Vascular System

Question 1

Hyperemia

Answer 1

Excess supply of blood

Question 2

Reactive Hyperemia

Answer 2

Myogenic & metabolic mechanism

Question 3

Active Hyperemia

Answer 3

Metabolic mechanism

Question 4

Angiogenesis

Answer 4

Growth of more capillaries - increase in s.a. - increased potential for greater flow

Question 5

Angiogenic Factors causes & examples

Answer 5

Decrease in O2 levels - increase in angiogenic factors

VEGF (vascular endothelial growth factor) makes endothelial cells grow, migrate & invade

Question 6

Anatomy of LHS coronary circulation

Answer 6

• Left main coronary
• LAD (left anterior descending artery) travels along intraventricular groove
• Circumflex artery travels posteriorly

Question 7

Anatomy of RHS coronary circulation

Answer 7

Right coronary artery runs posteriorly between RA & RV

Question 8

During systole

Answer 8

Marked compression of microvasculature (system of tiny blood vessels)

Question 9

Higher HR –>

Answer 9

Higher heart rate –> reduction in diastole –> mechanical reduction in time available for flow

Question 10

Intramural pressure is greatest in

Answer 10

Endocardium

Question 11

Blood flow equal between epi & endo

Answer 11

Despite intramural P greatest in endo - blood flow equal between epicardium & endocardium:
Higher vessel density in endocardium

Question 12

Major inducer of vasodilation in heart circulation

Answer 12

Adenosine

Question 13

How does Adenosine regulate VD:

Answer 13

Low levels of Ado - stimulate release of NO

Higher levels of ado - act directly on SMC

Question 14

Effect of sympathetic activation on coronaries

Answer 14

Sympathetic (norepinephrine) activation results in VD in coronaries

Question 15

Speed Up Diffusion

Answer 15

1) Thinner walls (thinner the membrane - faster diffusion rate)
2) Small molecular weight molecules (such as O2 & CO2 able to diffuse quicker)
3) Increase Pressure (increase O2 conc. - increase partial P of O2 across membrane - therefore faster diffusion rate)
4) Expand surface area (larger surface area
- higher diffusion rate)

Question 16

Functional Sympatholysis

Answer 16

Decreased VC during increase in sympathetic activity

1) Directly constricts via alpha 1 adrenoreceptor
2) Increased metabolic rate due to inotropy (increased strength of contraction), HR increases via beta-adrenoreceptors –> Functional Sympatholysis (overrides alpha 1)

Question 17

Primary role of cutaneous circulation

Answer 17

Heat exchange: mainly regulated by sympathetic activity controlled by hypothalamic thermoregulatory centers

Question 18

What holds the majority of blood volume in skin

Answer 18

Venous plexus

Question 19

Cardiac % - in cutaneous regulation

Answer 19

Low temp - 0-3%

Severe heat stress - can increase to 50%

Question 20

2 Stages of Vasodilation in Cutaneous Circulation

Answer 20

1 - Passive: reduction in sympathetic adrenergic activity - decrease in norephinerine - AVs dilate - increase flow
2 - Active: sympathetic cholinergic activity - acetylcholine stimulates VD

Question 21

Villi are supplied by what order arterioles & capillaries

Answer 21

Villi are supplied by 3rd order arterioles & capillaries

Question 22

Intestinal Circulation primary function

Answer 22

Nutrient & water absorption

Question 23

Capillaries in hepatic circulation termed

Answer 23

Sinusoids

Question 24

Cerebral perfusion pressure

Answer 24

Cerebral perfusion pressure = MAP - ICP

Question 25

Two systems in Pulmonary circulation:

Answer 25

1 - Bronchial system: supplies nutrients for lungs | 2 - Pulmonary system: supplies blood for gas exchange

Question 26

Pulmonary circulation haemodynamics & regulation

Answer 26

low pressure low resistance high compliance

Question 27

T/F: pulmonary circulation has autoregulation

Answer 27

F - does not have autoregulation of flow but does have autoregulation of pressure

Question 28

Coronary circulation: (1) Sympathetic, (2) Metabolic, (3) autoregulation control

Answer 28

1- Sympathetic control = weak 2 - metabolic control = strong 3 - autoregulation = strong

Question 29

Cerebral circulation (1) sympathetic, (2) metabolic & (3) autoregulation

Answer 29

1) sympathetic control = weak 2) metabolic control = strong 3) autoregulation = strong

Question 30

Skeletal muscle: 1 - sympat., 2- metabolic, 3 - autoregulation

Answer 30

1 - sympathetic control = moderate 2 - metabolic control = strong 3 - autoregulation = moderate

Question 31

Cutaneous circulation: 1 - sympathetic, 2 - metabolic, 3- autoregulation

Answer 31

1- sympathetic control = strong 2 - metabolic control = weak 3 - autoregulation = weak

Question 32

Intestinal circulation: 1 - sympathetic, 2 - metabolic, 3 - autoregulation

Answer 32

1 sympathetic control = strong 2 metabolic control = moderate 3 autoregulation = moderate

Question 33

Renal circulation - 1: sympathetic, 2: metabolic, 3: autoregulation

Answer 33

1 - sympathetic = strong 2 - metabolic = weak 3 - autoregulation = strong

Question 34

Pulmonary circulation: 1- sympathetic, 2 - metabolic, 3 - autoregulation

Answer 34

1 - sympathetic control = weak 2 - metabolic control = weak (hypoxic vasoconstriction - pulmonary arteries constrict in the presence of alveolar hypoxia) 3 - autoregulation = N/A

Question 35

During exercise - what mechanisms is used by skeletal muscle to increase flow

Answer 35

1 - Functional Sympatholysis 2 - Capillary recruitment 3 - Skeletal muscle pump X reactive hyperemia

Question 36

Interstitial hydrostatic pressure is generally very low due to mainly

Answer 36

Lymphatic system

Question 37

Major driving force for reabsorption of fluid in the circulatory system is:

Answer 37

Capillary oncotic pressure

Question 38

Increased sympathetic nerve activity causes the heart to experience

Answer 38

a - vasoconstriction b - vasodilation c - increased inotropy

Question 39

In which organ is its blood flow phasic in nature:

Answer 39

Heart