The heart Flashcards
(13 cards)
The heart general?
- muscular organ
- located between lungs, in centre of chest (thorax)
- pumps blood continuously around body
- 2 separate pumps - one for oxygenated blood, other w deoxygenated
- 2 relatively thin-walled collection chambers - atria (as don’t need to contract as hard - don’t pump blood far - only to ventricles)
- 2 thicker-walled pumping chambers - ventricles (bigger contraction w greater force - creates higher blood press - enable blood flow longer distances)
Septum?
separates oxygenated & deoxygenated blood
- maintains high conc. O2 in in oxygenated blood to maintain conc. gradient to enable diffusion at respiring cells
Cardiac muscle?
*walls of heart hv ts thick muscular layer
- myogenic - can contract & relax w/o nervous/hormonal stimulation
- never fatigues - as long as supply of O2
Coronary arteries?
supply cardiac muscle w oxygenated blood so - enable muscle cells to respire
- branch off from aorta
- if become blocked - cardiac muscle won’t receive O2 so - NOT able to respire & cells will die…
- result: myocardial infarction (aka heart attack)
2 large veins?
- Vena Cava (aka body vein): carries deoxygenated blood from body into right atrium
- Pulmonary Vein: carries oxygenated blood from lungs into left atrium
2 Large arteries?
- Pulmonary Artery: carries deoxygenated blood from right ventricle to lungs to become oxygenated
- Aorta: carries oxygenated blood from left ventricle
Valves?
Semi-lunar valves: in aorta & pulmonary artery (between ventricles & arteries)
Atrioventricular valves: between atria & ventricles
- bicuspid - left side
- tricuspid - right side
Pocket valves: in veins
Valves are controlled by pressure changes in the heart chambers…
- High pressure behind the valve forces it to open
- High pressure in front of the valve closes it
- prevent backflow of blood
- atrioventricular valves open when higher press in atria than ventricles (& vice versa)
- semilunar valves open when higher press in ventricles than arteries (& vice versa)
What happens during a heartbeat aka 1 cardiac cycle?
During a heartbeat the atria will receive blood from the veins
The atria will contract and push blood into the ventricles
The ventricles will contract pushing blood into the arteries
The atria and ventricles will relax allowing the heart to fill with blood
Atrial systole?
The muscles of the atria contracts
The pressure inside of the atria increases
The semi-lunar valves in the aorta and the pulmonary artery close
The tricuspid & bicuspid atrioventricular valves opens, allowing blood into the ventricles
Ventricular Systole?
The muscles of the ventricles contract
The pressure inside the ventricles increases
The tricuspid & bicuspid atrioventricular valves close
The semi-lunar valves in the aorta and the pulmonary arteries open
Blood flows out of arteries
Diastole?
- pressure in ventricles decreases
- semi-lunar valves in the aorta and the pulmonary arteries close
- All the heart muscles relax (atria & ventricular)
- Blood flows into the atria from the vena cava and pulmonary vein
- Blood pressure remains low inside the ventricles & blood starts to passively fill ventricles
Cardiac output?
*vol of blood which leaves 1 ventricle in 1 min
Cardiac output = heart rate * stroke volume
- heart rate: beats of heart per min -1
- stroke vol: vol of blood that leaves heart each beat
