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79 terms

Biology

Topic 9. Definitions thanks to Pearson Education.
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Tissue
Group of cells with common structure and function
Organ
Functional units of tissues
Organ system
Groups of organs that work together
Epithelial tissue
Sheets of tightly packed cells that cover the body, line the organs, and act as a protective barrier
Connective tissue
Supports and binds other tissues, and consist of scattered cells within an extracellular matrix
Muscle tissue
Responsible for nearly all types of body movement, and made up of the proteins actin and myosin
Nervous tissue
Divided into functional units called nerve cells, which senses stimuli and transmits signals from one part of the body to another
Homeostasis
Animals maintain a relatively constant internal environment, even when the external environment changes significantly
Set point
The "target" in homeostasis. Sensors detect stimuli below or above this point and trigger a physiological response to help the body return to the set point
Negative feedback systems
Animal responds to a stimulus in a way that reduces the stimulus (e.g. after exercise, the body temperature rises, so sweating cools the body)
Positive feedback systems
Change in a variable triggers mechanisms that amplify rather than reverse the change (e.g. during childbirth, pressure of baby's head stimulates greater contractions, which cause greater pressure, etc)
Thermoregulation
How animals maintain their internal temperature
Endotherms
Warmed by heat generated by metabolism, includes mammals and birds
Ectotherms
Gain heat from external sources, includes, fish, invertebrates, amphibians, and reptiles
Countercurrent exchange
Antiparallel arrangement of blood vessels result in warm blood from the core heating cold blood from the extremities
Essential nutrients
Minerals and preassembled organic molecules that an animal cannot produce from raw materials
Essential amino acids
About half of the 20 amino acids, cannot be obtained from food
Essential fatty acids
Used to make cell membranes, must be ingested
Vitamins
Organic molecules that must be ingested
Minerals
Inorganic nutrients that must be ingested
Ingestion
Act of taking in food
Digestion
Breakdown of food into small molecules capable of being absorbed by the cells of the body
Absorption
Stage of food processing where the body's cells take up small molecules such as amino acids and simple sugars from the digestive tract
Elimination
Passing of undigested material from digestive tract
Intracellular digestion
Occurs within a cell enclosed by a protective membrane, technique used by sponges
Extracellular digestion
Food is broken down outside cells, allows animals to devour larger food sources, technique used by most animals
Gastrovascular cavity
One chamber for digestion to take place in. Animals with this have one opening from which food enters and waste is eliminated.
Alimentary canals
Complete digestive tracts
Sphincters
Muscular, ringlike valves that regulate passage of material between digestive compartments
Peristalsis
Rhythmic waves of contraction by smooth muscle in the walls of the alimentary canal
Oral cavity
Mouth, where digestion begins
Amylase
Enzyme in saliva that begins hydrolyzing starch and glycogen into smaller polysaccharides and the disaccharide maltose
Bolus
What food is shaped into during chewing
Pharynx
Junction that opens to the esophagus and trachea
Epiglottis
Cartilage flap that covers the trachea and prevents food from entering the airway
Esophagus
Moves food down the pharynx down to the stomach through peristalsis
Gastric juice
Secreted by the stomach to begin digestion, includes hydrochloric acid and pepsin
Hydrochloric acid
Breaks down ECM of meat and plant materials, and kills bacteria. Has a pH of about 2
Pepsin
Hydrolyzes proteins into smaller polypeptides. Secreted as pepsinogen so the cells that produce it aren't digested themselves
Mucus
Protects stomach lining
Acid chyme
Result of stomach digestion
Pyloric sphincter
Moves acid chyme from stomach to small intestine
Duodeum
Major site of chemical digestion where acid chyme mixes with pancreatic and liver secretions
Bicarbonate fluid
Buffer, released from pancreas
Bile
Made in liver and stored in gall bladder, emulsifies fats in the duodenum
Carbohydrate digestion
Begins with breakdown of starch and glycogen by salivary amylase. In the small intestine, pancreatic amylases continue to break them down into the disaccharide maltose. This is broken into its monomers at the wall of the duodenum epithelium
Protein digestion
Begins with breakdown of proteins by pepsin in the stomach. In the duodenum, trypsin and cymotrypsin break the polypeptides into smaller chains. Dipeptidases, carboxypeptidase, and aminopeptidase break apart polypeptides into amino acids
Nucleic acid digestion
Starts with hydrolysis of DNA and RNA into nucleotides. Then they are broken into nitrogenous bases, sugar, and phosphate groups. Most enzymes involved are from the pancreas
Fats
Starts in the small intestine when bile coats the fat droplets. Then lipase from the pancreas hydrolyzes the droplets
Villi
Folds in the epithelial lining of the small intestine that increase surface area
Microvilli
Projections of villi
Lacteal
In the villi, a lymph vessel that absorbs small fatty acids
Hepatic portal vessel
Destination of capillaries in villi that drain away nutrients--the hepatic portal vessel takes the nutrients to the liver for distribution
Gastrin
Stomach hormone that increases gastric juice production
Enterogastrone
Hormone produced by the duodenum in the presence of fats to slow peristalsis and allow more time for fat digestion
Secretin and cholecystokinin
Hormone secreted by walls of the duodenum and increase the flow of digestive juices from pancreas and gall bladder
Colon
Large intestine
Cecum
Where small intestine connects with large intestine, has an extension called the appendix
Dentition
Correlates with diet
Open circulatory system
Blood bathes the organs directly, found in mollusks and arthropods
Hemolymph
Combined blood and lymph in an open circulatory system
Sinuses
Where hemolymph is pumped
Closed circulatory systems
Blood is contained in vessels and pumped around the body
Arteries
Carry blood away from the heart
Arterioles
Small branches of arteries
Capillaries
Composed of only a single layer of cells, the endothelium. Where diffusion occurs
Veins
Carry the blood back to the heart
Atria
Receive blood
Ventricles
Pump blood
Systole
Contraction phase
Diastole
Relaxation phase
Heart rate
Contractions per minute
Stroke volume
Amount of blood pumped by left ventricle per contraction
Atrioventricular (AV) valve
Prevents backflow of blood into the atria
Semilunar valves
Prevents backflow of blood into the ventricles
Sinoatrial (SA) node
Pacemaker, located in the upper wall of right atrium
AV node
Delays impulses from SA node to allow the atria to completely empty before the ventricles contract, located in the lower wall of right atrium
Blood pressure
Systolic pressure/Diastolic pressure (e.g. 120/70)
Lymphatic system
Returns lost fluid and proteins to the blood in the form of lympth