EXAM 2 A&P

what are the 3 types of blood vessels

arteries, capillaries, veins

how many km of vessels are in our body

100,000 km or 60,000 miles

which direction does blood flow in arteries and veins

arteries - away from heart

veins - towards heart

which blood vessels are composed of the three tunics

arteries, arterioles, venules, and veins

what are the three tunics of the blood vessels

tunica intima, tunica media, tunica externa

what tunic layer do capillaries have

only tunica intima - made of endothelium

what is the endothelium made of in the capillaries

only simple squamous tissue, NOT connective tissue

what is tunica intima composed of in non capillaries

endothelium and small amount of connective tissue

what is a lumen

central blood-filled space of a vessel (the tunics encase the lumen)

what is the tunica intima

inner most blood vessel

what is the tunica media

circular smooth muscles regulated by vasomotor nerve fibers - perform vasoconstriction and vasodilation

what is the tunica adventitia (tunica externa)

loose collagen fibers, large vessels have vaso vasorum

what is vaso vasorum

it's the smaller blood vessels that supply blood to the larger blood vessels

what are the three groups of arteries

-elastic or conducting arteries

muscular or

-distributing arteries

-arterioles

*in this order to the capillaries

what is the difference in appearance between veins and arteries

veins looks collapsed and arteries have thick circular walls

what is the order of blood vessels from the heart all the way back to the heart

elastic arteries, muscular arteries, arterioles, terminal arteriole, metarteriole, precapillary sphincter, capillaries, thoroughfare channel, post capillary venule, small veins, large veins

what are characteristic of elastic or conducting arteries

thick walled, largest and close to heart (aorta and it's branches), elastin, can withstand pressure changes, have smooth muscles

what happens if arteries become weak

they may balloon out as an aneurysm and potential burst

is blood flow continuous in arteries

no, blood flow is intermittent due to the pumping of the heart but supply to the tissues is continuous due to the elasticity of the large arteries

what are characteristics of muscular or distributing arteries

deliver blood to body organs, proportionately thicker tunica media, more smooth muscles, active vasoconstriction

what is an example of elastic or conducting arteries

aorta

what is an example of a muscular or distributing arteries

splenic artery

what are characteristics of arterioles

smallest arteries, larger ones will have 3 tunics, but smaller ones have just a little more than just a single layer of smooth muscles around the endothelium

what is example of an arteriole

resistance vessels

what are characteristics of capillaries

smallest blood vessels with thin walls, designed for exchange of materials, has 3 types

what are the three types of capillaries

-continuous

-fenestrated

-sinusoids

what is the diameter of a capillary

8-10 um

what are characteristics of continuous capillaries

common with tight junctions and uninterrupted endothelium

what is an example of continuous capillaries

abundant in skin and muscles

what are characteristics of fenestrated capillaries

pores or fenestration, located where filtrate is formed

what is an example of fenestrated capillaries

small intestine, endocrine organs, kidney

what are characteristics of sinusoid capillaries

discontinuous endothelium, highly modified, irregular, leaky capillaries with Kupffer cells

what are examples of sinusoid capillaries

liver, bone marrow, lymphoid tissues

what are capillary beds

branches of arteries for microcirculation with 2 types of arrangements

what are the two capillary bed arrangements

vascular shunt and true capillaries

what are vascular shunt capillary beds

arteriole, metarteriole, thoroughfare channel, post capillary venule

what are true capillaries (capillary beds)

they perform the actual exchange of vessels

-arteriole, metarteriole, true capillaries, thoroughfare channels, post capillary venule

what feature do all true capillaries have

precapillary sphincter

what are venules

smallest veins

what is the post capillary venule made of

entirely endothelium

what tunics are present in larger venules

the tunica media and adventitia begin to appear as well as tunica interna

do veins have all 3 tunics

yes, but the walls are thinner than arteries and the lumens are larger

which tunica is the heaviest in veins

tunica adventitia, which have less muscles and elastin

what is another name of veins

capacitance vessels or blood reservoirs (less resistance)

what are venous valves

the tunica intima will form valves for one way flow

what is potential problem with venous valves

they can dilate and form varicose veins in pregnant women and form hemorrhoids

what are venous sinuses

specialized flattened veins with thin walls made of endothelium

what are examples of venous sinuses

coronary sinuses of the heart and the dural sinuses of the brain

What are arterial anastomoses?

arteries supplying the same area often merge forming them - they are collateral channels

what is an example of an arterial anastomoses

metarteriole

what are venous anastomoses

common arrangements in the body that we can see under our skin

blood flow

actual volume of blood flowing in the system which is equal to cardiac output

blood pressure

force per unit area of the vessel wall by the blood

resistance

opposition to flow due to friction - mostly from peripheral resistance

what are three sources of resistance

blood viscosity, total blood vessels length, and blood vessel diameter

what is blood viscosity

thickness of blood due to number of blood cells (normally doesn't change)

what is total blood vessel length

direct relationship to resistance, the longer the vessel, the greater the resistance (normally doesn't change)

what is the most important source of blood vessel resistance

blood vessel diameter. the smaller the diameter, the greater the resistance

how does resistance varies in blood vessel diameter

inversely with 4th power of vessel radius (if radius is doubled then the resistance is 1/16 of the original)

how does blood pressure affect rate of flow

increase pressure means increase rate and decreased pressure means low rate of flow

what is blood flow (F) directly proportional to

the difference in blood pressure between two points

what is blood flow (F) inversely proportional to

peripheral resistance (R) in systemic circulation

how can blood flow be expressed mathematically

F= (delta) P/R

how does blood flow change

it's under a pressure gradient, it is highest closest towards the heart and decreases the further from the heart you get

where is the steepest drop in pressure

arterioles

what happens to blood pressure as it goes from arteries to veins

blood pressure decreases

what is arterial blood pressure

the clinical monitoring of circulatory efficiency

what contributes to venous blood pressure

muscular pump, respiratory pump, and sympathetic venoconstriction

what are two factors that affect arterial pressure

compliance or distensibility (how much they can stretch) and volume (of blood entering vessels at a given time)

how is blood pressure measured

pulsatile

what is systolic pressure and what does it average

the squeezing of the heart, averages 120 mm Hg

where is the peak of blood pressure

aorta

what is diastolic pressure and what does it average

relaxation of the heart, normally 80 mm Hg

what is pulse pressure

the difference between systolic and diastolic (normal should be about 40 mm Hg)

What is the mean arterial pressure (MAP)

diastolic pressure + pulse pressure/3 = 93 mm Hg

what is the mean arterial pressure 93 and not 100

because the heart spends more time in diastole than systole

what are vital signs

assessing the efficiency of a person's circulation by measuring pulse and blood pressure

what causes a pulse

the expansion and recoil of elastic arteries, which creates a pressure wave called a pulse. these can be monitored at pressure points

where is blood pressure measured and with what

indirectly from the brachial artery using a sphygmomanomater

what is the blood pressure by the time blood reaches the capillaries

35 mm Hg

what is the blood pressure by the time blood reaches the end of the capillary bed

17 mm Hg

why is the sudden drop in capillaries desirable

capillaries are fragile and most capillaries are extremely permeable and efficiently allow exchange of nutrients and wastes

is venous blood pressure pulsatile

no, it is steady and the lowest BP

what is the pressure gradient from venules to venae cavae

15 mm Hg

is a large lumen and valves enough for venous return

no, it wouldn't be enough. that's why we have three functional pumps to help this process

what are the 5 adaptation that are crucial for venous return

muscular pump, respiratory pump, sympathetic venoconstriction, venous valves, cardiac suction

what is the muscular pump made of

skeletal muscle activity, the contraction/relaxation of these muscles creates a pumping action on veins in extremities pulling blood towards the heart

what is the respiratory pump

results from the respiratory activity which pulls blood towards the lower pressure (trunk)

what is the pressure within the chest cavity

about 4 mm Hg less than atmospheric pressure

what is sympathetic venoconstriction

smooth muscle in tunica media, which is supplied with sympathetic nerve fibers and increases blood flow towards the heart due to decreased venous capacity

what is venoconstriction

sympathetic venoconstriction - the veins constrict which makes the vein small and forces the blood towards the heart

what are the two types of venous valves

varicose veins and superficial veins

what is enforce

the one way flow through veins

what are varicose veins

backflow of blood make the venous valves incompetent

do superficial veins receive support from skeletal muscles and other connective tissue

no, it receives little support

what is a serious consequence of venous valves

abnormal clot formation in the slow-moving pooled blood

how does cardiac activity help to return blood to the heart

during ventricular contraction, the AV valves pull down, creating a vacuum in the atria and during the relaxation of the ventricles, the blood gets pulled into the heart

what is the normal pressure of the atria

0 mm Hg

what type of control regulates blood pressure

short and long term controls

what are the main factors affecting blood pressure

peripheral resistance and blood volume