Hormonal coordination in humans 5.3 Flashcards
Give the name of the body’s coordination system which involves hormones
The endocrine system
What is a hormone?
A hormone is a chemical messenger secreted by a gland. It travels in the blood to a target organ, where it causes a response
What type of organ secretes hormones?
Glands
Which gland controls many other glands in the body?
The pituitary gland
Why is the pituitary gland considered a ‘master gland’?
It secretes a wide range of hormones, some of which may stimulate other endocrine glands
What is the role of the pituitary gland in the endocrine system?
- Secretes human growth hormone - controls human growth
- Stimulates the thyroid gland
- Stimulates ovulation and the production of oestrogen in the ovaries
- Stimulates the production of sperm and testosterone in the testes
What is the role of the thyroid gland in the endocrine system?
Secretes the hormone thyroxine - controls the metabolism, heart rate and body temperature
What is the role of the pancreas in the endocrine system?
Secretes the hormone insulin - controls the bloods glucose levels
What is the role of the adrenal gland in the endocrine system?
Secretes adrenaline - controls the body’s ‘fight or flight’ response
What is the role of the ovaries in the endocrine system?
Secrete oestrogen, which coordinates the menstrual cycle and the development of female secondary sexual characteristics
What is the role of the testes in the endocrine system?
Secrete testosterone, which coordinates the production of sperm and the development of male secondary sexual characteristics
Which organ monitors and controls blood glucose concentration
The pancreas
How does the pancreas respond when blood glucose levels are too high?
The pancreas secretes the hormone insulin. Insulin binds to receptors on the liver and muscles, causing excess glucose to be converted into glycogen and stored
How does the pancreas respond when blood glucose levels are too low?
The pancreas secretes the hormone glucagon. Glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood
How is blood glucose concentration controlled using a negative feedback loop?
- When the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas
- The action of either hormone (insulin or glucagon) helps bring back the concentration to the correct level
What is Type 1 diabetes?
Type 1 diabetes is an autoimmune disorder in which the pancreas does not produce sufficient insulin to control the blood glucose concentration. As a result, blood glucose levels are often very high, leading to excessive urination, tiredness and weight loss
How can Type 1 diabetes be treated?
- Insulin injections before meals - allows glucose to be converted into glycogen
- Limiting carbohydrate intake
- Attempts using pancreas and pancreatic cell transplants: investigation into genetic engineering of pancreatic cells
What is Type 2 diabetes?
Type 2 diabetes is a disorder in which the body’s cells stop responding to insulin, leading to an uncontrolled blood glucose concentration. Its onset is linked with increasing age and obesity
How can Type 2 diabetes be treated?
- Following a carefully controlled diet
- Doing regular exercise
- Losing weight
- Use of drugs which increase insulin production and effectiveness
What is osmosis?
Osmosis is the movement of water from a dilute solution to a concentrated solution through a partially permeable membrane
In what ways is water lost from the body?
- During exhalation via the lungs
- Sweating
- Urine (some reabsorbed in the kidney)
In what way are ions lost from the body?
- Sweating
- Urine (some reabsorbed in the kidney)
