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Cardiovascular sys.

MEDSCI 142

QuestionAnswer
Arteries in circuit -high pressure -away from heart -small outlets
Veins in circuit -low pressure -towards heart large inlets -8% of blood
Portal veins -connect two capillary beds -hepatic
Systematic circuit -bring oxygen to organs via aorta -high pressure & resistance -1pump=5L/min at rest
Pulmonary circuit -get oxygenated blood from lungs -via pulmonary artery & vein -medium pressure & resistance
Auricle appendage increasing volume of atrium
oxgen in heart -Pulmonary arteries & vena cava (deoxygenated blood) -Pulmonary veins & Aorta (deoxygenated)
Flow of blood around the body Lungs-pulmonaryvein-L atrium-mitralvalve-Lventrical-aorta-body/tissue-venacava-Ratrium-tricuspidvalve-Rventrical-pulmonary artery-lungs.......
Ventricular inlet valves -Mitral(L),tricuspid(R) -2/3 flat flats -fibrous CT -tethered by Cordae Tendinea
Ventricular outlet valves -Pulmonary(R),Atriac(L) -3cusps -pocket-shaped -parachute
Pericardium *double-walled bag that heart is enclosed in *visceral &parietal
Visceral pericardium *innerwall adheres to heart*forms outer space=epicardium
Parietal pericardium *tough fibrous outer wall
Pericardium space *serous fluid *layers slide over one-another without friction
Fibrous skeleton *maintains size of openings *electrical insulator
Conduction system step 1 *sino atrial node-->atrial muscle *slow 0.5m/s *atrial contraction
conduction system step 2 *atrioventricular node *slow 0.05m/s *100msec delay
Conduction system step 3 *AVbundle-->purkinje fibres *fast 5m/s *ventricular contraction
Elastic artery *V. large-fits finger *up to 100 elastic sheets *smooth pulsatile flow
elastic artery during diastole *elastic recoil *pumps blood into atrial tree
elastic artery systole *expand *bolus of blood leaving ventricle
Muscular artery *size:pin-pen *distribute blood at high pressure *small change r= large change in flow rate *many layers of smooth muscle
Arteriole *control blood flow to capillary beds *& change in blood pressure *size: hair *1-3 layers smooth muscle *1/2 size lumen *thickest wall in comparison
Capillary *exchanges nurtients, wastes & gas *slow blood flow *leaky vessels *thin, fits 1 red blood cells *single cell epithelium
Venule *drains capillaries *low pressure *during infection-site where WBC's leave blood
vein *low pressure *drain into atria *thin-walled *most blood stored here (64%) *soft walls stretch easily
*outlet: closed *inlet:open *80% filling *ventricle pressure below atrials
Atrial contraction *squeezes last 20% *blackflow due to no valves in atria
Isovolumetric ventricular contraction *ventricle contracts and causes pressure inside to rise *first beat *inlet & outlet closed
Ventricular ejection *inlet: closed *outlet: open *pressure inside V. becomes larger than in aorta *blood leaves vetricle
Isovolumetric ventricular Relaxation *inlet & outlet:closed *pressure inside ventricle lower than A *aortic valve prevents influx into ventricle *second beat
Cardiac cycle ventricular filling>atrial contraction>isovolumetric ventricular contraction>ventricular ejection>isovolumetric ventricular relaxation
Coronary arteries *arise from aorta *supply myocardium *small muscular *critical-supply heart with blood
what is the name for the disease where the blood runs low on oxygen? Ischemia-severe cases can cause infarction of local areas of myocardium
name for chest pain from lack of oxygen? Angina
Infarction? -tissue damage to the heart
myocardium -cardiac muscle
Mitral regugitation *mitral valves don't close properly *due to stretching of fibrous rings *blood flows back into atrium
Dilated cardiomyopathy *unkwown cause *muscles weak & slow to contract *mostly LV-high BP *LV dilates *ratio still 3:1 LV:RV *fibrous ring stretches *mitral valve no longer meets
mitral regurgitation effect on pressure *LA pressure rises due to regurgitation *hissing noise of heart beats dues to back flow
Discomfort during breathing= ??? *dyspnoea
Mitral regurgitation *breathlessness* *pressure in atrium rises-rise in capillary P-leaky capillaries-water logged lungs-difficulty breathing(dysponoea)
mitral regurgitation effects on system *lungs=rigid,heavy,wetter *LV pump more blood to maintain C.O *LA works harder to fill LV *breathing requires more work
Viscous cycle *cardiac muscle disease *LV dilation *mitral valve stretches *incr. mitral regurgitation *Volume load on LV *LV dilation.....
C.O= Heart rate (Beats per time) X Stroke Volume (volume ejected each contraction)
Cardiac Output *demand-> supply *O2use->O2 supply *brain communicates with heart
Cardiac reserve max C.O - rest CO
Venous return Volume of blood returning to heart per minute (vol/min)
Stroke volume *volume of blood ejected from the heart per heart beat *healthy heart pumps all blood *more out=more in
Frank-starlying law the more the heart is filled during diastole the greater the force of contraction in systole
Regulation of stroke volume *3 factors *pre-load *contraction *afterload
Pre-load (stroke vol. reg.) *stretch of heart *myocardium's response to stretch *more stretch=more force *starlings law
Contraction *strength of individual muscle contractions at any given preload *effected by inotropic agents
name of agents that effect contractility? Inotropic agent
+ve Inotropic agent -SV incr -constant preload -promote Ca2+ influx -strengthens F of next contraction -
-ve inotropic agent -decrease SV -inhibition of sympathetic ANS, anoxia, acidosis -incr k+, ca blockers
Afterload -pressure that must be exceeded before ejection can occur -high afterload=low SV *more blood left in ventricle
Regulating Heart Beat *critical in maintaining C.O & BP *rhythmic palpitations *controlled by excitatory signals within heart
Autorhythmicity *heart continues to beat when removed from body
Conduction system of heart (order) (1) sino Atrial Node (2)AV node (3)AV bundle (4)R&L bundle branches (5) purkinje fibres
Purkinje Fibres have large diameter=rapid conduction output & up from apex
refractory period *second contraction can't be triggered
ECG stands for? electrocardiogram
Electrocardiogram -APs generated detected at bodies surface -composite record of AP from all fibres during beat
Summation -combined AP of all areas of heart -gives measurable parameters
P wave *atrial depol *large=damage to aorta, large atria
QRS wave *onset of ventricular depol.(rapid) *large R=enlarged V *large Q=infarction
T wave *V repol.(slower) *flat=insufficient O2 *high=high k
nerve system (control of heart) *parasympathetic *sympathetic
Parasympathetic *vagus *slows HR *incr vagal nerve action *slows depol
Sympathetic *norepinephrine released from SA node *B-receptors activate-speed up depol. *incr HR *incr ca entry *incr contractions *incr SV
Blood Pressure *allow exchange in capillaries *movement of blood & intertitial fluid
Diffusion *[02 & nutrients] high in blood *[CO2 & waste] high in interstitial fluid *down [grad]
Arterioles & BP *resistance vessels *lots of SM * nerve impulses *hormones-activate SM *tonic vasoconstriction
Bulk flow filtration + reabsorption
Pressure promoting filtration (1)blood hydrostatic pressure- P of water in plasma on cap. walls (2)Interstitial fluid osmotic pressure- small, tiny amount s of protein in interstitial fluid
Pre-fusion pressure *driving force of exchange in capillary beds -Bp high=filtration -Bp low=absorption
pressure promoting reabsorption (1) blood colloid osmotic pressure- large components not freely filtered (2)interstitial fluid hydrostatic pressure- opposed blood hydrostatic pressure
BP during systole -highest arterial pressure -falls as distance from LV increases
BP during Diastole -lowest arterial pressure
Mean arterial pressure roughly 1/3 between diastole & systole P
BP= C.OxTPR (total peripheral resistance)
TPR -total peripheral resistance -effected by: *R small changes cause big changes in TPR *viscosity *blood vessel length
viscosity *high-dehydrated=polycytemia *low-anaemia=haemorrhage
Created by: meglet