Blood Vessels And The Heart Flashcards
Right side of the heart
Pumps deoxygenated blood to the lungs
Receives deoxygenated blood from the rest of the body tissues
Right side of the heart blood vessels
Pulmonary artery = pumps deoxygenated blood to lungs
Vena cava = takes deoxygenated blood to heart from body tissues
Left side of the heart
Pumps oxygenated blood to the rest of the body tissues
Receives oxygenated blood from the lungs
Left side of the heart blood vessels
Aorta = pumps oxygenated blood to body tissues
Pulmonary vein = receives oxygenated blood from the lungs
Atrioventricular valves
Pointing downwards
Separates atria from ventricles on both sides of the heart
Open when the pressure above is larger than below
Semi lunar valve
Separates the ventricles from the pulmonary artery/ aorta (vessels carrying blood away from heart)
Open when pressure below is larger than above
Cords
Attach the atrioventricular valves to the ventricles to stop them being forced up into the atria when the ventricles contract
What does the blood carry?
Respiratory gases
Products of digestion
Hormones
Metabolic wastes
What do arteries do?
Carries blood away from the heart to the rest of the body
Arteries structure
Thick muscle layer
Elastic layer
Large overall wall thickness
No valves
Folded endothelium
Why do arteries have a thick muscle layer?
So that contraction and dilation occurs to control volume of blood delivered to arterioles
Why do arteries have a thick elastic layer
To allow for arteries to stretch when blood surges under high pressure (due to ventricles contracting) then recoil in response to low pressure when ventricles relax
Maintains and smooths blood pressure therefore smooth blood flow
Why do arteries not need valves?
Because the pressure is very strong due to contraction thus can only flow in 1 direction
Valves not needed to control direction of blood flow
What do arterioles do?
So arteries can divide into smaller vessels then into capillaries to direct blood to flow to different areas of the body in demand
Structure of Arteriole
Relatively thinner elastic layer
Relatively thicker smooth muscle layer than arteries
More numerous than arteries
Thinner overall wall thickness than arteries
Why do arterioles have a thicker muscle layer?
To control and direct the blood flow to capillaries
in vasoconstriction (contraction) to restrict blood flow
In vasodilation (relaxation) to allow blood flow
Slows it down for smaller capillaries
What is the function of capillaries?
To provide an exchange surface between the blood and body cells
Structure of a capillary
1 cell thick endothelium
Contains fenestrations
Form capillary beds
Why are capillaries composed of 1 cell thick endothelium (with flattened cells)?
To reduce diffusion distance between blood and tissue vessels
So this increases rate of diffusion between blood and tissue fluid/cells over the endothelium
Why do capillaries form capillary beds, by being highly branched and very numerous?
Forms a very large surface area so more exchange can happen at once and also so the blood can run closer to the cells within the tissue
Why do capillaries have a narrow lumen?
So that red blood cells only just fit, to slow the blood flow down to allow for more diffusion of gases to occur
And Increases friction in blood which Reduces blood flow To allow for more time for diffusion
Why do capillaries have fenestrations?
To form tissue fluid
Vein function
To carry blood to the heart under low pressure
Structure of veins
Thin muscle wall
Thin elastic wall
Thin overall wall thickness
Contains valves
Why do veins have small elastic layer?
Because the blood is transported slowly under low pressure so no stretch or recoil is required to maintain pressure
Why do veins contain valves?
To prevent back flow of blood because the blood is travelling at low pressures
Why does pressure decrease along a blood vessel?
Due to friction
What do veins, arterioles and arteries have in common?
Tough fibrous outer layer to resist pressure changes from outside and inside
Thin endothelial lining which are smooth lining cells to reduce friction
Why do arteries have a thick overall wall thickness?
To prevent vessels bursting due to high blood pressure
Why is the elastic wall of arterioles not as thick compared to arteries?
Because the pressure is slightly lower than in arteries so no stretch and recoil is required to maintain pressure
Why do veins have a thin muscle layer
Because it cannot control blood flow
Why do veins have relatively thinner walls overall?
Because the blood travels under low pressure so does not need thicker walls to prevent bursting
No risk of bursting
Why does blood not accumulate in arterioles (because they divide into capillaries that are very small)?
Because of the formation of capillary beds so the total cross sectional area of capillary beds is higher than that of arterioles