2.8.10 The Heart Flashcards
The heart organ is a double, what?
Double Pump
Where does Oxygenated blood from the lungs enter
the left side of the heart and is pumped to the rest of the body (the systemic circuit)
Why does the left ventricle have a thicker muscle wall than the right ventricle
it has to pump blood at high pressure around the entire body,
Where does Deoxygenated blood from the body enter
enters the right side of the heart and is pumped to the lungs (the pulmonary circuit)
- The right ventricle is pumping blood at lower pressure to the lungs
What does the septum do?
A muscle wall called the septum separates the two sides of the heart
Where is blood pumped
Blood is pumped towards the heart in veins and away from the heart in arteries
The coronary arteries supply, what?
the cardiac muscle tissue of the heart with oxygenated blood
As the heart is a muscle it needs a constant supply, of what?
oxygen (and glucose) for aerobic respiration to release energy to allow continued muscle contraction
Where does Deoxygenated blood coming from the body flow
through the vena cava and into the right atrium
The atrium contracts and the blood is forced through, what?
through the tricuspid (atrioventricular) valve into the right ventricle
The ventricle contracts and the blood is pushed through the, what?
semilunar valve into the pulmonary artery
The blood travels to the lungs and moves through the capillaries past the alveoli where, what takes place?
gas exchange takes place
- Low pressure blood flow on this side of the heart prevents damage to the capillaries in the lungs
Oxygenated blood returns via, what?
the pulmonary vein to the left atrium
The atrium contracts and forces the blood through the, what?
bicuspid (atrioventricular) valve into the left ventricle
The ventricle contracts and the blood is forced through the, what?
the semilunar valve and out through the aorta
Exam Tip
Remember : Arteries carry blood Away from the heart
When explaining the route through the heart we usually describe it as one continuous pathway with only one atrium or ventricle being discussed at a time, but remember that in reality, both atria contract at the same time and both ventricles contract at the same time
Also, the heart is labelled as if it was in the chest so the left side of a diagram is actually the right hand side and vice versa
Describe the pathway of blood through the heart
1. Deoxygenated blood coming from the body flows through the vena cava and into the right atrium
How is a heart rate measured
by counting the number of times a heart beats in a minute (bpm)
The natural resting heart rate is controlled by a group of cells located in the right atrium called the, what?
pacemaker
What is the role of the pacemaker
The role of the pacemaker is to coordinate the contraction of the heart muscle and regulate the heart rate
Pacemaker cells send out, what?
electrical impulses which initiate a contraction in the cardiac muscle
Other factors can also influence the heart rate, such as the hormone, called?
adrenaline
The heart pumps blood around the body in order to supply respiring cells with what?
oxygen and glucose
The blood also removes, what? from respiring cells
waste products
During exercise, the cells of the muscles respire more rapidly in order to provide energy for, what?
muscle contraction
If exercise is moderate respiration may be, what?
aerobic
If exercise is intense respiration may be, what?
anaerobic
An increase in respiration means an increase in requirement for oxygen and glucose as well as an increase in production of, what?
waste products that need to be removed
The nervous system responds to this requirement by stimulating the following changes:
1. Heart rate increases to deliver oxygen and glucose and remove waste more frequently
Production of the hormone adrenaline increases the heart rate as part of a response called, what?
fight or flight’ response
At the end of a period of exercise, the heart rate may remain high for a period of time why is that?
as oxygen is required in the muscles to break down the lactic acid from anaerobic respiration
- This is how the oxygen debt is paid off
The time taken for the heart rate to return to the resting rate is called, what?
recovery time
- A physically fit person will have a lower resting heart rate and a shorter recovery time compared to an unfit person
Like all cells in the body, cardiac muscle cells need a supply of blood to, do what?
deliver oxygen and glucose and to remove waste products such as carbon dioxide
The blood is supplied to the heart by the, what?
coronary arteries which branch off directly from the aorta
- The heart needs to constantly respire, so it is vital that it receives oxygen
The coronary arteries supply the heart with, what?
oxygenated blood
In coronary heart disease (CHD), layers of fatty material (plaque) build up inside, what?
inside the coronary arteries
These fatty deposits are mainly formed from what?
cholesterol
There are two sources of in the body, what are they?
Dietary cholesterol (from animal products eaten)
Cholesterol synthesised by the liver
If a coronary artery becomes partially or completely blocked by these fatty deposits, what does it lose
it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts
The flow of blood through the arteries is reduced, resulting in what?
in a lack of oxygen for the heart muscle
- Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
- Complete blockage means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack
Treatment of CHD involves, what?
increasing the width of the lumen of the coronary arteries using a stent, or prescribing statins to lower blood cholesterol
There are several risk factors which will increase the chances of coronary heart disease, what are they?
Obesity
- Carrying extra weight puts a strain on the heart
- Increased weight can lead to diabetes which further damages your blood vessels
High blood pressure
- This increases the force of the blood against the artery walls and consequently leads to damage of the vessels
High cholesterol
- Speeds up the build up of fatty plaques in the arteries leading to blockages
Smoking
- Chemicals in smoke cause an increase in plaque build up and an increase in blood pressure
- Carbon monoxide also reduces the oxygen-carrying capacity of the red blood cells
