- Created by: abbiedye
- Created on: 20-06-18 19:57
What is homeostasis
Homeostasis - the regulation of the conditions inside your body (and cells to maintain a stable internal environment)
- thebody has lots of automatic control systems that maintain body temperature, blood glucose and water content
There are three components - receptors - coordination centres (brain, spinal cord, pancreas) - effectors
What is negative feedback?
Counteracts changes in the body
1. Receptor detects - level is too high or too low
2. Coordination centre organises a response
3. Effector produces a response - the level decreases or increases
What are the different parts of the nervous system
Central Nervous System (CNS) - vertebrates = brain and spinal cord - mammals = sensory neurones and motor neurone
Sensory Neurone - carry information as electrical impulses from receptors to the CNS
Motor Neurones -carry electrical impulses from the CNS to the effectors
Effectors - muscles and glands which respond to nervous impulses
What are receptors and effectors?
Receptors - cells that detect stimuli - taste/sound receptors - can form larger, comples organs (like a retina)
Effectors - respond to nervous impulses and bring about a change - muscles and glands
How does the CNS coordinate the response
Stimulus -> Receptor -> Sensory Neuron -> CNS -> Motor Neurone -> Effector -> Response
What are synapses?
- The connection between two neurones
- Nerve signal is transferred by chemicals which diffuse across the gap
- These chemical set off a new electrical signal in the next neurone
What are reflexes?
- Reflexes are rapid, automatic responses to certain stimuli that don't involve the conscious part of the brain - reduce chance of injury
- example = someone shining a bright light at someone's eyes
What is the reflex arc?
1. Cheeky be stings finger
2. Stimulation of the pain receptor
3. Impulses travel along the sensory neurone
4. Impulses are passed along a relay neurone, via a synapse
5. Impulses travel along a motor neurone, via a synapse
6. When impulses reach muscle, it contracts
What are the glands that release hormones?
Pituitary gland - regulates body conditions
Thyroid - produce thyroxine
Adrenal gland - produces adrenaline
Ovaries - produce oestrogen
Testes - produce testosterone
Pancreas - produce insulin
What do each of the hormones do?
Thyroxine - regulate metabolism, heart rate and temperature
Adrenaline - 'fight or flight' response
Oestrogen - menstrual cycle
Testosterone - controls puberty and sperm production
Insulin - regulate the blood glucose level
What are the differences between hormones and nerv
Nerves - very fast action - act for a very short tim - act on a very precise area
Hormones - slower action - act for a long time - act in a more general way
How can insulin / glucagon control blood glucose?
Glucagon by pancreas
- Blood glucose level TOO HIGH - INSULIN is ADDED
- Blood glucose level TOO LOW - GLUCAGON is ADDED
What is diabetes?
TYPE 1 - pancreas produces little or no insulin - blood glucose can rise to a dangerous level - insulin injected = depends on diet and activeness
TYPE 2 - resistant to their own insulin - blood sugar level can rise to a dangerous level - obesity is a risk factor
What are the stages of the menstrual cycle?
STAGE 1 - Day 1 - menstruation starts - uterus lining breaks down - 4 days
STAGE 2 - Day 4 to 14 - the uterus lining builds up again
STAGE 3 - Day 14 - an egg develops and is released - ovulation
STAGE 4 - Until day 28 - the uterus is maintained until a fertilised egg lands there
What are the four hormones in the menstrual cycle?
FSH - causes the egg to mature - produced in the pituitary gland - stimulates ovaries to produce oestrogen
Oestrogen - produced in the ovaries - causes lining of the uterus to grow
LH- produced by the pituitary gland - stimulates release of an egg (day 14)
Progesterone - produced in the ovaries - maintains lining of the uterus
How can hormones be used to reduce fertility?
Oestrogen - inhibits the production of FSH - stops egg development and production
Progesterone - stimulating the production of thick mucus - prevents sperm
The pill - oral contraception containing oestrogen and progesterone
- Contraceptive patch, implant and injection
What are the barrier methods?
Non-hormonal forms of contraception
What are the drastic ways to avoid pregnancy?
Sterilisation - cutting or tying the fallopian tubes or the sperm duct
'Natural' methods - looking at the menstrual cycle in advance
Abstinence - to not have intercourse
How can hormones be used to increase fertility?
Lower levels of FSH - fertility drugs - stimulate ovulation
PROS - help a lot of women to get pregnant
CONS - It doesn't always work and can result in multiple pregnancies
What is IVF?
In Vitro Fertilisation - in a lab
PRO - can give an infertile couple a child
CONS - multiple births, low success rate and emotional/physical stress
What is adrenaline?
A hormone released by the adrenal glands
Released in respone to stressful or scary situations
'fight or flight'
What is thyroxine
A hormone released by the thyroid gland
It regulates the basal metabolic rate
Released in response to thyroid stimulating hormone, released from the pituitary gland