Physiology- Heart Flashcards
The cardiac muscles are myocytes
- they are myogenic, meaning?
- is able to contract on its own without needing nerve impulses
What is known as the pacemaker of the heart?
Sing-atrial node
What is the purpose of the SA node and where is it?
- contracts and transmits electrical impulses throughout atria, causing both atrium to contract
- top of right atrium
Process of atrial systole:
- atria contract
- SAN contracts and transmits electrical impulse causing both atria to contract, pumping blood into ventricles
- ventricles are electrically insulated so do not contract
- semi lunar valves close to stop backflow
Ventricular systole:
- electrical impulse passes from atrioventricular valve to purkinje fibres
- there is a short delay, then the electrical impulse passes down the insulated walls of the septum as the bundle of His
- at the base of ventricles the purkinje fibres spread out initiating ventricular contraction
- squeezing blood from bottom up, also forcing AV valves shut
Diastole:
Atria and ventricles relax, while atria fills with blood
- semi lunar valves are shut as ventricular pressure drops below arterial pressure
What is a phonocardiogram?
A recording of the sounds made by the heart, due to AV and semi-lunar valve closing
What is an electrocardiogram and its use?
- a recording of the hearts electrical activity
- diagnostics of heart problems can be made from weird electrical activity
Equation for cardiac output?
Cardiac output= heart rate x stroke volume
What is the equation for measuring heart rate?
Heart rate=60/cycle time(s)
What is stroke volume?
Volume of blood pumped in each beat
What is an atheroma and how is it formed?
A collection of Cholesterol and other insoluble lipids on the inside of coronary artery
What is an aneurism and how is it formed?
The atheroma hardens to form a rough plaque which weakens artery wall, causing the wall to swell beyond what it should
What else can an atheroma lead to other than aneurism?
Coronary thrombosis: the plaque forms a blood clot in the coronary artery
What is myocardial infarction?
The death of myocytes due to the lack of oxygen and their inability to respire anaerobically
What worsens or causes coronary heart disease?
1) blood cholesterol
2) genetics- blood pressure and fat metabolism are genetic
3) Diet- high levels of saturated fats increases cholesterol, and astheosclerosis (restricted blood flow)
4) smoking- CO and nicotine increase blood pressure
5) blood pressure- high bp increases risk of aneurism and stimulates thickening of artery walls
