Podcast
Questions and Answers
What happens to cells in an isotonic solution?
What happens to cells in an isotonic solution?
- Cells retain their normal size and shape (correct)
- Cells rapidly divide
- Cells lose water and shrink
- Cells swell and burst
What happens to cells in a hypertonic solution?
What happens to cells in a hypertonic solution?
- Cells maintain their normal volume and shape
- Cells shrink due to water loss (correct)
- Cells swell and potentially burst
- Cells increase in metabolic activity
What do the kidneys produce when we are dehydrated?
What do the kidneys produce when we are dehydrated?
- A small volume of concentrated urine (correct)
- A large volume of concentrated urine
- A small volume of dilute urine
- A large volume of dilute urine
The descending limb of the nephron loop is permeable to:
The descending limb of the nephron loop is permeable to:
What is the role of the collecting ducts in the kidneys?
What is the role of the collecting ducts in the kidneys?
In a dehydrated state with maximal ADH, what happens to urine volume?
In a dehydrated state with maximal ADH, what happens to urine volume?
In an overhydrated state with no ADH, what happens to urine volume?
In an overhydrated state with no ADH, what happens to urine volume?
What is the normal osmolality of filtrate entering the nephron loop?
What is the normal osmolality of filtrate entering the nephron loop?
When does filtrate reach its highest concentration in the nephron loop?
When does filtrate reach its highest concentration in the nephron loop?
Where is filtrate most dilute as it travels through the nephron?
Where is filtrate most dilute as it travels through the nephron?
The kidneys help maintain a constant solute concentration, and this is important for:
The kidneys help maintain a constant solute concentration, and this is important for:
What is the role of ADH?
What is the role of ADH?
What creates the osmotic gradient in the kidney?
What creates the osmotic gradient in the kidney?
What is osmolality a measure of?
What is osmolality a measure of?
When ADH is released from the posterior pituitary, what occurs?
When ADH is released from the posterior pituitary, what occurs?
What effect does increased urea recycling have?
What effect does increased urea recycling have?
If a person is overhydrated, what happens to the number of aquaporins?
If a person is overhydrated, what happens to the number of aquaporins?
Flashcards
Isotonic Solutions
Isotonic Solutions
Cells retain normal size and shape due to balanced solute/water concentration; water moves in and out.
Kidney Response to Dehydration
Kidney Response to Dehydration
When dehydrated, kidneys produce a small volume of concentrated urine to conserve water.
Kidney Response to Over hydration
Kidney Response to Over hydration
When over hydrated, the kidneys produce a large volume of dilute urine to remove excess water.
Long Nephron Loops
Long Nephron Loops
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Filtrate at Loop Entry
Filtrate at Loop Entry
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Descending Limb Action
Descending Limb Action
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Ascending Limb Action
Ascending Limb Action
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Filtrate Leaving Nephron Loop
Filtrate Leaving Nephron Loop
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Role of Collecting Ducts
Role of Collecting Ducts
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Response to Maximal ADH
Response to Maximal ADH
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Response to No ADH
Response to No ADH
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Study Notes
- Constant solute concentration is important to maintain cell size and shape.
Isotonic Solutions
- Cells retain their normal size and shape.
- Solute and water concentration is the same inside and outside of cells.
- Water moves in and out.
Kidneys and Urine Regulation
- Kidneys regulate the volume and concentration of urine.
- When dehydrated, kidneys produce a small volume of concentrated urine.
- When over-hydrated, kidneys produce a large volume of dilute urine.
Nephron Loops
- Long nephron loops of juxtamedullary nephrons create the gradient.
- As water and solutes are reabsorbed, the loop first concentrates the filtrate, then dilutes it.
- The filtrate entering the nephron loop is isosmotic to blood plasma and cortical interstitial fluid.
- Water moves out of the filtrate in the descending limb, which concentrates the filtrate.
- Filtrate reaches its highest concentration at the bend of the loop.
- Na (Sodium) and Cl (Chloride) are pumped out of the filtrate.
- This increases the interstitial fluid osmolality.
- Filtrate is at its most dilute as it leaves the nephron loop (100 mOsm).
- It is hypo-osmotic to the interstitial fluid
Collecting Ducts
- Collecting ducts are key to changing the concentration and volume of urine.
Dehydration
- Osmolality of extracellular fluids increases.
- ADH release from posterior pituitary increases. This leads to less urine production.
- Number of aquaporins increases in the collecting duct.
- H2O reabsorption from collecting duct increases.
- Small volume of concentrated urine is produced.
Overhydration
- Osmolality of extracellular fluids decreases.
- ADH release from posterior pituitary decreases. This leads to more urine production.
- Number of aquaporins decreases in the collecting duct.
- H2O reabsorption from collecting duct decreases.
- Large volume of dilute urine is produced.
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