Unit 3.1.5 - The Heart Flashcards
Which side of your heart pumps deoxygenated blood?
Right side
Which side of you heart pumps oxygenated blood?
Left side
What is meant by a double circulatory system?
The blood flows through the heart twice during each circuit around the body
What are the two sections in the double circulatory system?
Pulmonary circulation and systemic circulation
Where does the pulmonary circulation take the blood?
From the heart to the lungs and back again
Where does the systemic circulation take the blood?
From the heart to the rest of the body and back again
On a diagram is the left side the left or right side of the heart and why?
The left side on the diagram would be the right side of the heart as it is reversed
Label the diagram of the heart?
See flash card 20
What is the name of the valve between the atriums and ventricles?
Atrioventricular valve
What is the name of the valve between the ventricles and the arteries that leave the heart?
Semi-lunar valve
What vein enters the heart with deoxygenated blood and what artery takes it to the lungs?
Vena cava, pulmonary artery
What vein enters the heart with oxygenated blood and what artery takes it to the rest of the body?
Pulmonary vein, aorta
How is the left ventricle adapted and why?
It has the thickest muscular walls because it needs to be able to pump the blood more powerfully around the body
Why are ventricles thicker than the artia?
Because they have to pump blood out of the heart instead of just of short distance down into the ventricles
What are the functions of the valves in the heart?
To stop blood from flowing backwards
Why are there cords attached to the atrioventricular valves?
To stop the valves being forces into the atria when the ventricles contract
If there is a higher pressure before a valve is it opened or closed?
Opened
If there is a lower pressure before a valve is it opened or closes?
Closed
What is the contraction and relaxation of the heart muscle known as?
Contraction - systole
Relaxation - diastole
What is a systole?
Contraction of the heart muscle
What is a diastole?
Relaxation of the heart muscle
What three stages can the cardiac cycle to simplified into?
Ventricles relax and atria contract, ventricles contract and atria relax and then ventricles and atria relax
Describe the 4 steps that happen when the ventricles relax and atria contract?
- ) The volume of the atria decreases
- ) This increases the pressure in the atria
- ) This forces the atrioventricular valve open
- ) And the blood moves into the ventricles down the pressure gradient
Describe the 5 steps that happen when the ventricles contract and atria relax?
- ) The volume of the ventricles decrease
- ) This increases the pressure in the ventricles
- ) As the pressure is now higher in the ventricles than the atria the atrioventricular valves shut
- ) However it forces then semi lunar valves open
- ) And the blood then moves out of the heart through the arteries down the pressure gradient
Describe the 3 steps that happen when the ventricles and atria relax?
- ) The higher pressure in the arteries forces the semi lunar valves shut
- ) Blood then returns to the heart again due to the higher pressure in the veins
- ) The cycle starts again
What is meant by the cardiac muscles being myogenic?
It can contract and relax without receiving signals from nerves
What two nodes control the heart beat?
Sino atrial node and the atrioventricular node
What can you shorten sino atrial node and the atrioventricular node to?
SAN and AVN
What does the SAN do and what does this cause?
Sends out regular waves of electrical activity to the atrial walls and the AVN, the waves to the atrial walls cause the left and right atria to contract at the same time
What prevents the ventricles contracting as well as the atria after the SAN sends out a wave of electrical activity?
There is a band of non conducting collagen tissue between the atria and ventricles which means the waves can’t reach the ventricles
Why does the AVN send out another day after a slight delay?
To make sure the ventricles contract after the atria are emptied
What transfers the waves of electrical activity from the AVN to the ventricular walls?
The bundle of His transfers the waves from the AVN to the purkyne fibres
The purkyne fibres carry the waves of electrical activity into the walls of the ventricles
Do the ventricles contract top down or bottom up and why?
Bottom up to empty the ventricles
What is meant by cardiac output?
The volume of blood pumped by the heart per minute
What calculation can you do to calculate cardiac output?
Cardiac output = stroke volume x heart rate
What does heart rate mean?
The number of heart beats per minute
What is the stroke volume?
The volume of blood pumped during each heart beat
What is an atheroma?
The presence of fatty material within the walls of arties
What causes an atheroma?
If damage occurs to the endothelium, white blood cells and lipids accumulate under the lining to form fatty streaks. This fatty streak can harden to form a fibrous plaque called an atheroma.
Why does an atheroma increase blood pressure?
It can partially block the lumen restricting blood flow and so increasing blood pressure
What is an aneurysm?
A balloon-like swelling of the artery
How can an atheroma cause an aneurysm?
An atheroma damages and weakens the artery and causes a high blood pressure. When blood flows through the narrowed, weakened artery at a high pressure it can push the inner layer of the artery out through the outer elastic layer forming an aneurysm
If an aneurysm bursts what can it cause?
Haemorrhage (bleeding)
What is thrombosis?
A formation of a blood clot?
How can an atheroma cause thrombosis?
If an atheroma bursts through the endothelium of the artery it damages the artery walls and leaves a rough surface. Platelets and fibrin accumulate at the site of damage and form a blood clot
What can a blood clot in the brain cause?
A stroke
What is myocardial infarction another word for?
A heart attack
How can a blood clot cause a myocardial infarction?
If the coronary artery becomes blocked by the blood clot it cuts the supply of blood to part of the heart, this means the cells receive no oxygen and die and it is this that causes the myocardial infarction
What are three symptoms of myocardial infarction?
Pain in the chest and upper body, shortness of breathe and sweating
What is coronary heart disease caused by?
When the coronary arteries have lots of atheromas in them restricting blood flow
What are four risk factors of coronary heart disease?
- ) high blood pressure
- ) high blood cholesterol
- ) poor diet
- ) cigarette smoking
Why does a high blood pressure increase your risk of coronary heart disease?
It increases the risk of damage to the endothelium, so increased risk of atheroma formation, causing a further increase in blood pressure and blood clots increasing your risk of coronary heart disease
How does high blood cholesterol increase your risk of coronary heart disease?
Cholesterol is one of the main parts of the fatty deposits that from atheromas, so there is increased risk of atheroma formation, causing a increase in blood pressure and blood clots increasing your risk of coronary heart disease
Why can the carbon monoxide from cigarette smoke cause myocardial infarction?
The carbon monoxide combines with haemoglobin and reduces the amount of oxygen transported in the blood and so reduces the amount of oxygen available to the heart tissue, if the heart muscle doesn’t receive enough oxygen it can lead to a myocardial infarction
Other than the carbon monoxide in cigarette smoke why does cigarette smoke increase your risk of coronary heart disease?
It decreases the amount of antioxidants in the blood which are important for protecting cells from damage, this means cell damage to the endothelium in the coronary artery is more likely and so there is increased risk of atheroma formation, causing a increase in blood pressure and blood clots increasing your risk of coronary heart disease
