Transport and Excretion (humans) Flashcards
what are the excretory products of the lungs, kidney and skin?
LUNGS: carbon dioxide
KIDNEY: urea, excess water + ions
WATER: sweat/urea
what happens in ultrafiltration?
- blood from the renal artery flows through the glomerulus
- a high pressure is built up which squeezes water, urea, ions and glucose out of the blood and into the Bowman’s capsule
- large molecules like proteins and blood cells are not filtered out as they are too large.
what happens in selective reabsorption?
as the filtrate flows along the nephron, useful substances are selectively reabsorbed back into the blood:
- ALL GLUCOSE is reabsorbed (by active transport) from the proximal convoluted tubule so it can be used in respiration.
- Sufficient ions are reabsorbed, excess are not.
- sufficient water is reabsorbed from the COLLECTING DUCT into the bloodstream (osmosis)
how do the kidneys carry out osmoregulation?
- ADH.
- Hypothalamus monitors water content of the blood, and if it is too low instructs the pituitary gland to release more ADH into the blood.
- More ADH makes the collecting ducts more permeable so the kidneys reabsorb more water.
- Visa-versa if water content too high.
- when kidneys reabsorb more water, the urine has a smaller volume and is more concentrated.
what does the urinary system contain?
kidneys, ureters, bladder and urethra (in that order)
what is the structure of a Nephron?
- Bowman’s capsule
- glomerulus
- proximal convoluted tubule
- loop of Henle
- distal convoluted tubule
- collecting duct.
(in that order)
where is water reabsorbed?
collecting duct
where is glucose reabsorbed?
proximal convoluted tubule. The PCT is highly permeable meaning it is easy for molecules to diffuse through it.
what does urine contain?
water, urea and ions
what is the blood made up of?
-RBC, WBC, platelets and plasma.
what does plasma do?
pale yellow liquid that carries everything:
- RBC + WBC and platelets
- glucose and amino acids
- CO2
- urea
- hormones
- heat energy
how are red blood cells adapted to their function?
- small and biconcave shape = large SA for absorbing and releasing oxygen
- contain haemoglobin which binds to oxygen to transport it from the lungs to body tissues. contains lots of iron
- no nucleus = more space for more haemoglobin and therefore more oxygen.
how do PHAGOCYTES deal with pathogens?
they INGEST PATHOGENS.
- they detect foreign objects eg. pathogens
- they then ENGULF the pathogen and digest them
- they are NON-SPECIFIC (attack anything that’s not supposed to be there).
how do LYMPHOCYTES deal with pathogens?
- every pathogen has unique antigens on its surface.
- when lymphocytes come across a foreign antigen, they start to produce antibodies. these lock onto the invading pathogens and mark them for destruction by phagocytes. the antibodies produced are specific to that type of antigen.
- antibodies are then produced rapidly and flow around the body to make all similar pathogens.
- MEMORY CELLS are also produced. these remain in the body and remember a specific antigen. they reproduce very quickly if the same antigen enters your body again.
how does vaccination protect you from future infections?
- involves injecting dead or inactive pathogens into the body. these still carry antigens so even though they’re harmless they still trigger an immune response.
- memory cells will also be produced and will remain in the body so if live pathogens of the same type ever appear, the antibodies to kill them will be produced much faster and in greater numbers.
