L8 Osmoregulation

Homeostasis

Internal environment needs to remain constant

Diffusion

solute molecules move from high to low concentration

osmosis

solvent molecules move from low to high soute concentration

Red blood cells in a hypotonic solution

Too low osmolarity, cells will explode

Red blood cells in a hypertonic solution

Too high osmolarity, cells will shrin

Skin properties terrestrial animals

• reptiles (birds) and mammals

impentreable (no respiration)

phospholipids/keratin (no evaporation)

osmoregulator

keep internal enivornment constant independently from outside

osmoconformer

internal osmolarity changes with external environment

advantage osmoregulator

changing environment is not harmful

advantage osmoconformer

saves a lot of energy

euryhaline -fish

broad range

stenholaine - fish

small range

osmoregulation is hard for fish because

only 1 cell layer between hypertonic/hypotonic environment and constant internal medium (blood)

fresh water fish: hyperosmotic regulator

hypotonic environment

water enters blood stream (cells explode)

loss of ions

active absorption of NaCl

salt water fish: hypo-osmotic regulator

hypertonic environment

water exists blood stream (cells shrink)

influx of ions

Active secretion of NaCl

marine animals - how to get rid of excess ions

via specialized glands

vetrebrate kidney function

filtration - glomerulus

reabsorption - loop of Henle, only in birds and mammals

secretion - urea

ion pumps in gills; ionocytes/chloride cell

seawater - ion secretion

fresh water - ion uptake

Hormonal effects on gills and gut

Renin/angiotensisn II

vasotocin (vasopressin)

Natriuretic peptide family (ANP)
isotocin (Oxytocin)

cortisol (aldosterone)

salt water ionocyte SW; secretion ions, GH/IGFI, cortisol

Fresh water ionocyte, FW, ion uptake, prolactin/cortisol

Why do we need kidneys

waste secretion (N-groups)
water-salt balance

acid-base regulation

blood pressure control

hormone production

detox and drug handling

Excretion of nitrogin

→ energy requirement

← toxicity, water requirement

ammonia, gills, aquatic animals (ammonotelic animals)

urea, urine, amphibians, mammals (ureotelic animals)

uric acid, insics, reptiles, birds (Uricotelic animals)

Thermoregulation and osmoregulation

Are correlated

Thermoregulation and osmoregulation are both homeostatic processes in organisms, meaning they help maintain internal stability, but they focus on different aspects of the body’s internal environment.

Longer loop of Henle

more concentrated *hyperosmotic) urine