Controlling Blood Water Potential Flashcards
(8 cards)
Explain the role of ADH in the production of concentrated urine.
4 marks
- When water potential of the blood too low;
- Detected by receptors in the hypothalamus;
- Pituitary secretes / releases (more) ADH;
- ADH increases the permeability / recruitment of aquaporins / opens channels for water in the DCT / collecting duct;
- More water is reabsorbed / leaves the nephron moves into the blood;
- By osmosis down the water potential gradient;
Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of both men and women. Affected individuals have proteinuria (high quantities of protein in their urine).
2 marks
- Affects/damages basement membrane
OR
More protein channels/carriers in basement membrane;
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- Proteins can pass into the (glomerular) filtrate/tubule;
Ignore nephron.
Glucose and water are reabsorbed by the proximal convoluted tubule of a nephron.
Put a tick (V) in the box next to the correct ways in which glucose and water are reabsorbed.
- Glucose by active transport and water against a water potential gradient
- Glucose by diffusion and water down a water potential gradient
- Glucose by facilitated diffusion and active transport and water against a water potential gradient
- Glucose by facilitated diffusion and active transport and water down a water potential gradient
- Glucose by facilitated diffusion and active transport and water down a water potential gradient
Furosemide and CVT are drugs used to remove excess fluid from the body.
Scientists investigated the effect of these drugs on the volume of urine produced by human volunteers. The scientists used the following method.
. They divided volunteers into three groups, A, B and C at random.
. They gave all the volunteers the same food for 3 days.
. After 3 days, they gave the volunteers in group A a tablet containing furosemide, the volunteers in group B a tablet containing CVT. and the volunteers in group C a placebo (a tablet that did not contain either drug).
.They then found the mean volume of urine produced by each group in the 4 hours after taking the tablets.
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Furosemide is sometimes used to treat high blood pressure
Suggest how furosemide would cause a decrease in blood pressure
Lower volume of blood;
Furosemide inhibits the absorption of sodium and chloride ions from the filtrate produced in the nephrons.
Explain how furosemide causes an increase in the volume of urine produced.
3 marks
- Water potential of filtrate/tubule decreased;
Accept correct reference to water potential gradient
Accept maintains low water potential.
Accept nephron for filtrate/tubule.
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- Less water (reabsorbed) by osmosis (from filtrate/tubule);
Accept nephron for filtrate/tubule.
Accept no water (reabsorbed) for ‘less’
Accept (more) water (absorbed) by osmosis (into filtrate/tubule)
——————-
- Collecting duct (is where osmosis occurs);
Accept proximal convoluted tubule or distal convoluted tubule or (descending) loop of Henle
Ignore PCT, DCT.
More than 99% of biological molecules are reabsorbed from the filtrate in the proximal convoluted tubule.
Despite this, the concentration of fluid in this tubule remains constant.
Explain why.
1 mark
Water is also reabsorbed
V receptors only bind with ADH.
Suggest and explain why.
2 marks
- Has a specific tertiary structure/ shape
- (Structures are) complementary
Suggest and explain how GLUT4 and CD36 transport proteins (lines 10-11) are beneficial during exercise.
3 marks
- (More) glucose enters (muscle) cells;
- (Glucose/fatty acids enter by) facilitated diffusion;
- Fatty acids used in Krebs cycle;
- Respiration provides (more) ATP:
——————
Max 2 marks if only in context of glucose or only in context of fatty acids.
1. Ignore more glucose leaves (liver)
cells.
1. Reject glucose
enters mitochondria.
2. Accept active
transport or cotransport.
3. Ignore gluconeogenesis.
4. Accept in context of glucose or fatty acids.
4. Accept for fatty acids ‘Krebs cycle produces ATP’.
