B10: Human Nervous System Flashcards
what is homeostasis
the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function, in response to the internal and external changes.
Internal conditions that are controlled
-body temperature
-water content
-blood glucose concentration
features of a control system
-receptor
-coordination centre
-effectors
what are receptors
cells that detect changes (stimuli) in the internal or external environment.
the main two automatic control systems in the human body
-nervous
-hormonal
what are coordination centres?
areas that receive and process the information from the receptors. They send out the signal and coordinate a response from the body.
what are some coordination centres in the body?
brain, spinal cord, pancreas
what are effectors?
muscles or glands that bring about responses to the stimulus that has been received, restoring the body’s conditions to optimum levels.
clear definition of stimulus
a thing or event that evokes a specific functional reaction in an organ or tissue.
what does the nervous system carry?
electrical impulses
where are the receptor cells found
sense organs, such as eyes and skin
what are the cells that carry electrical impulses called?
neurons
what do thousands of neurons make?
nerve
receptor ——> __________
Central nervous system (CNS)
what is the CNS?
the central nervous system is made up of the brain and the spinal chord. It sends impulses around the rest of the body to the effectors.
what are the neurons that travel from receptors to the CNS called?
sensory neurons
what do we call the neurons that carry electrical impulses from the CNS to effectors?
motor neurons
muscles respond to the arrival of impulses by what
contracting
glands respond to the arrival of electrical impulses by what
secreting chemical substances
arrow diagram of nervous system
stimulus->receptor->CNS->effector
what is an automatic response also known as?
reflex
Three types of neuron
-sensory
-motor
-relay
what are the relay neurons
connect a sensory neuron and a motor neuron, found in CNS.
what is the reflex arc
the pathway that a reflex takes in the body
what is the main goal when talking about reflexes
the time between the stimulus and the reflex action is as short as possible.
what is a synapse?
junctions between neurons
what happens when the impulse reaches the synapse from a relay neuron, what happens?
it releases a chemical that diffuses across the synapse.
reflex pathway:
stimulus-receptor-sensory neurone-relay neurone-motor neurone-effector-response
what is the brain an example of
CNS (Central nervous system)
what are the protective membranes that protect the brain called
meninges
the _____ is concerned with consciousness, intelligence, memory and language.
cerebral cortex
the _____ is concerned mainly with coordinating muscular activity and balance
cerebellum
the ______ is concerned with unconscious activities, such as controlling the heartbeat, the movements of the gut, and breathing.
medulla
what does the hypothalamus do?
controls body temperature
what does the pituitary gland do?
produces many different hormones
how do we find out more about the brain?
-studying people with brain damage
-electrically stimulating different parts of the brain
-MRI scans
where are all the light-sensitive cells in the eye?
at the back of the eye in the retina
properties of the sclera:
-white outer layer of the eye
-tough and strong
properties of cornea:
-front of eyeball
-transparent
-lets light into eye
-changes direction of light rays for optimum focus.
what does the muscular iris do?
controls the size of the pupil, allowing less or more light into the eye.
what would happen to your pupil in a dim room?why?
get bigger, allow more light in to see better.
once through the pupil, light passes through a clear disc called
the lens.
what is the lens held in place by?
-suspensory ligaments
-ciliary muscles
what does the lens do
makes the focus clear and changes the direction of the light to create a clear image for the retina.
what is the eyeball filled with
thick transparent jelly, thats why its round.
what sends impulses from the retina to the brain?
optic nerve
where is the blind spot
where the optic nerve leaves the eye.
what process does the eye use to focus the light
refraction (changing direction of the light)
what do the ciliary muscles do when they need to focus on a far away object
they relax so that the suspensory ligaments and pulled tight and the lens in flat and thin (less convex)
weaker refraction
what do the ciliary muscles do when they need to focus on a near object
they contract so the suspensory ligaments loosen. The lens is more convex.
strong refraction
what is myopia
short sightedness
what is hyperopia
long sightedness
what causes myopia
lens is too curved or a long eyeball
how do we treat myopia
wear glasses with a concave lens that spreads light out before reaching the eye.
what causes hyperopia
lens is too flat and thin, or a short eyeball.
how to treat hyperopia
convex lens that brings light rays together.
other ways to help eye problems:
-contact lenses
-laser eye surgery
-replacing the actual lens.
