B14 - Hormones, pancreas, diabetes Flashcards
Define an endocrine gland
Specialised cells that secrete chemials(hormones) directly into the blood stream
What does the pituitary gland produce? (1)
- growth hormones
- anti-diuretic hormone (ADH)
- gonadotropins (control ovaries and testes development
What hormone does the thyroid gland produce?
Thyroxine (controls metabolism, rate of glucose used in resporation, promotes growth)
What hormone(s) does the pancreas produce?
- insulin
- glucagon
what hormone(s) does the ovary produce?
- oestrogen (controls ovulation & secondary sexual characteristics)
- progesterone (prepares uterus lining for recieving an embryo)
What hormone does the pineal gland produce?
- melatonin (sleep/daily cycles, effects reproductive development)
What hormone does the thymus gland produce?
thymosin (production & maturation of white blood cells)
What hormone does the adrenal gland produce?
Adrenaline (increases heart rate, breathing rate, blood sugar levels)
What hormone does the testes produce?
Testosterone (control sperms production and secondary sexual characteristic)
what is a steroid hormone?
- 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
What is a non-steroid (protein) hormone?
- large hydrophilic/polar
- cannot pass through membrane
- bind to receptors on target cell membrane
- triggers cascade reaction controlled by secondary messengers
e.g. adrenaline
What is an exocrine gland?
Secretes fluid containing digestive enzymes directly in ducts to organs
What is a hormone? How are they transported? (2)
- 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.
What do the adrenal glands consist of and where are they located?
- on top of each kidney
- adrenal medulla
- adrenal cortex
What types of hormones does the adrenal medulla secrete?
- non essential
- released when sympathetic nervous system stimulated
- flight or fight
What are the two main hormones secreted by the adrenal medulla? Explain their functions. (4)
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
What types of hormones does the adrenal cortex produce? (1)
- essential/vital to life
Name and explain the role of some hormones secreted by the adrenal cortex. (3)
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
how does the pancreas function as both an exocrine and endocrine gland? (4)
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.
What are islets of langerhans? What do they consist of?
- regions of endocrine tissue within the exocrine tissue.
- alpha cells: produce & secrete glucagon
- beta cells: produce & secrete insulin
Name 3 digestive enzymes secreted by the pancreas (3)
Amylase:
Break starch into simple sugars
Protease:
Break protein into amino acids e.gm trypsin
Lipase:
Break lipids into fatty acids and glycerol
What processes decrease blood glucose concentration? (2)
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
What processes increase blood glucose concentration?
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
B cells secrete insulin. How does insulin interact with other cells to encourage glucose uptake? (3)
- 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.
How does insulin lower blood glucose levels? (3)
- increase glucose absorption into cells
- increase respiration rate
- increase glycogenesis
- Increase glucose conversion to fat.
- Inhibit glucagon release from alpha cells
Alpha cells secrete glucagon. How does glucagon interact with cells to increase blood glucose levels? (1)
- only fat and liver cells have glucagon receptors.
- glucagon binds.
How does glucagon raise blood glucose levels? (2)
- glycogenesis releases glucose into blood stream
- reduce amount of glucose absorbed by liver cells
- gluconeogenesis
How is insulin secreted by B cells? (5)
- 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.
Why are insulin and glucagon antagonistic hormones?
Work against each other in a system to maintain blood glucose.
Suggest why is blood glucose concentration self-regulating. (1)
- 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
Suggest why glucose in urine is a symptom of diabetes.
- Insulin function disrupted, blood glucose levels rise (hyperglycaemia)
- kidney’s can’t filter excess glucose in blood, therefore appears in urine.
What is the difference between type I and type II diabetes? (4)
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.
What is the difference between type I and type II diabetes? (4)
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.
What are some risk factors of type II diabetes? (3)
- 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
What are some common symptoms of diabetes? (4)
- high blood glucose
- glucose in urine
- excessive need to urinate
- excessive thirst
- weight loss
- constant hunger
- blurred vision
- tiredness
Name some treatments for type I (3)
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
Name some treatments for type II (2)
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)
Before insulin was medically produced, how was it orignially obtained and what were the problems?
- from pancreas of cows and pigs.
Problems: - hard & expensive
- Also cause allergic reactions as different to human insulin
What is recombinant DNA?
DNA altered by adding another source.
- Produces recombinant proteins (RP).
What are the advantages of medically produced insulin.
- Identical to human insulin (pure form)
- Insulin produced in higher quantities
- cheaper production
- fewer ethical, religious, moral concerns.
what are the issues with pancreatic transplants, despite them being 80% effective?
- Demand outweighs availability
- large risk with immunosuppressant drugs = susceptible to infection
What problem comes with beta cell injections? (1)
Immunosuppressant drugs increase metabolic demand, exhausting the cells’ capacity to produce insulin.
What concerns are there about stem cell therapy used in diabetes? How are these concerns overcame?
- 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.
Name some advantages of stem cell therapy.
- no issue of donor availability as unlimited source
- less chance of rejection
- human injections would no longer be needed
