This page needs the IB Demystified site-wide snippets. Ask the site administrator to install them.
A few micrograms of a chemical, released into your blood, can make your heart race, your liver release sugar or your body grow and mature. Hormones are the body's slower, longer-lasting messaging system, and when one fails, as in diabetes, the effects are felt everywhere.
Recommended for MYP 5 · eAssessment priority · About 3 lessons · Criteria A, B, C and D
By the end of this topic you should be able to:
You will use these skills. If any feel shaky, review them first.
Endocrine glands release hormones into the blood, which carries them to every part of the body. Only target cells with the right receptors respond. Key glands include the pituitary, thyroid, pancreas, adrenal glands, ovaries and testes.
Many hormones keep conditions stable by negative feedback. After a meal, rising glucose triggers insulin, which makes cells absorb glucose and the liver store it as glycogen. When glucose falls, glucagon makes the liver convert glycogen back to glucose.
In 1921 Frederick Banting and Charles Best, working in Toronto, extracted insulin and showed it lowered blood glucose in diabetic dogs; within a year it was saving the lives of children with diabetes. Today, glucose tolerance tests and blood tests measure hormone effects directly.
Diabetes affects hundreds of millions of people worldwide, and Pakistan has one of the highest rates. Hormones are also used in medicine, for contraception, fertility treatment and replacing missing hormones, and misused in sport.
Hormones link to the nervous system, homeostasis, reproduction and genetic engineering (bacteria that make human insulin) in biology, and to proteins and chemical signalling in chemistry.
Hormonal v nervous: hormones are slower, travel in the blood, act on many organs and last longer; nerve impulses are fast, electrical, targeted and brief.
People with type 1 diabetes use insulin injections, pens or pumps, and many now use continuous glucose monitors. Iodised salt prevents thyroid problems caused by iodine deficiency. Fertility clinics use FSH and other hormones to help people have children.
A person's blood glucose rises from 5 to 8 mmol/L after lunch, then returns to 5 within 2 hours. Explain.
A 10-year-old develops diabetes and needs insulin injections. Which type is it likely to be, and why?
Hormone questions often use graphs of blood glucose or hormone levels over time. Expect:
Common ways to lose marks: confusing glucagon with glycogen; saying insulin breaks down glucose; saying all diabetes is caused by sugar; and forgetting that hormones travel in the blood.
Quick questions on the ideas above. Try each one before using a hint.
Partially guided investigation · about 40 minutes · pairs
Safety. Wear eye protection. The samples are artificial, but treat them as you would real samples and do not taste them. Benedict's reagent is an irritant; handle the hot water bath with care and use test-tube holders.
Then evaluate: why would doctors confirm a diagnosis with a blood test rather than a urine test alone?
Harder problems in unfamiliar contexts. Plan before you calculate.
Five questions picked at random from the whole topic. Take a new set whenever you like.
Questions you got wrong on this device appear here so you can try them again. Answer one correctly and it leaves the list.
Tracked separately for each skill, on this device only.
| Skill | Correct | Status |
|---|
