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the three layers of the blood vessel walls, internal to external

tunica intima, tunica media, tunica externa

three layers of the tunica intima, internal to external

endothelium, sub-endothelial layer, internal elastic lamina

function of the tunica intima

reduces friction between the vessel walls and the blood

layer of the tunica intima that is not found in veins

internal elastic lamina

the basal membrane of the blood vessels

the sub-endothelial layer

function of the internal elastic lamina

elasticity for arteries due to arterial pressure (high pressure system)

composition of the tunica media

smooth and elastic muscles and the external elastic lamina

differences in the tunica media in arteries and veins

thinner in veins as it is a low pressure system

two layers of the tunica media in arteries

muscle layer and the external elastic lamina

function of the tunica media

controls vasodilation and vasoconstriction

composition of the tunica externa

collagen fibers

function of the tunica externa

protects, reenforces, and anchors the vessel to surrounding structures

feature of vessel structure found in veins only

internal, one way venous valves that are covered in endothelium

function of the venous valves

to prevent back flow of blood as it returns to the heart - found mostly in the extremities

how blood returns to the heart against gravity

the muscles of the leg pump it up as constricting occurs during use (e.g. walking)

how blood form the abdominopelvic region returns to the heart

the respiratory pump - contraction of the diaphragm creates high pressure in the lower region and low pressure in the upper region, causing blood to be drawn upward

the largest arteries as they lead away from the heart

elastic or conducting arteries

physical characteristic of conducting arteries allowing them to withstand changes in arterial pressure due to the heart action

contain large amounts of elastin, creating elasticity

second level of arteries

muscular or distributing arteries

function of muscular or distributing arteries

deliver blood to specific organs and very active in vasoconstriction

important physical characteristic of muscular or distributing arteries

they contain the largest tunica media of all arteries due to greater muscle content for vasoconstriction

smallest arteries


function of the arterioles

regulate blood flow into the capillary beds through vasoconstriction and vasodilation

important physical characteristic of arterioles

the muscle layer of the tunica media is made of smooth muscle only

physical characteristic of the capillaries

they are the smallest vessels

function of the capillaries

they allow the exchange of substances between the vessels and the interstitial fluid

continuous capillaries

contain no muscle, the capillary wall is one cell thick with a basement membrane, and are the least permeable and most common capillary; still allow the passage of fluids and small solutes

fenestrated capillaries

contain fenestrations (small pores) and are more permeable than continuous capillaries and are found in specialized locations like the kidneys and small intestine

sinusoidal capillaries

the most permeable capillaries allowing large molecules to pass through; found in the liver, spleen and bone marrow

where the smallest capillaries are found

in the spleen - sinusoidal

structure at the end of the arterial circulation

capillary beds

structure of the capillary beds

microcirculatory network with a vascular shunt and the true capillaries that act as exchange vessels

structure at the entry point for the capillary beds

pre-capillary sphincter

function of the pre-capillary sphincter

regulates the flow of blood through the capillary bed

structure of the pre-capillary sphincter

a cuff of smooth muscle surrounding each capillary at the metarteriole

blood flow when the pre-capillary sphincter is open

blood flows into the capillary bed allowing the plasma to leave the blood into the interstitial spaces with nutrients, etc for the tissues/cells they supply

blood flow when the pre-capillary sphincters are closed

blood passes through the vascular shunt, bypassing the capillary bed without release plasma and its solutes

where the plasma released into the interstitial fluids returns to the blood

in the venous side of the capillary bed - the beginning of venous system

percentage of plasma that is not returned to the blood by capillary re-uptake


where the capillaries converge

venules - allow fluid and WBCs to move easily between the blood and tissues

what venules form as they converge


physical characteristics of veins

thin walled with relatively large lumens

additional term for small and large veins

capacitance vessels

function of veins as capacitance vessels

store blood - 65% of the blood in the body is in the venous system at any given time

venous response when blood pressure drops

vasoconstriction - increases the blood volume in the arterial system

percentage of blood in systemic circulation at any given time


vascular anastomoses

where vascular channels unite forming alternative blood pathways to allow blood supply and drainage from an area even if one channel is blocked

blood pressure

measured in arteries - the force per unit area exerted by the blood on the blood walls expressed in millimeters of mercury

effect of High Blood Pressure

damages the endothelium of the vessels leading to atherosclerosis

how blood pressure results

the resistance of the blood during the pumping action of t heart

blood pressure levels throughout the systemic circuit

highest in the aorta, decreasing throughout the pathway until is reaches 0 in the right atrium

cardiac output

the amount of blood ejected from the ventricle each minute CO = SV (stroke volume) x HR (heart rate)

stroke volume

the amount of blood ejected by the ventricle on each contraction

what arterial Blood pressure signifies

how much the arteries close to the heart can be stretched (compliance or distensibility) and the volume of blood forced into them at any given time

systolic pressure

the peak pressure created when the left ventricle contracts forcing blood into the aorta (normally about 120mm Hg)

diastolic pressure

the pressure created when back flow into the ventricles is prevented by the semilunar valves (normally about 70-80 mm Hg)

characteristics of where arteries run

deep and are well protected

characteristics of where veins run

both deep (parallel to the arteries) and superficial (just under the skin

number of terminal systemic arteries

one - the aorta

number of terminal systemic veins

two - inferior and superior vena cava

three parts of the aorta

ascending aorta, arch of the aorta, thoracic aorta

the 4 paired arteries of the head and neck

costocervical trunk, thyrocervical trunk, vertebral artery, common carotid artery

from where the left common carotid artery arises

from the aortic arch

from where the right common carotid arises

from the brachiocephalic trunk as it branches from the aortic arch

two branches of the common carotid

the external and internal

area the internal carotid supplies

major supplier of blood to the brain

area the external carotid supplies

the scalp, face, larynx and some of the thyroid

from where the vertebral arteries arise

subclavian artery, the first and most medial branch

area the vertebral artery supplies

passes through the transverse processes of the cervical spine and supplies the brain

from where the thyrocervical artery arises

subclavian artery, lateral to the vertebral arteries

area the thyrocervical trunk supplies

thyroid gland and portions of the cervical spine

from where the costocervical artery arises

subclavian artery, lateral to the thyrocervical arteries

area the costocervical artery supplies

deep neck muscles

the three branches of the aortic arch from right to left

the brachiocephalic trunk, the left common carotid, the left subclavian

the two branches of the brachiocephalic trunk medial to lateral

the right common carotid, the right subclavian

area supplied by the subclavian arteries

the upper extremities

pathway of the subclavian arteries

becomes the axillary artery at the armpit, the brachial artery at the elbow and the radial and ulnar arteries at the wrist

from where the left and right coronary arteries arise

the ascending aorta

artery that supplies the abdomen

the abdominal aorta

from the where the abdominal aorta arises

from the thoracic aorta as it passes through the aortic hiatus in the diaphragm

most proximal artery that supplies the lever, stomach and spleen

celiac trunk

artery that supplies intestines, rectum and tissues

superior and inferior mesenteric arteries

from where the mesenteric arteries arise

the abdominal aorta

artery that supplies the kidneys

the renal artery

from where the renal arteries arise

between the superior and inferior mesenteric arteries off the abdominal aorta

arteries that supply the pelvis and lower extremities

the common iliac arteries

from where the common iliac arteries arise

the abdominal artery bifurcates at around the iliac crest/L-4 level, forming the right and left common iliac arteries

how blood supply moves to the pelvis

the common iliac bifurcates and the pelvis and pelvic organs are supplied by the internal iliac artery

how blood supply moves to the lower extremities

the common iliac bifurcates and the external iliac artery supplies the lower extermities

pathway of the external iliac arteries

becomes the femoral artery in the thigh, has multiple branches at the knee

area from which blood drains to the superior vena cava

head, neck, upper extermities

area from which blood drains to the inferior vena cava

the trunk and lower extremities

area from which blood drains to the coronary sinus

the heart

three pairs of veins to which blood drains from the head and neck

external jugular, vertebral, and internal jugular

area from which blood drains to the external jugular

scalp and face

area from which blood drains to the vertebral veins

the brain

area from which blood drains to the internal jugular

the brain

the area to which the external vein drains

the subclavian vein

area to which the subclavian, vertebral and internal jugular drain

the brachiocephalic branch bilaterally

area to which the brachiocephalic veins drain

the merge and become the superior vena cava

pathway by which the blood of the thoracic wall and tissues are drained

the accessory hemi-azygos veins to the hemi-azygos veins, which merge to the azygos vein which drains to the superior vena cava

pathway by which the abdominal viscera and abdominal walls drain

through the portal system - the splenic vein drains the spleen and merges with the superior mesenteric vein to become the hepatic portal vein which transports blood to the two lobes of the liver for the storage of unused nutrients which then drains the blood to the inferior vena cava via the Right and left hepatic veins

to where the inferior mesenteric circulation drains

to the splenic vein

pathway by which the blood drains from the pelvis and pelvic organs

via the internal iliac vein which merges with the external iliac vein to form the common iliac vein to the inferior vena cava

pathway by which the blood drains from the lower extremities

lower limbs via several veins to the femoral vein in th thigh to the external iliac vein which merges with the internal iliac vein to form the common iliac vein which feed to the inferior vena cava

function of the lymph system

takes up the 1% of the plasma that is not reabsorbed by the venus capillaries in the capillary beds during circulation and cleans it

flow of the lymphatic system

one way to the heart

beginning of the lymph system

lymph capillaries between the tissue cells and the blood capillaries in the loose CT - these are blind ends (not circular)

to where the lymph capillaries feed

to the lymph collecting vessels

to where the lymph collecting vessels feed

to the lymph trunks

to where the lymph trunks feed

the lymph trunks drain large areas of the body and feed to the thoracic duct and the right lymphatic duct

lymph nodes

collections of WBCs along the lymph collecting vessels and lymph ducts that clean the plasma

areas drained by the right lymphatic duct

head, neck, right trunk and the right upper extremities

pathway of the right lymphatic duct

drains to the right subclavian vein

areas drained by the thoracic duct

the majority of the lymph system, excluding the head, neck, right trunk, and right upper extremities

size and weight of the heart

fist sized; about 250-300g

location of the heart

mediastinum 2/3 lies left of the mid-sternal line

orientation of the top of the heart

the base of the heart points to the right shoulder

orientation of the bottom of the heart

the apex points toward the left hip

the covering of the heart

double layered pericardium

outer layer of the pericardium

loose fibrous pericardium

make-up of the fibrous pericardium

dense CT

function of the fibrous pericardium

protects and anchors the heart

inner layer of the pericardium

serous pericardium

make-up of the serous pericardium

thin, slippery two layered serous membrane

two layers of the serous membrane

parietal pericardium and visceral pericardium or epicardium

location of the parietal pericardium

lines the inside of the fibrous pericardium

location of the epicardium

covers the surface of the heart

area between the parietal pericardium and epicardium

pericardial cavity

structure of the pericardial cavity

filled with serous fluid

function of the serous fluid in the pericardial cavity

to provide lubrication for the serous membranes to allow smooth movement during contraction and relaxation of the heart

three layers of the heart wall outer to inner

epicardium, myocardium, endocardium

structure of the epicardium

serous membrane lining the outer wall of the heart

structure of the myocardium

composed mainly of cardiac muscle and forms the bulk of the heart


epithelial inner layer of the heart wall lining the chambers and valves of the heart

function of the endocardium

blood comes into contact with endocardium and enters the tissue

functions of the right atrium

receives the blood venous blood returning from the body through three veins

characteristic of venous blood

low oxygen content

three veins entering the right atrium

superior vena cava, inferior vena cava, coronary sinus

function of the superior vena cava

returns blood from the head, neck and upper extremities

function of the inferior vena cava

returns blood from the trunk and lower extremities

function of the coronary sinus

all veins from the heart drain into the coronary sinus which drains the coronary blood back to the right atrium

two networks in the heart

upper and lower

upper network of the heart

R & L atria

lower network of the heart

R & L Ventricles

how the upper and lower network interact

when one is performing a function, the other is doing the opposite

where the blood goes from the R atrium

passes to the right ventricle passing the tricuspid valve

function of the tricuspid valve

prevents back flow of blood from the right ventricle to the right atrium; closes when the ventricles contract and opens when they relax

functions of the right ventricle

pumps blood to the pulmonary trunk via the pulmonary valve

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