Human Biology Flashcards
(27 cards)
What are receptors?
A group of cells which are sensitive to a stimulus. They change stimulus energy (eg light energy) into electrical impulses.
What is a stimulus?
A change in the environment that you may need to react to.
Give 3 examples of stimuli
(Any 3 from) Light, sound, touch, pressure, change in position or change in temperature.
What does CNS stand for?
Central Nervous System
What does the CNS consist of?
The brain and spinal cord only.
What kind of receptors are in the eyes?
Light receptors.
What is the function of sensory neurones?
They are the nerve cells which carry signals as electrical impulses from the receptors in the sense organs to the CNS.
What is the function of Motor Neurones?
They are the nerve cells that carry signals to the effector muscles or glands.
What is an effector?
Muscles and glands which respond to receptors. Muscles contract in response to a nervous impulse and glands secrete hormones.
What is a reflex reaction?
A reflex is an automatic response to a stimulus. They help to prevent injury.
What is the path of a reflex reaction?
1- Receptors detect stimuli
2- Message travels along sensory neurones
3- Message passed along a relay neurone in the spinal cord (bypasses brain).
4- Message travels along motor neurone
5- Message reaches effector and it reacts (either by contracting or secreting a hormone)
What is a synapse?
The connection between two neurones. The nerve signal is transferred my chemicals which diffuse across the gap. These chemicals then set off a new electrical signal in the next neurone.
What are hormones?
They are chemical messengers which travel in blood to activate target cells. (They are carried in blood plasma to target cells. Hormones are secreted by different glands.)
Name a hormone produced by the pancreas.
Insulin
What are the 4 stages of the menstrual cycle?
1- lining of the womb breaks down (day 1-)
2- lining of the womb builds up (day 4 to 14)
3- egg released (day 14)
4- lining of the womb maintained (until day 28)
What are the three main hormones involved in the menstrual cycle?
FSH, Oestrogen and LH
Where is FSH produced and what does it do?
Produced in the pituitary gland, causes an egg to mature in one of the ovaries and stimulates the production of oestrogen.
Where is Oestrogen produced and what does it do?
It is produced in the ovaries, caused pituitary to produce LH and inhibits further release of FSH
Where is LH produced and what does it do?
Produced by the pituitary gland and stimulates the release an egg at around the middle of the menstrual cycle.
Which hormones are used in “the pill” (birth control)?
Oestrogen, as it prohibits the production of FSH and so eggs are unable to mature.
Which hormone can be used to increase fertility?
FSH as it stimulates egg production in the ovaries (eggs mature).
What are the stages of In Vitro Fertilisation (IVF)?
1- Hormones given to stimulate egg production
2- Oestrogen and Progesterone given to make embryo implantation more likely to succeed
3- Embryos implanted in womb
What is homeostasis?
It is our body keeping a constant internal environment
Name 4 body levels that need to be controlled
Ion content, water content, sugar content and temperature
