The Heart Flashcards
What is the cardiac muscle?
The thick muscular walls of the heart are called the cardiac muscle.
Cardiac muscle is mygoenic meaning it can contract and relat without nervous or hormonal stimulation.
Cardiac muscle never fatigues as long as it has a good oxygen supply
What do the coronorary arteries do?
Supply the cardiac muscle with oxygenated blood.
These branch off from the aorta.
If they become blocked cardiac muscle won’t receive oxygen, therefore will not be able to respire and the cells will die. This results in myocardial infarction (a heart attack)
What are the four chambers of the heart?
2 atria - left and right atrium
2 ventricles - left and right ventricles
What are the atria
Thinner muscular walls
No not need to contract as hard as they are not pumping the blood far (only to the ventricles)
They have elatic walls to stretch when blood enters
What are the ventricles
Thicker muscular walls to enable bigger contraction.
This creates a higher blood pressure to enable blood to flow longer distances (to the lungs and the rest of the body)
The right ventricle
Pumps blood to the lungs. This needs to be at a lower pressure to prevent damage to capillaries in the lungs and so blood flows slowly to allow time for gas exchange
Therefore, thinner muscular wall in comparison to the left ventricle
What is the function of the left ventricle
Pumps blood to the body. This needs to be at a higher pressure to ensure blood reaches all the cells in the body.
Therefore, much thicker muscular wall in comparison to the right ventricle to enable larger contractions of the muscle to create higher pressure.
What are the two veins in the heart?
Vena Cava
(Means body vein) Carries deoxygenated blood from the body into the right atrium
Pulmonary Vein
Carries oxygenated blood from the lungs to the left atrium
What are the two arteries in the heart
Pulmonary artery - carries deoxygenated blood from the right ventricle to the lungs to become oxygenated.
Aorta - carries oxygenated blood from the left ventricle to the rest of the body
What are the valves in the heart
Semi lunar valves
In aorta and pulmonary artery
Atrioventricular valves
Between atria and ventricles
Bicuspid (left side)
Tricuspid (right side)
What do valves do
Open when pressure is higher behind the valve.
Close when pressure is higher in front of the valve
Prevent backflow of blood
What is the septum
Separates the deoxygenated and oxygenated blood
Maintains high concentration of oxygen in oxygenated blood to maintain concentration gradient to enable diffusion at respiring cells.
What are the four types of blood vessels?
Arteries carry blood Away from the heart and into arterioles.
The arterioles are smaller than arteries and connect to the capillaries.
The capillaries connect the arterioles to the veins.
The veins carry blood back into the heart (hint to remember- velNs carry blood IN).
Properties of arteries - mucsle layer
Thicker than veins so that constriction and dilation can occur to control volume of blood.
Properties of arteries elastic layer
Thicker than veins to help maintain blood pressure. The walls can stretch and recoil in response to the heart beat.
Wall thickness of arteries
Thicker wall than veins to help
prevent the vessels bursting due to the high pressure.
Do arteries have valves
No
Muscle layer in the veins
Relatively thin so it cannot control the blood flow.
Elastic layer in the veins
Relatively thin as pressure is much lower
Wall thickness in the veins
Thin as the pressure is much lower so there is low risk of bursting. The thinness means the vessels are easily flattened, which helps the flow of blood up to the heart.
Do veins have valves
Yes
What are capillaries
Capillaries form capillary beds as exchange surfaces, which are many branched capillaries. These all have a narrow diameter to slow blood flow. Red blood cells can only just fit through and are squashed against the walls, and this maximises diffusion.
Muscle layer in arterioles
Thicker than in arteries to help restrict blood flow into the capillaries.
Elastic layer in arterioles
Thinner than in arteries as the pressure is lower