Unit 2-The Structure And Function Of The Heart Flashcards
What is the heart?
A muscular pump consisting of 4 chambers and various associated blood vessels.
Through what vein does deoxygenated blood arrive at the heart?
The vena cava.
Where does deoxygenated blood that has arrived at the heart from the vena cava go?
Moves into the right atrium and down into the right ventricle.
Which vessel carries deoxygenated blood from the right ventricle to the lungs?
Pulmonary artery
Which vessel returns oxygenated blood from the lungs to the heart?
Pulmonary vein
Where does blood from the pulmonary vein go?
What type of blood is this?
Will enter the left atrium.
Oxygenated blood
Where does blood from the pulmonary artery go?
What type of blood is this?
Goes to lungs
Is deoxygenated
What side of the heart is the pulmonary vein on?
Left hand side
What side of the heart is the pulmonary artery on?
Right hand side
What side of the heart is the vena cava on?
Right hand side
What side of the heart is the aorta on?
Left hand side
Where does blood from the aorta go?
Blood is pumped around the body.
Why is the left ventricle much thicker than the right ventricle?
Left side pumps blood all the way around the body
Right side has to pump blood to the lungs only.
What does AV stand for in AV valves?
Atrioventricular
What does SL stand for in SL valves?
Semilunar
Where is the right atrioventricular (AV) valve?
Between the right atrium and right ventricle.
Where is the right semilunar (SL) valve?
Between the right ventricle and pulmonary artery.
Where is the left atrioventricular (AV) valve?
Between the left atrium and the left ventricle.
Where is the left semilunar (SL) valve?
Between the left ventricle and the aorta.
Why does the heart contain valves?
The heart contains valves to prevent the back flow of blood.
Therefore the blood can only travel in one direction.
What is the definition of a heartbeat?
The number of heartbeats in one minute.
What is the definition of stroke volume?
The volume of blood pumped out by each ventricle during each contraction.
What is the definition of cardiac output?
The volume of blood pumped through each ventricle per minute.
What is the equation for cardiac output?
CO = HR x SV
What does the cardiac cycle refer to?
The cardiac cycle refers to the pattern of contraction and relaxation of the heart during one complete heartbeat.
What are the three stages of the cardiac cycle?
Atrial and Ventricular diastole
Atrial systole
Ventricular systole
What happens during atrial and ventricular diastole?
Chambers are relaxed and filling with blood.
What happens during atrial systole?
Atria contract and the remaining blood are pushed into ventricles.
What happens during ventricular systole?
Ventricles contract and push blood out through aorta and pulmonary artery.
What is the contraction of the heart known as?
Systole
What is relaxation of the heart known as?
Diastole
What happens in diastole of the heart?
Both the atria and ventricles are relaxed.
Blood returning to the atria flows into the ventricles.
The AV valves are open and the SL valves are closed due to the higher pressure in the arteries.
What happens in atrial systole?
The atria contract and ventricles relax.
The remainder of the blood in the atrium is transferred through the open AV valves to the ventricles.
The SL valves are shut/closed.
What happens in ventricular systole?
The ventricles contract and the atria relax.
What is responsible for the sounds heard with a stethoscope?
The opening and closing of the AV and SL valves are responsible for the heart sounds heard with a stethoscope.
What does the heart have that initiates each heartbeat?
A pacemaker.
What is the natural pacemaker in the heart and where is it located?
The pacemaker is the sino-atrial node (SAN) and is located in the upper wall of the right atrium.
How does the SAN work?
It starts electrical impulses which sets the rate at which the cardiac muscle cells contract.
How does the SAN cause the heart to contract?
The impulse from the SAN spreads through the muscular walls of both atria causing them to contract.
Causes atrial systole.
What happens after the impulse from the SAN cause atrial systole?
The impulse is passed to the atrioventricular node (AVN) which passes it through a bundle of conducting fibres down the central wall of the heart and up through the walls of the ventricles.
This causes the ventricles to contract at the same time (ventricular systole).
During diastole, what is happening to the AV and SL valves?
The AV valves are open and the SL valves are closed.
During atrial systole, what is happening to the AV and SL valves?
The AV valves are open and the SL valves are closed.
During ventricular systole, what is happening to the AV and SL valves?
The AV valves are closed and the SL valves are open.
What is an electrocardiogram (ECG)?
A test that can be used to check the heart’s rhythm and electrical activity.
What can an ECG show?
Problems with the heart’s rhythm
Underlying heart diseases such as atrial flutter, ventricular fibrillation or ventricular tachycardia.
What part of the brain regulates the rate of the SAN?
The medulla
How does the medulla regulate the rate of the SAN?
Regulates through the antagonistic action of the autonomic nervous system (ANS).
What two divisions is the autonomic nervous system made up of?
The sympathetic and parasympathetic division.
What do the sympathetic nerves release?
What happens to the heart rate?
Release noradrenaline.
Accelerates/increases the heart rate.
What do the parasympathetic nerves release?
What happens to the heart rate?
Releases acetylcholine.
Slow/decrease the heart rate.
What happens to the blood pressure as the ventricles contract (ventricular systole)?
Blood pressure increases.
As the heart relaxes (diastole), what happens to blood pressure?
It decreases.
What machine is used to measure blood pressure?
A sphygmomanometer.
How does a blood pressure machine work?
An inflatable cuff first stops blood flow in the arm.
The cuff then gradually deflates and the blood starts to flow again.
The blood flow is detected by a pulse and this is referred to as systolic pressure.
The blood eventually flows freely and is no longer detected as a pulse when diastolic pressure is reached.
When does blood pressure change in the aorta?
During the cardiac cycle.
What is the typical blood pressure reading for an adult?
120/80 mmHg (120 over 80).
If a blood pressure reading was 120/80, what does this show?
During contraction of the ventricles, blood pressure is 120mmHg. (systolic value).
During ventricular relaxation, it drops to 80mmHg. (diastolic value).
What is high blood pressure called?
Hypertension
What is hypertension a major risk factor for?
Many diseases including coronary heart disease.
