topic 8 - exchange and transport Flashcards
how do you find surface area to volume ratio?
SA : V simplifies
what substances do we need to get rid of?
waste (e.g. urea), CO2, water to prevent cell lysis
how is urea removed from the body?
-via skin through sweat
-via kidneys in urine after having diffused from cells in the blood plasma for removal
how does exchange occur in single-celled organisms?
-gases + dissolved substances can dissolve into / out of cell across membrane
-large SA:V
where does gas exchange occur in mammals?
alveoli of lungs
how are alveoli’s adapted for their function?
-large SA
-good blood supply
-thin walls (1 cell thick) - short diffusion pathway
-in clusters
what are the factors affecting the rate of diffusion? (4)
surface area of membrane, concentration gradient, diffusion distance and temperature
how does the surface area of a membrane affect the rate of diffusion?
-larger it is - more space for particles to move - faster rate of diffusion
how does the concentration gradient affect the rate of diffusion?
-bigger the difference, steeper the conc. - faster the rate of diffusion
what is the concentration gradient?
difference between 2 concentrations
how does diffusion distance affect the rate of diffusion?
-blood supply is in closer contact
-shorter/thinner it is = faster rate of diffusion
how does the temperature affect the rate of diffusion?
-higher the temp. - higher the Ke, therefore faster rate of diffusion
what is fick’s law:?
rate of diffusion ∝ SA x conc. difference / thickness of membrane
what are the 4 main components of blood?
- red blood cells
- white blood cells
- platelets
- plasma
what is the function of blood?
transport such as (Oxygen, Carbon dioxide etc.)
what are red blood cells (erythrocytes) role?
-rich in haemoglobin (iron-containing bio-molecule) - binds to oxygen
-develop in bone marrow
-circulate for 100-120 days - recycled by macrophages afterwards
what is the reversible reaction for haemoglobin and oxygen?
haemoglobin + oxygen ⇌ oxyhaemoglobin
how are red blood cells adapted for their function?
-no nucleus
-small and flexible
-biconcave shape - maximise SA
-thin - short diffusion distance
what are the 2 types of white blood cells?
phagocytes and lymphocytes
what are phagocytes?
white blood cells that engulf and destroy unwanted micro-organisms through phagocytosis
-produced in bone marrow
-lifespan of 4 - 15 days
what are lymphocytes?
-produced in bone marrow and thymus
-produces antibodies - bind and destroy pathogens, clump pathogens for phagocytosis, release chemical signals
-release antitoxins
-create memory cells
what are platelets?
cell fragments produced by giant cells in bone marrow
how do platelets stop bleeding? (2 ways)
- proteins on their surface - enable them to stick to breaks in a blood vessel and clump
- secrete proteins - result in formation of a blood clot - plug a would (converts fibrinogen to fibrin)
what is plasma and what is its role?
-straw-coloured substance
-carries blood cells around body and glucose, salts and waste
