ch 19--Blood Vessels

blood vessels

delivery system of dynamic structures that begin and end at the heart

consists of lumen and surrounded by a cell wall

three different walls/layers of vessels: tunica intima, tunica media and tunica externa

arteries

carry blood away from the heart, oxygenated except for pulmonary artery

veins

carry blood to the heart, deoxygenated except for pulmonary vein

capillaries

in direct contact with tissue cells

endothelium with sparse basal lamina

vasa vasorum

blood supply to the artery itself

flow of arteries

heart

elastic arteries

muscular arteries

arterioles

capillaries

elastic arteries

thick walled, large, low-resistance lumen

found near the heart

high in elastin

muscular arteries

deliver blood to an organ

more smooth muscle and less elastic tissue

medium sized lumen

arterioles

feed into capillaries

control distribution of blood using vasodilation/vasoconstriction

capillaries

microscopic vessels, only a single RBC can pass through at a time

microcirculation, exchange of nutrients and wastes

joined by tight junctions called intracellular clefts

continuous capillaries

no gaps/holes, most abundant

fluids, ions, and gases (not whole molecules)

skin, muscles, lungs, central nervous system, blood brain barrier

fenestrated capillaries

found in areas involved in active filtration (kidneys, intestines, endocrine hormone secretion)

allows for greater permeability

sinusoidal capillaries (discontinuous)

large intracellular clefts, incomplete basement membranes, larger lumens

found only in bone marrow

allows large molecules and whole cells

capillary beds

interwoven network of capillaries between arterioles and venules

microcirculation, filtration, and reabsorption

regulate tissue blood flow

regulate leukocyte migration into lymph

blood flow of veins

capillaries

venules

small veins

large veins

the heart

aspects of veins

larger lumen, thinner walls and larger in size

BP is lower than arteries

venous valves and muscular pump help with blood return

venous valves

prevent backflow of blood

blood flow

volume of blood flowing through a vesse, organ, or entire circulation in a given period of time

blood pressure

force with which blood pushes against artery walls as it flows

measured in mm Hg (grams of mercury)

vascular resistance

opposition to blood flow

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

systolic pressure

artery pressure exerted during ventricular contraction

diastolic pressure

lowest level of artery pressure when heart rests

pulse

throbbing of an artery

systemic pressure

highest in aorta and declines throughout pathway

artery to measure blood pressure

brachial artery

normal heart rate

70-85/105-130

pulse pressure/compliance

the difference between systole and diastole numbers (usually 40)

represents the force the heart generates each time it contracts

most common pulse points

carotid, radial, posterior tibial, dorsalis pedis

bodily regulation of blood pressure

cooperation of heart, blood vessels, kidneys, and brain

cardiac output, peripheral resistance, and blood volume

cardiac output

stroke volume and heart rate

peripheral resistance

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

short term regulation

neural controls

control peripheral nervous system by regulating cardiac output and peripheral resistance

altering blood vessel diameter, increasing/decreasing heart rate, redistributing blood to organs

operate via reflex arcs

vagus nerve

lowers heart rate

sympathetic nerve fibers

raise heart rate and modulate blood volume size

baroreceptor reflexes

located in carotid, aortic arch, and walls of large arteries

stimulated when MAP is high, decreases blood pressure using vasodilation and decreased CO2

turned of when MAP is low, increase in CO2 and blood pressure

chemoreceptor reflexes

speed up return of blood to heart and lungs

aortic arch and large arteries detect increase in CO2 or O2

indicated that gas exchange is occuring at a slower ideal rate

HR increases, vasoconstriction, and increase in respiration

long term mechanism

renal regulation

control blood pressure by altering blood volume via the kidneys (directly and indirectly)

direct renal regulation

alters blood volume independently of hormones by altering the amount of urine/filtration in the kidneys

indirect renal regulation

RAA pathay, decreased arterial blood pressure causes release of renin from kidneys

angiotensin II stabilizes arterial blood pressure: stimulation secretion of aldosterone from adrenal gland, increase ATC release, thirst and vasoconstriction

tissue perfusion

flowing, delivery of blood or a tissue/organ to meet its “needs",” changes depend on what you are doing

capillary exchange

passage of gases and nutriets into tissues via diffusion

involves gas exchange, absorption, urine formation, delivery/removal of nutrients

regulated by arterioles that feed capillaries that can change their diamters

bulk flow

fluid leaves capillaries at arterial end and most returns to blood at venous end

vascular system differences

1. Arteries run deep only, veins run deep or superficial
2. Venous pathways are more interconnected, there are more veins than arteries
3. The brain and digestive systems have unique venous drainage systems

aorta

the largest artery; divided into sections:
ascending aorta, aortic arch, descending thoracic aorta, suprarenal aorta, infrarenal aorta

celiac trunk

branch off descending aorta, blood to most abdominal organs except the intestines and kidneys

hepatic portal vein

takes blood out of most abdominal organs, carries blood from small/part of large intestines, stomach, spleen, and the liver

superior mesenteric artery

off of aorta, supplies small and part of the large intestines

internal carotids artery

delivers blood from the heart to the brain

circle of willis

joining area of several arteries at the inferior of the brain, takes blood and evenly distributes it to the whole brain

great saphenous vein

longest vein in the body, running along the length of the lower limb, returning blood from the foot, leg and thigh

vessel branches off the aorta

right side has a trunk and branches

left side only has branches (no trunk)

common carotid branches

external—facial/temporal, skin and face muscles

internal—to the brain

vericose veins

dialated and painful veins due to incompetent (leaky) valves, resulting in elevated venous pressure and swelling

edema

abnormal increase in amount of interstatial fluid, can be caused by decreased drainage of interstitial fluid through lymphatic vessels that have been blocked by diseases or surgically removed

angiography

medical imaging technique used to visualize the inside of blood vessels, detects abnormalities or blockages in the blood vessels