Mass transport- circulatory system Flashcards
What is the circulatory system is made up of?
Heart and blood vessels
Characteristics of arteries-
-Carry blood from heart to rest of the body
-Their walls are thick and muscular and have elastic tissue to stretch and recoil as the heart beats-helps to maintain the high pressure
-Inner lining (endothelium) is folded, allowing artery to stretch - helps it to maintain high pressure
-All arteries carry oxygenated blood except for the pulmonary arteries- take deoxygenated blood to the lungs.
-Divide into smaller vessels called arterioles
Characteristics of arterioles-
-Form a network throughout the body
-Blood is directed to different areas of demand in the body by muscles inside the arterioles, which contract to restrict the blood flow or relax to allow full blood flow.
-Branch into capillaries-smallest part of the blood vessels- adapted for efficient diffusion
Characteristics of veins-
-Take blood back to the heart under low pressure
-Have a wider lumen than arteries with very little elastic or muscle tissue.
-Contain valves to stop the blood flowing backwards
-Blood flow through the veins is helped by contraction of the body muscles surrounding them.
-All veins carry deoxygenated blood except for the pulmonary veins (carry oxygenated blood from lungs to heart)
Role of capillaries and how are they adapted-
-Substances are exchanged between cells and capillaries
-Adapted for efficient diffusion
-Found near cells in exchange tissues such as alveoli in lungs, so there is a short diffusion pathway.
-Their walls are one cell thick, shortens the diffusion pathway
-There is a large number of capillaries to increase surface area for exchange- networks of capillaries are called capillary beds
What is tissue fluid?
-Fluid that surrounds the cells in tissues.
-Made from small molecules that leave the blood plasma (oxygen, nutrients, water)
-cells take in oxygen and nutrients from the tissue fluid and release metabolic waste into it
