Week 3 Flashcards
what can cvd be caused by?
- plumbing (artery blockage)
- electrical (arrrythmias)
- both
macro-vascular diseases
- coronary artery/heart disease
- stroke
- peripheral vascular disease
example of coronary heart disease
coronary athersclerosis supplying ventricular myocardium with blood
example of stroke
cerebrovascular athersclerosis blocking cerebral artery (blocks neural tissues)
example of peripheral vascular disease
lower limb e.g. femoral artery blockages
microvascular disease types
- retinopathy
- nephropathy
- neuropathy
- amputation/ulceration
Pulmonary ___________ takes blood to lungs
Pulmonary arteries
Pulmonary ________ to left atrium
Pulmonary veins
role of tricuspid valve
- papillary muscles attach to chordae tendinae to valve leaflets
- leaflets block way and pull downwards to prevent blood from going back to atria
order of layers of heart wall
- fibrous pericardium
- parietal layer of serous pericardium
- pericardial cavity
- visceral layer of serous pericardium
- myocardium
- endocardium
- heart chamber
myocardium has what
- heart muscle
- connective tissue
fibrous pericardium
hard protective barrier
parietal layer of pericardium
has pericardial fluid to allow heart movement without much friction
functional syncytium
sodium and calcium deplorization in single cell and transmission throughout all cells
why is there a delay of impulse from atria to ventricle?
rubberized membrane between atria and ventricles (at valves) acting as insulator to prevent depolarization of entire myocardium
Cardiac Twist and Torsion
- heart base rotates during contraction
- allows ventricular twist causing transverse movements alloiwing heart muscle contraction longitudinally
tunica interna
- flattened squamous cells
- endothelial cells
- internal elastic membrane
tunica media
- mostly smooth muscle
- elastic laminae
- loose CT
tunica adventitia
- connective tissue connecting BVs to surrounding structures
- collagen and elastic fibres
elastic artery structure
tunica media has
- elastic laminae (tensile strength)
- muscle cells interspe
- cylindrical spiral arrangement (ejections in all directions)
- smooth muscle (contract and dilate)
dicrotic notch
a small dip of blood pressure waveform presenting brief interruption of normal blood flow after aortic valve closes
muscular arteries function
- branches off elastic arteries
- controls blood flow distribution
- blocks off pathways and allows flow in other areas
VC vs VD
vasomotor tone in muscular arteries…
- local vasodilator mechanisms regulated by neural constrictor reflexes by sympathetic NS
muscular artery structure
- smooth muscle content (25-35 layers) in spiral control for vasomotor control
- elastic tissue scarce in tunica media
- fenestrated internal elastic laminae in tunia intima
- external elastic laminae in tunica adventitia
L and R
resistance vessels
- small muscular arteries and arterioles
- resistance dependant on vessel length and radius
blood pressure equation
cardiac output x total peripheral resistance
how does SNS control vasomotor tone?
- release vasoactive hormones and local metabolic products to control BF distribution and O2 delivery by vasoconstriction
SNS vasomotor control example
- noradrenaline affects alpha receptors and vasoconstricts vessels in organs, allowing more blood flow distribution to vasodilated arteries in skeletal muscles, allowing more muscle contraction
examples of vasomotor tone metabolic by-products in tissue fluids (vasodilation)
- potassium ions
- CO2 release
- acidity increase (during exercise)
- ATP
- adenosine
exchange vessels (capillaries)
- thin walls / tunica intima with endothelial cells and basement membrane
- slow transport time and thin layer for gas exchange
oedema
- increased capillary pressure can cause filtration of H2O resulting in oedema
- oedema in tissue can caused increased perfusion distance, causing outcomes suich as drowning in tissue fluid
capacitence vessels
- venules (500 microns) to veins (4cm)
- tunica media has some SM cells and more collagen and elastic tissue
- tunica adventitia makes up 60% of wall
- increased pressure expands at vessels and deposits more volume
capacitence vessel distribution
- makes up 60-75% of blood (3.5L)
- 1/3 of blood in high capacitence circulations e.g. liver and skin
non compliant blood vessel example
- skeletal muscles
- vessels do not stretch or store extra blood (like rigid pipe)
compliant blood vessel example
- skin and splanchnic regions
- can expand or constrict (VC or VC)
atherosclerosis
- changes in arterial walls due to exposure of CVD risk factors
- disease causing thickening and loss of elasticity of arterial walls characterised by formation of lipid and cholesterol laden mass in intima or media of large/medium arteries
vasa vasorum
small BVs that supply walls of larger arteries and veins
atherogenesis stage 1
infiltration and entrapment
- LDL penetrates intima passing endothelial layer
- LDL interacts with substances within wall and cannot be reabsorbed by vasa vasorum
atherogenesis stage 2
modification of LDL
- LDL becomes oxidised by reactice O2 species (e.g. superoxide anions) released from macrophages
superoxide anions - O2 molecule with extra electron
highly oxidative and attacks foreign agents like viruses
fatty streaks
foam cells accumulated in subintimal space
atherogenesis stage 3
foam cell formation
- oxidatively modified LDL (Ox-LDL) ingested by macrophage to become foam cell
- Ox-LDL has greater affinity for foam cells (not regulated by negative feedback)
foam cells eventually rupture after consuming too much LDL - release of substances
fibrous plaques
fibrous cap covers lipid core
- SM cells proliferate and generate CT and collagen
complicated lesions
plaquie calcifies and can haemorrhage, rupture or cause thrombosis
thrombosis = formation of blood clot
CAD symptoms
- angina = chest pain or discomfort
- MI = blood to heart reduced or cut off
angiogram
visualization of presence of stenotic plaque
angioplasty
- insertion of balloon to expand stenosis
stent insertion
- expendable cage to hold artery open
coronary artery bypass surgery
graft to bypass stenosis
drug therapy for CAD examples
- clot busters for thrombosis
- blood thinners e.g. aspirin to prevent thrombosis
- lipid lowering drugs (decrease cholesterol)
- other miedcations to decrease MI e.g. ACE inhibitors
angina pectoris
- pain from limited blood passage
- gripping or deep pain in chest
example of when plaque may need removal
- referred pain in arms that comes/goes or increases during exercise
stroke
- interruption of blood supply to brain
- clot 85%
- haemorrhage 15%
peripheral artery disease
- atheroma in arteries of legs resulting in numbness, pain and eventually gangrene
atheroma - plaque as a fatty substance building up in arteries
