classes of arteries

elastic arteries

closest arteries closest to the heart

• tunica media consist of many (40-70) sheets of elastic fibers

muscular arteries

intermediate diameter

includes arteries that simply organs

tunica media is mostly smooth muscle

• allows for nervous and endocrine control of blood flow (vasoconstriction vasodilation)

arterioles

smallest arteries

all 3 tunics are present but very thin

vasoconstriction and vasodilation have major effects on blood flow to capillary beds in tissues

( blood flow can be completely cut off)

baroreceptors

detect blood pressure in aorta and carotid artery

chemoreceptors

detects O2, CO2, and pH within the aorta and carotid artery

capillaries

• extremely thin-walled vessels

• Endothelium (1-3 cells) rolled around a tube surrounded by little basal lamina (connected by tight junctions

• diameter 8-10 um

capillary exchange

the movement of nutrients, gases, ions, and wastes between blood in the capillary and tissue cells

continuous capillaries

• endothelial cells joined by tight junctions

• LOCATION skin , most nervous/connective tissue , muscle tissue

• least “leaky”- permit a narrow range of substances to cross walls

fenestrated capillaries

• contains fenestrations in the endothelial cells

• LOCATION

Kidneys, endocrine glands, small intestine

moderately leaky- allow large volumes of fluid and larger substances to cross capillary walls

sinusoidal capillaries

discontinuous sheet of endothelium, irregular basal lamina, very large pores

• LOCATION

liver, lymphoid organs, bone marrow, spleen

leakiest— allow large substances such as cells to cross the capillary walls

tissue perfusion

blood flow to tissue thru capillary bed, its tightly controlled

capillary beds

networks of capillaries that pass between the cells of most tissues

hemodynamics

physiology of blood flow within the cardiovascular system

pressure gradient

as ventricles of the heart contract, they push blood thru the blood vessels

• blood flows from high pressure areas- to low pressure areas

blood pressure

the outwards force the blood exerts on the walls of blood vessels

blood flow

the volume of blood that flows thru vessel during a period of time

• measured in liters per minute (L/m) usually ~5-6 L/m

• affected by

magnitude of the blood pressure gradient and resistance

peripheral resistance

anything that hinders blood flow thru vessels away from the heart

when this is 👆 so is the blood pressure 👆

DETERMINED BY

• blood vessel radius

• blood viscosity

• blood vessel length

• obstructions

cardiac output

will increase along with increases in either stroke volume or heart rate

blood volume

increases as the amount of water in blood increases