Regulation Of Composition Of Body Fluids Flashcards
Describe the fluid balance.
Fluid gain must equal fluid loss.
Fluids can be lost by the kidneys through the skin, surface of lungs and alimentary canal.
What are the two types of body fluids?
Intracellular - fluid inside cells aka cytoplasm.
Extracellular - includes blood plasma and fluid between cells.
What is excretion and what organs play a role in excretion?
Excretion: removal of waste products of metabolism.
Lungs: secretion of CO2 through breaths.
Sweat glands: secrete water containing by products of metabolism.
Alimentary canal: passes out bile.
Kidneys: maintain concentration of materials in fluids.
Describe the control of water loss by the kidneys.
Reabsorption through walls of nephron.
Reabsorption at PCT and loop of henle via osmosis while reabsorption at DCT and collecting duct is active.
Reabsorption levels controlled by ADH.
When concentration in plasma is high, tubules more permeable to water, so it can leave.
Outward flow of water reduces volume and increases concentration.
What does ADH (anti diuretic hormone) do in terms of control of water loss in kidneys?
Controls permeability of walls of DCT and collecting duct.
Briefly describe the process of urine formation.
1) ENTRY: blood enters glomerulus under high pressure.
2) FILTRATION: high pressure forces water & molecules out of blood to capsule.
3) COLLECTION: filtrate collected by bowmans.
4) REABSORPTION: filtrate thru PCT, LOH and CD. Water reabsorbed.
5) SECRETION: materials needed to be removed secreted into kidney.
6) URINE: carried by CD to ureter.
Describe the feedback loop of a person doing exercise in terms of increased osmotic pressure.
Stimulus - inc osmotic pressure when water concentration in plasma decreases.
Receptor - osmoreceptors in hypothalamus.
Modulator - hypo sends message to release ADH from post pituitary. Nerve impulses from post lobe.
Effector - kidney tubules more permeable to water. Stimulates drinking.
Response - concentrated, little urine. Increased water reabsorption causes decreased osmotic pressure.
Describe the feedback loop of decreased osmotic pressure.
Stimulus - decreased osmotic pressure when water conc in plasma increases.
Receptor - osmoreceptors in hypothalamus.
Modulator - hypo sends message to inhibit release of ADH from post pituitary.
Effector - nephrons less permeable to water.
Response - more urine to expel water, more dilute, decreased water reabsorption causes increased osmotic pressure.
A person who becomes dehydrated will experience an increase in the solute concentration of blood plasma. Where will this cause water to move from?
From tissue fluid to plasma due to an increased osmotic pressure of the plasma.
What is the process of the kidney driven by?
Blood pressure.
Describe two processes that would have occurred in the body during exercise to cause an increase in blood plasma osmotic pressure.
Sweating
Increased breathing rate
Which part of the brain centre triggers the thirst mechanism?
Hypothalamus
How would information travel from the hypothalamus and where would it be processed to make a person feel like they need to drink water?
Information would travel via nerve impulse from the hypothalamus and would be processed in the cerebrum.
What hormone controls urine output?
Antidiuretic hormone.
Why does urine output decrease during sport?
During exercise, vasodilation occurs and more water is excreted.
This increases the concentration of osmotic pressure in blood.
This is detected by hypothalamus which sends releasing factors to the posterior pituitary for the release of ADH.
ADH allows more water to be reabsorbed into the blood, therefore less urine output.
