what is the difference between the central nervous system and the peripheral nervous system?
the central nervous system is the brain and the spinal cord
the peripheral nervous system is every other part of the nervous system
stimulus
change in the environment
central nervous system
A) relay neurone
B) motor neurone
C) sensory neurone
D) stimulus
E) stimulus
F) receptor
G) impulses
H) sensory
I) relay
J) motor
K) impulses
L) effector
M) response
effector
a part of a body that brings about the response to a stimulus like a muscle or a gland
what is the cornea and what is its function?
the transparent outer layer of the eye
its function is to refract light and protect the eye
what is the iris and what is its function?
the coloured ring around the pupil
its function is that it can regulate the amount of light that can enter the retina by controlling the diameter or the pupil
what is the pupil and what is its function?
the pupil is the whole in the middle of the iris
its function is to let light into the eye
what is the optic nerve and what is its function?
the nerve coming out the back of the eye
its function is to send signals to the brain
function of the lens
focuses the light rays onto the retina
what is the retina and what is its function?
the retina is the back part of the eye
its function is that it converts visual stimuli into electrical impulses
what do the ciliary body and suspensory ligaments do?
control the shape of the lens (accomodation)
what defect in the eye causes short sightedness?
the lens focuses light rays in front of the retina so far away objects appear blurry
how is short sightedness corrected?
by wearing glasses that have concave lenses
what defect in the eye causes long sightedness?
the lens focuses light behind the retina so nearby objects appear blurry
how is long sightedness corrected?
by wearing glasses that have convex lenses
what is colour blindness?
an inherited condition where people find it difficult to tell the difference between colours
caused by a defect in the retina and there is currently no cure
structure of the eye
A) suspensory ligament
B) cornea
C) iris
D) pupil
E) lens
F) ciliary muscle
G) sclera
H) retina
I) fovea
J) optic nerve
where is the cerebrum located and what is its function?
located at the front of the brain
controls conscious functions, memory and language
where is the cerebellum located and what is its function?
located at the back bottom of the brain
controls muscular movement and balance
where is the medulla located and what is its function?
located in the brainstem in the middle at the bottom
controls unconscious functions like heart rate and breathing
what is the function of the hypothalamus?
acts as the regulatory centre
controls things like body temperature, water content and salt balance
what is the function of the pituitary gland?
releases hormones into the blood
two reasons why it is difficult to investigate brain function
surgery is not risk free
people with brain disorders may be unable to consent
why is it difficult to treat brain disorders?
the brain and spinal cord are very difficult to access
tissues in the CNS cannot regenerate
drugs cannot penetrate the blood-brain barrier
structure of the brain
A) hypothalamas
B) cerebrum
C) cerebellum
D) spinal cord
E) medulla oblongata
F) pituitary gland
hormones
hormones are chemical messengers that are secreted by glands of the endocrine system into the bloodstream
target cells
cells with the specific receptor for a hormone that produce an effect when the hormone binds
what does the hormone thyroxine control in the body?
metabolic rate
describe thyroxine as a negative feedback system
when the level of thyroxine decreases the pituitary gland produces thyroid stimulating hormone (TSH) which causes the thyroid gland to produce more thyroxine
when the level of thyroxine increases, the pituitary gland produces less TSH
when is adrenaline secreted?
during times of fear, anxiety or stress
three effects of adrenaline in the body
increases heart and breathing rate
increases blood glucose concentration
dilates the pupils
what does oestrogen do?
causes the uterus lining to thicken
what hormone does oestrogen inhibit?
follicle stimulating hormone (FSH)
what does progesterone do?
maintains the womb lining
what hormone does progesterone inhibit?
follicle stimulating hormone (FSH)
what does follicle stimulating hormone (FSH) do?
stimulates the follicle to mature and release oestrogen
what does luteinising hormone (LH) do?
a surge in LH causes the release of an egg from a follicle (ovulation)
how do oestrogen pills work to prevent pregnancy?
oestrogen pills inhibit FSH which stops the egg from maturing
how do progesterone pills work to prevent pregnancy?
progesterone pills cause a sticky mucus to form at the cervix which prevents the sperm from fertilising the egg
one advantage and one disadvantage of hormonal contraception (e.g. the pill)
advantage - more than 99% effective
disadvantage - it can cause side effects like weight gain