MAB 3

Question 1

Why is water needed by the body

Answer 1

1. It is an important solvent and forms the basic medium of most bodily fluids
2. It is a solvent for reactions to dissolve
3. It is a transport medium to carry dissolved minerals, nutrients, wastes
4. Allows for diffusing of substances to occur in and out of cells
5. is a life chemistry

Question 2

Why must the concentration of water be maintained within a narrow range for optimal functioning

Answer 2

1. It is vital for efficient metabolism
   - it allows correct concentration of substances to diffuse across and between cells as metabolic reactions only occur in solution
2. Cells can maintain a constant osmotic pressure so water loss through processes such as urination are compensated for
3. If cells are not isotonic, they are vulnerable to losing or gaining too much water

Question 3

What is a hypotonic and hypertonic solution

Answer 3

Hypotonic - there is less solutes outside the cell, so less water inside the cell. Therefore water moves into the cell causing it to burst

Hypertonic- there is more solutes outside the cell, and more water inside the cell so water will move outside the cell, causing it to shrivel

Question 4

What are the 3 main forms of nitrogenous waste

Answer 4

Ammonia
Utica acid
Urea

Question 5

What is ammonia

Answer 5

Secreted by fish and aquatic invertebrates. Soluble in water, very basic and very toxic

Question 6

What is Uric acid

Answer 6

Secreted by birds, reptiles and insects. Very insoluble in water, very basic and least toxic of all nitrogenous wastes

Question 7

What is urea

Answer 7

Excreted by mammals and amphibians. Soluble in water and diluted to reduce its toxicity

Question 8

Why is the removal of wastes essential for continues metabolic activity

Answer 8

Chemical reactions of metabolism sometimes produces chemicals which are toxic to cells. Hence metabolic wastes must be constantly removed from cells in order to maintain normal metabolic functioning

Question 9

Why must CO2 be removed and by what organ is it excreted by

Answer 9

CO2 is produced as a waste product of respiration. When it reacts with water in the cytoplasm of cells, it forms carbonic acid. This has the potential to lower the pH of the blood and other fluids affecting the body’s homeostatic balance, decreases metabolism and denatures enzyme functioning.
Excreted by lungs through exhalation

Question 10

Why must nitrogenous waste be removed

Answer 10

Nitrogenous waste is the by product of protein breakdown. It is toxic to cells as it changed the pH of cells making it more alkaline which effect is enzyme activity causing it to denature and interferes with transport of substances across cell membrane. All in all, decreases metabolic functioning
Excreted by kidneys through urine

Question 11

Why must excess salts and water be removed

Answer 11

Salts and water alters osmotic pressure and interferes with membrane functions (not isotonic). Cells could burst and create a less efficient metabolic process

Excreted by kidneys (urine) and sweat glands

Question 12

What is osmoregulation

Answer 12

Process of maintaining an internal balance of salt and water

Question 13

Role of the kidney

Answer 13

Responsible for filtering the blood and removing nitrogenous wastes.
Osmoregulation

Question 14

Role of kidney in freshwater fish

Answer 14

Excrete excess water. The kidney produces copious amounts of very dilute. Ammonia is excreted in large amounts of dilute urine

Question 15

Function of kidney in saltwater fish

Answer 15

Excreted salt
To avoid water loss, fish keep drinking water. They absorb both water and salts. Water is retained and salts are actively secreted some via gills/kidneys
Saltwater fish excrete very little urine

Question 16

Function of kidney in terrestrial mammals

Answer 16

Water and solutes are easily lost due to evaporation from lung surfaces during respiration and through excretory processes. Hormones adjust water and salt levels of the urine and maintain homeostasis. Kidneys regulate the body’s water concentration by either exerting diluted or concentrated urine

Question 17

What is the renal cortex

Answer 17

Filters blood and removed unwanted substances

With the help of nephrons and glomeruli

Question 18

What does the renal medulla do

Answer 18

Maintains the balance of water and salt within the blood

Question 19

What does the renal pelvis do

Answer 19

A reservoir that collects urine from the collecting ducts of the nephron system

Question 20

What does the ureter do

Answer 20

Carried urine from the kidney to the bladder

Question 21

What does the renal artery do

Answer 21

Carried oxygenated blood high in nitrogenous waste into kidney for filtration

Question 22

What does the renal vein do

Answer 22

Removes filtered blood low in oxygen and wastes from the kidney

Question 23

What do the kidney tubules do

Answer 23

Reabsorption and secretion

Question 24

What is renal dialysis

Answer 24

An artificial process to replace damaged kidneys.

Dialysis is performed by a large machine attached to a variety of computers and other equipment. Performed under hospital conditions. Concentrations of substances in blood and dialysis fluid are monitored by a computer so that wastes are removed during treatment. Renal dialysis removed waste only by diffusion

Question 25

Types of renal dialysis

Answer 25

Haemodialysis

Peritoneal dialysis

Question 26

Problems with diffusion

Answer 26

1. rate of movement is too slow

2. Not all wastes can be removed by diffusion

Question 27

Problems with osmosis

Answer 27

1. Too much water can be lost in urine

2. Movement of water can make wastes too dilute for excretion by diffusion

Question 28

Define enantiostasis

Answer 28

The maintenance of metabolic and physiological functions in response to variations in the environment