OVERVIEW OF CIRCULATION BERNE Flashcards
Pump of the heart that propels blood through the lungs for exchange of O2 and CO2
Pulmonary circulation
Pump of the heart that propels blood to all other tissues of the body
Systemic circulation
The unidirectional flow of the heart is achieved by appropriate arrangement of ________________
Flap Valves
Although cardiac output is intermittent, continuous flow to body tissues (periphery) occurs by:
Distension of aorta
and
Elastic recoil of walls of large arteries
The distribution of blood circulating to the different regions of the body is determined by:
Output of the LV
and
Contractile state of the resistance vessels (arterioles)
Blood entering the right ventricle via the right atrium is pumped through the pulmonary arterial system at a mean pressure about ______ that in the systemic arteries
One seventh
What layer predominates in arterioles, elastic or muscular?
Muscular
Frictional resistance reaches a maximal level in which blood vessels?
Arterioles
The “stopcocks” of the vascular system
Arterioles
Pressure drop is greatest across which segment of the small arteries and arterioles?
A. Initial
B. Elastic
C. Terminal
C. Terminal
Pulsatile arterial blood flow is caused by:
Intermittent ejection of blood from the heart
Pulsatile arterial blood flow is damped at the level of which blood vessels?
Capillaries
Pulsatile blood flow is dampened by the combination of which factors?
Distensibility (of large arteries)
and
Frictional resistance (in small arteries and arterioles)
What is the reason for the slow velocity of blood flow in the capillaries?
A. No muscular layer
B. Small cross-sectional area of individual capillaries than arterioles
C. Very large total cross-sectional areas of capillary bed
C. Total cross-sectional area is inversely proportional for the blood flow
Between the aorta and the capillaries, the total cross-sectional area increases about ____-fold
500
The volume of blood in the systemic vascular system is greatest in which blood vessels?
Veins and venules (64%)
How many percent of the volume of blood is found in the aorta, arteries and arterioles?
14%
Capillaries - 6%
Veins and venules - 64%
Which of the following is true?
A. The blood volume in the pulmonary vascular bed is about equally divided among the arterial, capillary, and venous vessels.
B. The cross-sectional area of the venae cavae is lesser than that of the aorta.
C. The velocity of blood flow is faster in the venae cavae than in the aorta
A.
The cross-sectional area of the venae cavae is greater than that of the aorta; thus, the velocity of blood flow is slower in the venae cavae than in the aorta
What effect does hyperthyroidism (Graves’ disease) have on arterioles and pulsatile flow?
Arteriolar vasodilation causing diminished dampening effect on pulsatile arterial pressure = pulsatile flow in capillaries (seen in fingernail beds)
