Homeostasis- Fluid Regulation

Question 1

What is Intracellular Fluid?

Answer 1

fluid inside cells. (cytosol, interstitial fluid or tissue fluid)
2/3 total body water

Question 2

What is Extracellular Fluid?

Answer 2

fluid outside the cells. (1/3 total body water)

e.g. blood plasma (1/4 of extracellular fluid)

Question 3

What is Intercellular Fluid?

Answer 3

fluid between cells (3/4 of extracellular fluid)

Question 4

What is the average fluid intake per day?

Answer 4

2500ml by food, metabolic water and drink

Question 5

What is the average fluid loss per day?

Answer 5

2500ml by lungs (vapour), skin (sweat), kidneys (urine) and alimentary canal (faeces)

Question 6

What is metabolic water?

Answer 6

small amount obtained as a by-product of chemical processes occurring within cells.

Question 7

Excretion

Answer 7

removal of waste products of metabolism from the body.

Question 8

4 main excretory organs

Answer 8

1. kidneys excrete urea produced by the breakdown of proteins by the liver
2. lungs excrete CO2, produced by cellular respiration.
3. sweat glands in the skin secrete water containing by products of metabolism (salts, urea and lactic acid)
4. alimentary canal excretes bile pigments by faeces, which are the breakdown products of haemoglobin from RBC.

Question 9

Alimentary canal not considered an excretory organ?

Answer 9

food materials in the excreted faeces are not produced by the cells.

Question 10

What is a nephron?

Answer 10

functional unit of the kidney that carry out the kidneys role in excretion and water regulation.

Question 11

Nephron: Filtration

Answer 11

1. blood enters the glomerulus under high pressure
2. the high blood pressure forces water and small dissolved molecules out of the blood and into the capsule. Large molecules and blood cells are retained in the blood
3. filtrate is collected by the Glomerulus.

Question 12

Nephron: Reabsorption

Answer 12

1. filtrate passes through the proximal convoluted tubule, the loop of Henle, the distal convoluted tubule and the collecting duct.
2. water and other useful substances are reabsorbed into the peritubular capillaries

Question 13

Nephron: Secretion

Answer 13

some materials that need to be removed from the body are secreted into the kidney tubule from the capillaries.

Question 14

What is the role of Antidiuretic Hormone?

Answer 14

Produced by the hypothalamus and released from posterior lobe of the pituitary. The permeability of the distal convoluted tubule and collecting duct walls are controlled by ADH. The level of absorption is controlled by ADH.

Question 15

Regulation of Body Water by ADH

Answer 15

1. H2O concentration in blood decreases and osmotic blood pressure increases
2. osmoreceptors in hypothalamus are stimulated
3. posterior pituitary is stimulated to release ADH
4. premeability of water of distal convoluted tubules and collecting duct is increased
5. increased amounts of water is reabsorbed into plasma
6. water concentration of plasma increases and osmotic blood pressure decreases

Question 16

Regulation of Body Water by Thirst Mechanism

Answer 16

1. H2O concentration in blood decreases and osmotic pressure increases
2. osmoreceptors in thirst centre of hypothalamus are stimulated
3. become thirsty
4. response by drinking
5. water is absorbed into blood from alimentary canal
6. water leaves blood and inter/extracellular fluids return to normal concentration

Question 17

Dehydration

Answer 17

when water loss exceeds water intake, this is caused by sweating, vomiting and diarrhoes

Question 18

Water Intoxication

Answer 18

when too much water is in the body, caused by replacement of H2O from sweat, body fluids become dilute and cells take in extra water