Cardiovascular and Respiratory Systems Flashcards
describe the pericardium (3)
- 2 layers of serous pericardium: visceral (attached to heart) and parietal (attached to fibrous peri.)
- fibrous pericardium attaches to surrounding structures (eg. diaphragm)
- pericardial space between serous layers to lubricate and decrease friction when the heart contracts within the pericardium
describe the epicardium (2)
- thin layer of connective tissue on the outside of the heart
- contains adipose tissue, nerves and coronary vessels
describe the myocardium
thickest layer of heart tissue made up of cardiac muscle cells
describe the layers of the endocardium (3)
- outer nerves, veins and Purkinje fibres
- middle connective tissue
- inner endothelium
describe the composition of heart valves (3)
- continuous with cardiac wall
- collagenous layer toughens to become highly fibrous
- avascular (vulnerable to endocarditis)
describe the fibrous heart skeleton (4)
- fibrocollagenous rings of connective tissue
- surround aorta, pulmonary trunk and AV openings
- where valves and cardiac muscle attaches
- electrically insulates atria from the ventricles
describe the intercalated discs at the branch points of cardiac myocytes (3)
- desmosomes - proteoglycan bridges between cells, preventing separation of cells during contraction
- gap junctions - permit electrical conductivity
- adherens - anchoring sites for actin
what is the 2 main difference between pacemaker cells and normal cardiac myocytes?
- pacemaker cells are specialised cardiac myocytes with no myofibrils, so they cannot contract
- have different transmembrane proteins which allow them to spontaneously trigger action potentials
describe the structure and function of the tunica intima of (3)
- single layer of endothelial cells - BP control, prevention of platelet aggregation, angiogenesis and act as a permeability barrier between plasma and interstitial fluid
- endothelial tight junctions prevent movement of blood cells and large proteins out of blood
- surrounded by internal elastic lamina - separates from tunica media
describe the structure and function of the tunica media of BVs (3)
- smooth muscle cells arranged in circular and spiral layers, supported by elastic fibres and collagen
- sympathetic innervation - vasoconstrictor tone (arterial blood pressure and compliance of systemic veins)
- surrounded by external elastic lamina - thick elastic tissue, separates from tunica externa
describe the main features of hypertrophic cardiomyopathy (4)
- myocardial hypertrophy (thickened wall due to enlarged cells)
- defective diastolic filling
- in 1/3, ventricular flow obstruction
- systolic function preserved, by myocardium cannot properly relax
describe the pathogenesis of hypertrophic cardiomyopathy (5)
- mutation to genes of contractile structures
- affect sarcometric proteins to increase myofilament function
- myocytes hyper contractility and increased energy use
- hypertrophy in response to stress
- often disproportionate thickening of ventricular septum (asymmetric septal hypertrophy)
how can hypertrophic cardiomyopathy result in functional LV outflow tract obstruction? (3)
- septal hypertrophy - septum is particularly thickened
- contact of thickened septum with mitral valve
- causes thickening of a mitral leaflet
describe the common symptoms of hypertrophic cardiomyopathy (often asymptomatic / mild symptoms) (4)
- dypnoea - reduced LV diastolic function, can result in pulmonary oedema
- syncope / presyncope - due to inadequate cardiac output or arrhythmias (can cause sudden cardiac death)
- chest pain - micro vascular complications or deficit in O2 demand of myocardium, and perfusion of coronary arteries (impaired diastolic function)
- palpitations - arrhythmias
what is the inheritance pattern of hypertrophic cardiomyopathy in most cases?
autosomal dominant - if one parent has one faulty gene, 1/2 chance of the condition being inherited by offspring (non-sex chromosome)
