Biology Paper 2

What is a reflex?

rapid automatic responses to certain stimuli that dont involve the conscious part of the brain

What is an example of a reflex?

If a bright light shines in your eyes, your pupils automatically get smaller so less light enters your eyes preventing damage

What is included in the central nervous system (CNS)?

the brain and the spinal chord

What does the nervous system do?

detects and reacts to stimuli (change jn the environment)

What do sensory neurones do?

carry information as electrical impulses from a receptor to a CNS

What does a relay neurone do?

carry impulses from sensory neurones to motor neurons

What does a motor neurone do?

carry instructions from the CNS to the effector

What is an effector?

muscles and glands which respond to the nervous impulses

What are receptors?

cells that detect stimuli

What are effectors?

they respond to nervous impulses and bring about a change

What do the muscles do as effectors?

they contract in response to a nervous impulse

What do glands do as effectors?

Glands secrete hormones in a response to a nervous impulse

What is the order that the nervous system reacts to stimuli?

What is a synapse?

the connection between 2 neurones

How does a synapse work?

the nerve signal is transferred by chemicals which diffuse across the gap, these chemicals then set off a new signal in the next neurone

What is a hormone?

a chemical messenger sent in the blood

What does a hormone do?

control things in the organs and cells that need constant adjustment

Where are hormones produced?

endocrine glands

Where is the pituitary gland located and what does it do?

In the brain and it regulates body conditions

Where is the thyroid gland located and what does it do?

in the throat and it adjusts body temperature, metabolism and heart rate

What does the gland in the pancreas do?

produces insulin which regulates the blood glucose level

What does the gland in the ovaries do?

produces oestrogen, needed for the menstrual cycle

What does the gland in the testes do?

produces testosterone, which controls puberty and sperm production in males

What is the difference between nerves and hormones

Nerves- very fast action, act for a very short time, act on a very precise area

Hormones- slower action, acts for a very long time, act in a more general way

What is stage 1 of menstruation?

menstruation stars- the uterus lining breaks down for about 4 days

What is stage 2 of the menstrual cycle