Circulatory systems Flashcards
why do larger organisms need transport systems?
-have small sa:v ratio
-cells further from surface so diffusion alone is not enough to supply oxygen and nutrients
what type of circulatory system do mammals have?
-we have a closed double cs
-blood flows through heart twice in two circuits
-blood is enclosed in blood vessels
what is the pulmonary system?
-where blood flows from heart to lungs for gas exchange
what is the systemic system?
-where blood flows from heart to rest of body
explain one advantage of a double circulatory system
-blood is at higher pressure in systemic circulation so the blood flows faster delivering nutrients and removing waste at higher rate, allowing for more activity
describe order of blood flow in vessels
arteries->arterioles->capillaries->venules->veins
artery structure
small lumen
thick muscular walls
elastic tissue
smooth muscle
endothelium - 1 cell thick
blood at high pressure
vein structure
wide lumen
valves
thin muscle wall
smooth endothelium
capillary structure
1 cell thick endothelium
narrow lumen
how is tissue fluid formed?
- high hp at arteriole end caused by ventricular systole, forces fluid out of capillary and into tissues
- plasma proteins remain behind in capillaries, lowering water potential and helping to bring fluid back in - at venous end, wp > hp so there’s net inward movement of fluid
- some tissue fluid is not absorbed into blood and drains into lymphatic vessels
what is diastole?
-the relaxation of all muscles of the heart
atrial systole
-occurs when both atria contract and its initiated by a wave of impulse from the sino-atrial node
what is ventricular systole?
-occurs when both ventricles contract after impulse is delayed at atrio-ventricular node
cardiac output =
heart rate times stroke volume
