BIO osmoregulation

Osmoregulation

is the maintenance of constant [solute] in the body fluids

Osmoregulatory

______ demands vary across environments

excretion

Osmoregulation is linked to _____ of metabolic wastes

Vertebrate kidney

produces waste fluid and regulates blood [solute]

Solute concentration

_______ of the body fluids is critical to cell function

solutes

are substances dissolved in fluid

ex: salt

Gradients in [solute]

what dictate water movement across cell membranes

[Solute]

_____ means solute concentration

osmosis

______ is movement of water from an area of low [solute] to an area of high [solute] Water Balance & Solute Concentration

isoosmotic environment:

fluid [solute] = cell [solute]

• Water moves into & out of the cell at equal rates
  • Cell does not gain or lose water

hypoosmotic environment:

fluid [solute] < cell [solute]

• Water moves into the cell
  • Cell can burst under pressure

hyperosmotic environment:

fluid [solute] > cell [solute]

• Water moves out of the cell
  • Cell can shrivel and die

Marine animals

high [solute] environment example organism

Freshwater animals

low [solute] environment example organism

Terrestrial animals

dehydrating environment example organism

osmoconformers:
• Body fluid [solute] = sea water [solute]

Many marine inverts are

osmoregulators:
• Body fluid [solute] < sea water [solute]
• Sea water is dehydrating!
• Tend to lose water and body fluid becomes too
concentrated

• Produce a concentrated waste fluid to retain water
  and shed [solutes]

Many marine vertebrates are

osmoregulators:
Body fluid [solute] > freshwater [solute]
• Body fluid tends to become too dilute
• Produce a dilute waste fluid to expel water and
retain [solutes]

Freshwater animals are

osmoregulators
• Water loss → increase body fluid [solute]
• Produce a concentrated waste fluid to retain water
and shed solutes

(Terrestrial animals lose water by evaporation)

Terrestrial animals are

Amount & type of waste affects water balance

Example

• Nitrogenous waste is particularly important
• Metabolism of amino acids & nucleic acids produces
ammonia (NH3)
• NH3 is toxic
• Forms NH4+ → interferes with ATP synthesis
• Ammonia can be excreted directly but must be diluted
• Can be converted to less toxic forms, but this costs energy

Animals that face water limitation convert ammonia to____

urea or uric acid
• Urea is more energetically expensive than ammonia
but requires less dilution
• Uric acid is more energetically expensive than urea &
ammonia and requires almost no dilution

Excretory systems

remove nitrogenous wastes
and perform osmoregulatory functions
• Collect nitrogenous waste from the body fluid
• Control the amount of water excreted with the
waste fluid
• Pump solutes in or out of waste fluid depending on
body fluid [solute]

Excretory System Function

Produce a waste fluid by refining a filtrate derived from blood/body fluid
1. Filtration - nonselective movement of body fluid into excretory tubule
2. Reabsorption – pump useful molecules back into blood
3. Secretion – pump toxins, waste, and unwanted solutes into filtrate
4. Excretion – release waste fluid (urine)

Excretory systems are

networks of tubules

Tubules separate

stages of waste processing

SA

Packing of tubules increases

higher rate of waste fluid processing

Increased SA allows for

Transport epithelium

Tubules are lined by

Transport epithelium

is made up of specialized cells that move particular solutes in specific directions

Kidneys

paired organs each made up of networks of highly folded tubules

Renal artery

brings blood to kidney

Renal vein

drains blood from kidney

ureter

Urine produced in the kidneys exits through the

urinary bladder

Ureter drains to the

urethra

Urine is expelled through the

renal cortex

Kidney has an outer

renal medulla

Kidney has an inner

Renal pelvis

collects waste fluid and drains to ureter

nephrons

Cortex and medulla are packed with ____ (excretory tubules)

blood vessels

Nephrons are associated with

Nephrons

collect blood filtrate and exchange materials with blood in capillaries

Bowman’s capsule

Filtration happens in what part of the Nephrons

glomerulus

Blood pressure causes fluid to leak out of the

glomerulus

is capillary bed housed within Bowman’s capsule

nonselective filtering

what type of filtering occurs in the Bowman’s capsule

1. Proximal tubule

2. Loop of Henle

3. Distal tubule

What three regions of nephron does processing of waste fluid happen in?

Descending arm of Loop of Henle

reabsorbs water from waste fluid

Ascending arm of Loop of Henle

pumps salt out of waste fluid

Waste fluid drains from distal tubule into

collecting duct

Proximal tubule

Reabsorbs water, nutrients, & some salts

Distal tubule

allows for more exchange of salts

collecting ducts

Water can be reabsorbed from waste fluid in

hormonal control

Collecting duct’s permeability to water is under