Biology- Coordination and response

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  • Created by: Kitsune
  • Created on: 13-02-17 20:46
What is a nerve impulse?
An electrical signal that passes along nerve cells called neurons
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What do the brain and spinal chord make up?
Central nervous system
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What do sensory and motor nerves make up?
Peripheral nervous system
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What connect the central nervous system to the body?
Peripheral nerves
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What are nerves?
Collections of thin nerve cells, neurones
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Describe the 5 stages in a reflex arc.
Receptor- sensory neurone- relay neurone- motor neurone- effector- response
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How do messages pass in neurons?
By electrical impulses called action potentials
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In a motor neurone, what does the cell body do?
Controls metabolism
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In a motor neurone, what do the dendrites do?
Collect information from other cells
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In a motor neurone, what does the axon do?
It carries information along the cell
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What is the fatty sheath on a neuron made of?
Myelin
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What is the purpose of a fatty sheath on a neuron?
Makes impulses travel faster, insulation between cells
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What part synapses with another neuron?
The end plate
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What is a synapse?
A junction between an end plate and a dendrite
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How is the synapse gap called?
The synaptic cleft
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Describe how an impulse travels across a synapse.
Impulse arrives at the end plate. Neurotransmitters are released form the vesicles in the end plate into the synaptic cleft. These diffuse to the dendrites, bind with receptor molecules and restart the impulse
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What is a reflex action?
Simplest type of response
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Reflex actions serve to...
Automatically and rapidly coordinate stimuli with responses of effectors
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What is a receptor?
A cell or an organ that converts received stimuli into an electrical impulse
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Why do relay neurons have no myelin sheath?
Time is needed to modify the reaction
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What can an effector be?
A muscle or a gland
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What d synapses ensure?
That impulses travel in one direction only
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What is a voluntary action?
One that requires a conscious decision and can vary in speed
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What is an involuntary action?
One that happens automatically and is fast
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What are sense organs?
Groups of receptor cells responding to specific stimuli
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What does the pupil do?
It lets light in
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What does the iris do?
Control the amount of light falling on retina
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What does the cornea do?
It refracts light
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What does the lens do?
Focuses the light on the retina
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What does the retina contain?
Light sensitive cells called rods and cones
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What does the optic nerve do?
It caries impulses to the brain
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Where are rods distributed?
On the edges of the retina
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What images do rods produce?
Black and white
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When are rods sensitive?
In the dark
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What vision so rods allow?
Night vision
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Do rods produce clear images?
No
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What prevents total internal reflection in the eye?
The layer of black pigment called choroid
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Where are cones distributed on the retina?
At the center
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At what light do cones work?
Under high light intensity
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Are images produced by cones clear?
Yes
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How to see an abject best during day-time?
Look directly at it
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What types of cones are there?
Sensitive to red, blue, green light
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What is the image formed on the retina?
Inverted and diminished
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By what process does the brain fix the image formed in retina?
By integration
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What is accommodation?
The ability of the lens system to produce images of objects at different distances
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Describe the accommodation when the objects is distant
Lens is long, suspensory ligaments are light, ciliary muscles relax, light is refracted a bit
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Describe the accommodation when the objects is close
Lens is short, ciliary muscles contract, suspensory ligaments relax, light is greatly refracted
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Describe the pupil reflex in 4 steps.
Stimulus- light falls on the retina. An impulse in the sensory neurons of the optic nerve. Integration in the visual center of the brain. Impulses in motor neurons.
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What happens to the iris at low light intensity?
Radia muscles contract and the pupil becomes wider
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What happens to the iris at low high intensity?
Circular muscles contact so pupil constricts
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The pupil reflex prevents...
the bleaching of retina
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Adrenaline makes the pupils...
dilate
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Heroin makes the pupils...
constrict
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What is a hormone?
A chemical produced by a gland and carried by blood which alters the activity of target organs
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Describe the mechanism of hormone action in 4 steps
Endocrine gland is stimulated to release a hormone. Hormone is distributed in blood. It is recognized by receptors on the cells of target organs. Target organ responds to stimuli.
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What do adrenal glands produce?
Adrenaline
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What does the pancreas produce?
Insulin and glucagon
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What do the ovaries produce?
Oestrogen and progesterone
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What do the testes produce?
Testosterone
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How do hormones control themselves?
By feedback
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Why is adrenalin weird compared to the normal actions of the endocrine system?
It acts very quickly
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When is adrenaline secreted?
In fight or flight situations
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What does adrenaline do to the skin?
Make it pale by diverting blood
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What does adrenaline do to breathing?
Make it deeper and faster
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What does adrenaline do to the heart?
Make it beat faster
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What does adrenaline do to the blood?
It diverts it from the digestive system to the muscles
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What does adrenaline do to glycogen?
Glycogen in muscles is converts to glucose and released into the blood
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When can adrenaline be released? Give 3 situations.
A fight, skydiving, roller coaster rides
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What is the speed of the nervous system compared to endocrine?
Fast
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What is the nature of messages in the nervous system?
Electrical impulses traveling along nerves
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What is the nature of messages in the endocrine system?
Chemical messengers traveling in the bloodstream
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What is the duration of response by the nervous system?
Usually completed within seconds
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What is the duration of response by the endocrine system?
May take years before complete
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What is the area of response in the nervous system?
Localised
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What is the area of response in the endocrine system?
Widespread
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What does insulin do?
Convert glucose to glycogen
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What does glucagon do?
Convert glycogen to glucose
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What does oestrogen do?
Controls puberty in girls
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What does testosterone do?
Controls puberty in boys
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What is homeostasis?
The maintenance of a constant internal environment within set limits
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What do factors have that allows them to be controlled by homeostasis?
Norms/set points and ranges around them
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What is a change from the factor norm?
A deviation
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Describe the concept of negative feedback.
When a deviation from norm occurs a signal is sent to the control centre. The control centre sends a response which cancels out the deviation
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What is an endotherm?
Who can maintain constant body temperature by generating heat internally
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What is the temperature control center called?
Hypothalamus
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How does skin reduce heat loss?
Shivering, vasoconstriction, sweat glands stop working, body hairs become erect
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How does skin increase heat loss?
Vasodilation, evaporation of sweat, hairs lie flat
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Where are insulin and glucagon secreted and what do they affect?
Secreted in the pancreas and affect the liver
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What is diabetes?
When the blood glucose concentration is higher than normal
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What happens during type 1 diabetes?
The immune system destroys insulin producing cells so the pancreas fails to secret insulin
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What are the symptoms of type 1 diabetes?
Excessive thirst and hunger, excessive urination, sweet smelling breath, high overflow of glucose into urine
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What is the treatment of type 1 diabetes?
Injection of pure insulin
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What are the effects of type 1 diabetes?
Premature aging, heart disease, hardening of blood vessels
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What is tropism?
Growth response by plant in response to direction of stimuli
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What is gravitropism?
When parts of a plant grow towards or away from gravity
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What is phototropism?
When parts of a plant grow toward or away from the direction of blood
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What is auxin?
A plant hormone responsible for growth
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Where is auxin made?
Only in the shoot of a plant
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How does auxin travel?
It spreads from the shoot tip down to the rest of the plant
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What does auxin stimulate?
Cell elongation
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What does light do to auxin?
It breaks it down
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What does auxin do in the roots?
It inhibits growth where it is present in higher concentration
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What hormone is used to kill weeds?
2, 4- D
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What does 2, 4-D do?
It upsets normal growth patterns
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Why can killing with 2, 4-D be selective?
Because different plants are sensitive to it to different extents
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Card 2

Front

What do the brain and spinal chord make up?

Back

Central nervous system

Card 3

Front

What do sensory and motor nerves make up?

Back

Preview of the front of card 3

Card 4

Front

What connect the central nervous system to the body?

Back

Preview of the front of card 4

Card 5

Front

What are nerves?

Back

Preview of the front of card 5
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