Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
72 Cards in this Set
- Front
- Back
|
how does gravity affect blood circulation
|
-pull blood downward into the lower parts of the body
|
|
|
how is gravity a problem?
|
we stand upright on two legs so our hearts have to pump blood against gravity from out heart to our brain
|
|
|
what kind of contractions help blood move along its way?
|
skeletal muscle contractions
as we walk/run, our leg muscles squeeze hte veins and force the blood upwared toward ht eheart |
|
|
our veins have valves that allow blood to flow in only one diretion
whic prevents |
it from flowing back down the legs
|
|
|
define CIRCULATORY SYSTEM
|
system that transports o2 and co2
distributes nurtients to body cells conveys the waste products to metabolism to specific sites for disposal;; co2 to lungs, wastes to kidneys maintains constant internal environment controls makeup of environment in which the tissue cells live |
|
|
define CAPILLARIES
|
intri ate network among the cells of a tissue, such that no substance has to diffuse far to enter or leave a cell
|
|
|
how do RBCs flow in capillaries
|
single file
|
|
|
hydras and other cnidarians make a circulatory system unnecessary
|
the body wall of a hydra is only two or three cells thick so all the cells can exchang ematerials directly w/ the water surroudnign th eanimal or w/ the water in its gastrovascular cavity
water is drawn into the gastrovascular cavity through th emouth and exits back out throught the mouth digestoin occurs in the gastrovascular cavity and in th cells lining it only these cells have direct access to nutrients but nurtients ahve only a short distance to diffuse to cells of th eouther layer |
|
|
jelly is a cnidarian w/ a mroe elaborate gastrovascular cavity
|
branches radiationg from the mouth to a circular canal
cilliated cells lining these branches and canals circulate the gastrovascular fluid |
|
|
planarians and flatworms have a gastrovascula cavity
|
exchanges materials w/ the environment through a single opening.
/tick, multiple layers of cells gastrovascular cavity provides adequqate internal transport for such flat, thin animals, but it is not adequate for animals w |
|
|
define BLOOD
|
specialized circulatory fluid
|
|
|
two basica types of circulatory systems
|
open circulatory system
cloesd circulatory system/cardiovasculat system |
|
|
invertebrates, inc most molluscs and arthropods, have
|
open circulatory system
|
|
|
why is it termed "open"
|
bloood is pumped through open-enneded vessesl and flows out among the cells;
there is no distinction btwn blood and interstitial fluid. |
|
|
When the heart relaxes, bloood returns to it through several poers
|
each pore has a valve that closes when teh heart contracts, preventing backflow of the blood
|
|
|
in a closed circulatory system
|
the blod is confined to the vells, which keep it distinct form the interstitial fluid
|
|
|
define ARTERIES
|
\carry blood away from the heart to organs and tissues trhought the body
|
|
|
define VEINS
|
return blood to the heart
|
|
|
define CAPILLARIES
|
convey blood btwn arteries and veins w/i each tissue
|
|
|
define ATRIUM
|
receives blood from the veins
|
|
|
define VENTRICLE
|
pumps blood to the gills via large arteries
|
|
|
definen ARTERIOLES
|
what arteriers branch into
small vessels that vie rise to capillaries |
|
|
define CAPILLARY BEDS
|
networkds of capillliares that infiltrate every organ and tissue in the body
the thin walls of the capillaries allow chemical exchang ebtwen the blood and the interstitial fluid. |
|
|
define VENULES
|
what the cappilaries converge into
which converge into veins that return blodo to the heart |
|
|
fish have a single circuit of blood flow and 2 heart chambers
|
blood pumped form the ventricle travels first to the gill capillaries, where it picks up o2.
the blood delivers o2 to the tissues of hte body as it passes through a second set of capillaries, known as SYSTEMIC CAPILLARIES, b4 returning to the atrium of the heart the blood slows down considerbale while passing through th egill capillaries, allthoguht it is helped on its way to the other organs by teh anima'sl wimming movements |
|
|
in terrestrial vrertebrates, a more virgorous flow fo blood is suppolied to bpdy organs by means of a double circulation
|
in which blood is pumped a second time after it slows down in the capillary beds o fth elungs
|
|
|
define PULMONARY CIRCUIT
|
it carries blood btwn the heart and the gas exchange tissues in the lungs
|
|
|
define SYSTEMIC CIRCUIT
|
carries blood btwn the heart and th erest of the body
|
|
|
frogs and other amphibians have a 3 chambered heart.
|
the right atrium reveives blood returining from the systemic capillaries.
the ventricle pumps blood to capillary beds in the lungs and skin |
|
|
define PULMOCUTANEOUS CIRCUIT
|
gas ecxchnage occurs both in the lungs and across the thin, moist skin
|
|
|
in birds and mammals , the ventricle is divded and the heart has four chamebrs which are
|
two atria and two ventricles
|
|
|
the left side of the heart
|
receives and pumps only oxygen rich blood
|
|
|
the right side of the heart
|
handles only oxygen poor blood
|
|
|
the evolution of a 4 chambered heart was an adaptation to support
|
the ghigh metabolic rate of birds and mammals which are endothermic
|
|
|
blood through the enitire ciculatorysystem
beginning w/ the pulmonary lung circuit |
1. the right ventricle pumps blood to the lungs via
2. 2 pulmonary arteries. As the blood flows through 3. capillaries in the lungs, it takes up o2 and unlods co2. o2 rich blood flows back through 4. pumonary veins to 5. left atrium. next, the o2 rich blood florws from teh left atrium into 6. the left ventricle. o2 rich blood leaves the left ventrical through 7. the aorta. the aorta is our largest blood vessel. the first branches from the aorta are the coronary arteries, which supply blood to the heart muscle itself. several large artiires branch from the aorta, leading to 8. the head, chest, and arms, and to the abdominal region and legs. the capillaries join as venule, whcih convey the blod back into veins 9. o2 poor blood from teh upper body is chenneled into a large vein called the SUPERIOR VENA CAVA, anand another large vein, the INFERIOR VENA CAVA, drains blood from the lower body. the two venae cavae empty their blod into 10. the right atrium. as th eblood flows from teh right atrium into the right ventricle. |
|
|
capillaries have thin walls formed of a single layer of epithelial cells, which is wrappeed in a thin basement membrane
|
the inner surfaces of the capillary is smooth and keeps th eblood cells form being abradeda s the ytumble alonge
|
|
|
arteries, arterioles, veins, and venules have thicker walls than those of capillaries
|
the walls have the same eithelium as capillares
they are reinforced by two other tissue layers: an ourter layer of connective tissue /w eslastic fibers enables the vessesl to stretch and recoil the middle laeyr consist mainly of smooth muscle. both these laeyrs are thicker and sturdier in arteirs, providing th strength and elasticity to accommodate the rapid flow and high pressure of blood pumped by the heart |
|
|
arteres are able to regulate blood flow by
|
constricting or relaxing their smooth muscle layer
|
|
|
the thinner walled veins convey blood back to the heart
|
at alow velocity and pressure
|
|
|
w/in large veins, flaps of tissue act as one way vales
|
valves prevent backflow, permititbng blodo to flow only toward the heart
|
|
|
define CARDIAC DCYCLE
|
a complete sequence of filling and pumping of teh heart which takes abotu .8 seconds, w/ heart rate of 75 bpm
|
|
|
cardiac cycle: DIASTOLE
|
when the entire heart is relaxed, in teh phase called
1. DIASTOLE, bloodf lows into all four of tis chambers. blood enters the right atrium from the venae caveae and th left atrium from teh pumponary veins. the valves btwn th atria and the ventricles are open. lasts about .4 sec, during which th eventricles fill up w/ blood |
|
|
SYSTOLE
2-3 |
2. systeo=le begins w/ a very breif contration of the atria tthat complete fills the ventricles w/ blood.
3. then the ventricles contract. the force of their contraction closes the AV valves, opens the semilunar valves located at th exit form each ventricle, and pumps blood into the large ateries. blood flows into th atria during th 2nd part of systole. |
|
|
define CARDIAC OUTPUT
|
the volume of blood/min that the left ventricle pumps ointo the systemic circuit
the volume is equal to the amount of blood pumped by the left ventricle each time it contracts times th eheart rate |
|
|
the heart valves, made of flaps of connective tissue, prevent
|
backflow and keep blood moving in teh correct direction
|
|
|
the closing of th AV vales when teh ventricles contract
|
keeps blood ffrom flowing back into th atria.
|
|
|
when the ventricles relax in diastole
|
blood in the artiers starts to flow back toward the heart, causing the flaps of the smilunar valves to close and preventing blood from flowing back into the venticles
|
|
|
the heart sounds we can hear w/ a stehoscope are caused by
|
these closign of th eheart valves.
lub: recoil of blood agaisnt h eclosed AV valves dub: semilunar valves snap shut |
|
|
hissing sound of a heart murmur indicates
|
a defect in one or more of the heart valves
|
|
|
a murmur occurs when
|
a stream of blood squirts backward through a vlave. some ppl are born w/ murmurs, while others have their vlaves damaged by infection. most valve defects don't reduce the effieiency of blood flow enough to warrant surger.
|
|
|
define PACEMAKER or SA/SINOATRIAL NODE
|
a specialized region of cardiac muscle that maintains the heart's pumping rhythm y setting the rate at which all the muscle cells of the heart contract
|
|
|
how the pacemaker that is situatef in the wall fo the right atrium works
define AV ATRIOVENTRICULAR NODE |
1. the pacemaker generates electrical signals
2. bc cardiac muscle cells are elctrically connected by speclized junctions btwn cells, signals spread quickly through both atria, making them contract in unison. the singnals also pass to a raly point called the AV node, in teh wall btwn th right atrium and right ventricle. |
|
|
why is there a delay after AV node
|
the delay ensures that the atria contrac t and empty b4 the ventricles contract
|
|
|
pace maker
3-4 |
3. specialized cardiac muscle fibers then relay the signals to the apex of the heart
4. and up through the walls of the ventiles, triggering the strong contractions that drive the blood out of the heart |
|
|
define ARTIFICIAL PACEMAKER
|
a tiny electronic device surgically implanted near the AV node. artificial pacemakers emit electrical signals that trigger normal heartbeats
|
|
|
heart rate can be influenced by hormones
|
such as epinefrine, the "fight or flight" horman realsed at times of stress
|
|
|
heart rate also increases w/ exercise
|
enabling the circulatory system to provide the additional o2 needed by hardworking muscles
|
|
|
define BLOOD PRESSURE
|
the force the blod exerts agsint the walls of our blood vessels.
|
|
|
when ventricles contract
|
blood si forced into the artiers faster than it can flow into the arterioles. this stretches teh elastic walls fo the parteris.
|
|
|
define PULSE
|
the rhythmic strectching of the arteries
|
|
|
ventricular contraction
|
systolic pressure
|
|
|
the elastic arteris snap back during diastole, maintaining pressure on the blood and a continous flow of blood into arterioles and capillaries
|
diastolic pressure
|
|
|
blood pressure and the blood's velocity are higest in the
|
aorta and arties
|
|
|
if bp in the veins drops to zero, how si it that blood velocity increases as blood flows form venules to veins
|
the combined diameter of the vessles throug hwhich the blodo flows decreases. the velocity of the flow increases just as water flows faster when a nozzle narrows the opening of a hose
|
|
|
units of blod pressure
|
mm Hg, indicating how tall a column of murcury the pressure could support
|
|
|
how do you measure blood pressure
|
sphygmomanometer, blood pressure cuff
|
|
|
smooth muscle controls
|
the distribution of blood
|
|
|
smooth muscles in arteriole walls
|
influence bp by chaning the resistance to blood flow oout of the artiers and into arterioles
|
|
|
PRECAPILLARY SPHINCTERS
|
passage of bblood into branching capillaries is regaulated by these rings of smooth muscle bc the yare located at the entereence to capillary beds
|
|
|
1. blood flows through a capillary bed when its precapillary sphincters are relaxed
|
2. it bypasses the capiillary bed when teh sphincters are contracted.
|
|
|
nerves and hormones influence
|
the contraction of the smooth muscles in both these mechanisms that reculate the flow of blood to capillary beds
|
|
|
what 2 mechanisms control the distribution of blood to th capillary beds of the body
|
-constriction of an arteriole, so that th eless blood reaches a capilarry bed,
-contaction of precapilarry sprhincters, so that blood flows through throughfare channels only, not capilarry beds. |
