Cardiovascular system Flashcards
cellular portion of body =
buffy coat (leukocytes, thrombocytes)
+
haematocrit (erythrocytes)
cardiac output equation
cardiac output (Q) = mean arterial pressure (ΔP)/ total peripheral resistance (R)
cardiac output = heart rate x stroke volume
cardiac output = venous return
cardiac output (CO)
amount of blood pumped by the heart per minute (L/min)
heart rate (HR)
number of beats per minute
stroke volume (SV)
amount of blood pumped out of heart per beat
venous return (VR)
rate of blood flow back to right side of heart
ejection fraction (EF)
fraction of blood ejected from ventricle of the heart with each heart beat
end-diastolic volume (EDV)
volume of blood in right and left ventricle at end load (preload) or filling in (diastole)
or amount of blood in ventricles just before systole
end-systolic volume (ESV)
volume of blood in ventricle at end of systole and beginning of filling (diastole)
(lowest volume of blood in ventricle at any point in cardiac cycle)
EF, SV and EDV equation
EF = SV/ EDV
SV, EDV and ESV equation
SV = EDV - ESV
parasympathetic innervation of the heart
left and right vagus nerve to pacemakers
parasympathetic decreases heart rate and strength of muscle contraction
acetylcholine increases K+ permeability (repolarisation)
sympathetic innervation of the heart
diffuse from ganglia chain along spinal cord into myocardium
sympathetic increases heart rate and strength of muscle contraction
noradrenaline increases Na+ and Ca2+ permeability (depolarisation)
ECG
P wave - atrial depolarisation (frequency is atrial rate)
PR segment - continuation of atrial depolarisation
QRS complex - ventricular depolarisation (frequency is ventricular rate)
ST segment - between ventricular depolarisation and repolarisation
T wave - ventricular repolarisation (flat line after T wave is ventricular diastole)
U wave - papillary muscle and Purkinje fibres repolarisation
bradycardia tachycardia arrhythmia ectopic asystole
slow heart rate fast heart rate normal increase in heart during inspiration earlier atrial/ ventricular heart beat flat line/ no electrical activity
heart failure
heart unable to fill with enough blood or unable to pump blood around body with enough force
causes of heart failure
direct (internal) - heart muscle/ valves
indirect (external) - circulation/ peripheral blood vessels (increased vascular resistance hypertension)
two types of hyperaemia
increase of blood flow in tissue/ organ
active hyperaemia - due to increased metabolic activity of organ/ tissue
reactive hyperaemia - following a period of ischaemia (blockage)
atheroma
degeneration of artery walls caused by accumulation of fatty deposits and scar tissue leading to restriction of circulation
atherosclerosis
hardening of arteries due to plaque formation
inotropic effects
alters muscular contraction by Ca2+
parasympathetic ⬇
sympathetic ⬆
chronotropic effects
alters heart rate by affecting electrical conducting system
parasympathetic ⬇
sympathetic ⬆
dromotopic effects
alters rate of electrical impulses/ conduction velocity by affecting conduction speed in AV node
parasympathetic ⬇
sympathetic ⬆
3 layers of blood vessels
tunica intima - endothelium
tunica media
tunica externa
triple response of Lewis to scratched skin
red reaction - red line, local vasodilation, cytokine, histamine
flare - red spreads
wheal - localised oedema (swelling)
vasodilation factors
histamine (released by basophils and mast cells)
NO inhibits Ca2+ release
vasoconstriction factors
thromboxane
angiotensin II
Korotkov sounds
when obstruction results in compressed artery so turbulent flow
(laminar flow if no obstruction)
control of arterial pressure
baroreceptors in carotid body, aortic bod, wall of arteries of neck and thorax
stretched –sensory afferent neurons–> medulla –motor efferent neurons (para/sympathetic)–> (heart??)
short term mechanisms to regulate bp (3)
baroreceptor reflexes - peripheral resistance, HR, SV
chemoreceptor reflexes - hypoxia, CO2 excess, low pH blood
central nervous system ischaemic response - decrease in blood flow of brain)
long term mechanism to regulate bp (1)
kidney control (renin-angiotensin system)
reduced kidney flow
prorenin-> renin (juxtaglomerular cells)
angiotensinogen -> angiotensin I (renin)
angiotensin I -> angiotensin II (angiotensin-converting enzyme ACE)
angiotensin II does stuff like: arteriolar vasoconstriction (increase bp) stimulates vasopressin (ADH) release stimulates aldosterone (increase Na+ and water reabsorption)
velocity of blood flow depends on branching
more branching, increase cross SA, decrease velocity of flow and bp
opposite for merging veins
