Transport in animals 3.2 Flashcards
(53 cards)
Why do very small organisms not need a separate transport system?
O2, nutrients and CO2 can diffuse directly between their body tissue and the external environment at a fast enough rate to meet their metabolic demands
Why do large organisms need a separate transport system?
Large organisms have a smaller SA:V so diffusion cannot provide and remove O2, nutrients and CO2 to meet their metabolic demands sustainably so they need a transport system to provide all the cells with the correct substances
what are the three main things that influence the need for a transport system?
- size (single or multicellular)
- SA:V
- level of metabolic activity
How do you find the volume of a sphere?
4/3 πr3
How do you calculate the SA of a sphere?
4πr2
How is tissue fluid formed from plasma?
- at the arterial end of the capillary there is a relatively high hydrostatic pressure which is larger than the oncotic pressure so there is a net outflow
- at the venule end the hydrostatic pressure is lower then the oncotic pressure so there is a net inflow
What is hydrostatic pressure and what does it do?
- the pressure the fluid exerts when pushing against the sides of the vessel
-t tends to push blood fluid out of the capillaries
If the tissue fluid does not go back into the blood where does it go?
- directed into the lymph system
- returns it to the blood system in the subclavian vein in the chest
What is oncotic pressure and what does it do?
- it is the pressure created by the osmotic effects of the solutes
- it tends to pull water back into the blood
- the movement of water into the blood by osmosis due to the tendency of plasma proteins to lower the water potential of the blood
what is a double circulatory system?
One in which the blood flows through the heart twice for each circuit of the body
What is a single circulatory system?
One in which the blood flows through the heart once for each circuit of the body
What is an open circulatory system?
One in which the blood is not held in vessels
What is a closed circulatory system?
One in which the blood is held in vessels
What are the advantages of a double circulatory pump system?
- blood pressure must not be too high in the pulmonary circulation to not damage the lungs
- heart can increase the pressure after the lungs to pump it round the body
- systemic circulation can carry blood at a higher pressure than the pulmonary circulation
What are the disadvantages of the single circulatory system?
- the blood pressure drops as blood passes through the tiny capillaries
- the blood flow is slow as it moves towards the body
- the rate at which O2 and nutrients are supplied to respiring tissues and CO2 and urea are removed is limited
What are the features of a good transport system?
- a medium to carry nutrients
- a pump to create pressure to push the fluid around the body
- exchange surfaces that allow substances to anter and leave the blood
- tubes or vessels to carry the blood by mass flow
- two circuits
What circulatory system do insects have?
An open circulatory system where body fluids act like body and tissue fluid
What circulatory system do fish have?
A closed and single circulatory system
What circulatory system do mammals have?
A closed and double circulatory system
What are the external components of a mammalian heart?
- ventricles
- atria
- coronary arteries
What are the internal components of a mammalian heart?
- vena cava
- pulmonary vein
- aorta
- pulmonary artery
- septum
- atrio-ventricular valves
- semilunar valves
What does myogenic mean?
Muscle that can initiate its own contraction
How is the heart action initiated and coordinated?
- impulse is generated in the sino atrial node
- wave of excitation travels to the atrioventricular node where it is delayed so the atria can finish contracting
- It is then carried down the bundle of his through the septum
- it then passes up the purkyne tissue which causes the ventricle walls to contract from the base up
Explain the cardiac cycle including pressure changes and valves, starting at atrial systole
Atrial systole - atria contract, AV valves open, blood flows into ventricles, ventricular pressure falls below atrial pressure
Ventricular systole- ventricles contract, AV valves close, semilunar valves open, blood leaves through arteries, ventricular pressure rises above atrial and aortic pressure
Cardiac diastole - atria and ventricles relax, pressure inside heart decreases, blood flows into heart passively, semilunar valves close, ventricular pressure falls below aortic pressure
