Blood Vessels Flashcards
What can be found on the external structure of the heart and what is the function of it?
- coronary arteries
- to provide oxygen and nutrients to the cardiac muscle cells so they can continuously work to make the heart contract
Why is the heart described as myogenic?
It has its own intrinsic rhythm
Describe the structure of arteries and how it’s related to their function?
- smooth endothelial layer helps withstand the great pressure by not tearing
- collagen helps withstand the pressure
- elastic fibres help maintain the pressure by their recoil action
- smooth muscle can constrict to increase the pressure
Describe the structure of veins and how they are related to its function?
- large lumen allows a big amount of blood to flow
- valves that are attached by tendinous cords stop back flow of blood down pressure gradient
Describe the structure of capillaries and how they help with its function?
- single celled thick with endothelial cells which give short diffusion distance for exchange of materials
- fenestrations between the endothelial cells allow for the formation of tissue fluid
What is the consequence of high blood pressure for arteries?
- high blood pressure can cause arteries to tear… high concentrations of low density lipoproteins can cause the endothelial layer of arteries to be damaged and tear
- and eventually cholesterol deposits on these tears and builds up
- this causes plaque which narrows the arteries
- blood is restricted to many organs causing them to fail
- eg. If blood cannot reach brain cells to deliver oxygen and nutrients, it can cause a stroke
How does blood move up against gravity in veins?
- the contraction of muscles pumps blood against gravity in veins
- the valves help prevent the back flow
- the pressure build up in the thorax
What do arteriolar have more of then arteries?
- smooth muscle
- can constrict.. vasoconstriction
- can expand … vasodilation
- controls how much blood flows to specific regions
Why can’t valves get pushed the other way due to pressure?
They are attached via tendinous cords
Name some diseased related to the heart?
- coronary heart disease
- atherosclerosis (hardened arteries)
How can we treat narrowed coronary arteries?
- unclogging drugs
- bypass surgery
Why is there a pressure decrease once blood is in the capillaries?
- the total cross sectional area of blood vessels further from the heart is greater os cross sectional area of capillaries is greater than arterioles
- friction and resistance causes pressure loss
- capillaries don’t have elastic fibres for the stretch and recoil action to maintain pressure
Why is it important that there is a low blood pressure in capillaries?
- so that the capillaries are not damaged
- absence of collagen layer to withstand high pressure
- low blood pressure allows slow movement of blood so that exchange of oxygen and nutrients can happen
