Topic 7 - Hormones and Endocrine system Flashcards
What is the endocrine system?
Communication system that sends hormones (chemical messengers) around the body, made of glands
Pituitary gland role
‘master gland’ controls all other glands
Thyroid gland role
secretes THYROXINE
controls metabolic rates, heart rate, temperature
Pancreas gland role
secretes INSULIN
controls blood-glucose levels
Adrenal gland role
secretes ADRENALINE
involved in fight or flight
7How does adrenaline prepare body for fight or flight?
- Increases heart rate (heart muscle cells contract rapidly)
- Increases blood pressure (heart muscle cells contract more strongly) and blood vessels going to other organs narrow, reducing blood flow to those organs and increasing blood pressure
- Increases blood flow to muscles (blood vessels going to muscles widen)
- More respiration - liver is the target organ. Glycogen breaks down into glucose, glucose is released into blood, raised blood sugar levels. Additional glucose to be used for respiration.
Ovaries gland role
secretes OESTROGEN
involved in menstrual cycle and female sexual characteristics
Testes gland role
secretes TESTOSTERONE
produces sperm and male sexual characteristics
How is hormone transported
via the blood to the target organ
What is a target organ
Organ affected by a specific hormone
What triggers adrenaline release
Increase in impulses from neurones reaching adrenal glands triggers adrenaline release into blood.
How does thyroxine work?
Thryxine affects metabolic rate.
1. Causes heart cells to contract more rapidly and strongly
2. Causes increase in rate of carb+ protein breakdown
3. Control of thryxoine conc is negative feedback.
Hypothalamus releases TRH.
Stimulates Pituitary gland to release TSH.
Stimulates Thryoid gland to release thryoxine to reach target organs.
If not enough thryoxine, more TRH produced.
What is metabolic rate?
Rate at which energy stored in your food is transferred by all reactions that take place in your body to keep you alive.
How is resting metabolic rate measured?
Body must be at rest in a warm room, long after meal.
What are the menstrual cycle changes?
- Day 1 - start of menstruation. thickened part of uterus lining broken down and lost with unfertilised egg during period.
- FSH causes maturation of an egg in the ovary within a follicle. Stimulates oestrogen production.
- When menstruation ends, uterus lining starts to thicken again. Caused by oestrogen. high levels stimulate more release of LH and inhibits FSH secretion.
- Day 14-15 ovulation begins (ovary releases egg) caused by LH release. Inhibits oestrogen.
- Progesterone mantains the uterus lining.
- Egg cell travels along fallopian tube to uterus and it starts again.
FSH role
causes maturation of an egg in the ovary within a follicle.
Produced in pituitary gland.
Stimulates oestrogen.