The Endocrine System

Question 1

Define hormone

Answer 1

Molecules released by endocrine glands, directly into the blood

Question 2

What is the job of a hormone

Answer 2

To act as a messenger carrying a signal from the endocrine gland to a specific target organ or tissue

Question 3

Define endocrine gland

Answer 3

A gland that secretes hormones directly into the blood

Question 4

Define exocrine gland

Answer 4

A gland that secretes molecules into a duct which carries the molecules to where they need to go

Question 5

Define target cell

Answer 5

Cells with a special receptor on their plasma membrane. The receptor is complementary to a hormone molecule

Question 6

What is adenyl cyclase used for

Answer 6

The enzyme associated with the receptor for many hormone molecules e.g. adrenaline

Question 7

What are the two types of hormone

Answer 7

Steroid

Protein

Question 8

Give three properties of a steroid hormone

Answer 8

Lipid soluble
Not water soluble
Diffuse through cell membrane and combine with receptor protein in cytoplasm
Hormone-receptor complex inside plasma membrane causes cell to respond to hormone by interacting with cell DNA and stimulating protein synthesis
Sex hormones e.g testosterone

Question 9

Give three properties of a protein hormone

Answer 9

Water soluble
Not lipid soluble
Cannot pass through the plasma membrane of target cell
Made up of amino acids
Combine with receptor hormones on the cell membrane
Hormone-receptor complex on the cell membrane induces an internal response by the cell
e.g. adrenaline, insulin, glycogen

Question 10

Give four effects of adrenaline on the body

Answer 10

• Relax smooth muscle in bronchioles
• Increase stroke volume of the heart
• Increase heart rate
• Causes general vasoconstriction (VS away from non-essential organs)
• Stimulates breakdown of glycogen to glucose
• Dilates pupils
• Increases mental awareness
• Inhibits action of the gut

Question 11

Describe the effect of adrenaline on liver cells

Answer 11

• Binds to glycoprotein receptors on the plasma membrane of target cells
• This stimulates the enzyme adenyl cyclase
• This produces cAMP from ATP
• This second messenger activates a cascade of enzymes
• The last enzyme is protein kinase A
• This binds to glycogen phosphorylase (GP)
• GP then converts glycogen into glucose in the liver

Question 12

Name the two regions of the adrenal gland

Answer 12

Adrenal cortex

Adrenal medulla

Question 13

What does the adrenal cortex do

Answer 13

Uses cholesterol to produce steroids

Question 14

What does the adrenal medulla do

Answer 14

Manufactures and secretes adrenaline in response to stress e.g pain

Question 15

What are the two types of steroid the adrenal cortex produces

Answer 15

Glucocorticoids

Mineralocorticoids

Question 16

What do glucocorticoids do

Answer 16

Stimulate synthesis of glycogen in the liver

Question 17

What do mineralocorticoids do

Answer 17

Control the Na+ and K+ in the blood

Question 18

What do alpha cells secrete

Answer 18

Glucagon

Question 19

What does glucagon do

Answer 19

Causes the conversion of glycogen and glucose 
Increase the rate of gluconeogenesis
Prevents Hypoglycaemia
Increases respiration of fats
Suppresses the release of insulin

Question 20

What do beta cells secrete

Answer 20

Insulin

Question 21

What does insulin do

Answer 21

Causes cells to take up glucose from the blood
-Stores it as glycogen
It causes the conversion of glucose to fat
Increases respiration of carbohydrates
Suppresses the release of glucagon