B10

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What is homeostasis?
Regulation of internal conditions of a cell to maintain functions
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What are some examples controlled by homeostasis?
Temp, water, glucose
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What can the automatic control systems involve?
Chemical or nervous responses
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What are receptors?
Cells that detect changes (Stimuli)
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What is the coordination centre?
Areas that receive and process information from receptors, they send out responses
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What are effectors?
Muscles or glands that bring about responses to stimulus that has been received
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What happens when sensory receptor detects stimulus?
Electrical impulse passed along neurones which in bundles are known as nerves
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What does impulse travel until?
The end of neurone where it reaches central nervous system
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What is the CNS made up of?
Brain and spinal cord
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What are sensory neurones?
Cells that carry impulses from cell organs to CNS
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What are motor neurones?
Carry info from CNS to body
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Simple way to know the nervous system?
Stimulus, Receptor,neurone, CNS, effector
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What are automatic responses known as?
Reflexes
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What is the difference between sensory neurone and motor neurone?
Sensory is from sense organs to CNS and motor is from CNS to muscles
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What are relay neurones?
They connect a sensory neurone and a motor neurone- found in CNS
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What is the pathway of reflexes called?
Reflex arc
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What is one key feature of a reflex arc?
Skips conscious area of brain so time is shortest
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What are synapses?
The gaps between the neurones
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What happens at a synapse?
Impulse arrives, sets sacs w chemicals in off which are released in synapse so chemical attach and diffuse to other side quicker
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Simple way to remember reflex pathway?
Stimulus, receptor, sensory neurone, relay neurone, motor neurone, effector, response
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What is labelled in the diagram?
Cerebral cortex
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What does the cerebral cortex do?
Concerned with consciousness, intelligence, memory and language
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What is labelled in the diagram?
Cerebellum
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What does the cerebellum do?
Concerned with coordinating muscular activity and balance
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What is labelled in the diagram?
Medulla
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What does the medulla do?
Unconscious activities, heartbeat, gut movement and breathing
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How can scientists test the brain?
Stimulate different areas and see what effect it has
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What is a more modern way to test the brain?
MRI
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Why is it difficult to test on the brain?
Delicate, range of chemicals, drugs may not reach brain
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What is labelled on the diagram?
Sclera
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What is the sclera?
White outer layer of eye
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What does it do?
Protects eye
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What is labelled in the diagram?
Retina
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What is the retina?
All the light sensitive cells arrange together in the back of the eye
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What happens when light hits the retina?
Light cells stimulated and send impulses along sensory neurones n the optic nerve
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What is labelled in the diagram?
Iris
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What does the muscular iris do?
Controls the size of the pupil
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What else does the iris show?
The coloured part of the eye
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What is labelled in the diagram?
Cornea
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What is the cornea?
Transparent area at front of sclera which allows light into eye
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What does the curved surface of the cornea do?
Changes direction of light rays coming to ensure they hit retina
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What happens in dim light?
The iris enlarges pupil to allow as much light poss,
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What happens in bright light?
The iris makes pupil small so light is reduced so doesn't damage retina
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What is labelled in the diagram?
Lens
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What does the lens do?
Changes the direction of the light rays so they produce a clear image on the retina
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What is the lens held in place by?
Suspensory ligaments and ciliary muscles
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What is labelled in the diagram?
Pupil
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What does the pupil do?
Is the hole in the eye that light goes through
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What is labelled in the diagram?
Ciliary muscle
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What does the ciliary muscle do?
Change the thickness of the lens
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What is labelled in the diagram?
Suspensory Ligaments
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What do suspensory ligaments do?
Control how much light is refracted
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What is labelled in the diagram?
Blind spot
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What is the blind spot?
The point where the optic nerve leaves the eye it has no retina
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What is labelled in the diagram?
Optic nerve
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What is the optic nerve?
Contains the sensory neurones that send impulses to brain to form an image
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What is the eyeball filled with?
Thick transparent jelly that mainatins eye shape
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What happens if light is focused in front of or behind retina?
Image is blurred
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What happens when ciliary muscle contracts?
Suspensory ligaments loosen
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What does this do to a lens?
Thicker and refracts stronger
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What happens when ciliary muscles relax?
Susupensory ligaments tightens
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What does this do to a lens?
Thin and only slightly refracts
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Here is a better diagram of the ciliary and suspensory, (sHAUN)
....
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What is accommodation?
The process of changing the shape of lens to focus on near or far objects
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How does the eye focus on a distant object?
The ciliary muscles relax, suspensory ligaments tighten, lens is flat and thin, light rays refracted slightly
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How does the eye focus on near objects?
The ciliary muscles contract, suspensory ligaments loosen, lens is curved and thicker, light rays refracted strongly
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What happens as people get older?
Lens hardens
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What is myopia?
Short sightedness (Cant see distant)
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Where is the light focused in myopia?
In front of retina
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What are some causes of myopia?
Lens too curved or long eyeball
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How to treat myopia?
Concave lens
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What does the concave lens do?
Spread light from distant objects before reaching eye
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What is hyperopia?
Long sightedness (Cant see close)
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Where is the light foused in hyperopia?
Behind retina
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What are some causes of hyperopia?
Lens too flat or thin, short eyeball
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How to treat hyperopia?
Convex lens
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What does the convex lens do?
Bring rays together before reach eye
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What eye defect does this lens treat?
Myopia
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What eye defect does this lens treat?
Hyperopia
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Three ways to treat eye sight?
Contact lenses, laser eye surgery, replacement lenses
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What are benefits of hard contact lenses?
Worn for longer, removed overnight, kept sterile
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What are benefits of soft contact lenses?
Short periods of time, comfortable, sterile overnight and worn every day for a month
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What audience is laser eye surgery offered to and why?
Adults, eyes have stopped growing and vision is stable
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How is laser eye surgery used to treat myopia?
Reduce cornea thickness so refracts light less strong so lens focuses on distant light on retina
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How is laser eye surgery used to treat hyperopia?
Lasers used to change curve of cornea so it refracts light from close objects more effective
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What are the two main techniques of replacement lenses?
Pernament contact lens implanted in eye and natural lens left or faulty lens replaced by artificial lens
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What is a risk of lens replacement?
Ridk to damage to retina, cataracts if original lens left and infections
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Other cards in this set

Card 2

Front

What are some examples controlled by homeostasis?

Back

Temp, water, glucose

Card 3

Front

What can the automatic control systems involve?

Back

Preview of the front of card 3

Card 4

Front

What are receptors?

Back

Preview of the front of card 4

Card 5

Front

What is the coordination centre?

Back

Preview of the front of card 5
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aabena

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is this topic 5 in the revision guide? :) x

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