B10 Human nervous system Flashcards Preview

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Flashcards in B10 Human nervous system Deck (30):

what is homeostasis

regulation of internal conditions to maintain optimum cell function in response to internal and external changes


what are 3 internal conditions that need to be kept balanced

body temperature

body water content

blood glucose concentration


what is an automatic control system

the system that detects changes and responds to them for example nervous responses in nervous system and chemical responses in hormone system


what are receptors

cells that detect changes (stimuli) in the internal or external environment


what is a coordination centre

areas that receive and process information from receptors. They send out signals and coordinate the response of the body eg brain, spinal cord and pancreas


what are effectors

muscles or glands that bring about responses to the stimulus that has been received


what happens when a sensory receptor detects a stimulus

the information is sent as an electrical impulse that passes along special cells called neurones (found in bundles known as nerves)
The impulse travels along the sensory neurone until it reaches the CNS (brain)
The brain sends impulses out along motor neurones which carry the information to the effectors which respond


what are reflexes

responses that are so fast that they happen subconsciously eg blinking


what are relay neurones

found in the CNS and they connect a sensory neurone and a motor neurone


what is the reflex arc pathway

receptor - sensory neurone- CNS - relay neurone- motor neurone- effector organ


what are synapses and how do they work

gaps between neurones. The electrical impulses have to travel across the synapses by chemical diffusion which is slower than the speed they travel in the neurone but is the only way


how is the reflex pathway different from a normal conscious action

in a reflex action the coordinator is a relay neurone either in the spinal cord or the unconscious area of the brain


what is the function of the cerebral cortex

consciousness, intelligence, memory and language


what is the function of the cerebellum

coordinating muscular activity and balance


what is the function of the medulla

unconscious activities eg controlling heartbeat, breathing and movement of the gut


what is the function of the hypothalamus

controlling body temperature


what is the sclera

white outer layer of the eye. tough and strong making the eyeball not easy to damage


what is the cornea

the transparent area at the front of the sclera. lets light into the eye and the curved surface is important for changing the direction of light as it enters the eye so that when they enter they are focused on the retina


what is the role of the muscular iris

controls the size of the pupil by contracting or relaxing to control the amount of light that enters the eye


what holds the lens in place in the eye

suspensory ligaments and ciliary muscles


what does the optic nerve do

carries impulses form the retina to the brain


how does the eye focus on a distant object

ciliary muscles relax so that the suspensory ligaments are pulled tight and the lens is pulled flat and thin. Only refracts light rays slightly so they are focused on the retina


how does the eye focus on a near object

ciliary muscles contract so the suspensory ligaments loosen. The lens is then thicker and more curved and refracts light rays strongly so they are focused on the retina


what causes you to see blurred images

when the light rays aren't focused on the retina


why do many old people need reading glasses

as you age, the lens hardens, accomodation gets more difficult making it harder to focus on close objects


what is myopia

when you can't see things far away because the light is focused in front of the retina maybe as a result of a lens that is too curved or a long eyeball
treated by wearing glasses with a concave lens


what is hyperopia

when close objects are blurred maybe as a result of a lens that is too flat and thin or a short eyeball. The light is focused behind the retina. Treated by wearing glasses with a convex lens


why is it difficult to study the brain

encased in the skull
delicate, easy to damage


why is it difficult to treat brain disorders

easy to cause damage during surgery
many drugs can’t pass through the surrounding membranes


how does light from an object form an image on the retina

light rays enter the eye through the cornea where they are refracted a little. they then travel through the pupil and lens. they are then refracted further to meet the retina and form an image upside down