The Circulatory System - Animal Phys

Survival of Body Cells

goal of the circulatory system

movement of fluid throughout the body

the fluid contains

proteins, electrolytes, chemical messengers, formed elements

simple pathway

one major artery delivers blood to organ or region

end artery

one that provides only one path for blood to reach an organ or region

and end artery branches into…

smaller arteries that become arterioles

each arteriole feeds into…

a capillary bed

capillary bed is drained by…

a venule

venules merge to…

one major vein

arterial anastomosis, arterial joining

two or more arteries converge to supply same region

example of arterial anastomosis:

superior and inferior epigastric arteries supplying abdominal wall

venous anastomosis

more common, two or more veins drain same body region

arteriovenous anastomosis, shunt

transport blood from artery directly to vein

examples of arteriovenous anastomosis:

fingers, toes, palms, ears

blood components:

formed elements and plasma

formed elements:

erythrocytes- red blood cells, leukocytes - white blood cells

help form clots to prevent blood loss

platelets

plasma

fluid portion of blood

blood is a…

collloid

plasma contains…

dispersed proteins

most proteins are produced in the…

liver

fibrinogen

makes up of 4% of plasma proteins

fibronogen contributes to…

blood clot formation

serum

plasma with clotting proteins removed

regulatory proteins

includes enzymes and hormones

arteries

convey blood from heart to capillaries

capillaries

microscopic porous blood vessels, exchange substances between blood and tissues

veins

transport blood from capillaries to heart

lumen

space inside of a vessel

vessel walls composed of three layers called…

tunics

tunica intima

innermost layer of vessel wall

tunica intima is the…

endothelium of simple squamous epithelium

tunica media

middle layer of vessel, circularly arranged layers of smooth muscle cells with elastic fibers

contraction of tunica media causes…

vasoconstriction, narrows lumen

relaxation of tunica media causes…

vasodilation, widens lumen

tunica externa

outermost layer of vessel, areolar connective tissue with elastic collagen fibers

tunica externa helps…

anchor vessel to other structures

tunica externa may contain…

vasa vasorum

vasa vasorum

small arteries required to supply very large vessels

companion vessels…

lie next to each other

arteries have…

thicker tunica media and narrower lumen

arteries have more…

elastic and collagen fibers, spring back to shape

veins have…

thicker tunica externa and larger lumen

veins have less…

elastic and collagen fibers

vein wall collapses if…

no blood in vessel

capillaries only…

contain tunica intima, no subenthothelial layer

capillaries are composed of….

endothelium and basement membrane

thin capillary walls allow for…

rapid gas and nutrient exchange

arteries branch into smaller vessels that…

extend from the heart

elastic arteries, conducting

largest arteries, conduct blood from heart to muscular arteries

muscular arteries, distributing

medium arteries, distribute blood to specific body regions

internal elastic lamina, muscular arteries

between tunica intima and tunica media

external elastic lamina, muscular arteries

between tunica media and tunica externa

arterioles

smallest arteries, regulate blood pressure and blood flow

afferent arteriole

enters renal corpuscle, some blood plasma filtered

efferent arteriole

blood exiting glomerulus, branches into peritubular capillaries or vasa recta

capillary charateristic

small vessels connecting arterioles to venules

erythrocytes travel…

single file, rouleau

continuous capillaries

endothelial cells form a continuous lining, tight junctions connect cells but dont form a complete seal

intercellular clefts

gaps between endothelial cells of capillary wall

fenestrated capillaries

continuous lining but have fenestrations, pores

fenestrated capillaries are found in…

areas where much fluid transport happens

sinusoid capillaries

endothelial cells form an incomplete lining with large gaps

the basement membrane of sinusoids are…

incomplete or absent

sinusoids are found in…

bone marrow, spleen, some endocrine glands

capillary beds

groups of capillaries functioning together

capillary beds are fed by…

metarteriole

metarteriole

vessel branch of an arteriole

true capillaries

vessels branching from meterteriole

precapillary sphincter

smooth muscle ring at true capillary origin

vasomotion

cycle of contracting and relaxing of precapillary sphincters

perfusion

amount of blood entering capillaries per unit time per gram of tissue

systemic veins

blood reservoirs

at rest, amt of blood in systemic circulation

70%

systemic veins amt of blood at rest

55%

systemic arteries amt of blood at rest

10%

systemic capillaries amt of blood at rest

5%

pulmonary circulation has…of blood

18%

heart has… blood

12%

venules

smallest veins, merge to form veins

portal system

two capillary beds in sequence

degree of vascularization:

extent of vessels in a tissue

metabolically active tissues have…

high vascularity

angiogenesis:

formation of new vessels

regression

return to previous state of blood vessels

vesicular transport

endothelial cells use pinocytosis and exocytosis

bulk flow

fluids flow down pressure gradient

hydrostatic pressure, HP

force exerted by a fluid

blood hydrostatic pressure, HPb

forced exerted per unit area by blood on a vessel wall

interstitial fluid hydrostatic pressure, HPif

forced of interstitial fluid on outside of blood vessel

colloid osmotic pressure, COP

the pull on water due to the presence of proteins, colloid

blood colloid osmotic pressure, oncotic pressure

draws fluid into blood due to blood proteins, promotes reabsorption

interstitial fluid colloid osmotic pressure

draws fluid into interstitial fluid

net filtration pressure, NFP

the difference between net hydrostatic pressure and net colloid osmotic pressure

net hydrostatic pressure

difference between blood and interstitial fluid hydrostatic pressures

net colloid osmotic pressure

difference between blood and interstitial fluid osmotic pressures

at the arterial end, NFP favors…

filtration

at the venous end, NFP favors…

reabsorption

lymphatic system…

picks up excess fluid not reabsorbed at venous capillary end, filters fluid, returns to venous circulation

total blood flow

amount of blood transported through vasculature per unit of time

myogenic response

smooth muscle in blood vessel wall keeps local flow relatively constant