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Regulation Of Water Content Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

The definition of osmoregulation

A

Osmoregulation is the maintenance of a stable water potential of body fluid in an organism

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2
Q

What is the importance of osmoregulation ?

A

It keeps the water potential of blood and hence the water potential of tissue fluid stable, so the cells can function properly to sub stain life

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3
Q

What is the major organs involved in osmoregulation ?

A

Kidneys of the urinary system

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4
Q

Where does the blood supplied and drained to the kidney ?

A

Supplied from the renal artery(arteries?) and drained by renal vein

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5
Q

what is the Function of kidney ?

A

Osmoregulation and excretion

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6
Q

What is the function of ureters ?

A

Carry urine from the kidneys to urinary bladder

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7
Q

What is the characteristic of urinary bladder ?

A

A hollow, muscular and elastic organ

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8
Q

What is the function of urinary bladder?

A

It stores urine temporiarily

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9
Q

How does the urinary bladder transfer urine to urethra ?

A

two rings of sphincter muscles are presented to control the release of urine from the urinary bladder to the urethra .

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10
Q

What is the mechanism of the urine passing out of the body?

A

When the volume of the urine increase in the urinary bladder, the wall of the bladder is stretched. This gives us the urge to urination. During urination, the muscle of the wall of the urinary bladder contract. The sphincter muscles relax. As a result, urine is passed out of body.

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11
Q

What is the function of urethra ?

A

It carries urine from urinary bladder to outside.

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12
Q

What is renal artery ?

A

They come from aorta and bring blood to the kidney

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13
Q

What is renal vein?

A

They takes blood away from kidney

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14
Q

What is nephrons ?

A

Nephrons are the functioning units of the kidney.

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15
Q

What is the structure of nephron ?

A

Nephron consists of the glomerulus, the Bowman’s capsule, the proximal convoluted tubule, the loop of Henle and the distal convoluted tubule.
The glomerulus is a network of capillaries which is enclosed with Bowman’s capsule. The kidney tubule is surrounded by another network of capillaries which is continuous with the glomerulus.

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16
Q

Where is the following structure located ?

  1. Proximal convoluted tubule
  2. Loop of Henle
  3. distal convoluted tubule
A
  1. Proximal convoluted tubule : cortex
  2. Loop of Henle: medulla
  3. Distal convoluted tubule: cortex
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17
Q 
The distal convoluted tubule finally leads to the (a)\_\_\_\_\_\_\_\_\_\_  which is joined to serval other nephrons. 
All the (a)\_\_\_\_\_ join together in the (b)\_\_\_\_\_\_\_\_\_
A

(a) collecting duct

(b) pelvis

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18
Q

How is the blood vessels surround the nephron ?

A

The afferent arteriole branched from the renal artery to form a network of capillaries called glomerulus. The glomerulus is enclosed in the Bowman’s capsule.
After leaving the Bowman’s capsule, the capillaries joined to form an efferent arteriole. The efferent arteriole then branches into another network of capillaries the surrounds the kidney tubule. The capillaries eventually join to form the renal vein.

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19
Q

What is the function of nephrons?

A

They are responsible for regulating the water content of the body (ie. osmoregulation) and the removing metabolic waste from the body (ie excretion) through the formation of urine.

20
Q

What is the mechanism of the ultrafiltration?

A

When the blood reaches the glomerulus, it is maintained at a relatively high pressure. The high blood pressure force water and other small soluble molecules (eg salt, glucose, amino acid and urea) in the plasma through the thin wall of the glomerulus and the Bowman’s capsule into the capsular space.

21
Q

Does ultrafiltration require energy?

A

No, it is a passive process

22
Q

What is glomerular filtrate ?

A

It is the fluid that is filtered into Bowman’s capsule

23
Q

Is the blood in pressure in the glomerulus higher than that in the afferent arteriole.

A

No. The blood pressure in the glomerulus is high , but still lower than that in the afferent arteriole. Because of the bumping action of the heart

24
Q

What is the definition of reabsorption ?

A

Reabsorption is the process that useful substances and most of the water in the filtrate are absorbed back into the surrounding capillaries

25
Q

What is adaptive features for reabsorption in proximal convoluted tubule?

A
  1. It is long and highly coiled .This features increases the surface area and the time for reabsorption.
  2. It’s wall consists of thin epithelial cell(ie.One cell thick).This shorten the distance for reabsorption of the substances from the filtrate into blood.
  3. The epithelial cells have many microvilli on the surface that is in contact with the glomerulus filtrate. These microvilli greatly increase the surface area for reabsorption.
  4. The epithelial cells contain many mitochondria, which are the site of cellular respiration. This provide energy for the active transport of the substances.
  5. It is surrounded by a dense capillary network, in which the blood allow rapid transport of substances away from the site of reabsorption. This help maintain a steep concentration gradient of substance between the blood and the filtrate for effective reabsorption.
26
Q

What substances are reabsorbed in the proximal convoluted tubule? How? Why?

A

1 glucose and amino acid and salt , active transport or diffusion

  1. Water , osmosis ;Cas filtrate is reabsorbed, so the filtrate becomes dilute ie. It’s water potential becomes higher
  2. Urea , diffusion ; Cas water reabsorbed, so the conc. Of urea increase
27
Q

What substances would be reabsorbed in
Proximal convoluted tubule:
Further:

A

Proximal convoluted tubule: glucose, amino acid ,salt ,water ,urea

Further: salt ,water ,urea

28
Q

Explain why the water content in the fluids from Bowman’s capsule is higher that that of afferent arteriole

A

Plasma protein is too large to pass through the walls of the glomerulus and Bowman’s capsule. Therefore, the proportion of water in the fluids taken from Bowman’s capsule is higher.

29
Q

What is the function of antidiuretic hormone (ADH) ? What is the mechanism

A

It controls the amount of water reabsorbed into the kidney tubules. ADH increases the permeability of the collecting duct to water so that a greater proportion of water can be reabsorbed from the filtrate. At the result , the volume of urine production is decreased and more water is retained in the body.

30
Q

What is antidiuretic hormone?

A

It is a hormone secreted by pituitary gland to control the amount of water reabsorbed in kidney tubule

31
Q

Which part of body controls the release of ADH?

A

Hypothalamus in the brain which contains osmoreceptors

32
Q

1How do the kidneys keep the water potential of the blood stable?

A

When the water potential of the blood becomes higher than normal, the osmoreceptors in the hypothalamus detects this change and causes the pituitary gland to release less ADH .The wall of the collecting duct becomes less permeable to water so that a smaller proportion of water is reabsorbed from glomerular filtrate . As a result, a larger volume of dilute urine is produced. The water potential of the blood falls and returns to normal.
When the water potential of the blood becomes lower than normal, the hypothalamus detects this change and stimulates the pituitary gland to release more ADH .The wall of the collecting duct becomes more permeable to water so that a larger proportion of water is reabsorbed. As a result, a smaller volume of concentrated urine is produced. The water potential of the blood rises and returns to normal.

33
Q

What is excretion ?

A

Excretion is the elimination of metabolic waste from the body

34
Q

Why is excretion necessary? What is the role of the kidneys in excretion?

A 
Metabolic waste (e-g. urea) is constantly produced and a high concentration of it is toxic to the body.
The kidneys remove metabolic waste from the blood by forming urine.
35
Q

What happens to a person if his/her kidneys do not function properly?

A

They cannot regulate the water content of body and remove the metabolic waste from body effectively. Metabolic waste (e.g. urea) accumulates in the body. If this builds up to a high level, it is toxic to cells and may cause death.

36
Q

How can the patient with kidney failure can be treated?

A

Haemodialysis is one of the methods. This is carried out using a dialysis machine.

37
Q

What is the feature and significance of the dialysis tubing?

A

Feature:
It is differently permeable. It only allows small molecules like urea to pass through.
Significance:
Help remove urea from the blood while retaining large blood components like plasma proteins and blood cells in the body

38
Q

What is the feature and significance of dialysis fluid ?

A

1.feature:
Has water potential similar to that of blood .
Significance:
Prevent water loss from the blood

2.feature:
The conc. of the nutrients (eg glucose and amino acid ) in it are similar to that of blood.
Significance:
prevent loss of nutrients from the blood

3.feature:
It contains no metabolic waste
Significance:
Allows metabolic waste in blood to diffuse into the dialysis fluid

39
Q

How does a dialysis machine help clean the blood of patients with kidney failure?

A

When the patient’s blood passes through the dialysis tubing in the dialysis machine, metabolic waste (eg, urea) diffuses out of the blood into the dialysing fluid which contains no metabolic waste. Useful substances (e.g. glucose and amino acids) remain in the blood as their concentrations in the dialysing fluid are similar to those in blood.

40
Q

State one similarity and one difference between the functioning of the artificial membrane in the dialysis machine and that of the wall of nephrons.

A

Similarity:
both the dialysis membrane and the wall of the nephron allow small molecules such as urea and other waste materials to pass through but not plasma proteins and blood cells
Difference :
the cell of the wall of the nephron actively reabsorb useful substances (e.g. glucose) into the blood, while the dialysis membrane has no such function

41
Q

Explain why diabetic patients urinate more frequently than healthy personas.

A

They failed to reabsorb all glucose from the glomerulus filtrate. Hence the glomerulus filtrate of diabetic patients has a lower water potential than that of healthy people. As the result, smaller proportion of water is reawakened back into blood from tubular filtrate at the collecting duct / distal convoluted tubule. The volume of urine produced will be higher, and they need to urinate more frequently.

42
Q

With reference to the physiological processes involved, explain why there is no change concentration of the fluid inside the tubule as the fluid flows from Bowman’s capsule (A) in the solute to proximal convoluted tubule. (B)

A
  • useful solutes, e.g. glucose, sodium ion,amino acids, are reabsorbed back into the blood capillary from tubular fluid by active transport along the first coiled tubule. - hence, water potential of the blood surrounding the tubule decreases/ water potential of the filtrate increases.
  • as a result, water moves out of the first coiled tubule along the water potential gradient by osmosis / water molecules move along with solute
  • the amount of water reabsorbed is proportional to the amount of solutes reabsorbed
  • hence, solute concentration remains the same as the fluid fow from point A to point B
43
Q

If protein is present in collecting duct, which part of nephron is most likely damaged? Explain your answer.

A
  • Glomerulus
  • the wall of glomerulus is impermeable to plasma protein/ protein molecules are too large to pass through the wall of glomerulus
    If protein is present in kidney tubule, it is most likely that the wall of glomerulus is damaged.
44
Q

In terms of the replenishment of water, which sports drink would you recommend for athletes to consume after exercise? Explain your answer.

-0 mmol/L sodium : larger urine volume
50 mmol/L sodium: medium
100 mmol /L sodium: smallest urine volume

A
  • 100 mmol/L sodium
  • smaller urine output, indicating that the body retains more water
  • the net fluid balance remains higher than 0 throughout the study
45
Q

With reference to the mechanisms involved in reabsorption, account for the differences in the amount of glucose and urea handled by the kidneys.

                    Amount in kidney      Reabsorbed in       
                                tubule            blood capillaries  Glucose.                     180.                          180 Urea.                            47.                          23.5
A
  • all glucose filtered in the kidney tubules is reabsorbed from tubular fluid into the blood in blood capillaries
  • because it is reabsorbed by means of active transport
  • however, only half of the urea is reabsorbed back into the blood
  • as urea is reabsorbed by means of diffusion only

Biology (15 decks)

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