Homeostasis and response Flashcards
What is homeostasis and what can it control
The regulation of the condition inside your body and cells to maintain a stable internal environment, in response to changes
Blood glucose concentration
Body temperature
Water levels
What does a nervous system do
Controls voluntary and involuntary actions and is responsible for transmitting and receiving impulses in different parts of the body
Contains the CNS (Central Nervous System) and a network of nerves throughout the body
How does the nervous the nervous system enable the body to respond to changes
Receptors detect a stimulus
The CNS coordinates your body’s response
Effectors cause a response by moving your body or secreting a hormone
How is the reflex arc done
Receptor detects a stimulus
Sensory neuron sends electrical impulses to relay neuron, which are located in the spinal cord
Motor neuron sends electrical impulses to an effector
Effector produces a response
What happens at a synapse
An electrical impulse travels along the first axon
This triggers the nerve-ending of a neuron to release neurotransmitters
The chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the second neuron
This stimulates the second neuron to transmit the electrical impulse
Required practical : Reaction times
What is the method
Keep your arm at a 90° angle to the table
Have a partner hold the ruler with 0 cm at your index finger and thumb and in your peripheral vision
Partner drops the ruler without warning and record the distance
Take a break between each drop to keep the test consistent
Repeat the steps with the other hand
What are the glands and what do they produce
Pituitary gland - hormones that affect other glands
Thyroid gland - thyroxine
Adrenal gland - adrenaline
Pancreas - insulin
Testes - testosterone
Ovaries - oestrogen
What is the difference between insulin and glucagon
Insulin - hormone produced in the pancreas that lowers blood glucose by converting it to glycogen, storing it in the liver
Glucagon - A hormone produced in the pancreas that raises blood glucose by breaking down glycogen, stored in the liver
What is type 1 diabetes and how is it controlled
Pancreas fails to produce enough insulin, uncontrollable high glucose levels
Injecting insulin
Careful with your diet
Exercise
Eating food that don’t increase blood sugar level
What is type 2 diabetes and how is it controlled
Cells no longer respond to insulin being produced
Carbohydrate controlled diet
Exercise regime
What is the key points in the menstrual cycle
Day 1 - 5:
The lining is lost from the uterus. This is called a period (menstruation)
Day 6 - 13:
The lining of the uterus thickens to get ready for a fertilised egg. On day 12, the egg starts to mature
Day 14:
A mature egg is released from an ovary. This is called ovulation
Day 15 - 28:
The lining of the uterus stops developing if the egg cell wasn’t fertilised
Where is FSH produced and what is the target organ and effect
Produced in the pituitary gland
Ovary - ovum matures in the ovary
Pituitary gland - stimulates ovaries to produce oestrogen
Where is oestrogen produced and what is the target organ and effect
Produced in the ovaries
Uterus - causes lining to thicken in the first half of the cycle
Pituitary gland - high oestrogen levels switch off FSH and switch on LH release
Where is LH produced and what is the target organ and effect
Produced in the Pituitary gland
Ovary - ovulation (release of ovum from ovaries)
Where is progesterone produced and what is the target organ and effect
Produced in the ovaries
Uterus - maintains the uterus lining if ovum implants. High concentrations of progesterone in pregnancy stops the cycle
What are the hormonal methods of contraception and what do they do
Oral contraceptive - contains oestrogen and progesterone. Inhibits the production of FSH (eggs can’t mature)
Contraceptive injections, implants and skin patches slows down the release of progesterone
What are the benefits and risks of an oral contraceptive
Benefits:
More than 99% effective if taken correctly
Reduce the risk of certain cancers
Risks:
Changes in weight, mood and blood pressure due to high levels of oestrogen
What are non hormonal methods of contraception
Physical barrier, e.g. condom and diaphragm - prevents sperm from reaching the egg
IUD/coil - prevents implantation of embryo/release of hormone
Spermicide - kill/disable sperm
Abstinence - when the egg isn’t in the oviduct
Surgical methods - vasectomy
What are the benefits for non hormonal methods of contraception
Condoms are quick and easy to use
IUDs can last for 10 years
Spermicide can be added as an extra layer of protection
What are the risks for non hormonal methods of contraception
Condoms can tear or rip
Diaphragms are left in several hours later
IUDs need to be fitted in a a health professional and there’s a risk of an ectopic pregnancy
Spermicide can cause allergic reactions
Abstaining has a high chance of pregnancy if the timing isn’t right
Surgical methods can’t be reversed
What happens during 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 a dish in the laboratory
The fertilised eggs develop into embryos
At the stage when they are tiny balls of cells one or two embryos are inserted into the mother’s uterus (womb)
What are the advantages of IVF
It allows people to have babies of their own, who otherwise can’t due to a variety of reasons
It has a safe track record and has been used since 1978. The embryos can be screened for genetic diseases, which is important for families that already have an affected child. Only unaffected embryos are used
Unused eggs can be used for research or donated to other couples
What are the disadvantages of IVF
There are side effects form the drugs used, such as hot flushes and severe headaches
There is a possibility of multiple births, which is dangerous for mother and babies
Ovarian hyper-stimulation syndrome (OHS), when too many eggs develop in the ovaries
It is very emotionally and physically stressful
The success rates are not high
What are ethical concerns of IVF
Some people worry about the ethical implications of IVF. They are concerned that couples may want ‘designer babies’ with ‘desirable’ qualities, so may only want certain fertilised eggs. For example, they may want a girl if they have lots of boys in the family
Also, the embryos that are not used may be destroyed. Some people consider embryos to be new lives and view their destruction as unethical
