Endocrine system

Question 1

Define hormone?

Answer 1

Mammalian hormones are substances that stimulate target cells via the blood.

Question 2

How does a hormone work?

Answer 2

Hormones are released directly into the blood plasma from endocrine glands. Each hormone has specific target cells on which it acts.

Once the hormone reaches a target organ, it affects the target cells by attaching onto specific receptors either on the surface of, or within the cells.

Hormones are part of the endocrine system, which produces slow, long-lasting and widespread responses.

Question 3

How does the nervous system differ from the endocrine system?

Answer 3

Endocrine system produces slow, long-lasting and widespread responses.
However the nervous system produces faster, but shorter lasting responses.

Question 4

Role of thyroid gland?

Answer 4

Produces thyroxine which controls rate of metabolism

Question 5

Role of adrenal gland?

Answer 5

Produces adrenaline which prepares the body for rapid activity by increasing the heart rate and level of sugar in blood and diverting blood to muscles and brain.

Question 6

Role of pancreas?

Answer 6

Produces insulin which controls blood sugar level

Question 7

Role of testes?

Answer 7

Produces testosterone which causes the changes at puberty and stimulates sperm production

Question 8

Role of ovary?

Answer 8

Produces oestrogen which causes changes at puberty and helps control the menstrual cycle

Question 9

Role of the brain?

Answer 9

Contains a sensitive centre called the hypothamalus, which controls the pituitry gland.

Question 10

Define negative feedback:

Answer 10

When the body responds to a negative change to bring it back to normal values.

Question 11

What two hormones do the islets of langerhan (in the pancreas) produce?

Answer 11

Insulin (produces by beta cells)
and
Glucagon (produced by alpha cells)

Question 12

Whats the function of glucagon?

Answer 12

Stimulates the liver when glucose levels in the blood are low
The glucose has GONE so GlucaGON is released
Converts Glycogen back into Glucose

Question 13

Describe the negative feedback loop of the endocrine system if there was an increase in glucose levels:

Answer 13

1) Normal glucose levels of blood
2) Increase in level of glucose in blood eg:after meal
3) Receptors in pancreas detect change
4) Insulin is released by beta cells in the islets of langerhan
5) Muscle and liver absorb glucose and store it as glycogen
6) This is known as glycogenesis.

Question 14

Describe the negative feedback loop of the endocrine system if there was a decrease in glucose levels:

Answer 14

1) Normal glucose levels of blood
2) Decrease in level of glucose in blood
3) Receptors in pancreas detect change
4) Glucagon is released by alpha cells in the islets of langerhan
5) Glucagon converts glycogen back into glucose
6) This is known as glycogenolosis.

Question 15

Whats a gland?

Answer 15

A gland is an organ which secretes substances such as hormones or enzymes.

Question 16

Why are blood glucose levels important ?

Answer 16

Glucose is essential for respiration, therefore it is important that the amount of glucose in the blood is kept at a fairly constant level.

Question 17

Whats the function of insulin?

Answer 17

Insulin – they take glucose INto cells for energy

Stimulates liver to convert glucose into GLYCOGEN – the stored version

Question 18

some causes of increases in blood glucose are…

Answer 18

Digestion of carbohydrates
Breakdown of GLYCOGEN called GLYCOGENOLYSIS
Producing glucose from non-carbohydrate compounds called GLUCONEOGENESIS

Question 19

Causes of decreases in blood glucose:

Answer 19

When demand for energy increases e.g. Exercise, respiration levels increase and therefore glucose levels decrease.
Lack of intake of carbohydrates/sugars (Starvation)
Glucose is Converted/Stored as glycogen GLYCOGENESIS

Question 20

What is diabetes?

Answer 20

Diabetes mellitus is a disorder that affects the body’s ability to regulate blood glucose levels. There are two different types – type 1 and type 2.

Question 21

Whats type 1 diabetes?

Answer 21

Also known as insulin-dependent diabetes, normally occurs suddenly in childhood.

The body is not able to produce its own insulin. This is thought to be caused by the immune system attacking the insulin-producing beta cells.

Type 1 diabetes can be controlled with regular insulin injections and the careful management of diet and exercise

Question 22

Whats type 2 diabetes?

Answer 22

Also known as insulin-independent diabetes, occurs mainly in people over 40, however it is becoming increasingly common in adolescents.

This condition is caused by glycoprotein receptors on the body cells losing their responsiveness to insulin, or an inadequate supply of insulin from the pancreas.

Type 2 diabetes can be controlled by careful regulation of diet and exercise.

Question 23

What are hormones secreted by?

Answer 23

Endocrine glands