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