Cardio Week 2 Flashcards
where are phrenic nerves located
descending across lateral borders of pericardium
the fibrous pericardium is lined internally by what
parietal serous pericardium
what covers the anterior surface of heart
epicardium (same thing as visceral pericardium) that excretes pericardial fluid
where is the pericardial cavity located
between the 2 layers of serous pericardium
what is cardiac tamponade
when pericardial cavity fills with blood and pressure around heart prevents it from contraction
what is pericardiocentesis
drainage of fluid from pericardial cavity - needle inserted via infrasternal angle and directed superioposteriorly
what is the transverse pericardial sinus
space within pericardial cavity (lies posterior to ascending aorta and pulmonary trunk) and surgeons use this to identify and isolate great vessels
what is the only artery that carries deoxygenated blood
pulmonary artery
what is the only vein that carries oxygenated blood
pulmonary vein
what is the coronary sinus
short venous conduit (in AV groove posteriorly) which receives deoxygenated blood from most of cardiac veins and drains into right atrium
what is the first branch of the aorta
coronary arteries as they come off ascending aorta
where do coronary arteries course
just deep to epicardium - usually embedded in adipose tissue
where is the right coronary arteries situated
right atrioventricular groove
where is the left (main stem) coronary artery situated
left AV groove between pulmonary trunk and left auricle
are left and right coronary arteries connected
yes - via anastomoses
what is the consequence of a septal defect
hole (mixes arterial and venous blood) - reduces O2 content of systemic arterial blood in aorta - hypoxaemia
where is mitral valve located
between left atrium and left ventricle
where is tricuspid valve located
between right atrium and right ventricle
what are examples of organic nitrates
glyceryl trinitrate (GTN), isosorbide mononitrate, isosorbide denigrate, erythrityl tetranitrate, pentaerythriol tetranitrate
when are organic nitrates used
angina - decreased myocardial O2 requirement via decreased preload, after load and improved perfusion
how do organic nitrates work
metabolised to release NO - elevates cGMP (vasodilation)
what are examples of ACE inhibitors
captopril and enalopril
when are ACE inhibitors used
chronic heart failure and hypertension
how do ACE inhibitors work
block conversion to angiotensin II (blocks sympathetic response) and promotes diuresis since it is blocking hormones that cause renal Na+ and water retention
give examples of angiotensin II receptor blocker (ARB)
losartan and valartan
how do ARBs work
selectively inhibit effect of angiotensin II without affecting bradykinin levels
what side effect is present in ACE inhibitors but not ARBs
chronic cough - ACE metabolises bradykinin and substance P whereas ARB does not
what can ACEI and ARB cause in pregnancy
renovascular disease and aortic stenosis
what are examples of calcium antagonists
verapamil, amiodipine and diltiazem
when are calcium antagonists used
hypertension (first line) angina (in combo with GTN) and in dysrhythmias
how do calcium antagonists work
prevent opening of L type Ca++ channels so limit increasing Ca2+ - reduced rate of conduction through AVN as well as reducing force of contraction
what is the adverse effects of calcium antagonists
excessive vasodilation - hypotension, dizziness and ankle oedema
give examples of potassium channel openers (K+ATP openers)
minoxidil and nicrorandil
when are potassium channel openers used
minoxidil - last resort hypertension but cause reflex tachycardia and salt and water retention, treat hair lossnicrorandil - NO donor activity, used in angina (side effect - mouth ulcers)
how do potassium channel openers work
open channels which causes hyper polarisation which switches off L type Ca2+ channels - less calcium causes vasodilation etc
what are examples of a1 adrenoceptors
prazosin and doxazosin
when are a1 adrenoceptors used
hypertension
how do a1 adrenoceptors work
vasodilation by blocking a1 adrenoceptors - decreases MABP
what are examples of diuretics
furosemide, bumetanide, torasemide and ethacrynic acid
what are the two different kinds of diuretics
thiazide (inhibit reabsorption in distal tube) and loop diuretics (inhibit reabsorption in thick ascending limb of the loop of hernie)
when are diuretics used
chronic heart failure and hypertension
how do diuretics work
act on kidney to increase excretion of Na, Cl and H2O and exert additional relaxant effects on vasculature
what are examples of class I drugs
disopyramide, lignocaine and flecainide (respective IA, IB and IC)
how do class I drugs work
block voltage gated Na+ channels
characteristics of IA drugs
associate and dissociate moderately - slow rise of AP and prolong refectory periodused in ventricular arrhythmias
characteristics of IB drugs
associate and dissociate rapidly - prevents premature beatsused in ventricular arrhythmias after MI
characteristics of IC drugs
associate and dissociate really slowly and depress conduction used for prophylaxis of paroxysmal atrial fibrillation
give example of class II drugs
metoprolol
how do class II drugs work
block b-adrenoceptor - decrease rate of depolarisation in SA and AV nodes
give examples of class III drugs
amiodarone and sotolol
how do class III drugs work
block voltage activated K+ channels - prolong AP duration increased refractory period
give examples of class IV drugs
verapamil, dilitazem
how do class IV drugs work
block voltage activated Ca2+ channels - slow conduction in SA and AV nodes - decrease force of contraction
what classes of drugs act on atria (rate control of supra ventricular tachycardia)
IC (flecainide) and III (amiodarone, sotolol)
what classes of drugs act on ventricles
IA, IB and II
what classes of drugs act on the AV node (rhythm control of SVT)
adenosine, digoxin, classes II (metoprolol) and IV (verapamil)
what classes of drugs act on atria and ventricles AV accessory pathways
amiodarone, sotalol, classes IA and IC
what are the four main types of SVT (supra ventricular tachycardia)
atrial fibrillation, paroxysmal supra ventricular tachycardia (PSVT), atrial flutter and Wolff Parkinson white syndrome
what is the inner layer
tunica intima (single layer of squamous epithelium - endothelium)
what is middle layer
tunica media (smooth muscle, thickness varies)
what is outer layer
tunica adventitia (supporting connective tissue)
what separates tunica intima from tunica media
internal elastic membrane (external elastic separates TM and TA)
largest arteries have their own vascular supply; what is this called
vasa vasorum
what are capillaries composed of
endothelial cells and basal lamina - often have pericytes (connective tissue with contractile properties)
where are continuous capillaries found
muscle, connective tissue, lung, skin and nerve
where are fenestrated capillaries found
mucosa of gut, endocrine glands, glomeruli of kidney
where are sinusoidal (discontinuous) capillaries found
liver, spleen and bone marrow - lack basal lamina and have large gaps
what is components of vein
tunica intima, thin but continuous tunica media (vena cava/HPV has thick tunica adventitia)
what veins have valves
small to medium sized veins - valves are inward extensions of tunica intima
what is the role of endocardium
lines entire surface of heart including valves
what is the structure of endocardium
endothelium, basal lamina, thin layer of collagen fibres, layer of denser connective tissuesome areas has subendocardium of loose connective tissue containing small vessels and nerves
what is the role of myocardium
thick middle layer
what is structure of myocardium
bundles and layers of contractile cardiac muscle cells, individual muscle fibres surrounded by delicate, continuous connective tissue with rich capillary network
what is the role of intercalated discs in myocardium
attach muscle cells and allow spread of electrical activity
what is role of epicardium
outer layer of heart
what is structure of epicardium
on surface: single layer of flattened epithelium (mesothelium)contains basal lamina, fibroelastic connective tissue and in some places adipose tissue
what are the two parts of pericardium
fibrous pericardium (sac of tough fibrocollagenous connective tissue)serous pericardium (simple squamous epithelium backed by basal lamina and connective tissue)
what is the two layers of serous pericardium
parietal serous pericardium - inner surface of fibrous visceral serous pericardium - covers surface of heart
what is the fibrous skeleton
formed by thick bands of connective tussle around heart valves which supports the valves but also provides attachment for cardiac muscle fibres
what is the structure of valves
have outer endothelial layer with basal lamina with layer of collagen and elastin fibreshave a core of dense connective tissue called lamina fibrosa in continuity with fibrous skeleton
the leaflets of the valves separating atria from ventricles are anchored to papillary muscles in wall of ventricles by what
chord tendineae (which merge with lamina fibrosa)
what is the structure of pacemaker cells
smaller than myocytes and embedded in more connective tissueappear pale because of paucity of organelles few myofibrils, little glycogen and no proper T tubule system
what is the structure of purkinje fibres
larger than myocytes, found in subendocardial layer, abundant glycogen, no T tubules, no intercalated discsappear pale and very pale/clear centre
what is the structure of lymphatic vessels
no central pump but smooth muscle in walls, hydrostatic pressure in tissue and the compression of vessels by voluntary muscle combined with valves in vessels, produce flow
how do sympathetic signals reach organs
exit spinal cord at one of T1-L2/3 and then travel either superiorly or inferiorly in sympathetic chain to another ganglion and synapse
what are the cardiopulmonary splanchnic nerves
postsynaptic fibres from cervical and upper thoracic sympathetic chainssympathetic nerves to heart and lungs
how do parasympathetic signals reach organs
via cranial nerves III (oculomotor nerves) VII (facial nerves), IX (glossopharyngeal nerves) and X
what is the role of CN V (vagus nerve) in parasympathetic signals
presynaptic parasympathetic fibres in vagus nerves then synapse onto postsynaptic neurones
AP’s arriving at postcentral gyrus of parietal lobe (somatosensory) bring what sensations into consciousness
body wall (somatic)
AP’s arriving at pre central gyrus of frontal lobe (somatomotor) bring what sensations into consciousness
contractions of body wall (somatic) skeletal muscle
what is the source of sharp central chest pain by herpes zoster (shingles)
patient with shingles developing in T4/T5 - pain precedes blisters
what could be the source of sharp central chest pain by muscle, joints or bones
pectorals major or intercostal muscle strain, dislocated costochondrial joint, costovertebral joint inflammation, slipped thoracic disc
what could be the source of sharp central chest pain by parietal pleura and fibrous pericardium
pleurisy and pericarditis
what would be the source of dull central chest pain by the trachea
tracheitis
what would be the source of dull central chest pain by aorta
ruptured aneurysm of aortic arch
what would be the source of dull central chest pain of the abdominal viscerae
gastritis, cholecystitis, pancreatitis, hepatitis
what would be the source of dull central chest pain of the heart
angina and myocardial infarction
how do pain signals from organs reach brain
visceral afferent APs pass bilaterally to thalamus and hypothalamus then diffuse areas of the cortex
what is an example of pain signals from organs reaching brain
ischaemic chest pain: cardiopulmonary splanchnic nerves plus visceral afferents from chest organs
if pain is originating in a somatic structure then where is the radiation felt
along the affected dermatome
is the pain is originating in the heart then where is the radiation felt
the dermatome supplied by the spinal cord at levels which the cardiac visceral afferents enter sympathetic chain
what is referred pain due to
afferent (sensory) fibres from soma and afferent (sensory) fibres from viscera (visceral afferents) entering spinal cord at same levels brain chooses to believe pain from organ is actually coming from soma
where is cardiac pain referred to
upper limbs (esp left) or from back, neck or jaw
what are the common sites of coronary atherosclerosis
anterior inter ventricular branch (LAD) of LCA, RCA, circumflex branch of LCA, left main stem coronary artery
what happens in coronary artery bypass grafting
grafts anastomosed proximally to ascending aorta
what is the main artery used for grafting
left internal thoracic (mammary artery) used - not disconnected from patient but instead cut distally and attached to coronary artery
what is the other arteries used for grafting
bilateral internal thoracic artery, gastroepiploic and radial arteries
what is shock
an abnormality of the circulatory system resulting in inadequate tissue perfusion and oxygenation
how does hypovolaemic shock (also known as haemorrhage shock) occur
loss of blood volume - decreased venous return - decreased EDV - decreased SV - decreased CO and BP.- inadequate tissue perfusion
what is the causes of hypovolaemic shock
haemorrhage (trauma, surgery, GI)vomiting, diarrhoea, excessive sweating results in decreased ECFV thus decreased blood
what is cardiogenic shock
sustained hypotension caused by decreased cardiac contractility
how does cardiogenic shock occur
decreased contractility - decreased SV - decreased CO and BP - inadequate tissue perfusion
how does tension pneumothorax (obstructive shock) occur
increased intrathoracic pressure - decreased venous return - decreased EDV - decreased SV - decreased CO and BP - inadequate tissue perfusion
how does neurogenic shock occur
loss of sympathetic tone - massive venous and arterial dilation - decreased venous return and SVR - decreased CO and BP - inadequate tissue perfusion
how does vasoactive shock occur
release of vasoactive mediators - venous and arterial vasodilation and increased capillary permeability - decreased venous return and decreased SVR - decreased CO and BP - inadequate tissue perfusion
what is the treatment for shock
ABCDE, high flow O2, volume replacement, inotropes for cardiogenic shock, immediate chest train for pneumothorax, adrenaline for anaphylactic shock, vasopressors for septic shock
what is an example of HDL
apoA1 and apoA2
what is an example of LDL/VLDL
apoB-100
what is example of chylomicrons
apoB-48
what is the role of ApoB containing lipoproteins
deliver triglycerides to muscle for ATP biogenesis and adipocytes for storage
where are chylomicrons formed and what is their role
intestinal cells and transport dietary triglycerides - carried in lymph to systemic circulation (subclavian vein) via thoracic duct - exogenous pathway
where are VLDL formed and what is their role
formed in liver cells from free fatty acids derived from adipose tissue (during fasting) and de novo synthesis and transport triglycerides synthesised in that organ - endogenous pathway
what is lipoprotein lipase (LPL)
lipolytic enzyme associated with endothelium capillaries in adipose and muscle tissueIt hydrolyses core triglycerides to free fatty acids and glycerol which enters tissues
what facilitates the binding of chylomicrons and VLDL particles to LPL
ApoCII
what are examples of statins
simvastatin and atorvastatin
when are statins used
drug of choice to reduce LDL - reduce LDL by 60% and triglycerides by 40%, also increase HDL by 10%other benefits: decreased inflammation, thrombosis and stabilisation of plaquesorally at night
how do statins work
competitive inhibitors of HMG-CoA reductase - rate limiting step in cholesterol synthesis decrease in cholesterol causes increase in LDL receptor thus enhances its clearance
give examples of fibrates
bexafibrate and gemfibrozil
when are fibrates used
pronounced decrease in triglycerides (first line drugs in patient with very high triglycerides)
how do fibrates work
act as agonists of nuclear receptor (PPARa) to enhance transcription of genes, including encoding LPL
what are adverse effects of fibrates
myositis, best avoided in alcoholics who are predisposed to hypertriglyceridaemias but also rhabdomyolysis other effects (GI symptoms, pruritus and rash) greater than for statins
give examples of drugs that inhibit cholesterol absorption
colestyramine, colestipol and colsevelam
how do drugs that inhibit cholesterol absorption work
bind to bile acid and cause excretion of bile salts resulting in more cholesterol to be converted to bile salt by interrupting enterohepatic recycling ingested orally, not absorbed from GI tract which prevents reabsorption of bile saltsalso causes decreased absorption of triglycerides and increased LDL receptor expression
what is adverse effects of drugs which inhibit cholesterol absorption
GI tract irritation
what is a drug which inhibits the transport of cholesterol
ezetimible
who do drugs which inhibit the transport of cholesterol work
act to inhibit NPC1L1 transport protein in enterocytes of duodenum, reducing the transport of cholesterol decrease in LDL with little change in HDL
when is drugs in inhibit transport of cholesterol work
used in combination with statins when latter alone does not achieve sufficient response orally - metabolised to activate metabolite that undergoes enterohepatic recycling that contributes to long half life (22hr)
what are adverse effects of drugs that inhibit transport of cholesterol
diarrhoea, abdominal pain and headache contradicted in breast feeding females
