The Endocrine system 5.4.1

Question 1

What are the function of homeostatic mechanisms?

Answer 1

To keep their internal body conditions near constant

Question 2

What are three key homeostatic mechanisms?

Answer 2

• Thermoregulation
• Osmoregulation
• Control of blood glucose concentration

Question 3

What is thermoregulation?

Answer 3

The control of body temperature

Question 4

What is osmoregulation?

Answer 4

The control of the water potential of body fluids

Question 5

What do homeostatic mechanisms require?

Answer 5

Information to be transferred between different parts of the body

Question 6

What is one of the system involved in homeostatic mechanisms?

Answer 6

The endocrine system

Question 7

What is a hormone?

Answer 7

A chemical messenger produce by an endocrine gland and carried by the blood - to transmit information and bring about a change

Question 8

What do hormones do?

Answer 8

They bring about a change and alter the activity of one or more specific target organs

Question 9

What do hormones not need?

Answer 9

They do not need instant responses

Question 10

What is a gland?

Answer 10

A group of cells that produces and releases one or more substances (known as secretion)

Question 11

What does the thyroid gland produce?

Answer 11

Thyroxine

Question 12

What is the pituitary gland?

Answer 12

The ‘master’ gland

Question 13

What does the pancreas produce?

Answer 13

Insulin

Question 14

What do the adrenal glands produce?

Answer 14

Adrenaline

Question 15

What do the testes produce?

Answer 15

Testosterone (male sex hormone)

Question 16

What do the ovaries produce?

Answer 16

Oestrogen (female sex hormone)

Question 17

What do endocrine glands have in order to maintain their functioning?

Answer 17

Good blood supply as they make hormones which are directly secreted into the blood plasma

Question 18

What do hormones bind to?

Answer 18

Complementary/specific receptors found on the cell surface membrane - required to have an effect

Question 19

What is a first messenger?

Answer 19

The hormone that brings the ‘information or signal’ from the endocrine gland

Question 20

What is a second messenger?

Answer 20

Inside the cell that causes an effect

Question 21

Describe the mode of action for the hormone adrenaline

Answer 21

• Adrenaline binds to specific receptors on the membrane of liver cells
• This causes the enzyme adenylyl cyclase to change shape and become activated
• Activated adenylyl cyclase catalyses the conversion of ATP to the second messenger cyclic AMP
• cAMP binds to protein kinase A enzymes, activating them
• Active protein kinase A enzymes initiate a series of enzyme activations that result in the breakdown of glycogen to glucose - known as glycogenolysis

Question 22

What is glycogenolysis?

Answer 22

Breakdown of glycogen into glucose

Question 23

What does an enzyme cascade do?

Answer 23

Amplifies the original signal from adrenaline and results in the release of extra glucose by the liver to increase blood glucose concentration

Question 24

Describe 5 differences between the nervous and endocrine system

Answer 24

• Nervous is electrical whereas endocrine is chemical
• Effectors of nervous are muscles or glands whereas effectors of endocrine are target cells in specific tissues
• Speed of transmission is very fast in nervous system compared to endocrine
• Nerves are used to transmit electrical messages in the nervous system whereas chemical hormones are transmitted through the bloodstream in endocrine system
• Nervous system has CNS and PNS, endocrine system involves glands

Question 25

Where are the adrenal glands?

Answer 25

Above each kidney

Question 26

Give an example of an endocrine gland

Answer 26

Adrenal glands

Question 27

What are the two main areas of the adrenal glands?

Answer 27

- Central medulla and an outer cortex

Question 28

What are steroid hormones?

Answer 28

They are made of lipids, such as phospholipids and cholesterol - therefore are fat soluble. This means they can diffuse across the plasma membrane of target cells

Question 29

Give 2 examples of steroid hormones

Answer 29

- Aldosterone (regulates the levels of salt and the water balance in the blood) - Cortisol (responsible for metabolism of glucose, proteins, and fats, to release usable energy)

Question 30

Where are steroid hormones produced in the adrenal gland?

Answer 30

Cortex

Question 31

Where are aldosterone and cortisol formed?

Answer 31

Cortex of the adrenal gland

Question 32

Is adrenaline non steroid or steroid hormone?

Answer 32

Non steroid as it cannot pass across the cell membrane - due to it being composed of amino acids

Question 33

What is the function of adrenaline?

Answer 33

It is released at times of stress or excitement, preparing the body to respond to emergency situations