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.
Oestrogen role
Causes lining of uterus to grow again.
Produced in ovaries.
Stimulates LH.
Inhibits FSH.
LH role
Release results in ovulation.
Produced in pituitary gland.
Produced as result of oestrogen.
Inhibits oestrogen.
Progesterone role
Maintains uterus lining and supports pregnancy if egg is fertilised.
Produced in ovaries.
Secreted in egg follicle.
Inhibits FSH and LH release.
What is contraception?
Prevention of egg fertilisation.
2 types of contraception
- hormonal
- barrier
How does hormonal contraception work?
Raising hormonal concentration prevents the natural fall of concentratioin at the end of the cycle.
Sperm cell path
vagina
cervix
uterus
oviduct
What is clomifene therapy
Clomifene drug is inserted and helps to increase FSH and LH concentration in blood so egg cells can be released in menstrual cycle
How does IVF work
- Egg cell follicle maturation stimulated by hormones
- Egg cells released by many follicles and taken from ovary
- Sperm cells taken from man
- Eggs and sperm combined to allow fertilisation
- One or two healthy embryos are placed in uterus
- Any healthy embryos not used in 1st attempt can be frozen and stored
Benefits of IVF
Provides way for infertile couple to have a child
Cons of IVF
- Success rate is low
- Woman may get sick symptoms to hormones
What is homeostasis
The maintenance of a constant internal environment
What is thermoregulation
Control of body temperatures, keeping temperature of major organs close to 37º
What monitors temperature and how
Hypothalamus - receptors detect change in brain/blood - recieves info from temp receptors in dermis of skin
What happens when too cold?
- Shivering
- Contraction of erector muscles
- Vasoconstriction
What does shivering do
Muscles contract and relax rapidly. Energy released from cell respiration from movement releases heat energy.
What does contraction of erector muscles do
Muscles contracting in skin dermis caues hair to stand upright. Traps air next to skin for insulation.
What does vasoconstriction do
Blood vessels near skin narrow.
- Hypothalamus sends nerve impulses to small arteries deep in skin so they narrow
- Reduces blood flow in capillaries near surface of skin, helps to reduce energy transfer to surroundings/air by heating
What happens when too hot?
- Sweating
- Vasodilation
Effect of sweating
Sweat spreads out as thin layer of skin epidermis where water evaportes. Heat is removed from surface of skin by latent heat.
Effect of vasodilation
- Arteries widen near skin
- Hypothalamus sends nerve impulses to small arteries to widen
- Increases blood flow through skin capillaries (brings warm blood nearer to surface of skin, increasing energy transfer to surroundings)
- So we cool down
What is osmoregulation
Control of balance of water and mineral salts in the body
What happens if osmoregulation doesnt occur
Cells take in or lose too much water by osmosis.
Can damage cells as water allows cell molecules to move and maintains cell shape
Carbs pathway after eating
During digestion carbs release glucose.
Glucose -> Blood -> Cells -> Broken down in respiration
How does insulin help blood-glucose levels.
- During time glucose takes to reach cells, blood-glucose levels rise
- Pancreas cells are stimulated to release insulin
- Insulin is hormone causing liver and muscle cells to take up glucose and convert it to GLYCOGEN for storage in liver cells.
- This causes fall in blood-glucose concentration
What happens if blood glucose levels are too low
GLUCAGON is released from pancreas (causes liver cells to convert glycogen into glucose) which is then released into blood
