blood vessels i

humans have a closed circulatory system which means

blood never leaves vessels; deliver nutrients to body areas and take wastes away

what is the circulation of blood, starting with heart

heart, elastic arteries - muscular arteries - arterioles - capillaries - venules - small veins - large veins

what is function of capillaries

fluid, nutrients and gasses are exchanged with tissues

which vessels are larger

those near the heart

blood vessel walls are made of three layers (name from innermost - outermost)

tunica intima, tunica media, and tunica externa

tunica intima is the innermost layer that is lined with endothelial tissue, specifically

squamous epithelial cells

what is function of tunica intima

barrier that keeps wbcs inside of bloodstream, immune recruitment, hemostasis (paracrine) and filtration

what is intima damage

damage to the intima of arteries in which endothelial cells release inflammatory chemicals that lead to inflammation

intima damage leads to inflammation that can lead to

plaque buildup and clotting

what are risk factors for intima damage

obesity, diabetes, smoking, age and high fat diets

what blood vessel layer/tunic has smooth muscle cells and elastin sheets (allow for stretch and strength)

tunica media

what subdivision of nervous system controls tunica media; what does it do

sympathetic nervous system; vasoconstriction and vasodilation

sympathetic nervous system is responsible for

regulating heart rate through vasoconstriction and vasodilation

tunica externa is

outermost blood vessel layer; supportive connective tissues with tiny blood vessels (vasa vasorum) to supply nutrients to cells within the layers

what is vasa vasorum

series of blood vessels located on outside of vessel layer to feed the vessel walls

what are the three types of arteries

elastic (conducting), muscular (distributing) and arterioles (resistance vessels)

why do arteries have thicker walls

withstand more pressure = more blood in lumen

out of all three artery types has a larger diameter, most elastic (stretchy)

elastic arteries

elastic arteries are considered __ which means what

pressure reservoirs; stores pressure from systole (left ventricle) and use it to move blood forward

what is atherosclerosis and its complications

hardened arteries that require increased blood pressure to push blood through

afterload leads to

loss of elasticity and loss of continuous flow

with atherosclerosis, weakened arteries (due to high pressure) balloon out:

aneurysm

what is the most common place to have an aneurysm

abdomen

what are common symptoms/signs associated with abdominal aortic aneurysm

abdominal/back pain, pulsating mass near belly and bruit

what is bruit

turbulent blood flow due to increased space from aneurysm

what is abdominal aortic aneurysm caused by

HTN, atherosclerosis, vessel disease and trauma

what is function of muscular (distributing) arteries

distribute blood to different body and organ areas

muscular arteries are composed of more __ and less elastic

smooth muscle

due to smooth muscle associated with muscular arteries, it is most active in

vasoconstriction that allows for blood to keep moving forward at lower pressures

what type of arteries are these: renal and gonadal arteries

muscular arteries

which artery type if smallest of all arteries, transition to capillaries

arterioles

larger arterioles all have 3 tunics while smaller have

1 tunic

why are arterioles considered resistance vessels

due to smaller diameter which makes it harder to blood to flow

decreased diameter =

more resistance for blood flow

arterioles due to their diameter size allows

blood flow to bypass tissues when necessary

what controls diameter size in resistance vessels (arterioles)

neural (sympathetic), hormonal (epinephrine) and chemical triggers

what is injected during facial surgery to decrease bleeding

epinephrine

what are the smallest blood vessels

capillaries

why is the diameter of capillaries only slightly larger than an erythrocyte

to allow for rapid diffusion

what layers do capillaries have

single layer of endothelial cells (simple squamous)

capillary types include (continuous, fenestrated and sinusoid) are determined by their

permeability (how easily substances can pass through walls)

what are the three types of capillaries

continuous, fenestrated and sinusoid

what type of capillary is the least permeable since it contains the most tight junctions

continuous capillary

where are continuous capillaries located

skin, muscles, lungs and CNS (areas where we don’t want H20 loss)

blood brain barrier is an example of continuous capillaries because

those endothelial cells lack intracellular clefts and have tight junctions that surround it

continuous capillaries contain tight junctions to

slow passage of substances and protect tissues from rapid concentration changes that occur in blood plasma

what type of capillaries are found in areas where filtration or absorption occur

fenestrated

fenestrated capillaries are found in which organs

kidneys, intestines and endocrine organs

fenestrated capillaries are found in areas where filtration or absorption occur to allow for

rapid fluid exchange with interstitial space or lumen of tubular structure

what is unique about sinusoid capillaries

large fenestrations and intrercellular clefts allowing proteins, fluid and cells to be exchanged, incomplete basement membranes and few tight junctions

within the sinusoid capillary, what type of wbc can extend processes through the clefts to clean the blood of foreign invaders/particles during increased tissue-blood contact in liver and spleen

macrophages and phagocytes

what type of capillaries are most permeable and occur in liver, bone marrow and spleen

sinusoid

capillary beds are considered

smallest vessels

capillary beds are controlled by

arteriole diameter and precapillary sphincters

what is a precapillary sphincter (least common)

round piece of CT that can contract and prevent capillary beds from filling and instead goes through vascular shunt

where are precapillary sphincters found

mesenteries and brain

veins have thin walls (especially tunica media) with large lumen because

job is to only collect not distribute the same amount of blood as arteries that have higher pressure

veins and venules carry at least __ of the blood at any one time because of higher diameter, making them a __

60%; blood reservoir

what is function of venous valves

prevent backflow of blood in low pressure lumen

venous valves resemble semilunar valves that are found in most veins except for

thoracic or abdominal cavities

what are varicose veins

incompetent veins when venous valves cannot withstand high pressure and therefore become twisted leading to backflow

what are venous sinuses

enlarged endothelium without tunics collect fluid

what provides alternative route for blood (also called collateral channels)

anastomoses

right coronary artery makes anastomoses with

circumflex artery

posterior interventricular artery makes anastomoses with

anterior interventricular artery (LAD)

anterior communicating artery makes anastomoses with

posterior communicating artery

anastomoses are more common in veins or arteries

veins

force of contraction equation

F = P/R

force of contraction = __ at rest under normal conditions

cardiac output

if cardiac output is 5l/min and resistance factor is 20, what is systolic pressure

100

increase in resistance factor increases

pressure and force of contraction

in atherosclerosis, decrease in diameter does what to resistance, pressure and force

increases