2.6 Structure&Function Of Heart Flashcards
What is heart rate?
Number of beats per minute (pulse)
What is stroke volume?
Volume of blood pumped per beat
What is Cardiac Output?
Volume of blood pumped out of ventricle per minute
CO=HRxSV
How long is the cardiac cycle?
0.8 seconds
What happens during Atrial Systole?
2 atria contract and send blood down to ventricles through AV valves.
Ventricles then fill up with blood and SL valves remain closed.
What happens during Ventricular systole?
0.1 second After atrial systole ventricles contract and AV valves close SL valves I’ve pushed open and blood is pushed out of heart into aorta and pulmonary arteries
What happens during Atrial and Ventricular Diastole?
Blood returns through vena cava and pulmonary veins to the atria which causes the volume of blood to increase in atria.
Pressure exceeds in the ventricle AV valves open and blood enters Ventricles
How is ‘Lubb’ heart sound made?
Ventricle pressure exceeds atrial pressure forcing AV Valves to close which makes lubb
How is ‘Dupp’ heart sound made
Ventricular pressure falls below aortic pressure SL valves close and we hear ‘dupp’
Where is the pacemaker (sino atrial node, SAN) found in the heart?
Wall of the right atrium
What is SAN?
A small region of specialised tissue composted of auto-rhythmic cells which exhibit spontaneous excitation
What does the pacemaker do?
Initiated electrical impulses that make cardiac muscle cells contract at a certain rate & continues this function in the absence of nerve connections from the rest of body.
What is an Electrocardiogram?
Tiny currents generated from electrical activity of heart picked up by electrodes on skin surface and once amplified on a oscilloscope screen produce a electrocardiogram
What is blood pressure?
Force exerted by blood against the wall of blood vessels
How is SYSTOLIC blood pressure measured?
Using a sphygmomanometer
Cuff inflated until pressure stops blood flowing in arm artery then deflates until blood heard splurting with stethoscope & pulse can be felt
How is diastolic pressure measured?
More air released from cuff until sound from splurting disappears and pulse is no longer detected.
What is average blood pressure?
Systolic/diastolic
120/80
Decrease in blood pressure as it travels around the circulatory system
Friction occurs between blood and vessel wall as blood flows through a narrow vessel making wall resist blood flow causing a decrease in pressure.
What is hyperstension(high blood pressure)
Prolonged elevation of blood pressure at rest & indicated by systolicpressure greater than 140mm Hg and diastolic pressure greater than 90mm Hg.
Risks of hypertension
Common in adults over 35, coronary heart disease, stroke
