Homeostasis- Function of Nervous and Endocrine systems

Question 1

Compare the action of the nervous and endocrine systems

Answer 1

Endocrine system is:
1. Slower.
2. Chemical (Hormonal).
3. Widespread.
4. Long lasting.
5. Transmitted through the bloodstream.
Nervous system is:
1. Fast
2. Electrochemical
3. Specific
4. Short lasting.
5. Transmitted via axons and synapse

Question 2

Describe the role of adrenaline in the ‘fight or flight’ response.

Answer 2

Adrenaline is a hormone released by the endocrine system into the bloodstream.

Fight or Flight is the response to stress.
Stimulus is immediate danger. Usually detected by eyes, ears, touch.

Question 3

what is the function of receptors in the nervous system during a fight or flight response and what are the responses to the secretion of adrenaline?

Answer 3

1. Receptors in the nervous system (usually in eyes or ears) send nerve impulses to stimulate the adrenal glands to release adrenaline into the blood.
2. Secretion of adrenaline increases:
   a. Heart rate (Nervous Response).
   b. Blood flow to muscles (Nervous Response).
   c. Dilation of pupils (Nervous Response).
   d. Blood pressure / increased ADH levels (Hormonal Response).
   e. Rate of metabolism / increased thyroxine levels (Hormonal Response).
   f. Blood glucose levels / increased glucagon levels (Hormonal Response).

Question 4

Describe the action of thyroid stimulating hormone and thyroxine in metabolism

Answer 4

Thyroxine increases the metabolic rate of cells. The metabolism releases heat energy as a biproduct. As such, an increase in metabolic rate increases heat production, which leads to an increase in body temperature.
Too much thyroxine can lead to body temperature rising too much, leading to potential denaturation of enzymes.

Question 5

Explain how the nervous and endocrine systems work independently or together to decrease body temperature

Answer 5

1. Thermoreceptors detect an increase in body temperature.
2. Nervous responses include:
   a. Sweating: release of moisture from sweat glands cools the body (decreases blood volume, increases blood osmolarity).
   b. Vasodilation: blood vessels near the surface of the skin dilate and allow heat loss through the surface of the skin.
   c. Hairs lay flat: increases air flow around the body, cooling.
3. Endocrine responses include:
   a. Decreasing thyroxine and adrenaline: slows reactions like aerobic respiration, producing less heat as a by-product.

Question 6

Describe the role of thyroid-stimulating hormone in the production of thyroxine.

Answer 6

Hypothalamus releases TRH which promotes the release of thyroid stimulating hormone (TSH) from the thyroid gland which releases thyroxine.

Question 7

Explain how the nervous and endocrine systems work independently or together to increase body temerature

Answer 7

1. Thermoreceptors detect a decrease in body temperature.
2. Nervous responses include:
   a. Vasoconstriction: blood vessels near the surface of the skin constrict and prevent heat loss through the surface of the skin.
   b. Hairs raise: traps air close to provide an insulating barrier to reduce heat loss.
3. Endocrine responses include:
   a. Shivering: causes the production and use of energy by moving, leading to heat being released.
   b. Increasing thyroxine and adrenaline: increases respiration rate, producing more heat.

Question 8

What is the effect of ADH on the nephron in osmoregulation?

Answer 8

ADH: Stimulates the synthesis of aquaporin channels.

Question 9

What does ADH stand for?

Answer 9

Antidiuretic hormone

Question 10

What is the response for the secretion of ADH?

Answer 10

1. Osmoreceptors in the hypothalamus detect decreased blood osmolarity.
2. Hypothalamus secretes ADH.
3. ADH binds to receptors of the collecting duct in the nephrons.
4. Stimulates synthesis of aquaporins, increasing permeability of the collecting duct.
5. The volume of water secreted (Urine) is decreased, meaning increased urine solute concentration.

Question 11

In what scenarios is ADH stimulated?

Answer 11

1. Increased blood osmolarity. (ADH decreases)
2. Decreased blood volume. (ADH Increases)
3. Decreased blood pressure. (ADH Increases)
4. Increased blood solute concentration. (ADH Decreases)

Question 12

In which scenarios is ADH not stimulated?

Answer 12

1. Decreased blood osmolarity. (Would Decrease)
2. Increased blood volume. (Would Increase)
3. Increased blood pressure. (Would Increase)
4. Decreased blood solute concentration. (Would Decrease)

Question 13

Explain how the nervous and endocrine systems work independently or together to enable osmoregulation

Answer 13

Nervous:
1. Osmoreceptors detect changes in osmolarity and the nervous system.
2. Nervous system transmits nerve impulse.

Endocrine:
1. The pituitary gland secretes ADH to regulate osmolarity.

Question 14

Compare the function of insulin and glucagon in blood sugar regulation.

Answer 14

Glucagon: stimulates the breakdown of glycogen into glucose.
Insulin: stimulates the storage of glucose as glycogen.

Question 15

describe the negative feedback loop of increased blood sugar

Answer 15

1. Beta cells detect increased blood sugar levels.
2. Beta cells in the pancreas secrete insulin into the bloodstream.
3. This causes the blood glucose level to fall, as glucose is converted into glycogen.
4. Glycogen is stored in liver and other body cells

Question 16

describe the negative feedback loop of decreased blood sugar

Answer 16

1. Alpha cells detect an increased blood sugar level.
2. Alpha cells release glucagon, which stimulates the breakdown of glycogen into glucose.
3. This causes blood sugar levels to increase.

Question 17

Describe how diabetes mellitus can result from a hormonal imbalance.

Answer 17

Type 1 Diabetes: Inability to produce insulin due to the autoimmune destruction of beta cells.

Type 2 Diabetes: Inability to produce insulin due to resistance developed from chronic exposure to high blood sugar. So, even if insulin is produced, it has diminished effect.

If insulin is not injected, blood sugar levels will not decrease. Increased blood sugar levels result in hyperglycaemia.

Question 18

Explain how the nervous and endocrine systems work independently or together to maintain blood sugar level:

Answer 18

Nervous:
1. During the flight or fight response, the nervous system detects stress.
2. Nervous system transmits nerve impulses from the brain to the adrenal gland; secretion of adrenaline leads to a increase in blood sugar levels (increase in glucagon levels).

Endocrine:
1. Pancreases secretes insulin and glucagon which regulate blood glucose levels.

Question 19

Explain how the nervous and endocrine systems work independently or together to monitor pH in the brain to maintain a constant carbon dioxide level in the blood.

Answer 19

When in the blood, CO2 dissolves into carbonic acid. Acidic substances decrease pH. As the blood is slightly basic (pH of 7.35), increases in CO2 (and thus carbonic acid, pH of 7) would decrease pH in the blood, and decreases in CO2 would increase pH of the blood.

Question 20

describe the negative feedback loop of the increase in CO2 levels

Answer 20

1. CO2 levels increase (most likely from exercise).
2. CO2 dissolved into carbonic acid in the blood, lowering blood pH.
3. Chemoreceptors detect decreased pH and send nerve impulse.
4. Nerve impulse transmitted by sensory neurons, to interneurons in the CNS, to motor neurons, to effectors.
5. Effectors, usually diaphragm, increase rate and depth of breathing, lowering CO2 intake.

Question 21

describe the negative feedback loop of the decrease in CO2 levels

Answer 21

1. CO2 levels decrease (most likely from hyperventilation: hyperventilation causes deep breathing, so CO2 breathed out more).
2. Less CO2 dissolves into carbonic acid in the blood, increasing blood pH.
3. Chemoreceptors detect increased pH and send nerve impulse.
4. Nerve impulse transmitted by sensory neurons, to interneurons in the CNS, to motor neurons, to effectors.
5. Effectors, usually diaphragm, decrease rate and depth of breathing, increasing CO2 intake.