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20 terms

Excretion and osmoregulation

Wastes
STUDY
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Homeostasis
the maintenance of stable internal conditions
Osmosis
diffusion of molecules through a semipermeable membrane from a place of higher concentration to a place of lower concentration until the concentration on both sides is equal
Hypotonic
when comparing two solutions, the solution with the lesser concentration of solutes
Osmoconformers
An organism that allows its internal salt concentration to change with the salinity of the surrounding water
Osmoregulators
An organism that controls its internal salt concentration
Marine animals
Invertebrates are osmoconformers - 3-4 % salt in sea isotonic but fish hypertonic to sea water as store urea bony fish hypotonic
Ammonia
Very toxic, soluble and permeable so diffuses
Urea
Nitrogenous waste, less toxic and produced in liver
Uric acid
Nitrogenous waste, less soluble than ammonia and urea can be excreted as precipitate
Protonephridia flame cells
Flatworms have tubes that terminate at flame bulbs, produce filtrate cilia draw water and solutes in urine released via pores
Metanephridia
Ciliated funnel ( nephrostrome) with tubes leading to the nephridiopores for excretion in annelida one for each segment
Malphigian tubules
Insects have wastes from haemolymphs into tubules then into rectum and uric acid via faeces
Kidneys
Filtration, secretion and reabsorption
Bowmans capsule
Filter small blood liquid particles into tubule, this is the filtrate
Filtrate
Nitogenous waste (urea) glucose, salts, vitamin, and small molecules in a serum
ADH
Antidiuretic hormone enhances fluid retention increases water permeability in epithelium of distal tubules, and collecting duct.
Osmoreceptors in hypothalmus
Activated and stimulates ADH in posterior pituitary to retain fluid which dilutes extracellular fluid and reduces osmolarity
Osmolarity
a measure of the total solute concentration per litre of solution
JGA
Juxtaglomerular apparatus tissue near glomerulus of kidney. Releases RENIN enzyme
Atrial natriuretic factor ANF
High blood pressure stretch the wall of the heart. ANF inhibits the release of RENIN and the reabsorption of NaCl