MoD lectures 13-16 Flashcards
What is atherosclerosis?
degeneration of arterial walls characterized by fibrosis, lipid deposition and inflammation which limits blood circulation and predisposes to thrombosis
What are some non-modifiable risk factors for atherosclerosis?
hyperlipidaemia (LDL:HDL), hypertension, smoking diabetes
What is a fatty streak?
a yellow linear elevation of the initma lining and is comprised of lipid-laden macrophages
What are foam cells?
macrophages that have phagocytosedd oxidized lipoproteins via a specialized membrane-bound scavenger receptor (e.g. ICAM-1)
What is a thrombosis?
the solidification of blood contents formed in the vessel during life
What are the differences between a clot and a thrombus?
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
What do platelets secrete?
alpha granules: attract fibrinogen, fibronectin, PDGF (platelet derived growth factor)
dense granules: attract other platelets
What 3 things are needed for thrombosis to occur? (VIRCHOW’S TRIAD)
changes in:
- the intimal surface of the vessel
- Pattern of blood flow
- blood constituents
What is an embolus?
mass of material in the vascular system able to lodge in a vessel and block it
What factors put you at a higher risk of developing venous thrombosis?
inflammatory mediators int he blood
immobility
factor V leiden
high oestrogen levels
What are thrombi in the heart known as?
mural thrombi
What is reperfusion injury?
generation of reactive oxygen species by inflammatory cells causing further damage
define infarction
ischaemia necrosis caused by occlusion of the arterial supply or venous drainage
define infarct
an area of infarction in tissues
What 4 factors influence the degree of ischaemic damage?
- nature of blood supply
- rate of occlusion
- tissue vulnerability to hypoxia
- blood oxygen content
How vulnerable are the brain and heart to hypoxia?
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
What are the clinical manifestations of ischaemia in the:
a) heart
b) brain
c) intestines
d) extremities
a) ischaemia heart disease
b) cerebrovascular disease (TIA/CVA)
c) iscahemic bowel
d) peripheral vascular disease/ gangrene
What is shock?
A physiological state characterized by a significant reduction of systemic tissue perfusion (severe hypotension) resulting in decreased oxygen delivery to the tissues
What is hypovolaemic shock?
intra-vascular fluid loss (blood, plasma etc.)
due to haemorrhade or generalized increase vascular permeability and/or dilatation
What is cardiogenic shock?
cardiac pump failure
e.g. acute MI reducing the functional capacity
What are the 4 causes of cardiogenic shock?
- myopathic (heart muscle failure- MI)
- arrhythmia-related (abnormal electrical activity- AF)
- mechanical (valvular and structural defects)
- extra-cardiac (obstruction t blood outflow e.g. PE)
What is distributive shock and what are the 4 sub-types?
excessive vasodilation and the impaired distribution of blood flow
septic, anaphylactic, neurogenic and toxic shock syndrome
What is septic shock?
severe, over whelming infections with gram pos or neg bacteria or fungi. the increase in cytokines and mediators causes vasodilation
What is anaphylactic shock?
severe type 1 hypersensitivity reaction
massive mast cell degranulation causes vasodilation
What is neurogenic shock?
disruption of the autonomic pathways within the spinal cord causing low blood pressure can be due to spinal injuries
What is toxic shock syndrome?
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
What is the urea pathway?
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.
What is porphyria?
a group of rare diseases in which porphyrins accumulate with high metabolism.
What causes hypoketonetoxaemia?
fatty acid oxidation defects which cause a lack of ketone production
What are the 3 mechanisms of disease for inborn errors of metabolism? and give examples
- accumulation of a toxin- hyperammonaemia
- energy deficiency- hypoketonetoxaemia
- deficient production of essential metabolic/structural component- defective receptors leading to androgen insensitivity syndrome
What is homocystinuria?
an abnormally high level of homocysteine in the blood die to folic acid, bit b12, vit B6 deficiency
What are 2 prenatal screening tests for IEM?
neural tube defects and down syndrome
