B13 Homeostasis

Question 1

Homeostasis

Answer 1

the maintenance of a constant internal environment. The conditions inside the body must be controlled within narrow limits. The conditions that need to be maintained include water content, ion content, body temperature and blood glucose concentration

Question 2

The internal environment

Answer 2

the surroundings of the individual cells of our body

Question 3

Factor to be kept constant in the pancreas

Answer 3

Glucose- which is converted into glycagon

Question 4

Factor to be kept constant in the skin

Answer 4

Temperature

Question 5

Factor to be kept constant in the liver

Answer 5

Temperature

Question 6

Factor to be kept constant in the kidney

Answer 6

Water/ Osmoregulation/ pH/ Urea

Question 7

Factor to be kept constant in the lungs

Answer 7

Oxygen and carbon dioxide

Question 8

Reasons for pH to be kept constant

Answer 8

So that a optimal pH for enzymes for metabolic reactions such as cellular respiration is provided, and to maintain the acidity of the blood

Question 9

Reasons for water content to be kept constant

Answer 9

So that a stable concentration of all water soluble substances in the blood and fluids in the body is provided. It is also to maintain the concentration gradient and avoid dehydration of cells. It is also a medium for many chemical reactions

Question 10

Reasons for oxygen content to be kept constant

Answer 10

To ensure sufficient provision for the blood to from oxyhaemoglobin and to load oxygen to cells for cellular respiration for growth, metabolic activities and to release energy

Question 11

Reasons for carbon dioxide levels to be kept constant

Answer 11

To maintain the constant acidity of the blood. Carbon dioxide combines with water to form carbonate acid and will release hydrogen and bicarbonate

Question 12

Reasons for temperature to be kept constant

Answer 12

Temperature has to be kept constant in order to maintain a stable metabolic rate and to provide the optimum temperature for enzymes

Question 13

Negative feedback

Answer 13

Ensures that in any controlled system, changes are reversed and returned back to the set level. It is the body correcting/ reversing and changes

Question 14

Hypothalamus

Answer 14

The area of the brain that monitors blood temperature and information sent from receptors in the skin

Question 15

What happens when we get too hot?

Answer 15

1) the erector muscles of the hair relax, allowing more heat out
2) Sweat glands produce sweat to cool down the body, as it evaporates and takes up energy and heat
3) Vasodilation- Arterioles near the surface of the skin dilate (get wider) to allow more blood to flow in the capillaries near the surface of the skin. This allows for more heat to be lost through radiation.
4) Metabolic rate will decrease/ respiration slows- as these reactions produce heat

Question 16

What happens when it gets too cold?

Answer 16

1) erector muscles of the hair contract, causing the hairs to stand up and trap a layer of air that acts as an insulator.
2) the sweat glands stop producing sweat
3) Vasoconstriction- The arterioles near the surface of the skin contract (get narrower), so less blood flows in the capillaries near the surface of the skin. This allows less heat loss through radiation.
4) Metabolic rate/ respiration increases- as these reactions produce more heat and muscular activity including shivering produces heat

Question 17

Why do blood sugar levels need to be kept constant?

Answer 17

So that complications and diabetes doesn’t occur

Question 18

What happens when blood sugar levels are too high?

Answer 18

The pancreatic beta cells secrete insulin, which travels via the bloodstream to the liver. The insulin causes the conversion of the excess soluble glucose into glycogen (insoluble) for storage in the liver and muscle cells

Question 19

What happens when blood sugar levels are too low?

Answer 19

The pancreatic alpha cells secrete glucagon, which travels to the liver and causes glycogen to be converted back into glucose