62 Questions
Which type of vessel is comprised of a single layer of endothelial cells and are the smallest vessels in the cardiovascular system?
Capillaries
Which type of vessel cannot constrict or dilate?
Capillaries
Which type of vessel is involved in the regulation of total peripheral resistance (TPR) and local blood flow?
Arteries
Which type of vessel regulates the distribution of blood flow among the capillaries?
Terminal arterioles
Which type of vessel is an important area of exchange and is devoid of smooth muscles?
Postcapillary Venules
Which type of vessel has an important capacitance function?
Venules and small Veins
Which type of vessels have intermittent contraction of metarterioles/precapillary sphincters?
Capillaries
Which type of vessels have special types of 'pores' in certain tissues, such as the brain and kidney?
Capillaries
Which type of vessel forms anatomical shunts and is only present in special areas, such as the skin?
Arterial-venous anastomoses
Which type of vessel has tight junctions in the brain, limiting what can pass through?
Capillaries
Which type of vessel has fenestrated glomerular capillaries in the kidney?
Capillaries
Which type of nerves primarily innervate the small arteries and arterioles?
Sympathetic nerves (neural control
Which type of control is primarily involved in the regulation of systemic blood pressure?
Neural control
Which hormone is released from the adrenal medulla and affects the diameter of arterial vessels?
Epinephrine
Which factor's byproducts of tissue metabolism can causes the vascular smooth muscle to relax and the vessels to dilate?
Metabolic control
What happens to the arterial microvessels when the transmural pressure decreases?
They dilate
Which type of vessels release both vasoconstrictors and vasodilators?
Endothelial vessels
What is the final determinant of the diameter of the precapillary resistance vessels?
All of the above
Which type of vessels are involved in the regulation of total peripheral resistance (TPR) and local blood flow?
Arteries
Which type of vessel is predominantly influenced by metabolic and myogenic mechanisms and is less influenced by neural control compared to small arteries and arterioles?
Terminal arterioles
Which type of vessel is the primary site of exchange across the circulation, with extremely thin walls composed of a single layer of endothelial cells and a large surface area?
Capillaries
What is the approximate rate of diffusion of water back and forth across the capillaries compared to the rate of filtration and absorption?
4,000 times
How do the majority of dissolved gas and nutrient molecules move across the capillaries?
Diffusion
What is the net transfer of molecules governed by Fick's Law?
Diffusion
What does 'J' represent in Fick's Law equation?
Net quantity of substance moved per unit time (Flux)
What does 'P' represent in Fick's Law equation?
Capillary permeability to the substance
What does 'A' represent in Fick's Law equation?
Capillary surface area
What is the direction of net transfer of molecules according to Fick's Law?
From areas of high concentration to areas of low concentration
Which hormones affect the diameter of arterial vessels?
Epinephrine and Angiotensin II
What happens to the arterial microvessels when the transmural pressure increases?
They constrict
What type of control influences the contraction of smooth muscle cells in arterial microvessels?
Myogenic control
According to the Starling-Landis Equation, what is the formula for fluid movement across the capillary wall?
Fluid movement = k(Pc + pi_i ) - (Pi + pi_c )
What is the approximate fraction of plasma that is filtered as it passes through the capillaries?
1-2%
What determines the magnitude of filtration and absorption by the capillaries?
Hydrostatic and osmotic pressures
What is the role of plasma protein oncotic pressure in filtration and absorption?
It favors absorption
What is the relationship between lipid solubility and diffusion through capillaries?
Diffusion is restricted to lipid-insoluble molecules
Which pressure is responsible for filtration in the capillaries?
Capillary hydrostatic pressure (Pc)
Which pressure is responsible for absorption in the capillaries?
All of the above
What is the equation that describes fluid movement in the capillaries?
Fluid movement = k(Pc + πi) – (Pi + πc)
Why is the plasma osmotic pressure higher than interstitial fluid osmotic pressure?
Capillaries are impermeable to proteins
What is the approximate difference between plasma osmotic pressure and interstitial fluid osmotic pressure?
25 mmHg
What is the net movement of fluid when the fluid movement equation is positive?
Filtration
What is the net movement of fluid when the fluid movement equation is negative?
Absorption
What is the role of tissue hydrostatic pressure (Pi) in filtration?
It inhibits filtration by decreasing capillary hydrostatic pressure
Which of the following factors INCREASES capillary hydrostatic pressure?
INCREASE IN Systemic arterial or venous pressure
What is the major function of lymphatics?
To return interstitial fluid and plasma proteins into the blood
What happens to capillary pressure when there is an increase in venous pressure?
Capillary pressure increases
Which of the following factors influences tissue hydrostatic pressure?
All of the above
What happens to capillary pressure when there is an increase in arteriolar resistance?
Capillary pressure decreases
What is the function of lymphatics in edema formation?
To return interstitial fluid and plasma proteins into the blood
How is interstitial fluid collected in the lymphatic system?
By terminal lymphatic capillaries
What propels lymph flow through the lymphatic system?
Spontaneous contractile activity of the lymphatic vessels and intermittent skeletal muscle contractions
Which of the following factors influences capillary hydrostatic pressure?
All of the above
What does an imbalance between the forces causing filtration and those causing absorption result in?
Edema formation
Under normal conditions, how is the interstitial fluid contained?
In a gel with no bulk flow of free fluid
Which of the following is the only mechanism for a net transport of plasma proteins into the blood?
Lymphatics
How is interstitial fluid collected in the lymphatic system?
By terminal lymphatic capillaries
What is the major function of lymphatics?
To collect and return interstitial fluid to the blood circulation
What does the osmotic pressure gradient across the capillary depend upon?
Plasma protein concentration
Which of the following is true about capillary hydrostatic pressure?
Greater resistance in venules and veins increases capillary hydrostatic pressure
What happens to capillary pressure when there is a decrease in arterial or venous pressure?
Capillary pressure decreases
What effect does greater resistance in venules and veins have on capillary pressure?
Greater resistance in venules and veins increases capillary pressure
Test your knowledge on capillaries and their role in the cardiovascular system. Learn about their structure, function, and their involvement in regulating blood flow and resistance.
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