Topic 8 - Exchange and transport in animals Flashcards
What are the names of substances that need to transported into and out of the body
water, urea, oxygen
how does urea form and leave the body
waste product of proteins, diffuses from cells to blood plasma for removal from body by the kidneys
How is water taken into the body
cells take up by osmosis. along with dissolved food molecules and mineral ions.
How do oxygen and carbon dioxide enter and leave the body
through diffusion
How easy an organism can exchange substances with its environment depends on its:
surface area to volume ratio
larger the animal- the smaller the S.A to volume ratio
How do single celled organisms exchanged substances with their environment
because they have a large surface area to volume ration, it allows substances to diffuse directly into and out of them across their membrane which is much quicker
How do multicellular organisms exchanged substances with their environment
more difficult to exchange substances over entire body so they have transport systems to move substances from exchange surface to rest of body due to smaller surface area to volume ratio.
What does the rate of diffusion depend on
Distance/thickness of membrane
concentration difference- faster if big difference
surface area- larger =faster more surface to diffuse across
Describe how gas exchange in mammals occurs
lots of alveoli in the lungs
- blood arrives at alveoli for gas exchange which contains lots of CO2 and no much O2.
- O2 diffuses out of air and into alveoli where O2 concentration is high and into blood where O2 concentration is low.
- CO2 diffuses in opposite direction so is breathed out
How are alveoli adapted for gas exchange
- moist lining for dissolving gases
- good blood supply to maintain the concentration gradients of O2 and CO2
- very thin walls
- very large surface area
whats ficks law
rate of diffusion = surface area x concentration difference
What is the function of red blood cells
and how are they adapted for this
to carry oxygen around the body
- bioconcave disc for large surface area to absorb oxygen
- no nucleus
- haemoglobin (contains iron) which binds to oxygen to become oxyhaemoglobin which is then reversed to release oxygen to cells
What is the function white blood cells
name the 2 types
to defend against infection
- phagocytes are white blood cells which can change shape to engulf unwelcome microorganisms through phagocytosis
- Lymphocytes -produce antibodies against microoragnisms. Some may produce antitoxins to neutralise any toxins produced by microoragnisms
Why you have an infection, how will the number of white blood cells change in a blood cell count
they will multiply to fight off infection
What do Platelets do and what are they
- help blood clot
- small fragments of cells clot round wound to stop blood getting out and microorganisms getting in
- without them we would have excessive bleeding and bruising