Biology paper 2 Flashcards
Define the nervous system
An organ system made up of nerves and neurons that transmit electrical signals around the body.
Define homeostasis
The regulation and control of internal conditions around an optimum point.
Explain why homeostasis is important
Maintains enzyme activity and cell functions.
Give the conditions that need to be controlled in the human body
Blood glucose concentration, temperature and water levels.
Define a stimulus
A change in the internal/external environment of an organism.
Define receptors
Cells that detect stimuli.
Define coordination centres
Areas that receive and process information from receptors (brain).
Define effector
Muscles or glands that respond to stimuli.
Define neurone
Specialised cells adapted to carry electrical impulses around the body.
Give the 3 types of neuron
Sensory, relay and motor neurons.
Describe the role of a sensory neuron
Carries impulses from receptors to the coordination centre (brain).
Describe the role of a relay neurone
Carries impulses across the Central Nervous System.
Describe the role of a motor neuron
Carries impulses from the coordination centre to effectors.
Define reflexes
Rapid, automatic responses.
Explain why reflexes are important
They keep us safe.
Explain why reflexes are so fast
They do not involve the brain.
Define the endocrine system
An organ system made up of glands that secrete hormones.
Define a hormone
Chemical messenger released from a gland.
Describe how a hormone gets to its target organ
In the bloodstream.
Name the glands that make up the endocrine system
Pituitary, Thyroid, pancreas, adrenal, testes, ovaries.
Give the role of the pituitary gland
Controls growth. Stimulates other glands.
Give the role of the thyroid gland
Controls metabolic rate.
Give a role of the pancreas
Controls blood glucose concentration.
Give the role of the adrenal gland
Prepares the body for fight or flight situations.
Give the role of the testes
Controls secondary sexual characteristics in men.
Give the role of the ovaries
Controls secondary sexual characteristics in women.
Describe why the pituitary gland is classed as the master gland.
It produces a number of different hormones, and it stimulates a number of different glands.
Name two hormones that are involved in controlling blood glucose
Insulin (lowers glucose levels) and glucagon (raises glucose levels).
Describe the effect of insulin secretion
Causes glucose to be taken up by cells and converted to glycogen by the liver.
Describe the effect of glucagon secretion
Liver converts glycogen to glucose.
What happens if you have type 1 diabetes?
Pancreas doesn’t produce enough insulin.
Describe how type 1 diabetes is caused
Genetic factors or damage to the pancreas.
Describe how type 1 diabetes is treated
Insulin injections, regular exercise, changing diet.
What happens if you have type 2 diabetes
Your cells stop responding to insulin.
Describe how type 2 diabetes is caused
Obesity, lack of exercise.
Describe how type 2 diabetes is treated
Regular exercise, changing diet.
Name the 4 hormones involved in the menstrual cycle
FSH, LH, oestrogen and progesterone.
Give the role of FSH
Causes eggs to mature.
Give the role of oestrogen
Stops FSH and starts LH production.
Give the role of LH
Causes an egg to be released.
Give the role of progesterone
Maintains uterus lining.
Give the advantages of IVF
Safe, helps same sex couples have children, increases the chances of older women having a baby, unused embryos can be donated for research.
Give the disadvantages of IVF
Expensive, not always successful, multiple pregnancies are possible, fertility drugs have side effects.
Define contraception
Methods used to stop the sperm and egg meeting or a fertilised egg implanting in the uterus.
Name methods of contraception that use hormones
Mixed pill, progesterone pill, patch, implant, injection.
Name the non-hormonal methods of contraception
Condoms, diaphragm, IUD, spermicides, sterilisation.
