Transport in animals 3.2 Flashcards
the need for transport systems in multicellular animals
- larger animals have a smaller surface area to volume ratio
- have a longer diffusion distance so they cannot rely on diffusion aloneas it will be too slow the high metabolic rates of animals
single circulatory system
the blood flows through the heart once for each circuit in the body
double circulatory system
blood flows through the heart twice for each circuit in the body
pulmonary circulation
-carries blood to the lungs to pick up oxygen
systematic circulation
carries the oxygen and nutrients around the body to the tissues,
why is having a double cirulatory system benefical for mammals
-Because blood pressure is reduced when being taken to the lungs to avoid damaging delicate capilaries but it would be too slow for the rest of the body so it allows blood to be carried at a high pressure around the rest of the body
closed circulatory system
blood remains within the vessels
disadvantages of open circulatory system
- blood pressure is low and blood flow is slow
- circulation of blood may be affected by body movements or lack of body movements
open circulatory system
blood is not held within the blood vessels
structure of the arteries
- thick walls to withstand high pressure
- small lumen to maintain high pressure
- inner layer(tunica intima) consist of a relatively thick layer of elastic tissue to allow the walls to stretch and recoil maintaining blood pressure
- middle layer(tunica media) consists of a thick layer of smooth muscle which controls the diameter of the artery
- outer layer(tunica adventitia) consists of collagen fibres to provide strength to withstand high pressure
function of the arterioles
distribute the blood from an artery to a capillaries
structure of the arterioles
- walls consists of a layer of smooth muscle which constrict the diameter of the arterioles
structure of the capillaries
- thin walls one endothelium cell thick
- red blood cells squeeze against the walls of the capillary reducing the diffusion distance
function of the venules
collect blood from the capillaries to the veins
structure of the venules
- Has elastic tissue and collagen