Systemic circulation basic concepts only

Question 1

Pulmonary Circulation

Answer 1

blood is pumped from the right atrium to the right evntricle through the pulmonary artery, pulmonary capillaries, and pulmonary vein back to the left atrium

Question 2

Systemic Circulation

Answer 2

blood is pumped from the left atrium to the left ventricle, through the aora, systemic capillaries, and vena cava and back to the right atrium

Question 3

Cardiac output (define)

Answer 3

volume of blood per unit time that is pimped out of either the right or left ventricle (for a 70 kg person usually about 5 L/min)

Question 4

what component of blood influences its viscosity

Answer 4

hematocrit

Question 5

Aorta and large arteries

Answer 5

greater amounts of elastic in their walls (high elastance) which when changed allows for expansion and recoil

Question 6

resistance vessels

Answer 6

small arteries, arterioles, and precapillary sphincters - capable of relatively large adjustments in their cross sectional area.

Question 7

Capacitance vessels

Answer 7

Veins. Ability to accommodate the majority of any blood volume added to circulation . Contraction of smooth muslce in their walls allows blood to be moved form the peripheral venous system pool to the central venous system pool wher eit can be pumped by the heart.

Question 8

where is blood “storage”

Answer 8

Most blood “storage” is within small veins

Question 9

Compare the elastance and compliance of arteries and veins

Answer 9

Arteries have greater stiffness (elastance) and less compliance than veins

Question 10

“unstressed” volume

Answer 10

the blood that “fills” the heart when transmural pressure is essentially zero

Question 11

what property determines where blood goes

Answer 11

Stiffness/compliance of the vessels

Question 12

Capacitance

Answer 12

volume of blood in a vessel at a given pressure. Veins have a higher capacitance to store blood (i.e at the same pressure as an artery the vein would contain a higher volume of blood)

Question 13

Mean circulatory pressure depends on what two factors

Answer 13

total blood volume and compliance of arteries and veins. In humans usally about 7 mmHg

Question 14

change in vascular cross sectional area

Answer 14

cross sectional area increases with branching

Question 15

hydrostatic effects

Answer 15

gravity causes lower pressures in the head vessels and higher pressures in the leg and foot vessels

Question 16

what determines venous conductance

Answer 16

venomotor tone

Question 17

what two factors prevent fluid translocation across the capillary walls of dependent tissues under normal circumstances

Answer 17

1.) venous valve system 2.) Skeletal muscle pump (forces blood toward the heart)