How the Cardiovascular System Fails

Question 1

Vessel Wall Compliance = stretchiness

Answer 1

• compliance = change in volume caused by a change in pressure
• gradient of black lines between corners on delta V against aortic pressure x

Question 2

Vessel wall compliance —— with age leading to

Answer 2

• decreases
• pathologies
• eg: atherosclerosis/calcification

Question 3

Atherosclerosis

Answer 3

• hardening of the arteries
• leading cause of heart attacks, strokes and
  peripheral arterial disease
• refers to the build-up of fats, cholesterol and other substances in and on the artery walls (plaque)
• which can restrict blood flow
• plaque can burst, triggering a clot

Question 4

Laminar flow diagram

Answer 4

• laminar flow
• slower at edges
• insert

Question 5

Is laminar or turbulent flow more likely in not smooth wall arteries? Why?

Answer 5

• turbulent
• higher velocity
• low fluid viscosity

Question 6

What causes turbulent blood flow?

Answer 6

• Junctions (eg: vessel branching)
• Obstacles (eg: foreign bodies)
• Mixing (eg: “holes in the heart”)

Question 7

Structure of the arterial wall diagram

Answer 7

Question 8

Atherosclerosis progression

Answer 8

Question 9

Atherosclerosis: Intimal Plaque:

Answer 9

• fatty streak leads to fibrous plaque leads to calcified plaque leading to plaque rupture
• can jump from fibrous plaque to plaque rupture

Question 10

Atherosclerosis: Medial Thinning:

• effect on compliance

Answer 10

• higher compliance results in adventitial erosion

Question 11

Two examples of vasodilator substances released by the endothelium

Answer 11

• nitric oxide
• prostacyclin

Question 12

Thrombogenic

Answer 12

• liable to provoke blood clotting
• either via the activation of platelets or the
  activation of the blood clotting cascade or
  activation of both

Question 13

Endothelial Function and Injury

Answer 13

• local control of vessel tone:
  
  • local control of perfusion
  • vasodilatation: NO, prostacyclin
• local control of thrombogenicity:
  
  • conceals collagen and plaque
    constituents
  • secretes antithrombotic factors (eg:
    prostacyclin)
• capillary filtration

Question 14

Plaque

Answer 14

• regions of build-up of fats, cholesterol and
  other substances in and on the artery walls,
  which can restrict blood flow. The plaque
  has a lipid rich core covered by a cap of
  fibrous tissue.
• the cap of the plaque can rupture revealing
  collagen and lipid

Question 15

Thrombus

Answer 15

• blood clot
• this forms here when blood is exposed to
  collagen and lipids, which activate platelets
  and the blood clotting pathways

Question 16

Myocardial Infarction - coronary thrombosis

Answer 16

• plaque rupture
• thin cap = vulnerable plaque
• collagen/lipid exposed increase
  thrombogenicity
• platelet adhesion
• clotting system activated
• occlusion

Question 17

ischaemic cascade

Answer 17

Question 18

Starling’s Law

Answer 18

Question 19

Heart Failure: Pathophysiology:

Answer 19

Question 20

Forces on H2O in capillaries

Answer 20

Question 21

Vascular Remodelling

Answer 21

• chronic response to injury
• change in shape, size and function
• Pressure overload: narrow valve, hypertension
• Volume overload: leaky valve
• myocardial damage eg MI, alcohol, viruses
• result is hypertrophy and or dilation
• is initially compensatory and becomes pathological

Question 22

Renin - Angiotensin - Aldosterone System

Answer 22

Question 23

Sympathetic Activation:

Answer 23

• low cardiac output activates the sympathetic system
• increases circulating catecholamines
• increases contractility: increases cardiac output but
• increases afterload
• initially compensatory and becomes pathological

Question 24

Catecholamine Cardiotoxicity

Answer 24

• structural/functional cardio-myocyte
  changes
• LV dilation and adverse remodelling
• increased LV systolic dysfunction