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innermost tunic


bulky middle tunic;contins smooth muscle and elastin


its smooth surface decreases resistance to blood flow


tunics of the capillaries


tunic of arteries and veins


is especially thick in elastic arteries


most superficial tunic

exchange of nutrients, respiratory gas and waste occur only through thin capillary walls

servicing the capillaries is the essential function of the organs of the circulatory system, explain:

-high blood pressure in arteries propel blood through them.
-Blood pressure in veins is low and often the blood is flowing against gravity.
-Valves prevent backflow

Why are valves present in veins but not in arteries

-skeletal muscle "milking action"
-changes in thoracic cavity pressure during breathing

name two evens occuring within body that aid in venous return


what organ serves as respiratory/digestive/excretory organ for fetus?

internal carotid

what two paired arteries enter the skull to supply the brain?

cerebral arterial circle (circle of Willis)

Branches of paired arteries just named cooperate to form a ring of blood vessel encircling the pituitary gland, at the base of brain. What name is given to this communication network?

Provides an alternative set of pathway for blood to reach brain tissue in case of impaired blood flow anywhere in the system

Function of Circle of Willis

The bulk of cerebral hemisphere

What portion of brain is served by anterior and middle cerebral arteries

internal carotid arteries

both the anterior and middle cerebral arteries arise from the ___

subclavian artery
vertebral artery
basilar artery
posterior cerebral artery
occipital brain tissue

trace pathway of a drop of blood from aorta to left occipital lobe of brain, noting all structures through which it flows


visceral pericardium


lining of the heart chambers


actual pumps of the heart

enforce one way of blood through heart

function of valves found in heart


can the heart function with leaky valves

anchor AV valve flaps during ventricular systole, preventing backflow of blood into atria

function of chordae tendineae


equals cardiac muscle


if mitral valve does not close properly, which circulation is affected

inferior vena cava
right atrium
tricuspid valve
right ventricle
pulmonary semilunar valve
pulmonary trunk
right or left pulmonary artery
lobar artery
pulmonary capillary beds in lungs
air sacs (alveoli) of lungs

trace pathway of carbon dioxide gas molecule in blood from inferior vena cava until it leaves the bloodstream

digital vein
L radial vein
L brachial vein
L axillary vein
L subclavian vein
L brachiocephalic vein
superior vena cava
R Atrium
R ventricle
pulmonary trunk
pulmonary artery
lobar artery
pulmonary capillaries of lung,
lobar veins
pulmonary veins
L atrium
L ventricle
aortic arch
brachiocephalic artery
R subclavian artery
R axillary artery
R brachial artery
R radial artery
digital artery

trace blood flow from capillary beds of left thumb to capillary beds of right thumb

through bicuspid or mitral valve into
L ventricle
common iliac artery
external iliac artery
femoral artery
posterior tibial artery
lateral plantar artery
digital artery
capillary beds
digital vein
plantar arch
plantar vein
posterior tibial vein
femoral vein
external iliac vein
common iliac vein
inferior vena cava
right atrium
through tricuspid valve

trace blood flow from mitral valve to tricuspid valve by way of great toe

1. major pathway serves 80% of cerebral tissues:
pulmonary vein
L atrium
L ventricle
aortic arch
brachiocephalic trunk
R common carotid artery
R internal carotid artery
R middle cerebral and R anterior cerebral arteries
capillary beds
dural sinuses
internal jugular vein
brachiocephalic vein
superior vena cava
R atrium
R ventircle
pulmonary trunk
pulmonary artery

trace blood flow from pulmonary vein to pulmonary artery by way of right side of brain: ( the major pathway)

pathway supplies occipital lobe and part of temporal lobe:
pulmonary vein
L atrium
L ventricle
aortic arch
brachiocephalic trunk
R subclavian artery
R vertebral artery
basilar artery
R posterior cerebral artery
capillary beds
return route same as pathway 1

trace blood flow from pulmonary vein to pulmonary artery by way of right side of brain: 2nd pathway

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