The Cardiovascular System Flashcards
deoxygenated blood return to the heart via the..
wrong blood goes to the right side
superior & inferior vena cava -> right atrium -> right ventricle -> pulmonary trunk (wrong blood goes to the right side)
The pulmonary trunk…
branches into the left and right pulmonary artery, pumps to lungs to get oxygenated
oxygenated blood returns to the heart via the..
left and right pulmonary veins -> left artium -> left ventricle -> aorta
Valves:
open and close in response to pressure changes as the heart contract and relaxes. prevents backflow
Atrioventricular valves
Right: tricuspid
Left: bicuspid
(we try before we buy)
Semilunar valves
right: pulmonary valve
left: aortic valve
Tricuspid
keep blood flowing in the right direction.
Bicuspid
connects to aorta. helps the blood flow through the heart’s 4 chambers and out to the body or into the lungs.
pulmonary valve
one-way door from your heart’s right ventricle to the lungs.
aortic valve
unidirectional flow of blood out of the left ventricle, the optimising of coronary blood flow, and preservation of myocardial function.
Pathway of blood - right side
inferior & superior vena cava -> r atrium -> r ventricle -> pulmonary artery -> L & R pulmonary arteries -> L&R lobes of lungs
pathway of blood - left side
L&R lobes of lungs -> L&R pulmonary veins -> L atrium -> L ventricle -> Aorta -> Systemic circulation
Cardiac cycle
One cardiac cycle consists of the contraction (systole) and relaxation (diastole) of both atria, rapidly followed by the systole and diastole of both ventricles
Coronary circulation:
blood flow through coronary arteries delivers oxygenated blood & nutrients to the myocardium. coronary veins remove CO2 & waste from myocardium
ECG
?
Heart Rate
the number of beats per minute
Stroke volume
the volume of blood pumped out of any one ventricle in one heartbeat ~70ml
cardiac output
the volume of blood ejected from one ventricle into the aorta or pulmonary trunk each minute. = heart rate x stroke volume. measured in L/min
Arteries Structure:
thick walls, small lumen, thick layers of muscles and elastic fibres, no valves
Veins Structure:
thin layer of muscle fibres, large lumes, thin outer wall, valves to prevent back flow
Capillary Structure
very small & thin, semi-permeable walls
Arteries Fuction
carries oxygenated blood away froom the heart (except pulmonary artery)
Veins Function
Carries deoxygenated blood to the heart (except pulmonary vein)
capillaries Function
diffusion of gases & nutrients from blood to cells of the body. Slow blood flow to allow exchange.
why is BP higher in arteries
Heart is pumping directly to arteries. they must adjust their diameter to maintain blood pressure and to control blood flow.
BP of 120/80 mmHg
Blood pressure is determined by contraction of the ventricles. Average blood pressure is 120/8mmHg. Systolic (highest pressure measured when ventricles contract) of 120 and a diastolic (lowest pressure measured when ventricles are relaxed) of 80
short-term regulation of BP
- vasomotor centre
- baroreceptors
- chemical - hormonal
long term regulation of BP
Renin-angiotensin-aldosterone system
Negative Feedback loop decreasing BP
Stimulus: decreasing BP Receptors: Barorecptors Control Centre: Medulla Oblongata & Adrenal Medulla Effectors: Heart & Blod vessel Response: increased BP
Feedback Loop increasing BP
stimulus: increased BP
Receptors: barorectors
Control Centre: cardioinhibitory & inhibit vasomotor centres
Effector: heart
Response: decreased CO & BP returns to normal
Pulmonary circulation
deoxygenated blood goes to lungs
Systemic Circulation
oxygenated blood goes to entire body organ systems
Conduction System
? SA & VA
Action Potentials of Autorhythmic Cells **
- Sodium starts to entry (reaches -40 the threshold potential)
- Calcium enters the cell (reaches 0)
- Potassium leaves the cell
Heart Sounds
S1 - AV - Lub
S2 - SV - Dub
Cardiac Muscle (contractile cells) Action Potentials
Starts at -90
- Depolarisation due to sodium inside the cell become positive
- Plateau phase due to calcium influx keeps cell depolarised
- Repolarisation due to calcium inactivating potassium channels opening
three factors that regulate stroke volume
- preload: degree of stretch of cardiac muscle before contraction
- contracility: strength of muscle
- afterload: pressure that must be overcome for ventricle to eject blood
Effects sympathetic nervous system on heart rate
increases heart rate
Effects of parasympathetic nervous system on heart rate
decreases heart rate
three layers of blood vessels
- tunica interna/intima: innermost, incontact w blood
- tunica media: smooth muscle & elastic fibres - can cause vasconstrition & vasodilation
- Tunica Externa: outer layer, connective tissue
Blood Pressure
determined by contraction of the ventricles
Venus Return:
the volume of blood flowing back to the heart through the systemic veins, in response to the pressure generated by contractions of the heart’s left ventricle
arterial blood pressure:
force exerted on the artery walls by the blood
Systolic Pressure
Highest pressure measured when the ventricles are contracting (avg = 120mmHg)
Diastolic Pressure:
Lowest pressure measured when the ventricles are completely relaxed (avg = 80mmHg)
Venous Blood Pressure:
low pressure system does not rise and fall with heartbeat
Vasoconstriction
increases BP
Vasodilation
decreases BP
Barorecptors
Pressure receptors located in carotid arteries and aortic arch, detects changes in BP which stimulates sympathetic/parasympathetic nervous system to control heart rate
RAAS
Renin-Angiotensis-Aldosterone System
The liver produces a protein (angiotensinogen), lungs produce (angiotensin converting enzyme (ACE))
If there is a drop in renal profusion. Cells detect this and produce Renin; renin causes conversion of angiotensinogen into angiotensin I -> ACE -> angiotensin II
