81 terms

AP BIO ch 42

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Gaining O2 and nutrients while shedding CO2 and other waste products occurs with every cell in the body. However, diffusion is rapid only over small distances. Describe the 2 general solutions to this problem.
a body size and shape that keeps many or all cells in direct contact with the environment and a circulatory system that moves fluid between each cells immediate surroundings and the tissues where exchange with the environment occurs
what are the 3 basic components of a circulatory system?
circulatory fluid (blood or lymph), a set of interconnecting tubes (vessels), a muscular pump (heart)
a circulatory system in which the circulatory fluid bathes in organs directly
open circulatory system
a circulatory system in which blood is confined to vessels and is distinct/separated from the interstitial fluid
closed circulatory system
the movement of molecules from high concentration to low concentration
diffusion
the body fluid that bathes tissued (blood and interstitial fluid)
hemolymph
what does an artery do
carries oxygenated blood AWAY from the heart to the organs
what is an arteriole
small vessels that convey blood to the capillaries; carry blood away from arteries to the capillaries
what does a vein do
carries deoxygenated blood BACK TO the heart
what do a venule do
conveys blood between capillary bed and vein; bridge between capillaries and veins
what does a capillary do
allows exchange between blood and interstitial fluid; where has exchange occurs
what is the function of the atria
a chamber that received blood entering the heart; when blood comes back from veins; IN HEART
what is the function of the ventricles
chamber that pumps blood out of the heart; OUT HEART
in a circulatory system, exchange occurs in 2 general places. Blood goes out of the respiratory surface or to the organs and tissues of the body. At which type of blood vessels does exchange actually occur?
capillaries
why is a 4 chambered heart a key adaptation required for endothermy?
bc endotherms use about 1ox as much energy as ectotherms so circulatory systems need to deliver more fuel and O2 tot heir tissues; be able to put that much more blood; pump harder; get more volume of essential things in body
what is endothermy
heat by internal
explain why the 4 chambered heart of birds and mammals are considered an example of convergent evolution.
mammals and birds descended from different tetrapod ancestors and 4 chambered hearts evolved independently; 4 chamber heart needed to regulate the system
what is convergent evolution
come from different ancestors with the same problem so they evolve i the same way to develop the same adaptations
explain the cardiac cycle
one complete sequence of pumping and fulling; contractions create blood pressure
explain systole
the ventricular contraction phase; the stiffening of muscles to pump blood
explain diastole
the ventricular relaxation phase
explain cardiac output (the 2 factors that determine it)
rate of contraction is the heart rate (number of beats per minute) and the stroke volume (the amount of blood pumped by a ventricle in a single contraction)
what is the stroke volume
the amount of blood pumped by a ventricle in a single contraction
Heartbeat rhythm is maintained by electric impulses that are generated from modified cells found in the wall of the right atrium, called the sinoatrial (SA) node. what is the common name for the SA node?
pacemaker
what is the pacemaker
the sa node that sets the rate and timing at which cardiac muscles will contract
where is the pacemaker located
in the wall of the right atria where the superior vena cava enters the heart
how is blood pressure calculated
systole number/diastole number
Electrical impulses from the SA node cause the atria and are conducted to a relay station, the atrioventricular (AV) node. When an impulse is generated by the AV node, what contracts?
ventricles (perkinjie fibers)
what are perkinjie fibers
extensions of ventricles
how do sympathetic nerves affect the pacemaker
speeds up (increases) heart rate (more oxygen to the system like when you stand up or walk around)
how do parasympathetic nerves affect the pacemaker
slows down (decreases) the heart rate
why is it so important that the arteries are so much thicker than the veins
arteries have to accommodate the blood pumped at high pressure coming from the heart (more constricted vessels=higher blood pressure); the elastic recoil of the arteries maintain the blood pressure
how do structure and function correlate in the capillaries
the structural organization facilitates the exchange between the blood and interstitial fluid; the walls are very thin which helps the facilitation; they're the only vessels that allows transmission of substances to occur
what anatomical feature of the veins maintains a unidirectional flow of flood toward the heart
(one way) valves (act like sphincters- prevent back flow of deoxygenated blood in the veins)
as blood vessel diameter decreases, blood velocity will ____
decrease bc there are so many capillaries so it slows the blood (an increase in area slows the blood down) (capillaries have a huge cross area section- 1 cm/sec thru them)
where do semilunar valves flow from and what do they do
ventricle to the lungs or body; contract and prevent back flow of blood
where do atria ventricular valves flow from and what do they do
atria to the ventricles; contract and prevent back flow of blood
why does blood slow as it moves from arteries to arterioles to capillaries? why is this important?
each artery conveys blood to so many capillaries that the total cross sectional area is much greater in capillary beds than in arteries or any other part of the circulatory system; 500x slower in capillaries than arteries and veins
changes in blood pressure as the heart contracts and relaxes can be felt, such as a gentle throb at the wrist or neck. what is this called
pulse (number of beats per minute) (the bulging of arteriole wall- the elastic recoil maintains blood pressure)
blood flows from areas of _____ pressure to ___ pressure
high to low (there is greater gas exchange bc slower blood flow)
how does vasoconstriction affect blood pressure
arteries narrow which increases blood pressure upstream in arteries (physical and emotional stress triggers hormonal responses that cause vasoconstriction)
if the blood pressure is reported as 110/80, what is the diastolic pressure
80
why does the presence of blood proteins tend to pull fluid back into the capillaries
proteins stay in the capillaries and cause a difference in pressure; blood cells are too big so they stay in the capillaries. the osmotic pressure is different between the capillary interior and interstitial fluid; they're too large to slip through or diffuse into the membranes of the endothelium cells
what are endothelium cells
cells that make up capillaries
what is lymph
colorless fluid in the lymphatic system
is lymph more like blood or interstitial fluid
interstitial fluid
we don't have a second heart to pump lymph. what keeps it moving along
lymph vessels have valves that prevent back flow. contractions help draw fluid into lymphatic vessels; skeletal muscle contractions
name 3 places you have lymph nodes
neck, armpits, groin
what are 2 function of lymph nodes
filtering lymph and housing cells that attack viruses and bacteria
blood separates into 2 components, a liquid matrix called ___ and the cellular elements
plasma
describe 3 ways in which the structure of an erythrocyte enhances its function, which is to transport oxygen.
human ones are thinner in the center than the edges which increases the surface area which increases the rate of diffusion
what is the role of hemoglobin
fills in the space from the lack of nuclei
an iron-containing protein that transports O2
hemoglobin
what is the name of the protein that actually forms a clot
fibrin
if a clot forms within a blood vessel and blocks the flow of blood, what is it called
thrombus
where are blood stem cells found
red marrow of bones (ribs, vertebrae, sternum, pelvis)
what is erythropoietin (EPO)
a hormone that stimulates erythrocyte production
what will stimulate erythropoietin production
kidneys
what causes the development of a plaque in atherosclerosis
accumulation of fatty deposits in the arteries harden
what are 3 known predictors of cardiovascular disease
smoking, lack of exercise, and a diet rich in animal fat
what is meant by the partial pressure of a gas
the pressure exerted by a particular gas in a mixture of gases
a gas always diffused from a region of ___ partial pressure to a region of __ partial pressure
higher to lower
there are several requirements for a respiratory surface. the first is that it must be moot. the second is that it must have a large surface area and be thin. what 4 organs satisfy these requirements
gills, trachea, lungs, skin
the exchange of a substance or heat between 2 fluids flowing in opposite directions (water and blood move in opposite directions)
countercurrent exchange
the difference in concentration in molecules across a distance
concentration gradient
what is the most common respiratory structure among terrestrial animals? what groups has this system
tracheal system- insects (most common bc most numerous) (trachea= largest tube that branches out into the rest of the body)
negative pressure breathing is an example of a ___ feedback system. why
negative bc the lungs expand to fill up so much until they can release and fill back up
where are the 2 breathing control centers located in the brain
medulla oblongata and the pons
what does the medulla oblongata do
establishes the breathing rhythm
what do the pons do
establish the berthing tempo
how does blood pH change as CO2 increases
increases metabolic activity decreases pH; Co2 reacts w water in cerebrospinal fluid and forms carbonic acid which drops the pH
what is a bicarbonate ion and how is it formed
HCO3-; formed from reaction of CO2 and water- it looses hydrogen ion from carbonic acid
what has greater effect on the rate of respiration, low levels of O2 or high levels of CO2
high levels of CO2 bc it is very toxic and it makes the medulla increase the depth and rate of breathing (O2 has little effect on the medulla)
where is the partial pressure of oxygen higher, in the alveoli or in the tissues
alveoli bc it moves from high to low (100mm of mercury in alveoli--> 40 mm of mercury in tissues)
what is the respiratory pigment in vertebrates
when proteins that O2 bound to circulate with blood or hemolymph
Hemoglobin is a protein with quaternary structure. how many subunits does it have? what is the role of iron?
4; each iron atom binds to a molecule of O2
as pH of the blood decreases, the affinity of hemoglobin for oxygen decreases, and oxygen is released from hemoglobin. what is this called
bohr shift
because of the effect of subunit cooperatively, a slight drop in Po2 causes an ____ in the amount of O2 the blood unloads
increase
where is carbonic anhydrase found? what is its role in CO2 transport?
water; forms H2CO3 which dissociated into H+ and HCO3-
what is myoglobin
an oxygen storing protein
why is fetal hemoglobin and adult hemoglobin different?
fetus has lower partial pressure per saturation bc O2 is coming from the mother to the fetus (saturation wise they're about the same); the difference in partial pressure allows it to move and reach infant
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