Nerves
- Electrical signal
- Very fast response
- Act on precise area
- Act for short time
Hormones
- Chemical signal
- Slow response
- Act on general area
- Act for long time
What are hormones?
Hormones are chemical messengers produced by endocrine glands and released directly in to the blood
How do hormones work?
- The gland makes a hormone
- The hormone diffuses in to the blood
- The blood carries the hormone to the target organ
Glands of the body: Ovaries Pancreas Adrenal Thyroid
Ovaries - Make oestrogen and progesterone. Controls female development during puberty
Pancreas - Insulin and glucagon. Controls blood sugar levels
Adrenal - Adrenaline. Gets body ready for ‘flight of fight’ response.
Thyroid - Thyroxin. Controls how quickly chemical reactions happen in the body.
Adrenalin
• Produce by adrenal glands
• ‘Fight or flight’ response
- Increased heart rate
- Increased blood pressure
- Increased blood flow to muscles
- Stimulates liver to turn glycogen in to glucose increasing sugar
levelsWhy is it important that we eat every few hours?
Energy stored in food is constantly being transferred by all the reactions in your body to keep you alive
The rate at which this happens is known as your metabolic rate
Where is thyroxine produced?
In an endocrine gland, the thyroid gland.
Effects of thyroxine
- Causes heart cells to contract more
* Causes proteins and carbohydrates to break down more quickly
Thyroxine levels to low
Steps:
- Detected by the hypothalamus which produces TRH
- TRH is detected by the pituitary gland which releases TSH
- TSH causes the thyroid gland to produce thyroxine
- Blood thyroxine levels increase
Glucose levels are controlled by two hormones made in the pancreas:
- Insulin - decreases the level of glucose
- Glucagon - increases the level of glucose
insulin Glucose ————>Glycogen Glucagon Glycogen ————> Glucose
Glucose levels too high
Steps:
- Pancreas releases insulin
- Insulin travels to liver
- Liver converts glucose to glycogen
- Glucose levels decrease
Controlling blood glucose
After a meal, the amount of glucose in your blood goes up. When it gets above a certain level, the pancreas releases a hormone called insulin. This causes the liver to convert glucose to glycogen.
Diabetes: Type 1
- Treated using insulin injections
- Thought to be caused by genetic factors
- The pancreas doesn’t produce insulin
Diabetes: Type 2
- Treated by a change in lifestyle or tablets
- Causes by a number of risk factors: being overweight, poor diet, lack of exercise
- The pancreas doesn’t produce insulin or the cells stop responding
BMI
Calculation
BMI = Mass (kg) / height (m)2
FSH
Causes the egg to mature and stimulates the ovaries to produce oestrogen. Produced in pituitary gland
Progesterone
Secreted by the follicle after egg has been released and becomes the corpus luteum. Produced in the ovaries
LH
Stimulates the release of a mature egg. Produced in pituitary gland
Oestrogen
High levels cause the pituitary gland to stop producing FSH and produce LH instead. Produce in the ovaries
Contraception
Contraception is the prevention of fertilisation
Male condom
Placed over the penis and stops sperm entering the vagina. Prevents fertilisation of the egg
Diaphragm or cap
Blocks the cervix so the sperm cannot leave the vagina and reach the egg cell
Hormone pill or implant
Causes the body to release hormones to prevent ovulation and thickens the mucus around the cervix to prevent the sperm leaving the vagina.
