SB8 Flashcards
where and why does exchange happen for Oxygen
in the alveoli in lungs
needed for respiration
where and why does exchange happen for carbon dioxide
in the alveoli in lungs
to get rid of carbon dioxide as a waste product
where and why does exchange happen for water
occurs in the nephrons in kidneys
it is needed for cells to function properly
where and why does exchange happen for dissolved food molecules
occurs in the small intestine
needed for energy
where and why does exchange happen for mineral ions
occurs in the small intestine
needed for cells to function properly
where and why does exchange happen for urea
occurs in the nephrons in kidneys
its is a waster product of metabolism
How does surface area:volume ration affect organisms?
- the surface area: volume ratio will decrease as the organism gets larger
- so the organism cant solely rely on diffusion as particles may not be able to get through larger organisms and tissue
how are alveoli adapted for gas exchange by diffusion
- millions of alveoli
creates a large surface area for diffusion of gases - alveoli is associated closely with a capillary
capillary is one cell thick to allow for easy diffusion - ventilation of alveoli
creates a high concentration gradient which maximises the rate of diffusion
what are the factors which affect the rate of diffusion
(all increases diffusion)
increased surface area
short diffusion distance
maintained high concentration gradient
why does a greater concentration gradient lead to a faster diffusion
more particles are randomly moving down the gradient than are moving against it
why does a higher temperature lead to a faster diffusion
more energy in particle therefore they can move faster
why does a larger surface area increase the rate of diffusion
the more space for particles to move through, resulting in a faster rate of diffusion
what is ficks law
rate of diffusion ∝ (surface area x concentration difference) ÷ thickness of membrane
what are the main 4 components of blood
plasma (55%)
red blood cells (45%)
white blood cells and platelets ( < 1%)
Explain how the structure of red blood cells is related to its function
- contains haemoglobin which carries oxygen
- biconcave which allows for a large surface area for easier diffusion
- no nucleus which allows for more space for haemoglobin to carry more oxygen
Explain how the structure of white blood cells is related to its function
- part of the immune system to attack pathogens
- phagocytes surround pathogens and destroys them
- lymphocytes creates antibodies that attach to antigens of pathogens and destroys them
Explain how the structure of plasma is related to its function
the liquid part of blood
carries dissolved substances such as co2 glucose and urea
Explain how the structure of the platelets is related to its function
- are tiny fragments of cells which contains no nucleus
- they cause blood to clot when a blood vessel has been damaged
- the clot blocks the wound and prevents pathogen from entering the blood
what are the 3 types of blood vessels
arteries, vein and capillaries
explain the function and structure of arteries
- carries blood AWAY from the heart
- layers of muscles in the walls makes them strong, thick walls
-elastic fibres allow them to stretch - helps to withstand high pressures of blood
- carries oxygenated blood
explain the function and structure of veins
- carries blood TOWARDS the heart
- the lumen ( the tube which bloods flows through) is wide to allow the low pressure blood to flow through
- they have valves to ensure the blood flows in the right direction
- carries deoxygenated blood
explain the function and structure of capillaries
- allow for blood to flow close to cells to allow substances to move between them
- one cell thick for a short diffusion pathway
- permeable walls so substances can move across them
what is the purpose of the heart
- an organ in the circulatory system
- the heart pumps blood around the body in a double circulatory system
what is the purpose of the circulatory system
to carry oxygen and nutrients to every cell in the body and remove the waste products
