blood vessels Flashcards
define systemic vessels and pulmonary vessels
SYSTEMIC VESSELS: transport blood through most body parts from the left ventricle and back to the right atrium
PULMONARY VESSELS: transport blood from the right ventricle through lungs and back to left atrium
name the 5 types of capillaries, describe and give examples
- continuous - no gaps between endothelial cells, less permeable to large capillary types, eg, muscle, nervous tissue
- fenestrated - have pores and are where cytoplasm is absent and plasma membrane is thin, eg, intestinal villi, glomeruli or kidney
- sinusoidal - large diameter with large capillaries, eg, endocrine glands.
- sinusoids - large diameter sinusoidal capillaries, eg, liver, bone marrow.
- veneous sinuses - small in structure, eg, spleen
list the layers of a blood vessel wall and state the function of each
TUNICA INTIMA - endothelial, basement membrane, internal elastic membrane, fenestrated layer of elasrtic fibres
TUNICA MEDIA - allows for vasodilation and vasoconstriction
TUNICA EXTERNA - connetive tissue, merges with surrounding C.T.
describe muscular and elastic artery
elastic artery -
largest diameters, pressure high and flucatuates between systolic and diastolic. eg, tunica intima and thin tunica externa
muscular artery - smooth muscle allows to regulate blood supply by constricting or dilating. distributes to different regions of the body.
define arterioles and state its function
transport blood from small arteries to capillaries
smallest arteries where three tunics can be differentiated
like small arteries, capable of vasoconstriction and dilation
define venules and small veins
VENULES - drain capillary network, Endothelial cells and basement membrane with a few smooth muscle cells. As the diameter of venules increases, the amount of smooth muscle increases.
SMALL VEINS - Smooth muscle cells form a continuous layer. Addition of tunica adventitia made of collagenous connective tissue
define vasa vasorum
blood vessels that supply the walls of arteries and veins. Penetrate the vessel walls from the exterior. Branches of arteries.
define portal veins
veins that begin in a primary capillary network, extend some distance and end in a secondary capillary network without a pumping mechanism, such as the heart, between (eg hepatic portal vein).
define the neural innervation of blood vessels
Unmyelinated sympathetic nerve fibers form plexi in tunica adventitia: vasoconstriction
Small arteries and arterioles innervated to greatest extent
Vessels of penis and clitoris innervated by parasympathetic
Some blood vessels innervated by myelinated fibers and act as baroreceptors that monitor stretch and detect changes in blood pressure
define vasoconstriction and vasodiation
vasoconstriction - Vasoconstriction is narrowing or constriction of the blood vessels. It happens when smooth muscles in blood vessel walls tighten.
vasodilation - the widening of blood vessels, happens naturally in your body when an increase in blood flow to tissues in your body is needed.
what are some of the arterial changes that occur with age?
arteriosclerosis - General term for degeneration changes in arteries making them less elastic
atherosclerosis - Deposition of plaque on walls
what does pulmonary circulation do?
moves blood to and from the lungs
includes:
PULMONARY TRUNK - arises from right ventricle
PULMONARY ARTERIES - branches of pulmonary trunk which project to lungs
PULMONARY VEINS - exit each lung and enter left atrium
what is systemic circulation and what does it include?
all arteries:
AORTA:
- from which all arteries are derived either directly or indirectly
- branches into ascending, descending, thoracic, abdominal.
CORONARY ARTERIES
- supply the heart
give examples of where baroreceptors are located?
carotid arteries
aorta
and other larger arteries in the neck
what is blood pressure and how is it measured?
measure of the force exerted by blood against the vessel wall.
measured by listening (auscultation) for Korotkoff sounds produced by turbulent flow in arteries as pressure is released from a blood pressure cuff
what is laminar flow ?
a streamlined blood flow; interior of blood vessel is smooth and of equal diameter along its length
Outermost layer moving slowest and centre moving fastest
what is turbulent flow?
Interrupted flow
Rate of flow exceeds critical velocity
Fluid passes a constriction, sharp turn, rough surface
Partially responsible for heart sounds
Sounds due to turbulence not normal in arteries and is probably due to some constriction
list the factors that are involved in the dynamics of blood flow
Rate of flow through a tube is expressed as the volume that passes a specific point per unit of time. E.g.; cardiac output at rest is 5L/min, thus blood flow through the aorta is 5L/min
Flow = (P1 – P2/R)
P1 and P2 are pressures in the vessel at points one and two; R is the resistance to flow
Directly proportional to pressure differences, inversely proportional to resistance
define poiseuille’s law
flow decreases when resistance increases and vice versa.
eg, during exercise, the heart beats with greater force, increasing the blood pressure in the aorta. capillaries located in skeletal muscles increase in diameter, decreasing resistance and increasing flow. Flow in the aorta can increase from 5L/min to 25L/min.
define viscocity
the measure of resistance of liquid to flow eg, a lid sliding on top of a container of water, which will make the water move as it is in direct contact.
as viscocity increases, pressure required to flow increases. eg, water has low viscocity, honey has higher.
viscosity greatly influenced by hematocrit (% of composition of red blood cells). eg, dehydration of RBS will increase viscosity
define laplace’s law
force acting on blood vessel wall is proportional to diameter of the vessel x blood pressure
F = D x P, thus a diameter of a vessel increase, force on the wall increases. weakened part of a vessel wall bulges out and is an aneurysm.
what is vascular compliance?
the tendency for blood vessel volume to increase as blood pressure increases.
eg, venous system has a large compliance and acts as a blood reservoir.
what is the systemic circulation determined by?
- anatomy of circulatory system
- dynamics of blood flow
- regulatory mechanisms that control heart and blood vessels
what is the difference between systolic and diastolic pressures?
systolic - the amount of pressure in your arteries during the contraction of your heart muscle.
diastolic - refers to your blood pressure when your heart muscle is between beats. This is called diastolic pressure
Increases when stroke volume increases or vascular compliance decreases. . Compliance tends to decrease with age (arteriosclerosis) and pressure rises.
