tubules
Contractile vacuoles are found in the cytoplasm of various protists, such as paramecia and amoebas. These vacuoles accumulate water, merge with the plasma membrane, and release the water to the environment.
Flame cells (protonephridia) are found in various Platyhelminthes, such as planaria. The flame cells are distributed along a branched tube system that permeates the flatworm. Body fluids are filtered across the flame cells, whose internal cilia move the fluids through the tube system. Wastes (water and salts) are excreted from the tube system through pores that exit the body.
Nephridia(or metanephridia) occur in pairs within each segment of most annelids, such as earthworms. Interstitial fluids enter a nephridium through a ciliated opening called a nephrostome. Fluids are concentrated as they pass through the collecting tubule due to selective secretion of materials into the surrounding coelomic fluid. Blood capillaries that surround the tubule reabsorb the secreted materials. At the end of the collecting tubule, the concentrated waste materials are excreted through an excretory pore. Nephridia exemplify a tube-type excretory system, where body fluids are selectively filtered as they pass through the tube. Materials to be retained are secreted back into the body fluids, while concentrated wastes continue through the tube to be excreted at the far end.
Malpighian tubules occur in many arthropods, such as terrestrial insects. Tubes attached to the midsection of the digestive tract of insects (midgut) collect body fluids from the hemolymph that bathe the cells. The fluids, which include both nitrogen wastes and materials to be retained (salts and water), are deposited into the midgut. As the fluids pass through the hindgut of the insect (along with digested food), materials to be retained pass back out though the walls of the digestive tract. Wastes continue in the tract and are excreted through the anus.
From kidney where go?
The vertebrate kidney consists of about a million individual filtering tubes called nephrons.Two kidneys produce waste fluids, or urine, which pass through ureters to the bladder for temporary storage. From the bladder, the urine is excreted through the urethra
individual nephrons consists of
a tube and closely associated blood vessels
position of nephron
The nephron is strategically positioned in the kidney so that the tube winds from the outer portion of the kidney, the cortex, down through the medulla, then back up into the cortex, then back down through the medulla, draining into the center of the kidney, the renal pelvis.
parts of nephron
The nephron tube begins with a bulb-shaped body at one end, the Bowman's capsule.A branch of the renal artery (the afferent arteriole) enters into the Bowman's capsule, branches to form a dense ball of capillaries called the glomerulus, and then exits the capsule (efferent arteriole).
The convoluted tubule is a winding tube that begins with the proximal convoluted tubule at the Bowman's capsule and ends with the distal convoluted tubule where it joins with the collecting duct.The middle of the tubule, called the loop of Henle, is shaped like a hairpin and consists of a descending and ascending limb.
what is around convoluted tubule?
Surrounding the tubule is a dense network of capillaries that originate from branches of the efferent arteriole that exited the glomerulus. These capillaries merge into the renal vein as they exit the nephron. The blood flow through the nephron, then, actually passes through two capillary beds, the glomerulus and the capillary network surrounding the tubule.
The distal convoluted tube empties into the collecting duct which descends in the same direction as the descending limb toward the center of the kidney. A single collecting duct is shared by numerous nephrons and empties into the renal pelvis, which, in turn, drains into the ureter.
3 processes of operations of human nephron
When blood enters the glomerulus, pressure forces water and solutes through the capillary walls into the Bowman's capsule. Solutes include glucose, salts, vitamins, nitrogen wastes, and any other substances small enough to pass through the capillary walls. Larger substances, such as red blood cells and proteins, remain in the capillaries. The material that enters the Bowman's capsule, or filtrate, flows into the convoluted tubule.
As the filtrate passes through the proximal tubule and, later, through the distal tubule, additional material from the interstitial fluids joins the filtrate. This added material, which originates from the capillary network surrounding the nephron, is selectively secreted into the convoluted tubule by both passive and active transport mechanisms.
As the filtrate moves down the loop of Henle, it becomes more concentrated due to passive flow of H2O out of the tube. As the filtrate moves up the loop of Henle, it becomes more dilute due to passive and active transport of salts out of the tubule. At the end of the loop of Henle, then, the filtrate is not more concentrated. Rather, the interstitial fluids surrounding the nephron are more concentrated with salts. Next, the filtrate descends through the collecting duct toward the renal pelvis. As it passes through the salts concentrated in the interstitial fluids, water passively moves out of the collecting duct and into the interstitial fluids. When the filtrate drains into the renal pelvis, it is concentrated urine.
ways to loosing water in the body?
-digestive system struggles with a bacteria infection (diarrhea)
-eat very salt foods
what two hormones influence osmoregulation?
-They both regulate the concentration of salts in urine
-antidiuretic hormone (ADH)
Antidiuretic hormone(ADH) or vasopressin increases the reabsorption of water by the body and increases the concentration of salts in the urine. It does this by increasing the permeability of the collecting duct to water.As a result, urine becomes more concentrated as water diffuses out of the collecting duct as the filtrate descends into the renal pelvis.
-secreted by posterior pituitary of hypothalamus in response to elevated osmolarity (solute concentration) in the blood (low blood pressure)
-desired effect: increase blood pressure
Way to remember: diuretic makes you urinate more, so this hormone has opposite effect
Aldosterone increases both the reabsorption of water and the reabsorption of Na+. It does this by increasing the permeability of the distal convoluted tubule and collecting duct to Na+.As a result, more Na+ diffuses out of this tubule and duct. Since the Na+ increases the salt concentration outside the tubule, water passively follows.
-produced in the cortex of adrenal gland (above kidneys)
-increase blood volume
what is a major waste product in animals? source?
When amino acids and nucleic acids are broken down, they release toxic ammonia (NH3).
mechanisms used to get rid of toxic ammonia (NH3)
1. Aquatic animals excrete NH3 (or NH4+) directly into the surrounding water.
2. Mammals convert NH3 to urea in their livers. Urea is significantly less toxic than NH3 and thus requires less water to excrete in the urine.
3. Birds, insects, and many reptiles convert urea to uric acid. Since uric acid is mostly insoluble in water, it precipitates and forms a solid. This allows considerable water conservation by permitting the excretion of nitrogen waste as a solid. In birds, the precipitation also allows the nitrogen wastes to be securely isolated in a special sac in the egg (the allantois), apart from the vulnerable developing embryo.
digestion in a cell
In an individual cell, digestion is accomplished by intracellular digestion when a lysosome containing digestive enzymes merges with a food vacuole
lipids or fats are broken down into
glycerol and 3 fatty acids
what enzyme acts in the mouth?
secreted into the mouth by the salivary glands, begins the breakdown of starch into maltose (a disaccharide made of two glucoses).
why we chew?
Chewing reduces the size of food particles, thereby increasing the surface area upon which amylase and subsequent enzymes can operate. Food is shaped into a ball, or bolus, and then swallowed.
When food is swallowed and passed into the throat, or pharynx, a flap of tissue, the epiglottis, blocks the trachea so that solid and liquid material enter only the esophagus.
Food moves through the esophagus, a tube leading to the stomach, by muscular contractions called peristalsis.
stomach what secretes?
secretes a gastric juice, mixture of digestive enzymes and HCl
functions of stomach
storage function of stomach
Because of its accordionlike folds, the wall of the stomach can expand to store two to four liters of material.
mixing function of stomach
The stomach mixes the food with water and gastric juice to produce a creamy medium called chyme.
physical breakdown (include function of HCl)
Muscles churn the contents of the stomach, physically breaking food down into smaller particles. In addition, HCl from the gastric juice denatures (or unfolds) proteins and loosens the cementing substances between cells of the food. Also, the HCl kills most bacteria that may accompany the food.
Proteins are chemically broken down (digested) by the enzyme pepsin. Stomach cells producing pepsin are protected from self-digestion because they produce and secrete an inactive form, pepsinogen. Pepsinogen is activated into pepsin by HCl, which is produced by other stomach cells. Thus, only after pepsinogen is secreted into the stomach cavity can protein digestion begin. Once protein digestion begins, the stomach is protected by a layer of mucus secreted by still other cells in the stomach lining
Failure of the mucus to protect the stomach can lead to lesions, or peptic ulcers. Long believed to be caused by stress, diet, or other factors, most ulcers are now known to be caused by bacteria and can be successfully treated with antibiotics.
controlled release function of stomach
Controlled release. Movement of chyme into the small intestine is regulated by a valve at the end of the stomach, the pyloric sphincter
parts of small intestine
(way to remember: DJ I)
how long duodenum is?
first 25 cm of small intestine
what happens in duodenum
continues the digestion of starches and proteins (which began in the mouth and stomach, respectively) as well as all remaining food types (including fats and nucleotides).
enzymes produced by small intestine involved in duodenum digestion
-.The wall of the small intestineis the source of various enzymes, including proteolytic enzymes (or proteases, enzymes that digest proteins, such as aminopeptidase), maltase and lactase (for the digestion of disaccharides), and phosphatases (for the digestion of nucleotides).
enzymes produced by pancreas involved in duodenum digestion
.The pancreas produces various enzymes, including trypsin and chymotrypsin (proteases), lipase (digestion of fats), and pancreatic amylase (digestion of starch). These and other enzymes, packaged inan alkaline solution that serves to neutralize the HCl in the chyme, enter the duodenum through the pancreatic duct.
enzymes produced by liver involved in duodenum digestion. function of gall bladder
.The liver produces bile, which functions to emulsify fats. Emulsification is the breaking up of fat globules into smaller fat droplets, increasing the surface area upon which fat-digesting enzymes (lipase, for example) can operate. Since bile does not chemically change anything, it is not an enzyme. Bile is also alkaline, serving to help neutralize the HCl in the chyme. The bile is stored adjacent to the liver in the gallbladder and flows through the bile duct where it merges with the pancreatic duct.
what happens in the remainder of small intestine?
The remainder of the small intestine (nearly six meters) absorbs the breakdown products of food. It is characterized by villi and microvilli, fingerlike projections of the intestinal wall that increase its total absorptive surface area. Amino acids and sugars are absorbed into blood capillaries, while most of the fatty acids and glycerol are absorbed into the lymphatic system.
large intestine function
The main function of the large intestine, or colon, is the reabsorption of water to form solid waste, or feces.
rectum (where go after this?)
Feces are stored at the end of the large intestine, in the rectum, and excreted through the anus.
who lives in large intestines?
Various harmless bacteria live in the large intestine, including some that produce vitamin K, which is absorbed through the intestinal wall.
At the beginning of the large intestine, there is a short branch to a dead-end pouch which bears a fingerlike projection called the appendix. Other than a possible role in the immune response, the appendix is significant only when it becomes inflamed, causing appendicitis
cecum (how different in herbivores?)
In herbivores, the dead-end pouch is much enlarged and is called the cecum. It harbors bacteria that help in the digestion of cellulose.
hormones involved in digestive process?
is produced by cells in the stomach lining when food reaches the stomach or when the nervous system, through smell or sight, senses the availability of food. Gastrin enters the blood stream and stimulates other cells of the stomach to produce gastric juices.
Secretin is produced by the cells lining the duodenum when food enters. Secretin stimulates the pancreas to produce bicarbonate which, when deposited into the small intestine, neutralizes the acidity of the chyme.
Cholecystokinin is produced by the small intestine in response to the presence of fats. Cholecystokinin stimulates the gallbladder to release bile and the pancreas to release its enzymes.
what are the parts of the neuron?
basic structural unit of nervous system
nerve cell or neuron
The dendrite is typically a short, abundantly branched, slender extension of the cell body that receives stimuli.
The axon is typically a long, slender extension of the cell body that sends nerve impulses.
The types of neurons
Sensory neurons (or afferent neurons) receive the initial stimulus. For example, sensory neurons embedded in the retina of the eye are stimulated by light, while certain sensory neurons in the hand are stimulated by touch.
Motor neurons(or efferent neurons) stimulate effectors,target cells that produce some kind of response. For example, efferent neurons may stimulate muscles (creating a movement to maintain balance or to avoid pain, for example), sweat glands (to cool the body), or cells in the stomach (to secrete gastrin in response to the smell of food, perhaps).
Association neurons (or interneuron neurons) are located in the spinal cord or brain and receive impulses from sensory neurons or send impulses to motor neurons. Interneurons are integrators, evaluating impulses for appropriate responses.
why nerve impulses occur?
The transmission of a nerve impulse along a neuron from one end to the other occurs as a result of chemical changes across the membrane of the neuron
explain normal state of nerve cell
The membrane of an unstimulated neuron is polarized, that is, there is a difference in electrical charge between the outside and inside of the membrane. In particular, the inside is negative with respect to the outside. Polarization is established by maintaining an excess of sodium ions (Na+) on the outside and an excess of potassium ions (K+) on the inside. A certain amount of Na+ and K+ is always leaking across the membrane, but Na+/K+ pumps in the membrane actively restore the ions to the appropriate side. Other ions, such as large, negatively charged proteins and nucleic acids, reside inside the cell. It is these large, negatively charged ions that contribute to the overall negative charge on the inside of the cell membrane compared to the outside.
study figure 12-3
pg 194 or 203/363
General events that characterize the transmission of a nerve impulse
1. Resting potential and graded potentials
2. Depolarization and action potential
5. Refractory period
The resting potential describes the unstimulated, polarized state of a neuron (at about -70 millivolts).
what is depolarization?
when a stimulus arriving at the plasma membrane of a neuron can open or close a gated ion channel that causes an ion channel activated, so the inside of the cell becomes positive (-60mV for example)
what is hyperpolarized?
when a stimulus arriving at the plasma membrane of a neuron can open or close a gated ion channel that causes an ion channel activated, so the inside of the cell becomes more negative (-80mV for example)
weak stimuli that causes small variations in the membrane potential.
-Because ion leakage across the membrane reestablishes the resting potential, a graded potential is a local event, with the magnitude of the stimulus decaying as the stimulus flows along the neuron
depolarization and action potential
In response to a stimulus, voltage gated ion channels in the membrane suddenly open and permit the Na+ on the outside to rush into the cell.As the positively charged Na+ rush in, the charge on the cell membrane becomes depolarized, or more positive on the inside (from -70 toward 0 millivolts). If the stimulus is strong enough—that is, if it is above a certain threshold level—more Na+ gates open, increasing the inflow of Na+ even more, causing an action potential, or complete depolarization (about +30 millivolts). This, in turn, stimulates neighboring Na+ gates, further down the neuron, to open. In this manner, the action potential travels down the length of the neuron as opened Na+ gates stimulate neighboring Na+ gates to open
the action potential is an _event. explain
The action potential is an all-or-nothing event: when the stimulus fails to produce a depolarization that exceeds the threshold value, no action potential results, but when threshold potential is exceeded, complete depolarization occurs.
what happens once action potential is attained?
Na+ channels become inactivated (Na+ flow stops and the channel cannot respond to new stimuli), but neighboring Na+ channels are activated (positive feedback mechanism)
-because Na+ channels become inactivated by action potential, the nerve impulse can travel only in the forward direction
In response to the inflow of Na+, another kind of voltage gated channel opens, this time allowing the K+ on the inside to rush out of the cell. The movement of K+ out of the cell causes repolarization by restoring the original membrane polarization. Unlike the resting potential, however, the K+ are on the outside and the Na+ are on the inside. Soon after the K+ gates open, the Na+ gates close.
By the time the K+ gated channels close, more K+ have moved out of the cell than is actually necessary to establish the original polarized potential. Thus, the membrane becomes hyperpolarized (about -80 millivolts).
With the passage of the action potential, the cell membrane is in an unusual state of affairs. The membrane is polarized, but the Na+ and K+ are on the wrong sides of the membrane. During this refractory period, the neuron will not respond to a new stimulus. To reestablish the original distribution of these ions, the Na+ and K+ are returned to their resting potential location by Na+/K+ pumps (3 Na+ out and 2 K+ in) in the cell membrane. Once these ions are completely returned to their resting potential location, the neuron is ready for another stimulus.
Some neurons possess a myelin sheath, which consists of a series of Schwann cells that encircle the axon
function of schwann cells
The Schwann cells act as insulators and are separated by gaps of unsheathed axon called nodes of Ranvier.
Instead of traveling continuously down the axon, the action potential jumps from node to node (saltatory conduction), thereby speeding the propagation of the impulse.
In PNS, which cells produce myelin sheaths?
In CNS, which produces myelin sheaths?
difference between oligodendrocytes and schwann cells
Schwann cells myelinate axons in the peripheral nervous system, while Oligodendrocytes myelinate axons in the central nervous system. Another interesting difference is that when Schwann cells myelinate, their cell body's actually wrap around the axon. Oligodendrocytes secrete the myelin sheaths around the axons
In electrical synapses, the action potential travels along the membranes of gap junctions, small tubes of cytoplasm that connect adjacent cells. (like in heart)
In most animals, most synaptic clefts are _
traversed by chemicals
A synapse, or synaptic cleft, is the gap that separates adjacent neurons.
explain how transmit nerve impulse through synaptic cleft by using chemicals
1. calcium (Ca^2+) gates open
2. Synaptic vesicles release neurotransmitter
3. neurotransmitter binds with postsynaptic receptors
4. The postsynaptic membrane is excited or inhibited
5. The neurotransmitter is degraded and recycled
explain calcium gates open
Calcium (Ca2+) gates open.When an action potential reaches the end of an axon, the depolarization of the membrane causes gated channels to open and allow Ca2+ to enter the cell.
explain synaptic vesicles release neurotransmitter
Synaptic vesicles release neurotransmitter.The influx of Ca2+ into the terminal end of the axon causes synaptic vesicles to merge with the presynaptic membrane, releasing molecules of a chemical called a neurotransmitter into the synaptic cleft.
Neurotransmitter binds with postsynaptic receptors
The neurotransmitter diffuses across the synaptic cleft and binds with proteins on the postsynaptic membrane. Different proteins are receptors for different neurotransmitters.
Depending upon the kind of _and the kind of membrane receptors, there are two possible outcomes for postsynaptic membrane
explain when postsynaptic membrane is excited
If Na+ gates open, the membrane becomes depolarized and results in an excitatory postsynaptic potential (EPSP). If the threshold potential is exceeded, an action potential is generated.
explain when the postsynaptic membrane is inhibited
If K+ gates open, the membrane becomes more polarized (hyperpolarized) and results in an inhibitory postsynaptic potential (IPSP). As a result, it becomes more difficult to generate an action potential on this membrane.
explain neurotransmitter is degraded and recycled
After the neurotransmitter binds to the postsynaptic membrane receptors, it is broken down by enzymes in the synaptic cleft. For example, a common neurotransmitter, acetylcholine, is broken down by cholinesterase. Degraded neurotransmitters are recycled by the presynaptic cell.
gamma aminobutyric acid (GABA)
Acetylcholine is commonly secreted at neuromuscular junctions, the gaps between motor neurons and muscle cells, where it stimulates muscles to contract. At other kinds of junctions, it typically produces an inhibitory postsynaptic potential.
which neurotransmitters are secreted between neurons of central nervous system and what are they made of?
Epinephrine, norepinephrine, dopamine, and serotonin are derived from amino acids and are mostly secreted between neurons of the central nervous system.
function of GABA
Gamma aminobutyric acid (GABA) is usually an inhibitory neurotransmitter among neurons in the brain.
(way to remember: gueba!)
parts of central nervous system
consists of the brain and spinal cord
peripheral nervous system
The peripheral nervous system consists of sensory neurons that transmit impulses to the CNS and motor neurons that transmit impulses from the CNS to effectors
two parts of motor neuron system
-The somatic nervous system directs the contraction of skeletal muscles.
-The autonomic nervous system controls the activities of organs and various involuntary muscles, such as cardiac and smooth muscles.
two divisions of autonomic nervous system
sympathetic nervous system
parasympathetic nervous system
sympathetic nervous system
The sympathetic nervous system is involved in the stimulation of activities that prepare the body for action, such as increasing the heart rate, increasing the release of sugar from the liver into the blood, and other activities generally considered as fight-or-flight responses (responses that serve to fight off or retreat from danger).
parasympathetic nervous system
The parasympathetic nervous system activates tranquil functions, such as stimulating the secretion of saliva or digestive enzymes into the stomach.
how sympathetic and parasympathetic work with respect to each other?
Generally, both sympathetic and parasympathetic systems target the same organs but often work antagonistically. For example, the sympathetic system accelerates the cardiac cycle, while the parasympathetic slows it down. Each system is stimulated as is appropriate to maintain homeostasis.
A reflex arc is a rapid, involuntary response to a stimulus. It consists of two or three neurons—a sensory and motor neuron and, in some reflex arcs, an interneuron. Although neurons may transmit information about the reflex response to the brain, the brain does not actually integrate the sensory and motor activities.
three bulges found in the vertebrate brain that appears early in embryonic development, which subsequently leads to the various parts of adult brain
forebrain forms what structures?
-cerebrum (left and right hemispheres)
-hypothalumus and pituitary gland
left cerebral hemisphere is in charge of _
language, math, and logical skills
-right side of the body
right cerebellum is in charge of what?
-nonverbal thinking and image recognition
-left side of body
Forms in and around the cerebrum (though not technically derived from the forebrain). It is a network of neurons that are associated with emotions (way to remember: kill the lamb and cry)
forms upper portion of brainstem. The brainstem connects the spinal cord to cerebrum (midbrain, pons, medulla oblongata)
-contributes to the formation of cerebellum
evalutes body movements and coordinates those movements (balance) with sensory stimuli coming from sight and hearing. Eye-hand coordination is established by cerebellum
child birth, which is an important example of positive feedback system
examples of positive feedback?
-child birth by oxytocin
-milk production by prolactin
-During sexual intercourse, increasing sensitivity and stimulation until orgasm is reached
energy requirements increase depending: energy per unit weight and size of organism
-larger organisms need more energy than smaller organisms
-however, the amount of energy required per unit weight decreases as size increases because smaller animals have higher surface area to volume that increases heat lost (more are for heat to escape) ad need to spend more energy to thermoregulate. Another reason, efficiency in numbers. The cost of servicing a single cell may decrease as the number of cells to service increases
cells of skeletal muscle
plasma membrane of muscle cell
how sarcolemma is different from plasma membrane?
The sarcolemma,or plasma membrane of the muscle cell, is highly invaginated by transverse tubules(or T tubules) that permeate the cell.
The sarcoplasm, or cytoplasm of the muscle cell
what organelle is found in the sarcoplasm of muscle cells that is not found in other cells?
The sarcoplasm, or cytoplasm of the muscle cell, contains calcium-storing sarcoplasmic reticulum, the specialized endoplasmic reticulum of a muscle cell.
how many nucleus skeletal muscles have?
Skeletal muscle cells are multinucleate. The nuclei lie along the periphery of the cell, forming swellings visible through the sarcolemma.
what is the main component of the volume of muscle cells?
Nearly the entire volume of the muscle cell is filled with numerous, long myofibrils. Myofibrils consist of two types of filaments
two types of filaments that form myofibrils
thin filament or actin
thick filament or myosin
Thin filaments consist of two strands of the globular protein actin arranged in a double helix. Along the length of the helix are troponin and tropomyosin molecules that cover special binding sites on the actin.
what troponin vs. tropomyosin do?
troponin binds to Ca2+ and tropomyosin is taking the place myosin should have so it covers the active site where myosin binds to actin
Thickfilaments consist of groups of the filamentous protein myosin. Each myosin filament forms a protruding head at one end. An array of myosin filaments possesses protruding heads at numerous positions at both ends.
parts of sarcomere
defines boundaries of a single sarcomere and anchor the thin/actin filaments
Runs down the center of the sarcomere
is the region containing thin filaments only
H zone is the region containing myosin/thick filaments only
spans the entire length of thick filaments (myosin that are found in the middle of sarcomere) and any overlapping portions of the thin filaments (actin)
what happens to the zones and lines of sarcomeres during contraction?
-when muscles contract, the z lines move toward each other
-A bad is not reduced in size, whereas the H zone and I band are (reduced)
why skeletal muscles are striated?
Within a myofibril, actin and myosin filaments are parallel and arranged side by side. The overlapping filaments produce a repeating pattern that gives skeletal muscle a striated appearance. Each repeating unit of the pattern, called a sarcomere, is separated by a border, or Z-line, to which the actin filaments are attached. The myosin filaments, with their protruding heads, are located between the actin, unattached to the Z-line.
muscle contraction is described by the _
steps of sliding-filament mode
1. ATP binds to a myosin and forms ADP + Pi. When ATP binds to a myosin head, it is converted to ADP and Pi, which remain attached to the myosin head.
2. Ca2+ exposes the binding sites on the actin filaments: Ca2+ binds to the troponin molecule causing tropomyosin to expose positions on the actin filament for the attachment of myosin heads.
3. Cross bridges between myosin heads and actin filaments form: When attachment sites on the actin are exposed, the myosin heads bind to actin to form cross bridges.
4. ADP and Pi are released and sliding motion of actin results: The attachment of cross bridges between myosin and actin causes the release of ADP and Pi. This, in turn, causes a change in shape of the myosin head, which generates a sliding movement of the actin toward the center of the sarcomere. This pulls the two Z-lines together, effectively contracting the muscle fiber.
5. ATP causes the cross bridges to unbind: When a new ATP molecule attaches to the myosin head, the cross bridge between the actin and myosin breaks, returning the myosin head to its unattached position.
Without the addition of a new ATP molecule, the cross bridges remain attached to the actin filaments. This is why corpses are stiff (new ATP molecules are unavailable).
synaptic clefts found at muscles
Neurons form specialized synapses with muscles called neuromuscular junctions.
steps of muscle contraction stimulation at neuromuscular junctions
1. Action potential generates release of acetylcholine.When an action potential of a neuron reaches the neuromuscular junction, the neuron secretes the neurotransmitter acetylcholine (after releasing Ca2+ which cause the release of this neurotransmitter), which diffuses across the synaptic cleft.
2. Action potential is generated on sarcolemma and throughout the T-tubules. Receptors on the sarcolemma initiate a depolarization event and action potential. The action potential travels along the sarcolemma throughout the transverse system of tubules.
3. Sarcoplasmic reticulum releases Ca2+.As a result of the action potential throughout the transverse system of tubules, the sarcoplasmic reticulum releases Ca2+.
4. Myosin cross bridges form.The Ca2+ released by the sarcoplasmic reticulum binds to troponin molecules on the actin helix, prompting tropomyosin molecules to expose binding sites for myosin cross-bridge formation. If ATP is available, muscle contraction begins.
Smooth muscle lines the walls of blood vessels and the digestive tract where it serves to advance the movement of substances. Due to its arrangement of actin and myosin filaments, smooth muscle does not have the striated appearance of skeletal muscle. In addition, the sarcolemma does not form a system of transverse tubules, and as a result, contraction is controlled and relatively slow, properties appropriate for its function
Cardiac muscle is responsible for the rhythmic contractions of the heart. Although striated, cardiac muscle differs from skeletal muscle in that it is highly branched with cells connected by gap junctions. In addition, cardiac muscle generates its own action potential, which spreads rapidly throughout muscle tissue by electrical synapses across the gap junctions.
three levels of defense (specific vs. nonspecific)
first and second level of defense are nonspecific and third level of defense is specific
what is part of first line of difense
The skin and mucous membranes provide a nonspecific first line of defense against invaders entering through the skin or through openings into the body. A nonspecific defense is not specialized for a particular invader. Rather, it is a general defense against all kinds of pathogens
5 structures involved in first line of defense
antimicrobial proteins (lysozymes)
Skin is a physical and hostile barrier covered with oily and acidic (pH from 3 to 5) secretions from sweat glands.
Antimicrobial proteins (such as lysozyme, which breaks down the cell walls of bacteria) are contained in saliva, tears, and other secretions found on mucous membranes
Cilia that line the lungs serve to sweep invaders out of the lungs.
Gastric juice of the stomach kills most microbes.
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