Cardiac cycle + blood vessels Flashcards
what is diastole
relaxing
what is systole
contracting
what are the bicuspid + tricuspid valves generally called
atrio-ventricular valves (AV valves)
what are the aortic and pulmonary valves generally called
semi-lunar valves (SL valves)
describe atrial systole
- atria contracts
- pressure greater in atria than ventricle
- blood flows into ventricle, fully filling it
describe ventricular systole
- atria relaxes, ventricle contracts
- AV valve closes
- pressure greater in ventricle than aorta, SL valve opens
- blood flows into the aorta
describe diastole
- ventricle relaxes
- pressure in aorta greater than ventricle
- SL valve closes
- AV valve opens
- blood flows from the atria into ventricle, passively refilling
pressure graph cardiac cycle
FLASHCARD
describe the structure of the arteries (4)
- thick muscle layer
- relatively thick elastic layer
- overall thickness of wall is large
- no valves (except in arteries leaving the heart)
how does the structure of arteries relate to its function
+thick muscle layer- maintain high pressure flow to tissues (from heart)
+relatively thick elastic layer- stretch and recoil allow for high pressure flow
+overall thickness of wall is large- muscle can contract
+no valves- due to high pressure from stretch and recoil
describe the structure of veins (4)
- overall thickness of wall is small
- muscle layer relatively thin
- elastic layer relatively thin
- contain valves at intervals throughout
how does the structure of veins relate to its function
+overall thickness of wall is small, muscle layer + elastic layer thin (relatively)- slow, low pressure transport of blood (from tissues to heart)
+valves- prevent backflow of blood due to low pressure
describe the structure of arterioles (3)
- muscle layer relatively thicker than in arteries
- elastic layer relatively thinner than in arteries
- smaller and more numerous than arteries
how does the structure of arterioles relate to its function
+thicker muscle layer, thinner elastic layer (than arteries) - allow for vasodilation/vasoconstriction controlling blood flow to arteries
+smaller and more numerous than arteries - decreasing pressure, increasing speed of blood due to greater cross-sectional area
describe the structure of capillaries (5)
- wall consists of mainly the internal lining layer (endothelium)
- numerous and highly branched
- pores (fenestrae) between endothelial cells
- narrow lumen
- narrow diameter
size of capillary lumen
7um
how does the structure of capillaries relate to its function
+lining layer (endothelium)- very thin, reduced diffusion distance between blood and body cells
+numerous, highly branched- large SA for gas exchange
+fenestrae- for formation of tissue fluid
+narrow lumen- red blood cells closer to cells (reduce diffusion distance)
+narrow diameter- squeeze between tissues so all cells very close to capillaries (reduces diffusion distance)
what solute is found in the capillaries
plasma proteins
describe features of the arterial end (in relation to water potential)
- higher hydrostatic pressure than venous end
- lower solute (plasma protein) concentration than venous end
- higher water potential than outside capillary- so a net movement of water out of the capillary
describe the features of the venous end (in relation to water potential)
- lower hydrostatic pressure than arterial end
- higher solute (plasma protein) concentration than arterial end
- lower water potential than outside capillary- net movement of tissue fluid into the capillary
what happens to some of the tissue fluid when inside the tissues
a small portion of it is drained into the lymph vessels then moves back into the circulatory system. (Allows for products of tissue cells to be carried into the bloodstream)
function of tissue fluid
contains dissolved materials such as glucose. cells can exchange materials with the tissue fluid
where does tissue fluid come from
it is water from blood plasma
why do all blood vessels have a thin endothelial lining
to reduce friction
why do all blood vessels have a tough, fibrous outer layer
to resist pressure changes from inside and outside
pressure graph blood flow
FLASHCARD
