B8 | exchange & transport in animals Flashcards
what is the definition of diffusion?
the net movement of particles (gas or liquid) from an area of high concentration to an area of low concentration
how does distance affect the rate of diffusion?
smaller distance to travel = faster rate of diffusion
how does the concentration gradient affect the rate of diffusion?
greater difference in concentration = faster rate of diffusion
how does the temperature affect the rate of diffusion?
higher temperature = faster rate of diffusion because high thermal energy = high kinetic energy = particles move more/faster
how does surface area affect the rate of diffusion?
larger surface area = faster rate of diffusion because there is more surface space for the particles to move across
what is the equation for Fick’s Law?
rate of diffusion (a.u) ≈ surface area x concentration difference / thickness of membrane
what is the relationship between rate of diffusion and surface area/concentration difference?
directly proportional
what is the relationship between the rate of diffusion and the thickness of membrane?
inversely proportional
how to calculate surface area:volume ratio?
1) calculate area of one side
2) multiply this by the number of sides (surface area)
3) calculate volume of the shape
4) write out SA:V ratio
5) divide both sides by the volume (n:1)
what is the relationship between cell size and the SA:V ratio?
as the cell increases in size, the SA:V ratio decreases
what can cells do to increase their SA:V ratio?
- divide into smaller cells
- change shape to increase surface area
why is the SA:V ratio important for living cells?
- a high SA:V ratio means substances diffusing into the cell can reach all parts of it
- if the ratio is too low/the cell is too big, substances such as oxygen cannot reach all parts of the cell
- leading to cell death
what is the pulmonary circuit?
the circuit between the heart and the lungs which transports deoxygenated blood from the heart to the lungs and oxygenated blood from the lungs back to the heart
what happens when deoxygenated blood arrives at the lungs from the heart?
- carbon dioxide diffuses from the blood into the air in the alveoli
- oxygen diffuses from the air in the alveoli into the blood and is absorbed by haemoglobin in the red blood cells
- oxygenated blood is carried back into the heart
what is the systemic circuit?
the circuit between the heart and the other organs which transports blood around the body in order to:
- transport oxygen and nutrients to the body tissues
- carry away deoxygenated blood containing carbon dioxide and other waste materials
which side of the heart carries deoxygenated blood?
right side
which side of the heart carries oxygenated blood?
left side
how does the left side of the heart transport oxygenated blood to the rest of the body?
1) oxygenated blood from the lungs enters the left atrium via the pulmonary vein
2) left atrium contracts (beats)
3) oxygenated blood passes through the bicuspid valve into the left ventricle
4) left ventricle contracts
5) oxygenated blood passes through the semi-lunar valve, then through the aorta and travels to the rest of the body
how does the right side of the heart transport deoxygenated blood to the lungs?
1) deoxygenated blood from the body enters the right atrium via the vena cava
2) the right atrium contracts (beats)
3) deoxygenated blood passes through the tricuspid valve into the right ventricle
4) right ventricle contracts
5) deoxygenated blood passes through the semi-lunar valve, then through the pulmonary artery and travels to the lungs
what is the function of the bicuspid valve?
prevents oxygenated blood from flowing back into the left atrium from the left ventricle which increases flow of oxygenated blood around the body
what is the function of the tricuspid valve?
prevents deoxygenated blood from flowing back into the right atrium from the right ventricle
what is the function of the semi-lunar valve?
prevents blood from flowing back into the ventricles after it moves into the blood vessels
why are atrium walls thinner than ventricle walls?
- atrium walls are thin because the blood only needs to be pumped a short distance which doesn’t require much muscle
- ventricle walls are thicker because the blood has to be pumped further
why are the walls of the left ventricle thicker than the right ventricle?
- left ventricle walls are thickest because the muscle has to pump blood around the entire body under high pressure
- right ventricle walls are thinner because it only needs to pump blood to the lungs
why is the circulatory system of a frog less efficient at carrying oxygen to the body tissues than the human system?
- frogs have one ventricle whereas humans have two
- unlike humans, frogs have no septum to separate their ventricles which leads to oxygenated and deoxygenated blood mixing together
what is the function of the septum?
separates the right and left side of the heart, preventing oxygenated and deoxygenated blood from mixing
how does the nervous system control the beating of our heart?
sends electrical impulses to the heart causing it to contract
what is the definition of stroke volume?
the volume of blood (cm3) pumped from the left ventricle to the rest of the body
what is the definition of cardiac output?
the volume of blood pumped into the aorta from the left ventricle per minute
what is the formula for cardiac output?
cardiac output = stroke volume x heart rate
compared to a fit person, what is an unfit person’s heart rate like at rest?
an unfit person’s heart rate is always higher than a fit person at rest because the heart has to work harder