fundamentals of circulation: Physiology and pathology of O2 Delivery and Perfusion

Question 1

what is hemodynamics

Answer 1

how blood flows through the cardiovascular system

Question 2

what is heterogenous

Answer 2

from different origins

Question 3

what are factors used to describe blood flow

Answer 3

• continual changing of the dimensions of blood vessels
• different physical and chemical stimuli to the heart muscle
• blood is not a uniform fluid but a heterogenous mixture of cells and proteins

Question 4

what is velolcity

Answer 4

Velocity- the linear displacement of fluid per unit of time

Question 5

what is cross-sectional area

Answer 5

Cross-sectional area (A)- the area the fluid moves through in any given section of the blood vessel by pi^2

Question 6

what is flow

Answer 6

flow (q)- the volume of fluid that passes through vessel per unit of time

Question 7

how do you calculate blood flow

Answer 7

blood flow Q=VA

Question 8

what is laminar flow

Answer 8

• streamlined flow
• flow that occurs in concentric layer as the layers slide past each other at different velocities

Question 9

what happens to fluid in laminar flow

Answer 9

fluid at the center will flow at the highest velocity but fluids in periphery will flow much slower due to higher frictional resistance

Question 10

what is a turbulent flow

Answer 10

• involves rapid mixing which can disrupt normal laminar flow
• much higher pressure is necessary to maintain a constant flow
• less efficient
• if theres prolonged turbulence it may lead to hypertension

Question 11

How does blood flow

Answer 11

• blood flows down a pressure gradient
• flow is pulsatile in the aorta and large arteries and becomes laminar in the capillaries and veins

Question 12

what is pulmonary circulation

Answer 12

Question 13

where is the mitral valve

Answer 13

left atrium and left ventricle

Question 14

where is the aortic valve

Answer 14

between left ventricle and aorta

Question 15

where is the tricuspid valve

Answer 15

between right atrium and right ventricle

Question 16

where is the pulmonary valve

Answer 16

between right ventricle and pulmonary artery

Question 17

what side of the heart has a lower pressure

Answer 17

right

Question 18

what happens if there is an issue with the aortic valve

Answer 18

Left ventricle and aorta systolic pressures will be different

Question 19

what happens if there is an issue with the pulmonary valve

Answer 19

the right ventricles and pulmonary artery systolic pressures will be different

Question 20

what happens if there is an issue with the mitral valve

Answer 20

difference in left atrium and left ventricle diastolic pressure

Question 21

what happens if there is an issue with the tricuspid valve

Answer 21

difference in the right atrium and right ventricle diastolic pressure

Question 22

which has a higher arterial mean pressure: arteries in the systemic or pulmonary system

Answer 22

systemic

Question 23

what are the arterial walls like in systemic circulation

Answer 23

thick
elastic

Question 24

what are the arterial walls like in pulmonary circulation

Answer 24

thin
distensible

Question 25

what are lumens of arterioles in systemic circulation like

Answer 25

small

Question 26

what are lumens of arterioles in pulmonary circulation like

Answer 26

large

Question 27

what is the resistance of the arterioles in systemic circulation like

Answer 27

high

Question 28

what is the resistance of the arterioles in pulmonary circulation like

Answer 28

low

Question 29

what are arterioles response to hypoxia in systemic circulation

Answer 29

vasodilation

Question 30

what are arterioles response to hypoxia in pulmonary circulation

Answer 30

vasoconstriction

Question 31

what is the wall thickness like for capillaries in systemic circulation

Answer 31

thin

Question 32

what is the wall thickness like for capillaries in pulmonary circulation

Answer 32

thin

Question 33

what is the flow like for capillaries in systemic circulation

Answer 33

continuous

Question 34

what is the flow like for capillaries in pulmonary circulation

Answer 34

pulsatile

Question 35

which has a higher venous mean pressure: veins in the systemic or pulmonary system

Answer 35

pulmonary

Question 36

which has a higher venous capacity : veins in the systemic or pulmonary system

Answer 36

systemic

Question 37

what is autoregulation

Answer 37

Maintains relatively constant flow over a wide range of blood pressures

Question 38

what are the blood flow control mechanisms

Answer 38

- metabolic demand - myogenic (originating from muscle) response - local vasoactive mediators - autonomic nervous system - hormones

Question 39

how does metabolic demand control blood flow

Answer 39

low O2, high CO2 and low pH cause vasodilation

Question 40

how does myogenic response control blood flow

Answer 40

arteriolar smooth muscle contraction in response to stretch- to maintain a certain pressure

Question 41

how does local vasoactive mediators control blood flow

Answer 41

- vasodilators: e.g. adenosine, NO - vasoconstrictors: eg endothelin

Question 42

how does the autonomic nervous system control blood flow

Answer 42

- external control - basal sympathetic tone and responses

Question 43

how do hormones control blood flow

Answer 43

external control

Question 44

what is a portal system

Answer 44

2 sets of capillaries in series

Question 45

what are the steps of renal circulation

Answer 45

liver secrets angiotensinogen angiotensinogen binds with renin --> angiotensin I angiotensin I binds with Lung/renal endothelial ACE (more lung compared to renal)--> angiotensin II

Question 46

what happens overall when renal arterioles are constricted

Answer 46

increases overall resistance & reduces renal flow

Question 47

what happens when renal afferent arterioles are constricted

Answer 47

decreases GFR- glomelular filtrate rate

Question 48

what happens when renal efferent arterioles are constricted

Answer 48

increased GFR

Question 49

what is blood flow controlled by in renal

Answer 49

- Autoregulation - Renin-angiotensin-aldosterone system - Tubulo-glomerular feedback

Question 50

how is cerebral blood flow autoregulated

Answer 50

maintains constant flow for mean arterial pressures Low pH and high CO2 levels increase flow to wash out H+ and excess CO2 Oxygen is a weaker controller Flow only increases when PaO2 is very low

Question 51

how is skin blood flow autoregulated

Answer 51

Arteriolar constriction Arteriovenous anastomoses that bypass capillary beds

Question 52

what are the control mechanisms for autoregulation of the skins blood flow

Answer 52

Sympathetic nervous system Skin ambient temperature receptors NO local metabolic control

Question 53

how is skeletal muscle blood flow autoregulated

Answer 53

vasodilation due to tissue hypoxia (low PaO2) High CO2, low pH (lactic acid), high K+ Local mediators, eg adenosine, NO Sympathetic nervous system (b2 vasodilation)

Question 54

what happens to blood flow during fight or flight response

Answer 54

To skeletal muscles and the heart (b2 – mediated vasodilation) Away from skin, kidneys, GI system (a1 – mediated vasocontriction) But… Blood flow to the brain is preserved (autoregulation)

Question 55

what is ischemia

Answer 55

Blood flow to a part of the body is inadequate to meet the metabolic demands of the tissue Oxygen Nutrients Removal of waste products (eg CO2)