Hormonal communication

Question 1

What are hormones secreted by? (1)

Where are hormones secreted into? (1)

Answer 1

• Endocrine glands (1)
• Directly into bloodstream (1)

Question 2

Describe the action of hormones once in the blood. (4)

Answer 2

• Transported all over the body. (1)
• Diffuse out of blood, binding to receptors specific to the hormone (1) on the cell-surface membrane or cytoplasm of target cells. (1)
• The hormones stimulate the target cells to produce a response. (1)

Question 3

Oestrogen is an example of a steroid hormone. Describe how steroid hormones work. (4)

Answer 3

• Lipid soluble (1), so they diffuse through the lipid component of the cell-surface membrane. (1)
• Receptors are present in the cytoplasm/nucleus (1)
• Hormone-receptor complex facilitates or inhibits the transcription of a specific gene. (1)

Question 4

Adrenaline is a non-steroid hormone. Describe how non-steroid hormones work. (4)

Answer 4

• Hydrophillic (1), so cannot pass through the cell-surface membrane directly. (1)
• Receptors are present on the cell-surface membrane. (1)
• Cascade of reactions triggered within the cell, carried out by ‘second messengers’. (1)

Question 5

Fill in the blanks about the hormones released by the adrenal gland and their functions (4) :

Adrenal cortex: cortisol controls how the body converts fats, proteins and carbohydrates into ___. Corticosterone regulates the ___ response and suppresses ___ reactions. Aldosterone controls ___ ___ through managing salt/water concentrations.

Answer 5

• Energy (1)
• Immune (1)
• Inflammatory (1)
• Blood pressure (1)

Question 6

Describe the effects of adrenaline and noradrenaline, released by the adrenal medulla. (2)

Answer 6

Adrenaline and noradrenaline work together to:
- Increase heart rate. (1)
- Rapidly increases blood-glucose concentration. (1)
- Dilates pupils. (1)
- Vasoconstriction of blood vessels (in non-essential organs). (1)

Question 7

What hormones does the pancreas produce. (1)

Answer 7

Insulin and glucagon (1)

Question 8

What are the two types of cells that make up islets of Langerhans and what hormones do they secrete? (4)

Answer 8

• Alpha cells (1); secretes glucagon. (1)
• Bete cells (1); secretes insulin. (1)

Question 9

Explain three ways blood-glucose concentration is increased.

Answer 9

• Eating carbohydrate rich foods. (1)
• Glycogenolysis; glycogen (stored in liver/muscle cells) being broken down into glucose. (1)
• Gluconeogenesis; the production of glucose from non-carbohydrates. (1)

Question 10

Explain two ways blood-glucose concentration is decreased.

Answer 10

• Respiration; glucose in the blood is used by cells to release energy. (1)
• Glycogenesis; glycogen is produced. (1)

Question 11

When blood-glucose concentration is too high, which hormone is released? (1)

Answer 11

Insulin (from beta cells) (1)

Question 12

Fill in the blanks about insulin action (5) :

Insulin binds to specific ___ on cell-surface membranes. This causes a change in the tertiary structure of ___ ___ protein channels, causing them to ___. This allows more glucose to enter cells, increasing the rate of glucose absorption by cells. Insulin also activates ___ which converts glucose to ___ (glycogenesis) and fat.

Answer 12

• Receptors (1)
• Glucose transport (1)
• Open (1)
• Enzymes (1)
• Glycogen (1)

Question 13

Describe how beta cells initiate negative feedback. (2)

Answer 13

• Beta cells detect that the blood-glucose concentration is back to normal. (1)
• In response, they reduce their secretion of insulin. (1)

Question 14

Explain what happens once alpha cells detect a blood-glucose level lower than normal. (4)

Answer 14

• Alpha cells secrete glucagon directly into the bloodstream. (1)
• Only fat and liver cells have glucagon receptors. (1)
• Glycogenolysis; converts glycogen to glucose. (1)
• Reduces the amount of glucose absorbed by liver cells. (1)
• Gluconeogenesis; increases conversion of non-carbohydrates to glucose. (1)

Question 15

Explain how beta cells release insulin in response to blood-glucose concentration rising. (7)

Answer 15

• Glucose enters beta cell via glucose transporter. (1)
• Glucose is metabolised in mitochondria, leading to ATP production. (1)
• ATP binds to potassium channels, causing them to close. (1)
• Potassium ions are prevented from diffusing out the cell (1) causing depolarisation. (1)
• (Due to depolarisation) voltage-gated calcium channels open. (1)
• Calcium ions enter the cell and trigger secretory vesicles to release insulin via exocytosis. (1)

Question 16

What are the two types of diabetes? (1)

Answer 16

Type 1 and type 2 (1)

Question 17

Match the symptoms/facts to the type of diabetes:

a) Unable to produce insulin
b) Cannot effectively use insulin
c) Caused by obesity
d) Caused by physical inactivity
e) May be caused by an autoimmune disease
f) Controlled by insulin injections
g) Treatment involves managing carbohydrate intake and increasing physical activity