7.6 Flashcards
What the basic structure include of vessels
Tough fibrous outer layer resist pressure change within and outside
Muscle layer can contract to control the flow of blood
Elastic layer helps maintain pressure by stretching and recoiling
Thin inner lining smooth friction free to allow diffusion
Lumen central cavity allows blood to flow
Artery function and comment of feature
Transport blood rapidly away from the heart to the tissues
Thick muscle layer so that arteries can be constructed and dilated to control the flow of blood through them
Elastic layer thick important to keep blood at high pressures so it can reach the extremities the elastic wall stretches when the heart beat and recoils this allows to maintain pressure and create smooth pressure surges
Overall thickness is great twist vessel bursting
No valves as pressure ensure blood l flowing in one way
Arterial and features
Carrie blood under lower pressures from arteries to capillaries
Muscle layer is thicker compare to arteries need control of flow of blood so can construct and dilate to control flow of blood into the capillaries
Elastic layer is thinner than in arteries as bp is lower
Vein feature and structure
Take blood away from tissues and back to the heart transport blood slowly and low Bp
The muscle layer is relatively thin compared to arteries as bloood is carried away from tissue thus contraction and dilation doesn’t control flow
Elastic layer is relatively thin as low no stretching and recoiling has no effect and no recoil action can be made
Overall thicknesss is small of wall as not under high pressure so not gonna burst it can also be flattened easily aiding flow of blood
Valves within so blood doesn’t flow backward as pressure is low
Muscles contract veins are compressed the valves ensure blood flows in one way
Capillary structure and function
Exchange materials between blood and cells of the body the flow of blood in capillaries is slower for max time of absorption
Walls are only lining layer one cell thick so diffusion pathway is short
Numerous and highly branched increase as
Narrow diameter they permeate tissue so no cell is far from capillaries
Lumen is narrow red blood cells are squeezed flat against the side of the capillary this brings them even close to the cells which supply oxygen
Spaces between the lining so white blood cells can escape and deal with infections
What is tissue fluid
Watery liquid contains glucose amino acids ions in a solution and oxygen it receives carbon dioxide and other waste materials from the tissues it is the immediate enviroment of the cell and where they live
It’s formed from blood plasma
How is tissue fluid formed
Pumping heart create hydrostatic pressure at the arterial end of the capillaries the hydrostatic pressure cause tissue fluid to move out of the blood plasma however it’s opposed by
Hydrostatic pressure of the tissue fluid outside the capillaries resist outward movement
And the lower water potential in the capillaries due to water moving out and not plasma protiens
Combine effect leads to an outward pressure which pushes tissue fluid out of the capillaries at the arterial end forcing only small molecules out ultrafiltaration
How is tissue fluid returned
The loss of tissue fluid reduced the hydrostatic pressure inside
The hydrostatic pressure is lower in the venous end compared to the tissue fluid outside
Tissue fluid is forced in by the higher hydrostatic pressure outside
Also the water potential is lower so water leaves the tissue via osomosis into the capillary down a concentration gradient
Where does excess tissue fluid go
The remainder is carried via the lymphatic system they are dead end tubes and gradually merge into larger tubes that form a network around the boody these larger vessels then drain the contents into the bloodstream near the heart
Body muscle contraction ensure the movement of tissue fluid in lymph and there are valves to ensure the fluid goes back to the heart
