transport in animals Flashcards
what are the three main factors that influence the need for a transport system
size
SA:V ratio
level of metabolic activity
how does size influence the need for a transport system
large organisms will have more than one layer of cells, also the cells will be further away from the diffusion surface meaning a larger diffusion distance meaning rate of diffusion is too slow. also substances such as o2 and nutrients will be used up by the outer layer of cells before they get to the deeper layers
how does SA:V ratio influence the need for a transport system
larger organisms have smaller sa:v ratio and so theres less area of body surface per gram of tissue for diffusion
how does the level of metabolic activity influence the need for a transport system
animals need to convert food into energy by aerobic respiration. animals that are active need good supplies of nutrients and oxygen to supply energy for movement. animals that need to keep themselves warm such as mammals need even more energy. all of these factors require more energy via a transport system.
what are the features of a good transport system
a fluid or medium to transport o2, nutrients and waste around the body e.g blood.
a pump to create pressure and push fluid around the body e.g heart.
exchange surfaces that enable substances to enter the blood and leave it when needed e.g capillaries.
tubes or vessels to carry the blood by mass flow
two circuits- one to pick up the o2 and one to deliver it to tissues
what is a single circulatory system
the blood flows through the heart once for each circuit of the body
what route does blood take in fish
heart > gills > body > heart
what is the circuit called where blood is carried to the lungs to pick up oxygen
pulmonary circulation
what is the circuit called where o2 and nutrients are carried to pick up oxygen
systemic circulation
what is hydrostatic pressure
pressure that a fluid exerts when pushing at the sides of a container or vessel
what is lymph
fluid held in the lymphatic system which is a system of tubes that return excess tissue fluid to the blood system
what is oncotic pressure
presure created by osmotic effects of solutes
whats tissue fluid
fluid surrounding tissues and cells
how is tissue fluid formed
at the arteriole end of a capillary there is high hydrostatic pressure. this pressure tends to push the plasma through gaps in the cells of capillary wall.
what is the formation of hydrocarbonate ions
co2 diffuses to the blood cells from the plasma. it then combines with water to create a weak acid called carbonic anhydrase (H2CO3). this carbonic acid then dissociates to release hydrogen ions and hyrdrogen carbonate ions. the hydrogen carbonate ions diffuse out of the red blood cell into the blood plasma. the charge of the red blood cell is maintained by chloride ions (Cl-) moving from the plasma to the red blood cells. this is called the chloride shift. the hydrogen ions building up in the red blood cell could cause the contents to become very acidic. to prevent this hydrogen ions are taken out of the solution by associating with hameoglobin to produce haemoglobinic acid (HHb). the haemoglobin is acting as a buffer (compound that maintans a constant pH)
