Blood Vessels Flashcards
What are the three layers of veins and arteries?
The tunica intima, tunica media, and tunica externa
The diameter of the lumen is wider in veins or arteries?
Veins
What is in the tunica intima?
Endothelium, subendothelial layer, internal elastic membrane (in arteries)
What is in the tunica media?
smooth muscles and elastic fibers as well as more external elastic membrane (in arteries)
What is in the tunica externa?
It is rich in collagen fibers and has vasa vasorum which are tiny blood vessels that serve the heart wall.
What do veins have that arteries don’t?
Valves
What is the makeup of a capillary?
A basement membrane outside of endothelial cells
What are the three types of arterial vessels? What are their characteristics?
Elastic Arteries are thick walled, large diameter, and are close to the heart
Muscular arteries distribute blood to organs and have more smooth muscle than elastin due to a more even pressure
Arterioles generally have a tunica media of entirely smooth muscle and determine which capillary beds are flushed
What substance is found a lot in elastic arteries?
Elastin
What are the three types of capillaries? Where are they found?
Continuous capillaries (least leaky), skin, brain, muscles
Fenestrated Capillaries, small intestine, kidneys, endocrine
Sinusoidal capillaries (most leaky), liver, bone marrow
What is microcirculation?
It is the flow of blood from an arteriole to a venule through a capillary bed
What is a true capillary
An actual exchange vessel
What are some factors aiding venous return?
- Venous valves plus the muscular pump
- The respiratory pump (decrease pressure in thoracic cavity)
- Sympathetic vasoconstriction
What is the formula for pulse pressure?
Systolic P - Diastolic P
What is the formula for MP?
Diastolic + 1/3 pulse pressure
How is resistance measured?
Proportional to = Length*viscosity / radius ^ 4
Where is most blood found?
The venous system
Why are pressure points called that?
They are areas where when pressure is applied it closes down the artery.
How would one treat short term and long term blood pressure issues?
Short term would deal with resistance (blood vessel diameter), and long term help would be needed at the kidney level
What is the vasomotor tone?
It is a constant output of NE to arterioles
Where is the vasomotor center located?
The medulla
Where does vasomotor input come from?
Baroreceptors, chemoreceptors, and higher brain centers
Where are baroreceptors found?
The carotid sinuses and aortic arch
What does increased MAP lead to?
dilation of arterioles, venodilation, and inhibition of the symp ns
What happens of O2 is too low, or CO2 concentration is too high?
chemoreceptors will reflexively vasoconstrict and speed the return of blood to the heart and lungs
What are the 4 blood pressure hormones?
Adrenal medulla hormones = NE
Angiotensin II = generalized vasoconstriction, also release of long term hormones
ANP = generalized vasodilation
ADH = long term vasoconstriction, a lot at once can lead to vasoconstriction in severe cases
What is direct renal mechanism?
increased water volume/pressure causes increased filtrate
What is indirect renal action?
If MAP decreases, the kidneys will undergo reactions to yield angiotensin II, which secretes aldosterone, which increases absorption of Na+, and ADH also promotes water reabsorption
What is myogenic control of veins?
It is a response to stretch with increased tone to vasoconstrict, but decreased stretch = vasodilation
What is the result of myogenic vein control?
homeostasis so cells aren’t deprived in low bp and capillaries aren’t damaged in high bp
How close does a cell need to be to a capillary?
0.02mm
What is NFP?
Net filtration pressure is the outwards pressures minus the inward pressures
