5.1.4 Hormonal communication

Question 1

What are the main differences between neuronal and hormonal communication?

Answer 1

1. Hormonal transmission is relatively slower than nervous transmission
2. Hormones travel to all parts of body (only target cells respond), nerve impulses travel to specific parts
3. Response to hormones is widespread, response to nerve impulse is localised
4. Hormonal effect is long-lasting, nerve impulse is short-lived
5. Hormonal effect may be permanent, nervous effect is temporary and reversible

Question 2

State the hormone(s), and their functions, produced by the pituitary gland

Answer 2

1. Growth Hormone - controls muscle and bone growth
2. ADH - increases water re-absorption
3. Gonadotrophins - controls development of ovaries and testes

Question 3

State the hormone(s), and their functions, produced by the thyroid gland

Answer 3

Thyroxine - controls metabolic rate and promotes growth

Question 4

State the hormone(s), and their functions, produced by the pineal gland

Answer 4

Melatonin - helps establish circadian rhythms

Question 5

State the hormone(s), and their functions, produced by the thymus

Answer 5

Thymosin - promotes production and maturation of WBCs

Question 6

State the hormone(s), and their functions, produced by the pancreas

Answer 6

Insulin - glucose to glycogen

Glucagon - glycogen to glucose

Question 7

State the hormone(s), and their functions, produced by the ovaries

Answer 7

Oestrogen - controls ovulation and sexual characteristics

Progesterone - prepares uterus lining for embryo

Question 8

State the hormone(s), and their functions, produced by the testes

Answer 8

Testosterone - controls sperm production and sexual characteristics

Question 9

What are steroid hormones?

Answer 9

Lipid-soluble hormones that pass through the membrane and bind to receptor in cytoplasm. Hormone-receptor complex acts as transcription factor - binds to receptor on DNA
e.g. sex hormones and hormones secreted from adrenal cortex

Question 10

What are non-steroid hormones?

Answer 10

Hydrophilic hormones that can’t pass through so bind to receptors on cell membrane. Uses second messenger model to trigger response
e.g. adrenaline

Question 11

Describe the position and function of the adrenal cortex

Answer 11

Outer region of adrenal glands

Produces vital hormones

Question 12

Describe the position and function of the adrenal medulla

Answer 12

Inner region of adrenal glands

Produces non-essential hormones

Question 13

State which hormones are produced by the adrenal cortex. What is their function?

Answer 13

1. Glucocorticoids e.g. cortisol - regulate metabolism, blood pressure and cardiovascular function. Corticosterone - regulates immune response
2. Mineralocorticoids e.g. aldosterone - maintains salt water conc
3. Androgens (male sex hormones) - small impact

Question 14

State which hormones are produced by the adrenal medulla. What is their function?

Answer 14

1. Adrenaline - causes physical response to stress - e.g. increase heart rate and blood glucose conc
2. Noradrenaline - works alongside adrenaline

Question 15

What mechanism controls the production of hormones at the adrenal cortex?

Answer 15

Pituitary gland, which is stimulated by the hypothalamus

Question 16

What mechanism controls the production of hormones at the adrenal medulla?

Answer 16

Sympathetic NS, which is stimulated by the hypothalamus

Question 17

Define glycogenolysis

Answer 17

Breakdown of glycogen to glucose

Question 18

Define gluconeogenesis

Answer 18

Production of glucose from sources other than carbohydrates e.g. fats and amino acids

Question 19

Define glycogenesis

Answer 19

Production of glycogen from glucose - method of decreasing glucose other than respiration

Question 20

Describe the process if blood glucose levels rise

Answer 20

1. Beta cells of pancreas detect change
2. Insulin secreted
3. Receptors of liver and muscle cells (in particular) uptake insulin
4. Glycogenesis occurs, Glucose to fat, increased respiration, cells absorb glucose
5. Returns to normal

Question 21

Describe the process if blood glucose levels fall

Answer 21

1. Alpha cells of pancreas detect change
2. Glucagon secreted
3. Liver cells uptake glucagon
4. Glycogenolysis occurs, amino acids to glucose, glucose into blood from intestines
5. Returns to normal

Question 22

How does insulin trigger the uptake of glucose?

Answer 22

All cells have insulin receptors, except RBCs.

Triggers opening of more glucose co-transporter proteins (changes tertiary)

Question 23

How does glucagon trigger glycogenolysis?

Answer 23

Only liver and fat cells have glucagon receptors - activates enzyme

Question 24

How is the negative feedback mechanism controlled?

Answer 24

Alpha and beta cells reduce the secretion of their hormones once the glucose conc returns to normal

Question 25

Describe the secretion of insulin by beta cells

Answer 25

1. Higher influx of glucose through co-transporter protein (GLUT-2) 2. Rapid breakdown of glucose produces ATP 3. ATP binds to Katp channels - close 4. Depolarisation - K+ can't exit 5. Voltage-gated Ca2+ channels open 6. Vesicles fuse with cell membranes - insulin secreted

Question 26

What is the difference in the cause of Type 1 and Type 2 diabetes?

Answer 26

Type 1 - insulin dependent- pancreas doesn't produce any insulin Type 2 insulin resistant - cells non-responsive to insulin or beta cells don't produce enough insulin

Question 27

What are some symptoms of diabetes?

Answer 27

1. Excessive urination 2. High blood glucose conc 3. Weight loss 4. Blurred vision 5. Excessive hunger/thirst 6. Glucose in urine

Question 28

What are the differences in treating Type 1 and Type 2 diabetes?

Answer 28

Type 1 - Insulin injections and regular blood tests | Type 2 - Regulate diet and exercise, drugs to stimulate insulin production/slow glucose absorption if necessary

Question 29

What is hypoglycaemia?

Answer 29

Low blood glucose concentration

Question 30

What is hyperglycaemia?

Answer 30

High blood glucose concentration

Question 31

How was insulin previously produced? What were the issues?

Answer 31

From the pancreas cells of pigs and cows. Issues of 'allergic reactions' and difficulty of access

Question 32

How is insulin presently produced? What are the benefits?

Answer 32

Genetically modified bacteria - less likely to cause 'allergic reactions', high quantity production, cheaper costs, no ethical issues

Question 33

What are the issues with having a pancreas transplant?

Answer 33

1. Demand outweighs availability | 2. Health risk - immunosuppressant drugs

Question 34

What are the issues with having beta cells transplanted?

Answer 34

1. Fewer than 8% have been successful | 2. Immunosuppressant drugs increase metabolic demand of insulin - exhausts natural stock

Question 35

What are the potential uses of stem cells for type 1 diabetes?

Answer 35

Results due to loss of a single cell type ( beta cells) - totipotent cells can differentiate into any cell type. Best stem cells are embryonic (wasted anyway - small number can treat many patients. Alternative would be from an umbilical cord

Question 36

What are the advantages of stem cell treatment?

Answer 36

1. Donor availability isn't an issue - unlimited source 2. No more injections 3. Reduced likelihood of rejection

Question 37

What is a disadvantage of stem cell treatment?

Answer 37

Implanting stem cells may promote growth of tumour - more research to be done on controlling growth and differentiation

Question 38

Describe the difference of the results of a glucose tolerance test for a diabetic and non-diabetic person

Answer 38

Diabetic - Higher starting blood glucose conc, and slower return to normal level - no insulin response Non-diabetic - Increases less than diabetic - Fast return to normal level - insulin response