B14 - Hormones, pancreas, diabetes

Question 1

Define an endocrine gland

Answer 1

Specialised cells that secrete chemials(hormones) directly into the blood stream

Question 2

What does the pituitary gland produce? (1)

Answer 2

• growth hormones
• anti-diuretic hormone (ADH)
• gonadotropins (control ovaries and testes development

Question 3

What hormone does the thyroid gland produce?

Answer 3

Thyroxine (controls metabolism, rate of glucose used in resporation, promotes growth)

Question 4

What hormone(s) does the pancreas produce?

Answer 4

• insulin
• glucagon

Question 5

what hormone(s) does the ovary produce?

Answer 5

• oestrogen (controls ovulation & secondary sexual characteristics)
• progesterone (prepares uterus lining for recieving an embryo)

Question 6

What hormone does the pineal gland produce?

Answer 6

• melatonin (sleep/daily cycles, effects reproductive development)

Question 7

What hormone does the thymus gland produce?

Answer 7

thymosin (production & maturation of white blood cells)

Question 8

What hormone does the adrenal gland produce?

Answer 8

Adrenaline (increases heart rate, breathing rate, blood sugar levels)

Question 9

What hormone does the testes produce?

Answer 9

Testosterone (control sperms production and secondary sexual characteristic)

Question 10

what is a steroid hormone?

Answer 10

• small and lipid soluble
• pass through membrane and binds to steroid hormone receptors
• form hormone-receptor complex, which acts as a transcription factor (facilitates or inhibits transcription of a specific gene)
  -e.g. oestrogen

Question 11

What is a non-steroid (protein) hormone?

Answer 11

• large hydrophilic/polar
• cannot pass through membrane
• bind to receptors on target cell membrane
• triggers cascade reaction controlled by secondary messengers

e.g. adrenaline

Question 12

What is an exocrine gland?

Answer 12

Secretes fluid containing digestive enzymes directly in ducts to organs

Question 13

What is a hormone? How are they transported? (2)

Answer 13

• chemical messenger that carries info to body parts
• secreted into blood when a gland is stimulated
• transported in blood plasma
• diffuses out blood and binds to specific receptors on target cell, which evokes a response.

Question 14

What do the adrenal glands consist of and where are they located?

Answer 14

• on top of each kidney
• adrenal medulla
• adrenal cortex

Question 15

What types of hormones does the adrenal medulla secrete?

Answer 15

• non essential
• released when sympathetic nervous system stimulated
• flight or fight

Question 16

What are the two main hormones secreted by the adrenal medulla? Explain their functions. (4)

Answer 16

Adrenaline:
- Inc heart rate & sends blood to muscles/brain
- Inc blood glucose as converts glycogen to glucose in the liver

Noradrenaline
- works alongside adrenaline in response to stress
- increase heart rate
- pupils widen
- air passage in lungs widen
- blood vessels narrow so higher blood pressure

Question 17

What types of hormones does the adrenal cortex produce? (1)

Answer 17

• essential/vital to life

Question 18

Name and explain the role of some hormones secreted by the adrenal cortex. (3)

Answer 18

glucocorticoids:
-released by pituitary gland caused by hypothalamus
- e.g. cortisol - regulates metabolism, blood pressure & cardiovascular function in response to stress
- e.g. corticosterone - regulates immune response & suppress inflammatory reactions

mineralcorticoids:
- aldesterone helps control blood pressure as maintains blood water balance.

Androgens:
- small amounts of sex hormones released
- small impact compared to larger amounts of hormones e.g. oestrogen but are still important
- important in menopause in women

Question 19

how does the pancreas function as both an exocrine and endocrine gland? (4)

Answer 19

Exocrine(majority):
- produce pancreatic juice(alkaline) containing digestive enzymes
- secreted into pancreatic duct
- released into duodenum (top of small intestine)

Endocrine:
- produce hormones glucagon and insulin
- islets of langerhans = regions of endocrine tissue within exocrine tissue.

Question 20

What are islets of langerhans? What do they consist of?

Answer 20

• regions of endocrine tissue within the exocrine tissue.
• alpha cells: produce & secrete glucagon
• beta cells: produce & secrete insulin

Question 21

Name 3 digestive enzymes secreted by the pancreas (3)

Answer 21

Amylase:
Break starch into simple sugars

Protease:
Break protein into amino acids e.gm trypsin

Lipase:
Break lipids into fatty acids and glycerol

Question 22

What processes decrease blood glucose concentration? (2)

Answer 22

Respiration: glucose used to release energy/ATP. Exercising uses more glucose as more ATP needed for muscle contraction.

Glycogenesis: glycogen produced from excess glucose in blood and is stored in the liver

Question 23

What processes increase blood glucose concentration?

Answer 23

Diet:
- carb rich foods & sweet foods(high in glucose)
- carbs broken down in digestive system and absorbed into bloodstream.

Glycogenolysis:
- glycogen stored in liver & muscle cells.
- breakdown into glucose & absorbed into blood stream.

Gluconeogenesis:
- glucose made from non-carb sources
- e.g. liver makes glucose from glycerol(lipids) and amino acids

Question 24

B cells secrete insulin. How does insulin interact with other cells to encourage glucose uptake? (3)

Answer 24

• Insulin binds to glycoprotein receptor on cell surface.
• Changes tertiary structure of glucose transport protein channels
• Channels open so glucose enters the cell.
• Also activates enzymes to convert glucose to glycogen or fat.

Question 25

How does insulin lower blood glucose levels? (3)

Answer 25

- increase glucose absorption into cells - increase respiration rate - increase glycogenesis - Increase glucose conversion to fat. - Inhibit glucagon release from alpha cells

Question 26

Alpha cells secrete glucagon. How does glucagon interact with cells to increase blood glucose levels? (1)

Answer 26

- only fat and liver cells have glucagon receptors. - glucagon binds.

Question 27

How does glucagon raise blood glucose levels? (2)

Answer 27

- glycogenesis releases glucose into blood stream - reduce amount of glucose absorbed by liver cells - gluconeogenesis

Question 28

How is insulin secreted by B cells? (5)

Answer 28

- K+ channels open at normal blood glucose levels, K+ diffuses out, polarised membrane -70mV - glucose enters cell via transporter when blood glucose level rises - glucose metabolised in mitochondria to produce ATP - ATP binds to K+ channels, closing them (ATP-sensitive K+ channels) - K+ can't diffuse out, potential difference reduces to +30mV and membrane becomes depolarised. - Depolarisation causes Ca2+ channels open, Ca2+ enter causing vesicles to release insulin via exocytosis.

Question 29

Why are insulin and glucagon antagonistic hormones?

Answer 29

Work against each other in a system to maintain blood glucose.

Question 30

Suggest why is blood glucose concentration self-regulating. (1)

Answer 30

- Blood glucose levels determines the amount of insulin or glucagon secreted to lower or increase glucose levels. - Not constant: fluctuates around a set point due to negative feedback

Question 31

Suggest why glucose in urine is a symptom of diabetes.

Answer 31

- Insulin function disrupted, blood glucose levels rise (hyperglycaemia) - kidney's can't filter excess glucose in blood, therefore appears in urine.

Question 32

What is the difference between type I and type II diabetes? (4)

Answer 32

type I: - Unable to produce insulin - Usually begins in childhood type II: - more common - Insulin produced but glycoprotein receptor doesn't work properly. - cells lose responsiveness to insulin = less glucose uptake = high levels in bloodstream - Risk increases with age.

Question 33

What is the difference between type I and type II diabetes? (4)

Answer 33

type I: - Unable to produce insulin - Usually begins in childhood - autoimmune response: T cells attack beta cells so they can't secrete insulin. type II: - more common - Insulin produced but glycoprotein receptor doesn't work properly. - cells lose responsiveness to insulin = less glucose uptake = high levels in bloodstream - Risk increases with age.

Question 33

What are some risk factors of type II diabetes? (3)

Answer 33

- excess body weight - inactivity - overeating (carbs) - risk increases with age (40+) - similar symptoms to type I but less severe and develop slowly. - genetics/ more likely inherited

Question 34

What are some common symptoms of diabetes? (4)

Answer 34

- high blood glucose - glucose in urine - excessive need to urinate - excessive thirst - weight loss - constant hunger - blurred vision - tiredness

Question 35

Name some treatments for type I (3)

Answer 35

Insulin injections: BUT too much = hypoglycaemia (low bgc) -regular blood tests e.g. finger pricks, blood drop analysed to find glucose concentration and determine insulin dose. - healthy diet

Question 36

Name some treatments for type II (2)

Answer 36

Diet & exercise: - regulate carb intake - increse exercise overweight people encourages to lose weight sometimes diet & exercise not enough, so use drugs to stimulate insulin production (sometimes use insulin injections)

Question 37

Before insulin was medically produced, how was it orignially obtained and what were the problems?

Answer 37

- from pancreas of cows and pigs. Problems: - hard & expensive - Also cause allergic reactions as different to human insulin

Question 38

What is recombinant DNA?

Answer 38

DNA altered by adding another source. - Produces recombinant proteins (RP).

Question 39

What are the advantages of medically produced insulin.

Answer 39

- Identical to human insulin (pure form) - Insulin produced in higher quantities - cheaper production - fewer ethical, religious, moral concerns.

Question 40

what are the issues with pancreatic transplants, despite them being 80% effective?

Answer 40

- Demand outweighs availability - large risk with immunosuppressant drugs = susceptible to infection

Question 41

What problem comes with beta cell injections? (1)

Answer 41

Immunosuppressant drugs increase metabolic demand, exhausting the cells' capacity to produce insulin.

Question 42

What concerns are there about stem cell therapy used in diabetes? How are these concerns overcame?

Answer 42

- stem cells likely to be taken from embryo but the embryo must be destroyed - ethical concerns surrounding destroying a potential human life Overcame: - Use 'spare' embryos from infertility treatments/ terminated pregnancies, therefore are usually destroyed anyway.

Question 43

Name some advantages of stem cell therapy.

Answer 43

- no issue of donor availability as unlimited source - less chance of rejection - human injections would no longer be needed