Chapter 11C Endocrine System

Question 1

Mammary glands produce milk to feed babies. The production and secretion of milk is stimulated by the hormone prolactin.
Define the term hormone

Question 2

Suggest the function of the structure labelled A (mammary duct) [1] (2013/A7)

Answer 2

Transport milk from glands to outside the body.

Question 3

Explain why the insulin levels decreased during fasting [2] (2015/A5)

Answer 3

During fasting, no intake of glucose causes blood glucose concentration to decrease below normal [1]
and this stimulates the islets of Langerhans of the pancreas to release less insulin into the blood to reduce the conversion of glucose to glycogen by the liver for storage.[1] resulting in blood sugar levels returning to normal.

Question 4

Suggest and explain why the adrenaline concentration increases during excersise.[3] (2015/A5)

Answer 4

1. During exercise, there are increased muscular contractions.
2. There is an increased rate of respiration to release more energy to meet the higher energy demand. More glucose and oxygen are required by the muscles
3. Adrenaline is produced to stimulate the conversion of stored glycogen in muscles into glucose to be the substrate for respiration. It also increases heartbeat which leads to an increase in blood flow rate
4. This causes glucose and oxygen to be transported to the muscles faster.

Question 5

Explain, using a named example, what is meant by an endocrine gland [2] (2016/B10 OR)

Answer 5

Adrenal glands are ductless glands that secrete the hormone adrenaline directly into the bloodstream. The blood transports adrenaline to target organs and tissues such as the heart, liver and muscles to bring about fight or flight responses. Adrenaline increases heart rate and muscle contraction.

An endocrine gland is a ductless gland that produces and secretes hormones directly into the bloodstream.
The hormones are transported toone or more target organs/tissues and alters the activity of these target organs/tissues.

Question 6

Describe the roles of insulin and glucagon in the human body [6] (2016/A10 OR)

Answer 6

1. Insulin and glucagon regulate blood glucose concentration.
2. When the blood glucose concentration increases above normal, the islets of Langerhans in the pancreas are stimulated to produce more insulin. [1]
3. Insulin stimulates the liver and muscle cells to be more permeable to glucose. It also stimulates the liver to convert excess glucose into glycogen for storage. [1]
4. This reduces the blood glucose concentration to normal. [1]
5. When the blood glucose concentration decreases below normal, the islets of Langerhans in the pancreas are stimulated to produce more glucagon. [1]
6. Glucagon stimulates the liver cells to convert stored glycogen into glucose and releases it into the bloodstream. [1]
7. This increases the blood glucose concentration to normal. [1]

Question 7

Define an endocrine gland

Answer 7

Endocrine glands are ductless glands that produces and releases hormones directly into the blood.

Question 8

what are the effects of adrenaline? [6] (self)

Answer 8

Effects of adrenaline:
● Stimulates liver and muscle cells to convert stored glycogen to glucose, increasing the blood glucose levels
● Increase in heart rate and blood pressure, hence more oxygen and glucose is supplied to muscles for a higher rate of respiration to release more energy
● Constriction of arterioles in the skin to allow more blood to the muscle tissues
● Rate of ventilation is increased for increased oxygen supply for respiration and removal of carbon dioxide
● Increase in metabolic rate to release more energy during respiration
● Dilation of the pupils to allow more light in to enhance vision

Question 9

state the similarities and differences between the nervous and endocrine system [3/6] (self)

Answer 9

Similarities:
● Both have receptors that detect stimulus.
● Both involve transmission of a signal or message.
● Both involve an effector/ target organ that carries out a response.
diferrences

Differences:
- Neurons/hormones
- Mode of transmission
via neurons/blood
- transmission time
- long/short-term effects
-voluntary
the nervous response can be voluntary or involuntary while the endocrine response is always involuntary.
- locality
one or few target organs (localised) vs multiple target organs or (widespread)