Blood Vessels and Tissue Fluid Flashcards
Why do organisms need mass flow?
Their SA:Vol ratio is too small, meaning that the diffusion distance may be too long.
Describe the human circulatory system.
Closed unit, double circulatory system
Describe the structure of arteries.
Thick muscular layer which allows the artery to stretch and recoil under high pressure.
Small lumen to maintain high pressure.
Describe the structure of veins.
Thin muscle and elastic layer as blood is at a lower pressure, therefore has a large lumen as a result.
Contains veins to prevent backflow of blood.
Why do mammals have a double circulatory system?
Blood needs to be pumped to the lungs to pick up oxygen before it can be pumped around the body.
What are arterioles?
Smaller branches off the main artery.
What are capillaries?
Very small blood vessels that branch off arterioles and venule and are only one cell thick.
What are venules?
Smaller branches off veins
What is tissue fluid?
Name 4 things that it contains.
A fluid that surrounds all cells in the body, containing dissolved ions, gases, biomolecules, water etc
What is the purpose of tissue fluid?
To provide cells with vital substances such as water, ions, dissolved gases etc
What is tissue fluid formed from?
Blood plasma
What surrounds capillaries to prevent them from leaking?
Collagen
What is hydrostatic pressure?
Pressure exerted by a fluid on walls
- Formation of tissue fluid
Where is hydrostatic pressure created in a capillary and how?
Hydrostatic pressure created at the arterial end by the heart pumping.
- Formation of tissue fluid
A build of hydrostatic pressure at the arterial end causes tissue fluid to move from/to?
What is the name of this process?
Tissue fluid moves out of blood plasma in the capillery.
This is called ultrafiltration.
How is tissue fluid different to plasma and why?
Contains fewer proteins. This is because proteins are too large to leak through gaps in the capillary wall.
- Formation of tissue fluid
How is a water potential gradient created between protein and tissue fluid?
Where does water move from/to despite this?
As plasma contains more proteins, the water potential is more negative than the tissue fluid.
But still, water moves from capillaries to tissue fluid.
- Formation of tissue fluid
At the venule end of the capillary, why is less fluid pushed out of the capillary?
There is a lower pressure in the capillary here.
- Formation of tissue fluid
How does the water potential gradient at the venule end compare to the water potential gradient at the arteriole end?
Where does water start to move from/to?
Water potential is the same, so water begins to flow back into the capillary from the tissue fluid.
How can hypertension (high blood pressure) affect pressure at the arteriole end?
How does this affect the volume of tissue fluid that leaves the capillary?
Increases pressure, leading to more fluid leaving the capillary and accumulating around tissue.
What is lymph?
What system does it travel to?
Fluid containing large molecules that cannot pass through the capillary wall. Passes through the lymphatic system.
Describe the difference between lymph capillaries and normal blood capillaries.
They have closed ends and large pores that allow large molecules to pass through.
How is lymph fluid pushed through the body?
By movement and compression
How is backflow of lymph prevented?
Due to the presence of valves.
