ch 22- Vessels & circulation

arteries

deliver blood to arterioles in tissues

arterioles deliver blood to...

capillaries

capillary walls

where substances are exchanged

venules (blood flow)

drain blood from capillaries into veins

veins

return blood to the heart

3 layers of blood vessels

Intima, media, adventitia

intima

innermost layer of simple squamous epithelium on top of an internal elastic membrane

artery walls

thicker to withstand pressure of the heart

vein walls

thinner allowing them to stretch and contain more blood

thick vessels

too thick for diffusion of gasses and need to get their blood from vasa vasorum

elastic arteries

closest to heart. withstand high pressure. 1.5cm lumen and thick walls.

elastic artery media

prominent elastic membranes and less muscle

examples of elastic arteries

pulmonaries, aorta, carotids, subclavians, common iliacs

muscular arteries

further from heart, moderate pressure, .4cm lumen and wall thickness, media is smooth muscle

examples of muscular arteries

femoral, ex. carotids, brachials, mesenterics

arterioles

vessels within tissues, low pressure, microscopic, thin adventitia, 1-2 layers of smooth muscle media

capillaries

low pressure vessels within tissues, microscopic, only consist of intima, thin enough for nutrient exchange

3 types of capillaries

continuous, fenestrated, sinusoid

continuous capillaries

tight junctions, desmosomes, and pinocytes. movement by passive diffusion and active transport

where are continuous capillaries found?

dermis, CNS, PNS, muscles, and lungs

fenestrated capillaries

porous, small proteins and anything smaller that will leak out of plasma

where are fenestrated capillaries found?

kidneys, intestines, endocrine glands, choroid plexuses

sinusoid capillaries

flattened with large gaps between intima cells. all plasma components

Where are sinusoid capillaries found?

red marrow, spleen, and liver

capillary beds

interconnected networks between arterioles and venules

precapillary sphincters

smooth muscle rings that regulate blood flow into the capillary

thoroughfare channels

an arteriole through the bed. allows blood flow when bed is closed off

arteriovenous anastomosis

an arteriole around the bed. allows blood flow when the bed is hindered by postural changes

venules

vessels within tissues, low pressure, microscopic, thin adventitia, lack complete media, few scattered muscle cells

medium veins

furthest from heart, low pressure, .4cm lumen and thin walls, thin media with little muscle, thick adventitia, valves

examples of medium veins

radial, ulnar, femoral

large veins

closer to heart, low pressure, 2cm lumen and thin walls, thin media with little muscle, thick adventitia

examples of large veins

superior/inferior vena cava, renal, mesenteric, portal

blood reservoir

additional blood in venous circulation

what occurs to move blood reservoir along to arteries quicker?

smooth muscles in veins contract

valves

flap-like folds of media projecting inward to stop backflow

skeletal muscle pump

contraction of muscles squeeze veins and push blood through

thoracoabdominal pump

expansion of thoracic cavity expands veins pulling blood through

arterial development

superior heart tubes branch into 6 sets of pharyngeal arches arteries

what happens to the 1st, 2nd, and 5th sets?

they disappear

forms carotid arteries

3rd set

forms brachiocephalic trunk and aorta

4th set. connect at left ventricle

forms pulmonary arteries

6th set. connect at right ventricle

venous development

inferior heart tubes become sinus venosus and 3 major sets of veins

sinus venosus becomes...

part of right atrium

umbilical veins

bring blood with nutrients from mother to fetus

umbilical veins right vs left

R: atrophies at week 12

L: branches into hepatic portal vein/ atrophies after birth

anterior cardinal veins

veins superior to heart. ex. vena cava, jugulars, brachiocephalics, subclavians

posterior cardinal veins

separate to become iliacs

where does the inferior vena cava develop from?

vessels in the liver. connects heart to iliacs, kidneys, and digestive system

pulmonary circuit

short. 9% of blood total. vein= oxygenated. arteries= deoxygenated

pulmonary circuit pathway (deoxygenated blood)

right ventricle -> pulmonary trunk/arteries -> lungs. blood is oxygenated in alveolar capillaries

pulmonary circuit pathway (oxygenated blood)

is sent out of the lungs through the pulmonary veins to the left atrium

systemic circuit

long with 84% of blood total. arteries= oxygenated. veins= deoxygenated

systemic circuit pathway (oxygenated blood)

left ventricle -> aorta -> muscular arteries, arterioles -> nutrients and oxygen delivered to peripheral tissues

systemic circuit pathway (deoxygenated blood)

blood is sent back through venules, medium veins, and large veins to the right atrium