Formation of Urine
Formation of Urine
Steps in forming urine
Three steps to forming urine:1) Filtration2) Reabsorption3) Secretion
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1) FiltrationLabel Glomerulus and Bowman’s CapsuleFunction: -Moves waste from glomerulus to the
Bowman’s capsule-Done using the high blood pressure that
occurs in the kidney Moves: - Water, Urea, Uric acid, glucose, Hydrogen
ions, amino acids, salt,
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2) ReabsorptionLabel Proximal Convoluted TubuleFunction: - Moving molecules back to the blood from
the nephron.- The molecules returned to blood are the
ones needed by the bodyMoves: - Active (Using ATP): Glucose and Amino
acids, Na ions, - Osmosis: Moves water- Passive (Diffusion): Some Urea
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3) Reabsorption of NaClLabel Loop of HenleFunction: - Some NaCl moves back to the blood
from the Loope of Henle
Moves: - NaCl
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4) Tubular ExcretionLabel Distal Convoluted TubuleFunction: -Molecules move from the blood to the
nephronMoves: - Uric Acid, Ammonia, H ions
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5) Excretion
Label Collecting DuctFunction: -Urine is formed and travels to the ureterMoves: - Water, Salt, Urea, Uric Acid,
Water Balance
Need to Balance Water:- Increased water intake = increases urine production- Increased exercise or decreased water intake = decreased urine formation
Making the adjustments:1) Nervous System2) Endocrine System
Regulating (ADH)
ADH = antidiuretic hormone: A hormone that helps regulate the osmotic pressure of the body fluids
How: Can increase the amount of water reabsorbed into the kidney (produces more concentrated urine) which hydrates the body
ADH
ADH Production- Produced in the brain by nerve cells- Moves from the hypothalamus to the pituitary
gland where it is stored until it is needed.ADH Release control:1) Osmoreceptors in the hypothalamus trigger the
release of ADH if...1) There is a decrease in water intake2) There is an increase in water loss
Physiological response to Osmotic Pressure Increase
2) The increase of ADH = more concentrated blood
3) The highly concentrated blood pulls water out of the hypothalamus causing it to shrink
4) The shrinking hypothalamus sends a nerve impulse to the brain causing the release of ADH
5) ADH travels in the blood stream to the kidney causing it to reabsorb water
Behavioural response to Osmotic Pressure increase
Behavioural response: Shrinking hypothalamus leads to the sensation of being thirsty
= Drinking
ADH and the Nephron
Normal Osmotic pressure: 85% of the water absorbed into the nephron will be reabsorbed into the blood at the proximal tubule.
Loop of Henle and Water Reabsorption: Down (descending) part of loop = Permeable to
water and ionsUp (Ascending) part of loop = Only permeable to
ions (more )
ADH and the Kidney cont...
Distal Convoluted Tubule and Collecting duct: Impermeable to water (all water stays in kidney and goes out into urine).
Distal Convoluted Tubule and Collecting Duct + ADH: Both permeable to water so water can be reabsorbed into the blood stream
Assignment
Pg 808 7-11Urinary System-the
nephron elcheguevarra