2.6 Flashcards
What is stroke volume?
the volume of blood pumped from the left ventricle of the heart during each contraction.
What is heart rate?
the number of times the heart beats in a minute
How do you calculate cardiac output?
heart rate x stroke volume
What is diastole? - 1
relaxation of cardiac muscle which causes the chambers to fill with blood.
What is atrial systole?
contraction of the cardiac muscle surrounding the atria of the heart. This causes the blood in the atria to be ejected into the ventricles.
What is ventricular systole?
contraction of the cardiac muscle surrounding the ventricles of the heart. This causes the blood to be ejected from the ventricles into the pulmonary artery and aorta.
What is diastole? - 2
During diastole, the higher pressure of blood in the arteries closes the SL valves again and the next cardiac cycle begins.
What is the role of the coronary arteries?
provide the heart muscle with blood
How does atrial systole affect the valves in the heart?
causes the opening of the atrio-ventricular valves
How does ventricular systole affect the valves in the heart?
causes the closure of the atrio-ventricular valves and the opening of the semi lunar valves.
Why is there a difference in the thickness of the ventricle walls?
The wall of the left ventricle is particularly thick and muscular since it is required to pump blood all round the body. The wall of the right ventricle is less thick since it only pumps blood to the lungs.
What is the pathway of blood from the vena cava to the aorta?
vein cava - right atrium - right ventricle - pulmonary artery - lungs - pulmonary vein - left atrium - left ventricle - aorta
What areas of the heart control cardiac muscle contraction and heart rate?
the sino-atrial node and the atrio-ventricular node
Break down how the heart contracts (4 stages)
Stage 1 - the sino-atrial node (SAN) at the top of the right atrium acts as the pacemaker of the heart.
Stage 2 - electrical impulses are sent out from the SAN and transmit through the atria of the heart, causing atrial systole.
Stage 3 - the electrical impulse reach the atrio-ventricular node (AVN) in the sptum.
Stage 4 - the AVN the passes the impulse through conducting fibres around the cardiac muscle in the ventricles, causing ventricular systole
How can heart contractions be monitored?
using an electrocardiogram (ECG)
How does the brain control heart rate?
the medulla controls the rate of the heart using the autonomic nervous system.
What kind of neural pathway increases heart rate?
sympathetic neural pathway
What neurotransmitter is released by these nerves to increase heart rate?
noradrenaline
What kind of neural pathway decreases heart rate?
parasympathetic neural pathway
What neurotransmitter is released by these nerves to decrease heart rate?
acetylcholine
What instrument is blood pressure measured with?
sphygmomanometer
How is a sphygmomanometer used?
(3 stages)
Stage 1 - a cuffis inflated until the pressure that it exerts stops blood flowing through the arm artery.
Stage 2 - the cuff is allowed to deflate gradually until the blood starts to flow at systolic pressure.
Stage 3 - more air is released from the cuff until a pulse is no longer detected as the blood flows freely through the artery. This is at a diastolic pressure.
How does blood pressure in the aorta vary during the cardiac cycle?
the blood pressure in the aorta is higher during systole and lower during diastole.
What units are used to measure blood pressure?
mmHg
What is hypertension and what is it a risk factor for?
Hypertension is high blood pressure (above 140/90 mmHg) and is a risk factor for cardiovascular disease
What is commonly found to be associated with hypertension?
- being overweight
- not taking enough exercise
- eating a diet excessively rich in fatty food
- consuming too much salt
- drinking alcohol to excess regularly
- being under continuous stress
The circulation of blood flow - showing deoxygenated to oxygenated
The right atrium receives deoxygenated blood from all parts of the body via two main veins called the venae cavae. The deoxygenated blood passes into the right ventricle and the leaves the heart by the pulmonary artery which divides into two branches each leading to a lung.
Following oxygenation in the lungs, blood returns to the heart by the pulmonary veins and enters the left atrium. It flows from the left atrium into the left ventricle and leaves the heart by the aorta.
What is a person systolic and diastolic pressure on average?
systolic - 120 mmHg
diastolic - 80 mmHg
