Homeostasis and Response Flashcards
what is homeostasis?
maintaining a stable internal environment
why is homeostasis important?
because it stabilises your body or cells when an internal or external condition has changed.
2 kinds of communication systems in your body?
nervous and hormonal
what three components are your automatic control systems made up of?
cells called receptors, coordination centres and effectors
how do automatic control systems keep your internal environment stable?
negative feedback
what does a receptor do?
detects when a stimulus level is too high or low
What does a coordination centre do?
Receives information and processes it then organises a response
what does an effector do?
produces a response to counteract the change and restores the optimum level
do you think about the process of automatic control systems?
No, it happens on its own
What is stimuli?
A change in the environment
what do multicellular organisms do to communicate with each other to survive?
they form communication systems like the nervous and hormonal.
Name the different parts of the nervous system.
Central nervous system, sensory neurones, motor neurones, and effectors
What is the central nervous system?
In vertebrates (Animals with backbones) it consists of the brain and spinal cord only. It takes in sensory information, process is the information, and sends out motor signals
What are sensory neurons?
The neurones (communication cells) that carry information as electrical impulses from the receptors to the CNS
what are motor neurones?
The neurons that carry electrical impulses from the CNS to effectors
what are Effectors?
All your muscles and glands which respond to Nervous impulses
Give two examples of receptors.
taste receptors on the tongue and sound receptors in the ears
Receptors can form parts of larger complex organs, give an example.
The retina of the eye is covered in the light receptor cells
Muscles and glands are both effectors but do different things, what are they?
Muscles contract in response to nervous impulse whereas glands secrete hormones
What are synapses?
the connection between two neurones.
how are nerve systems transferred?
Chemicals diffuse (move) across the gap then set up a new electrical signals into the next neurone
What are reflexes?
Rapid automatic responses to certain stimuli that don’t involve the conscious part of the brain.
What is the name of the passage of information in a reflex (from receptor two a factor)?
The reflex arc.
Where does the reflex arc go through?
The central nervous system
What is the passage of a reflex arc?
stimulus is detected by receptors, impulses move along the sensory neurones to the CNS. Synapses cause the impulses to move from the sensory neurones to the relay neurones which move to the motoneurons which travel to the effector . 
What are hormones?
Chemical messengers sent in the blood.
What do hormones do?
They move around the body to target organs and control things in organs and cells that need constant adjustments
Do hormones tend to be long-lasting?
yes organs tend to have long-lasting effects.
Where are hormones produced?
Endocrine glands, these glands make up your Endocrine system.
name the different glands in the endocrine system.
pituitary gland
Thyroid
Ovaries
Adrenal gland
Pancreas
Testes
What does the pituitary gland do?
it produces many hormones that regulate body conditions. Sometimes called the ‘master gland’, these hormones act on other glands directing them to release hormones and make changes.
What does the thyroid do?
produces thyroxine, which is involved in regulating things like rate of metabolism, heart rate and temperature
What do the ovaries do?
only in women, They produce Oestrogen which is involved in the menstrual cycle.
What does the adrenal gland do?
this produces adrenaline which is used to prepare the body for the ‘fight or flight’ response
What does the pancreas do?
this produces insulin, which is to regulate blood glucose level.
What do testes do?
they produce testosterone, which controls puberty and sperm production in males.
hormones and nerves do very similar jobs – the both carry information instructions, what are the differences between them?
Nerves-
very fast action, act for a short time, and act in a very precise area
Hormones-
Slower action, act for a long time, and act in a more general way
How does glucose get into the body?
it is contained in carbohydrates and enters the blood from the gut.
how do you remove glucose from the blood?
The normal metabolism of cells removes glucose from the blood.
Vigourous exercise remove much more glucose from the blood.
What does insulin do?
If there is too much glucose in the blood the pancreas releases insulin, which moves the glucose into the liver and muscles where it can be stored and turned into glycogen.
What does glucagon do?
when the blood has two little glucose, the pancreas secretes glucagon which makes the liver turn the glycogen back into glucose and is released back into the bloodstream.
What is the difference between type one diabetes and type two?
type one diabetes means little or no insulin is made in the pancreas.
Type two diabetes mean there is insulin resistance. This can be caused by being overweight.
What do people with type one diabetes need?
I need insulin therapy which involves taking injections of insulin throughout the day. This gives your body the insulin that the pancreas does not produce.
What are the features of type two diabetes?
Type two diabetes is worse person becomes resistant to their own insulin (they still produce it but the body cells don’t respond properly)
Being overweight can highly increase your chances of developing it as obesity is a major risk factor.
Type two diabetes can be controlled by eating a carbohydrate control diet and getting exercise regularly.
When do you start producing sex hormones?
Puberty
What is the first stage of the menstrual cycle?
The menstrual cycle starts, the uterus lining breaks down for about four days
What is the second stage of the menstrual cycle?
The uterus lining builds up again, from day 4 to 14, into a thick spongy layer full of blood vessels ready to receive a fertilised egg
What is stage three of the menstrual cycle?
an egg develops and is released from the ovary of a 14 – This is ovulation.
What is stage four of the menstrual cycle?
at 28 days, if no fertilised egg lands on the wall of the uterus, the spongy lining starts to break down and the whole cycle starts again
What are the hormones involved in the menstrual cycle?
FSH, oestrogen, LH, progesterone
What does FSH do?
produced in the pituitary gland, it causes an egg to mature in a structure called a follicle, it also stimulates the ovaries to produce Oestrogen
What does oestrogen do?
it’s produced in the ovaries, it causes the lining of the uterus to go and stimulates the release of LH and inhibits the release of FSH
What does LH do?
produced in the pituitary gland, it stimulates the release of an egg 
What does progesterone do?
produced in the ovaries by the remains of the follicle after ovulation, it maintains the lining of the uterus during the second half of the cycle And inhibits the release of LH and FSH
Why can oestrogen be used to prevent fertility?
If taken every day it will inhibit the production of FSH which means there will be no egg development
How can progesterone be used to reduce fertility?
it stimulates the production of thick mucus which prevents sperm from getting to an egg
what are the downsides And upsides of the oral contraception pill?
Although it’s 99% effective, the side effects can be headaches, nausea and not protecting against sexual transmitted diseases
What are some alternatives to the pill?
A contraceptive patch which contains oestrogen and progesterone.
The contraception implant which goes in the arm and releases progesterone.
The IUD which kills sperm and prevents implantation in the egg.
name a non-hormonal form of contraception?
condoms are also the only form of contraception that prevent against sexually transmitted disease.
What are the ways to avoid pregnancy?
sterilisation, natural methods (avoiding sexual intercourse with a woman is Most fertile), and abstinence
What are the pros and cons of using hormones to increase fertility?
Pros- Giving women hormones that they didn’t previously have Hopsin to get pregnant.
Cons- It may not work which is a waste of money because it can be expensive, and two mini eggs could be stimulated resulting in multiple pregnancies.
What are the pros and cons of IVF?
Pros- Women who would not otherwise be able to get pregnant or have a child can.
Cons- Multiple births can happen if more than one embryo turns into a baby which is dangerous and can lead to miscarriage,  success rates are low (25%) which is wasteful Because it’s so expensive, and it can be physically and emotionally distressful for women.
What is adrenaline?
adrenaline is a hormone released by the adrenal glands, it’s released in response to stressful situations and Triggers mechanisms that increase the supply of Augustine and glucose to cells in the brain and muscles e.g. increases heart rate
What is thyroxine
released by the thyroid gland, thyroxine regulates the basal metabolic rate (the speed at which chemical reactions in the body occur while at rest)
What is thyroxine produced in response to?
it’s produced in response to TSH (thyroid stimulating hormone) which comes from the pituitary gland.
