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homeostasis - Coggle Diagram
homeostasis
CONTACEPTION
Fertility can be controlled and prevented by different method of contraception. it includes the use of hormones and non-hormonal methods
why is contraception important ? to keep family sizes small and limit the increase in population also some contraceptions give protection from sexually transmitted diseases or infections.
- issues with contraception can not be answer by science alone : Catholic Church say that its unethical apart from natural methods
other people say that its a persons right to choose and its also good because it protects against STI's
- there are barrial, chemical , surgical and natural contraception methods to prevent pregnancy
CHEMICAL: oral contraceptives that contain hormones
- the combine pill - contains oestrogen and progesterone --> high levels of oestrogen inhibits FSH and prevent egg maturation.
progesterone --> inhibits release of mature eggs and stimulates the production of thick mucus witch prevents sperm from reaching released eggs
Advantage is the contraceptive pill is highly effective if its take correctly
disadvantage is it must be take every day and if forgotten there is a risk of pregnancy. in addition there are side effects including risk of breast cancer and blood clots.
- implants, skin patch or an injection - contains progesterone --> stops eggs from being released and maturing.
advantage is they are much more convenient then taking a pill
disadvantage is they down protect against sexually transmitted diseases.
- intrauterine devices or IUD (coils) - they can prevent an embryo from implanting. some coils release hormones to reduce chances of fertilisation
advantage - highly effective and can prevent pregnancy of up to 10 years
disadvantage is they have a few side effects and don't protect agains sexually transmitted diseases
BARRIER: methods that prevent the sperm from reaching a egg
- condoms or diaphragms
advantages:
- are they are very effective if used correctly
- they don't use hormones so no side effects
- they can reduce the risk of sexually transmitted diseases
disadvantages:
- they can break or slip of
both condoms and diaphragms are more effective if they are used with spermicide gel, they kill and disable sperm and reduce chances of fertilisation
SURGICAL: surgical methods of male and female sterilsiation
female: the oviducts are cut and tied. The oviducts connect the ovaries to the uterus
male: the sperm ducts can also be cut and tied in a procedure can a vasectomy
advantage : highly effective
disadvantage : is difficult to reverse they also done protect against STI's
NATURAL: abstaining from intercourse when an egg may be in oviduct
advantage: you can be 100% sure that you are preventing preganancy
disadvantage : its hard to know when you are in oviduct
The Human Nervous System
the veracious system enables humans to react to their surroundings and coordinate their response
CNS- central nervous system
the CNS receives information from the receptors and coordinate a response accordingly, the response is carried out by the effector.
the CNS is the brain or spinal cord --> the information from the receptors passes along cells (neuron's) as electrical impulses to the CNS
stimulus-->receptor-->CNS-->effector-->response
CNS- connected to the body by sensory and motor neurons
sensory neurons - they carry information as electrical impulses from the receptor to the CNS
motor neurone - carry electrical impulses from the CNS to the effector.
THE CONNECTION BETWEEN TWO NEURONS ARE CALLED SYNAPSES. THE NERVE SIGNAL IS TRANSFERRED BY CHEMICALS WHICH DIFFUSE ACROSS THE GAP
human endocrine system
the endocrine system is composed of glands which secrete hormones directly into the bloodstream
the blood carries the hormone to a target organ where it produces and effect
(compared to the nervous system the effects are slower but act for longer)
'the master gland'
pituitary gland - secretes several hormones into the blood in response to body conditions, these hormones can then act on other glands to stimulate other hormones to be released to bring effects
thyroid gland - produces thyroxine. it stimulates the basal metabolic rate--> it plays an important role in growth and development
adrenal gland - produces adrenilin in times of fear or stress. it increases the heart rate and boosts delivery for oxygen and glucose to the brain and muscles preparing the body for flight or fight
pancreas - produces insulin
testes - produce testosterone
ovaries - produce oestrogen and progestorone
CONTROL OF BLOOD GLUCOSE CONCENTRATION
glucose is needed by cells for respiration, its important that the concentration of blood glucose is monitored closely and controlled by the pancreas and kept at a constant level
if the blood glucose gets too high:
the pancreas produces hormone insulin and that causes the glucose to move from the blood into the cells. in the liver and muscle cells excess glucose is converted to glycogen for storage. when the glycogen stores are full in the liver and muscle cells the excess glucose is turned into lipids and stored
if the blood glucose concentration is too low:
the pancreas produces the hormone glucagon that causes the glycogen in the liver and muscle cells to be converted back into glucose and released into the blood
the backup plan is converting lipids back into glucose
DIABETES -inability to control blood glucose levels TYPE 1:
insulin is NOT produced by the pancrease, its typically developed in childhood and its an autoimune disease. the treatment is regular insulin shots
TYPE 2:
insulin is produce but the cells of the body (live and muscle cells) no longer respond to it . its risk factor is obesity and its treatment is carbohydrate controlled diet and exercise regime
NOTE: must know the blood glucose concentration by time graph
HORMONES IN HUMAN REPRODUCTION
puberty :
during puberty reproductive hormones cause secondary sex characteristics to develope
males produce testosterone which stimulates sperm production
females produce the hormone oestrogen
, this plays an important role in the menstrual cycle. during the mensural cycle eggs in the ovaries mature and one is released every 28 days, this is called ovuation
HORMONES IN THE MENSTRUAL CYCLE
- F.S.H --> produced in the pituitary gland. target is the ovaries. it causes egg (folicule) to mature and causes the production and release of oestrogen
- oestrogen --> produced in the ovaries, target is uterus where it repairs the uterus wall and also targets the pituitary gland where it inhibits F.S.H and stimulates production and release of LH
- LH (luteinising hormone)--> produced in the pituitary gland and targets the ovaries. it causes ovulation and stimulates production and release of progesterone
- progesotone --> produced in the ovary (corpus luteum) it targets the uterus where it maintains the uterus wall and also targets the pituiatry gland where it inhibits F.S.H and LH
(note : know the graph thing)
THE USES OF HORMONES TO TREAT INFERTILITY
infertility occurs when a couple are unable to conceive naturally --> this can be due to reals of insufficient levels of reproductive hormones effecting the development of eggs nd sperm cells. or as a result of issues with the reproductive system of a female.
there are two ways to treat infertility
- using hormones to increase fertility
- some woman have levels of FSH or LH that are too low to cause eggs to mature. this means they can't get pregnant
the hormones FSH can be given to a woman in a fertility drug to stimulate ovulation --> she then become pregnant naturally
a disadvantage to this method is that too many eggs could be stimulated which may realist in triplets or twins. it also doesn't have a high success rate and can be expensive
- IVF treatment
- an alternate method is for eggs to fertilised outside the body in a lab. how this works:
- give the mother FSH and LH to stimulate maturation of several eggs
- collect the eggs and fertilise them with the fathers sperm
- wait for the fertilised eggs to develop into embryos (at this stage they are ting balls of cells) one or two embryos are inserted into the mothers uterus
the advantage is it gives a woman a chance to have a baby of her own
the disadvantages are success rates are not high and IVF fails can be emotionally upsetting and physically stressful for couples
also IVF can lead to multiple births if more than one embryo grows into a baby, which is dangerous for the mother
there have been advancements in medical technology which are helping to increase success rates
--> additionally these advancments include being able to gentically the embryo to check if its healthy and see if there are any genetic defaults that the couple may want to consider SOME PEOPLE ARE AGAINST IVF
- the process often results in unused embryos that are eventually destroyed. many say this is unethical because you are killing a potential life.
- the genetic testing for embryos before implantation also rases ethical issues as it may leed to selection of preferred characteristic eg gender
What is homeostasis ?
Homeostasis is the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function and response to internal and external changes
What does homeostasis do ?
Homeostasis maintains optimal condition for enzyme action and all cell functions in the human body. These include:
- blood glucose concentation
- body tempiture
- water levels
in your body you have many automatic control syestem, these may include nervous responses or chemical responses
all control systems include :
- receptors - they detect stimuli
- coordination centres - (eg spinal cord, brain or pancreas) they receive and process information from the receptors
- effectors - (muscles or glands, muscles contract and glands secret hormones) they carry out the response which restore optimal levels (the errors respond with either a chemical response or nervous response)
reflex arc
reflexes are unconscious actions, they are rapid and automatic response to stimulus to minimise damage to the body
it follows this general sequence:
- receptors in the skin detects a stimulus (eg touching hot water)
- sensory neurone sends impulses to relay neurone
- relay neurone sends impuse down the motor neurone which sends a impulse to the effector
- effector produces a response (eg muscle contracts to move the hand away)
negative feedback mechanism
it responds when conditions change from its ideal set point and returns conditions to its set point
- conditions change in the body
- change detected
- corrective mechanism activated
- conditions return to set point
- mechanism switched off
back to step 1
(an example of the negative feedback is if you get too hot your body responds with sweat )