Biology Paper 2 GCSE Flashcards
What is Homeostasis?
The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to external and internal changes
What does Homeostasis do?
maintains optimal conditions for enzyme action and all cell functions
Homeostasis contains control of what 3 things?
Blood glucose concentration
body temperature
water levels
All control systems include what?
- Cells called receptors
- coordination centers
- effectors
What do receptors do?
detect stimuli (changes in the environment)
What is an example of a coordination centre and what do they do?
brain, spinal cord, pancreas
They receive and process information from receptors
What do effectors do?
muscles or glands, which bring about responses which restore optimum levels
What do nervous systems do?
enables humans to react to their surrondings and to coordinate their behaviour
How does the nervous system work?
information from receptors passes along cells (neurones) as electrical impulses to the central nervous system. The CNS is the brain and spinal cord. The CNS coordinates the response of effectors which may be muscles contracting or glands secreting hormones
What is a synapse?
a junction between two nerve cells, consisting of a minute gap across which impulses pass by diffusion of a neurotransmitter.
What does sensory neurones do?
carry signals from receptors to the spinal cord and brain.
What does a relay neurone do?
carry messages from one part of the CNS to another.
What do motor neurones do?
carry signals from the CNS to effectors.
What is the endocrine system?
composed of glands which secrete chemicals hormones directly into the bloodstream. The blood carries the hormone to a target organ where it produces an effect
What is the pituitary gland?
a ‘master gland’ which secretes several hormones into the blood in response to body conditions. These hormones in turn act on other glands to stimulate other hormones to be released to bring about effects.
How is blood glucose concentration monitored and controlled?
Pancreas
If the blood glucose concentration is too high what does the pancreas do?
pancreas produces the hormone insulin that causes glucose to move from the blood into the cells and glucose is converted to glycogen in liver
In liver and muscle cells excess glucose is converted to what?
glycogen for storage
What is Type 1 diabetes?
disorder in which the pancreas fails to produce sufficient insulin. It is characterised by uncontrolled high blood glucose levels and is normally treated with insulin injections
What is Type 2 diabetes?
the body cells no longer respond to insulin produced by the pancreas. A carbohydrate controlled diet and an exercise regime are common treatments. Obesity is a risk factor for Type 2 diabetes
If the blood glucose concentration is too low what does the pancreas do?
the pancreas releases glucagon. The glycogen is broken down to glucose and amino acids/fats are broken down
What is the post-synaptic neurone?
neurone after the synpase
What is the neurotransmitter?
a type of chemical released by the neurone
How do nerve impulses travel from one neurone to the next?
- A chemical called a neuronetransmitter is released from the presynaptic neurone.
- The neuronetransmitter diffuse across the synpase.
- The neurotransmitter bind to the receptors on the post-synaptic neurone causing a new impulse to be sent along the post-synaptic neurone
- the neurotransmitters diffuse back across the synapse and are absorbed by the pre-synaptic neurone to be used again
What is reaction time?
time between the presentation of a stimulus and the imtiation of the muscular response to that stimuli
How is glucose controlled using negative feedback control?
Blood glucose is controlled by the liver. When the blood glucose level is too high insulin is released and glucose is taken in by cells. Then if the blood glucose gets too low glycogen is released and is broken down into glucose. Insulin allows glucose to move from your blood into your cells where its used for respiration. Excess glucose is converted into glycogen and stored in the liver and muscle cells. Glycogen is insoluble and can be converted back into glucose
How is glucose controlled using negative feedback control?
Blood glucose is controlled by the liver. When the blood glucose level is too high insulin is released and glucose is taken in by cells. Then if the blood glucose gets too low glycogen is released and is broken down into glucose. Insulin allows glucose to move from your blood into your cells where its used for respiration. Excess glucose is converted into glycogen and stored in the liver and muscle cells. Glycogen is insoluble and can be converted back into glucose
What is Oestrogen?
Main female reproductive hormone produced in the ovaries. It causes the lining of the uterus to get thicker. It prevents FSH and LH.
What is ovulation?
At puberty eggs begin to mature and one is released every 28 days
What is Testosterone?
Main male reproductive hormone produced by the testes and it stimulates sperm production
What is follicle stimulating hormone (FSH)?
pituitary gland in the brain it causes egg to mature stimulates ovaries to release oestrogen
What is luteinsing hormone (LH)?
Produced in the ovaries. It is released on day 15 and causes eggs to be released.
What is progesterone?
secreted in the empty egg follicle in the ovary during ovulation
Helps maintain pregnancy and it stops production of FSH and LH. It maintains the lining of the uterus during 2nd half of the menstrual cycle so its ready to receive a developing embryo if egg is fertilised
What happens during menstrual cycle?
FSH: causes egg to mature stimulates ovaries to produce oestrogen
Oestrogen: build lining of uterus. inhibits FSH stimulates LH production
LH: causes release of mature egg from ovary
Progesterone: maintains uterus lining
What is a hormone?
A chemical messenger which controls body functions
How are hormones transported?
blood
How does the uterus change for pregnancy?
Lining thickens to prepare uterus for pregnancy. There is also an increases in blood vessels to make sure the baby is being supplied with the right amount of oxygen and vitamins.
What is contraception?
prevention of pregnancy. There are several categories of contraception hormonal and non hormonal methods
How does the contraceptive pill work?
- Use female hormones to prevent pregnancy
- contains low doses of oestrogen and progesterone
- hormones release FSH by the pituitary gland so no eggs mature
What are the cons of contraceptive pills?
- Raised blood pressure
- thrombosis
- Breast cancer
How does a condom work?
Thin latex sheath placed over the penis during intercourse to collect specimen.
Prevents egg and sperm meeting
What is a pro of a condom?
protection against STD’s
What is a Con of condoms?
can get damaged and let sperm through
How does the IUD (Intrauterine devices) work?
- Small structures inserted into the uterus by a doctor
- Some contain copper and prevent any early embryos implanting in the lining of the uterus
- others contain progesterone to prevent build up of uterus lining
What is a pro of a IUD?
Very effective
What is a con of a IUD?
may cause period problem or infections
How does a diaphragm/cap work?
thin rubber diaphragm placed over the cervix before sex to prevent the entry of sperm
What is a Con of the diaphragm/cap?
If not placed correctly sperm may get past
How does an implant work?
Tiny tube inserted under your skin by a doctor and slowly releases progesterone
What is a pro of a implant?
99.5% effective
How does a patch work?
- Contains a mixture of oestrogen and progesterone
- stick patch to your skin replacing it every 7 days
- Hormones are absorbed directly into your blood stream
What is abstinence?
refraining from sexual activity
How does abstinence/rhythm method work?
- If people do not have sex they will not get pregnant
- Abstaining from intercourse around ovulation or when an egg is in the oviduct means sperm cannot fertilise the egg
What is a con of Abstinence/rhythm method?
very unreliable
How does the surgical method for men work?
Sperm ducts are cut and tied prevents sperm getting into semen
What is the pro of the men surgical method?
permanent contraception
What is a con of a mans surgical method?
Needs a general anasthetic
How does the surgical method for women work?
oviducts are cut or tied to prevent the egg reaching the uterus and sperm reaching the egg
What is a pro of surgical method for women?
permanent contraception
What is a con of surgical method for women?
needs a general anaesthetic
What happens during In Vitro Ferilisation (IVF) treatment?
- IVF involves giving a mother FSH and LH to stimulate the maturation of several eggs
- The eggs are collected from the mother and fertilised by sperm from the father in the lab
- The fertilised eggs develop into embryos
- At the stage when they are tiny balls of cells, one or two embryos inserted into the mother’s uterus
What is a way of using hormones to treat infertility?
Includes giving FSH and LH in a ‘fertility drug’ to a woman. She may then become pregnant in the normal way.
Even though fertility treatments gives a woman the chance to have a baby of her own what are some cons?
- very emotionally and physically stressful
- success rates are not high
- can lead to multiple births which are a risk to both the babies and the mother
Where is adrenaline produced and when is it released?
Produced by the adrenal gland in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.
Where is thyroxine produced and what does it stimulate?
Thyroxine from the thyroid gland stimulates the basal metabolic rate. It plays an important role in growth and development.
What is thryroxine levels controlled by?
negative feedback