Microanatomy 1 CVS Flashcards
(30 cards)
what is the another term for atherogenesis
the response to injury hypothesis
what does atherogenesis do
it aims to conceptualise how atheromatous plaques arise, mature and change
where does atheroma formation occur in
- it occurs in the intimal of the artery
what is in the fibrous cap on the atheroma in the tunica intima
smooth muscle cells macrophages foam cells lymphocytes collagen elastin proteoglycans neurovascularisation
what is in the necrotic centre of the atheroma
cell debris
cholesterol crystals
foam cells
calcium
what is the treatment of coronary artery occlusion aim to do
- it is aimed at re-establishing blood flow in order to reduce the effects on the area at tis
how long does it take for permanent damage to occur with an occlusion of the heart
- if perfusion is severely reduced for an extended period of at least 2-4 hours permanent damage occurs
how does the heart tissue repair after the myocardial infraction
- solid muscle is replaced with granulation tissue
- between at 5-10 days the infracted myocardium is at its weakest and most susceptible to rupture
what happens in day 10 of healing myocardial infract
- necrotic muscle is mainly removed by the neutrophils and macrophages
- cells remaining are mainly macrophages and lymphocytes and plasma cells
- there is a loose oedematous mesh with capillaries and fibroblasts which is indicative of early granulation tissue
what happens in day 14 of healing myocardial infract
- firbovascular granulation tissue replaces the infract .
- over the next 6-8 weeks this becomes progressively more fibrocollagneous and less vascular resulting in avascular and acellular myocardial scar
what is acute rheumatic fever characterised by in the heart
- nodular inflammatory lesions
where are the lesions found that are caused by rheumatic fever
- they are found in the interstitial connective tissue of the myocardium, particularly near the vessels in the suberpicardial fibrous tissue
- they exhibit fibrinoid change with lymphocytes, large distinctive macrophages and central areas of necrosis
what is the effect of rheumatic fever on the heart
- causes Aschoff bodies these are associated with the valve leaflets therefore can cause chronic damage to the valves
- Rheumatic mitral stenosis - there is fibrotic thickening of the leaflets and fusion of the commissures
- chord tendinae fusion and shortening
what are heart valves
- they are mechanical devices that permit the flow of blood in one direction only
what are heart valves formed from
formed by leaflets of collagenous tissue that have a central dense irregular connective tissue core
- the leaflets have considerable elastin content
what are heart valves covered by
- covered by endothelium
what is the valve annulus
The dense connective tissue of the heart valve leaflets condense around the attached margins forming a fibrous ring (valve annulus
what is the fibrous skeleton of the heart valves
e 4 valve rings together form a fibrous ‘skeleton’ of the heart continuous with the other fibrous supporting components of the myocardium, endocardium and epicardium.
what does the fibrous skeleton do
- skeleton supports the heart valves
- site of attachment for myocardial muscle fibres
- acts as an electrical barrier between the myocardium of the atria and ventricles
what are mitral and tricuspid valve leaflets connected to
papillary muscles
what are papillary muscles
- these are extensions of the myocardium of the ventricles by chord tendinae
what do the chord tendinae merge with
These fibrocollagenous cords merge into the lamina fibrosa of the leaflets and together with the papillary muscles stabilise the leaflets of the mitral and tricuspid valve valves.
what size veins contain valves
- large veins that are larger than 2mm in diameter
what is varicose veins caused by
- due to ageing
- there is retrograde blood flow that leads to tortuous dilatation and lengthening of the veins
