MoD lectures 13-16

Question 1

What is atherosclerosis?

Answer 1

degeneration of arterial walls characterized by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis

Question 2

What are some non-modifiable risk factors for atherosclerosis?

Answer 2

hyperlipidaemia (LDL:HDL), hypertension, smoking diabetes

Question 3

What is a fatty streak?

Answer 3

a yellow linear elevation of the initma lining and is comprised of lipid-laden macrophages

Question 4

What are foam cells?

Answer 4

macrophages that have phagocytosedd oxidized lipoproteins via a specialized membrane-bound scavenger receptor (e.g. ICAM-1)

Question 5

What is a thrombosis?

Answer 5

the solidification of blood contents formed in the vessel during life

Question 6

What are the differences between a clot and a thrombus?

Answer 6

clot: formed in stagnant blood, it is an enzymatic process, elastic and they adopt the shape of the vessel
thrombosis: form within the body during life, they depend on platelets and are very firm

Question 7

What do platelets secrete?

Answer 7

alpha granules: attract fibrinogen, fibronectin, PDGF (platelet derived growth factor)
dense granules: attract other platelets

Question 8

What 3 things are needed for thrombosis to occur? (VIRCHOW’S TRIAD)

Answer 8

changes in:

1. the intimal surface of the vessel
2. Pattern of blood flow
3. blood constituents

Question 9

What is an embolus?

Answer 9

mass of material in the vascular system able to lodge in a vessel and block it

Question 10

What factors put you at a higher risk of developing venous thrombosis?

Answer 10

inflammatory mediators int he blood
immobility
factor V leiden
high oestrogen levels

Question 11

What are thrombi in the heart known as?

Answer 11

mural thrombi

Question 12

What is reperfusion injury?

Answer 12

generation of reactive oxygen species by inflammatory cells causing further damage

Question 13

define infarction

Answer 13

ischaemia necrosis caused by occlusion of the arterial supply or venous drainage

Question 14

define infarct

Answer 14

an area of infarction in tissues

Question 15

What 4 factors influence the degree of ischaemic damage?

Answer 15

1. nature of blood supply
2. rate of occlusion
3. tissue vulnerability to hypoxia
4. blood oxygen content

Question 16

How vulnerable are the brain and heart to hypoxia?

Answer 16

brain: more so than heart- if a neuron is derived of oxygen then there is irreversible cell damage within 3-4 minutes (needs 15% of cardiac output and 20% of oxygen consumption)
heart: still vulnerable but myocyte death takes 20-30 minutes

Question 17

What are the clinical manifestations of ischaemia in the:

a) heart
b) brain
c) intestines
d) extremities

Answer 17

a) ischaemia heart disease
b) cerebrovascular disease (TIA/CVA)
c) iscahemic bowel
d) peripheral vascular disease/ gangrene

Question 18

What is shock?

Answer 18

A physiological state characterized by a significant reduction of systemic tissue perfusion (severe hypotension) resulting in decreased oxygen delivery to the tissues

Question 19

What is hypovolaemic shock?

Answer 19

intra-vascular fluid loss (blood, plasma etc.)

due to haemorrhade or generalized increase vascular permeability and/or dilatation

Question 20

What is cardiogenic shock?

Answer 20

cardiac pump failure

e.g. acute MI reducing the functional capacity

Question 21

What are the 4 causes of cardiogenic shock?

Answer 21

1. myopathic (heart muscle failure- MI)
2. arrhythmia-related (abnormal electrical activity- AF)
3. mechanical (valvular and structural defects)
4. extra-cardiac (obstruction t blood outflow e.g. PE)

Question 22

What is distributive shock and what are the 4 sub-types?

Answer 22

excessive vasodilation and the impaired distribution of blood flow
septic, anaphylactic, neurogenic and toxic shock syndrome

Question 23

What is septic shock?

Answer 23

severe, over whelming infections with gram pos or neg bacteria or fungi. the increase in cytokines and mediators causes vasodilation

Question 24

What is anaphylactic shock?

Answer 24

severe type 1 hypersensitivity reaction

massive mast cell degranulation causes vasodilation

Question 25

What is neurogenic shock?

Answer 25

disruption of the autonomic pathways within the spinal cord causing low blood pressure can be due to spinal injuries

Question 26

What is toxic shock syndrome?

Answer 26

caused by staphylococcus aureus and pyogenes which produce exotoxins
non-specific binding of class II MHC to T cell receptors and the widespread release of massive amounts of cytokines causes

Question 27

What is the urea pathway?

Answer 27

it removes ammonia from the body which is made from the breakdown of amino acids, it occurs in the liver and breaks down ammonia into urea.

Question 28

What is porphyria?

Answer 28

a group of rare diseases in which porphyrins accumulate with high metabolism.

Question 29

What causes hypoketonetoxaemia?

Answer 29

fatty acid oxidation defects which cause a lack of ketone production

Question 30

What are the 3 mechanisms of disease for inborn errors of metabolism? and give examples

Answer 30

1. accumulation of a toxin- hyperammonaemia
2. energy deficiency- hypoketonetoxaemia
3. deficient production of essential metabolic/structural component- defective receptors leading to androgen insensitivity syndrome

Question 31

What is homocystinuria?

Answer 31

an abnormally high level of homocysteine in the blood die to folic acid, bit b12, vit B6 deficiency

Question 32

What are 2 prenatal screening tests for IEM?

Answer 32

neural tube defects and down syndrome