Homeostasis And Response Flashcards
1
Q
What is homeostasis
A
The regulation of he conditions inside your body to maintain a stable internal environment in response to changes in both internal and external conditions
2
Q
What do the receptors do
A
Detects a stimulus
3
Q
What’s a stimulus
A
A change in the environment
4
Q
What dos the coordination centre do
A
Receives and processes the information then organises a response
5
Q
What does the effector do
A
- Produces a response which counteracts the change and restores the optimum level
- all muscles and glands
6
Q
What do sensory neurones do
A
The neurones that carry information as electrical impulses from the receptors to the CNS
7
Q
What does CNS stand for
A
Central nervous system
8
Q
What do motor neurons do
A
The neurones that carry electrical impulses from the CNS to effectors
9
Q
What parts of body is the CNS
A
- in vertebrate this consist of brain and spinal chord only
- in mammals, the CNS is connected to the body by sensory neurones and motor neurones
10
Q
Examples of receptors in the body
A
- taste receptors
- sound receptors in the ears
11
Q
Examples of effectors
A
- muscles: contrast in response to a nervous impulse
- glands: secrete hormones
12
Q
What is the CNS
A
- its a coordination centre
- it receives information from the receptors then coordinates a response. The response is carried out by effectors
13
Q
Simple Order of how nervous system processes
A
Stimulus
Receptor
Sensory neurone
CNS
Motor neurone
Effector
Response
14
Q
Wha is a synapse
A
- The connection between 2 neurones
- the nerve signal is transferred by chemicals which diffuse across the gap
- these chemicals set off a new electrical signal in the next neurone
15
Q
What is a reflex arc
A
The passage of information in a reflex (from receptor to effector)
16
Q
What are reflexes
A
- rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain
- they can reduce the chances of being injured
17
Q
What are relay neurones
A
Connect sensor neurone to motor neurones
18
Q
Reflex arc explanation (big paragraph)
A
- When a stimulus is detected by receptors, impulses are sen along a sensory neurone to a relay neurone in the CNS
- When the impulse reaches a synapse between the sensory and relay neurone, chemicals diffuse down the synapse and the chemicals cause an impulse to be sent along the relay neurone
- When the impulse reaches a a synapse between the relay neurone and a motor neurone, the same thing happens with the chemicals and an impulse is sent along the motor neurone
- The impulse travel along the motor neurone to the effector
- The effector will then carry out the response
19
Q
What is reaction time
A
The time it takes to respond to a stimulus
- can be affected by factors such as age drugs or gender
20
Q
What is adrenaline/ why is it released
A
- a hormone released by the adrenal glands
- released in response to stressful or scary situations - your brain detects fear or stress and sends nervous impulses to the adrenal glands, which respond by secreting adrenaline
21
Q
What does the release of adrenaline prepare the body for
A
- gets the body ready for ‘fight or flight’ by triggering mechanisms that increase the supply o oxygen and glucose to cells in the brain and muscles
- for example, adrenaline increases heart rate
22
Q
How is hormone release affected by negative feedback
A
- when the body detects that the level of a substance has gone above or below the normal level, it triggers a response to bring it back to normal again
23
Q
What is basal metabolic rate
A
The speed at which chemical reactions in the body occur while the body is at rest
24
Q
What is thyroxine and why is it produced
A
- hormone released by thyroid gland
- its released in response to thyroid stimulating hormone (TSH), which is released from the pituitary gland
25
Why is thyroxine important
- plays important role in regulating basal metabolic rate
- important for other processes in body such as stimulating protein synthesis for growth and development
26
How does negative feedback system help regulate thyroxine levels in blood
- when the level of thyroxine in the blood is higher than normal, the secretion of TSH from the pituitary gland is inhibited
- this reduces the amount of thyroxine released from the thyroid gland, so the level in the blood falls back towards normal
- its the opposite if thyroxine levels drop
27
How to measure reaction time
- drop ruler test (look at physics forces flash cards)
- computer tests (can give more accurate times because there can’t be human error, removes possibility that person can predict when to respond, and more accurate results as it’s in milliseconds)
28
What are hormones
- chemical molecules released directly into the blood
- they are carried in the blood to other parts of the body, but only affect particular cells in particular organs
- they control things in organs and cells that need constant adjustment
- they tend to have relatively long-lasting effects
29
Where are hormones produced
- produced and secreted by various glands, called endocrine glands
30
Pituitary gland
- ‘master gland’
- produces many hormones that regulate body conditions
- these hormones act on other glands, directing them to release hormones that bring about change
- in brain
31
Thyroid
- produces thyroxine
- involved in regulating rate of metabolism, heart rate and temperature
- in throat
32
Adrenal gland
- produces adrenaline which is used to prepare the body for ‘fight or flight’ response
- above liver
33
The pancreas
- produces insulin which is used to regulate blood glucose level
34
Ovaries
- females only
- produce oestrogen which is involved in menstrual cycle
35
Testes
- males only
- produce testosterone which controls puberty and sperm production in males
36
Difference between hormones and nerves
Nerves:
- very fast action
- act for very short time
- act on very precise area
Hormones:
-slower action
- act for a longtime
- act in a more general way
37
How is glucose affected
- eating foods containing carbohydrates puts glucose into e blood from the gut
- the normal metabolism of cells removes glucose from the blood
- vigorous exercise removes much more glucose from the blood
- excess glucose can be stored as glycogen in the liver and in the muscles
- the level of glucose in the blood must be kept steady. Changes are monitored and controlled by the pancreas, using the hormones insulin and glucagon in a negative feedback cycle
38
Explain what happens when blood glucose level is too high
- insulin secreted by pancreas into blood
- glucose moves from blood into liver and muscle cells
- insulin makes liver turn glucose into glycogen in the
- blood glucose is reduced
- so insulin removes glucose from the blood
39
Explain what happens when blood glucose level glucose level is to low
- glucagon secreted by pancreas
- glucagon makes liver turn glycogen into glucose
- glucose released into blood by liver
- blood glucose is increased
40
What is Type 1 diabetes
- the pancreas produces too little or no insulin
- this means a person’s blood glucose level can rise to a level that can kill them
41
How do you help type 1 diabetes
- people with it need insulin therapy
- this usually involves several injections of insulin throughout, most likely at mealtimes
- this makes sure hat glucose is removed from the blood quickly once the food has been digested, stopping the level getting too high
- its very effective
- the amount of insulin injected depends on the persons die and how active they are
42
What is type 2 diabetes
- where a person becomes resistant t their own insulin
- they till produce insulin, but their body’s cells don’t respond properly to the hormone
- this can also cause a persons blood sugar level to rise to a dangerous level
43
How to control type 2 diabetes
- being overweight ca increase your chance of developing type 2 diabetes
- obesity is a major factor of the disease
- can be controlled by eating a carbohydrate-controlled diet and getting regular exercise
44
FSH
- follicle stimulating hormone
- produced in the pituitary gland
- causes an egg to mature in one of the ovaries in a structure called a follicle
- stimulates the ovaries to produce oestrogen
45
Oestrogen
- produced in ovaries
- causes lining of uterus to grow
- stimulates the lining of LH (which causes release of an egg) and inhibits release of FSH
46
LH
- luteinising hormone
- produced by the pituitary gland
- stimulates the release of an egg at day 14 (ovulation)
47
Progesterone
- produced in the ovaries by the remains of the follicle after ovulation
- maintains the lining of the uterus during the second half of the cycle
- when the level of progesterone falls, the lining breaks down
- inhibits the release of LH and FSH
48
Progesterone
- produced in the ovaries by the remains of the follicle after ovulation
- maintains the lining of the uterus during the second half of the cycle
- when the level of progesterone falls, the lining breaks down
- inhibits the release of LH and FSH
49
4 stages of menstrual cycle
1. Day1 - menstruation starts. Uterus lining breaks down for about 4 days
2. Uterus lining builds up again from day 4 - 14 into a thick spongy layer full of blood vessels, ready to receive a fertilised egg
3. An egg develops and is released from the ovary at day 14 - this is called ovulation
4. The wall is ten maintained for about 14 days until day 28. If no fertilised egg has landed on the uterus wall by day 28, the spongy lining starts to break down and the whole cycle starts again
50
How can oestrogen be used to prevent the release of an egg
- if oestrogen is taken every day to keep the level of it permanently high, it inhibits the production of FSH
- after a while egg development and production stop and stay stopped
51
How is progesterone used to stop fertility
- by stimulating the production of this mucus which prevents any sperm getting through and reaching an egg
52
How does ‘the pill’ work for contraception
- an oral contraceptive containing oestrogen and progesterone (known as combined oral contraceptive pill)
- its over 99% effective at preventing pregnancy but can cause side effects like headaches and nausea and it doesn’t protect against STDs
53
The contraceptive patch
- contains oestrogen and progesterone
- its a small patch that’s stuck to the skin
- each patch lasts one week
54
The contraceptive implant
- inserted under the skin of the arm
- it releases a continuous amount of progesterone which stops the ovaries from releasing eggs, makes it hard for sperm to swim to the egg and stops any fertilised egg implanting in the uterus
- an implant can last for 3 years
55
Contraceptive injection
- contains progesterone
- each dose lasts 2-3 months
56
Intrauterine device (IUD)
- t-shaped device that is inserted into the uterus to kill sperm and prevent implantation of a fertilised egg
- there are 2 main types:
- plastics IUDs that release progesterone
- copper IUDs that prevent the sperm surviving the uterus
57
Barrier methods
- condoms
- diaphragm
- spermicide
58
Condoms
- worn over penis during intercourse to prevent sperm entering vagina
- only form of contraception that protect against STDs
59
Diaphragm contraception
- shallow plastic cup that fits over the cervix to form a barrier
- it has to be used with spermicide
60
Spermicide
- a substance that disables or kills the sperm
- not as effective: only about 70%-80%
61
Sterilisation
- involves the cutting or tying of the fallopian tubes in a female or the sperm duct in a male
- this is a permanent procedure
- very small chance that the tubes can rejoin
62
Natural methods of contraception
- pregnancy can be avoided by finding out when in the menstrual cycle the woman is mot fertile and avoiding sex on those days
- its popular with people who think hormonal and barrier methods are unnatural, but it’s not very effective
63
Abstinence
The only way to make sure that sperm an egg don’t meet is to not have sex
64
What happens when a woman has low levels of FSH
- it means no eggs are released and women can’t get pregnant
- FSH and LH can be given to women in a fertility drug to stimulate ovulation
65
Pros of giving women FSH and LH if they have low FSH
- helps a lot of women get pregnant when they previously couldn’t
66
Cons of giving women FSH and LH if their FSH levels are low
- doesn’t always work, some women may do it many times which can be expensive
- too many eggs could be stimulated, resulting in unexpected multiple pregnancies
67
IVF
- collect eggs from woman’s ovaries and fertilise them in a lab using the man’s sperm
- the fertilised egg are then grown int embryos in a laboratory incubator
- once the embryo are tiny balls of cells, one or two of them are transferred to the woman’s uterus to improve the chance of pregnancy
- FSH and LH are given before egg collection to stimulate several eggs to mature
68
Pros of IVF
Can give an infertile couple a child
69
Cons of IVF
- multiple births can happen if more than one embryo grows into a baby: risky for mother and babies (higher risk of miscarriage/stillbirth etc)
- the successful rate of IVF is low. It makes the process extremely stressful and often upsetting, especially if it ends in multiple failures
- also physically stressful for the woman as some women have. Strong reaction to the hormones
- expensive
70
People against IVF
- the process often results in unused embryos that are eventually destroyed. Some people think its unethical because each embryo is a potential human life
- the generic testing of embryos before implantation makes some people think that it can lead to the selection of preferred characteristics
