coordination & response Flashcards

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1
Q

What is the role of nervous system?
What does it contain?
What does it split into?

A

1) coordination & regulation of body function
2) Contains neurones/nerve cells which go to all parts of body.
3) splits into CNS PNS.

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2
Q

define cns

A

brain & spinal cord

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3
Q

define pns

A

nerves outside of brain & spinal cord.

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4
Q

Describe the process/steps in a reflex arc

A
  1. Neurones in reflex arcs go to through the spinal cord or through an unconscious part of the brain.
  2. Stimulus -> detected by receptors -> impulses sent along a sensory neurone to the CNS.
  3. When impulses reach synpase between sensory neurone & relay neurone the impulses are sent along the relay neurone.
  4. When the impulses reach a synapse between relay neurone & motor neurone, the impulses are sent along the motor neurone.
  5. Impulses travel along the motor neurone to the effector e.g muscle, causing it to contract or move.
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5
Q

Define reflex action

A

automatically & rapidly integrating
and coordinating stimuli
with the responses of effectors (muscles and glands)

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6
Q

define synapse
what its purpose?

A
  1. junction between 2 neurones
  2. ensure impulses travel in one direction only.
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7
Q

Describe the events at a synapse

A
  • An impulse stimulates release of neurotransmitter molecules from vesicles into the synaptic gap
  • The neurotransmitter molecules diffuse across the synaptic gap
  • Neutrotransmitter molecules bind w/ receptor proteins on the next neurone
  • Impulse in then stimulated in the next neurone.
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8
Q

define sense organs

A

groups of receptor cells
responding to specific stimuli:
light, sound, touch,
temperature and chemicals

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9
Q

Function of cornea, iris, lens, retina, optic nerve

A

Cornea - refracts light
Iris - contains radial & circular muscles which control diameter of pupil therefore how much light enters pupil
Lens - focuses light onto the retina
Retina - contains light receptors, some sensitive to lights of diff colors
Optic nerve - carries impulses from the receptors on the retina, to the brain.

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10
Q

Iris reflex (pupil reflex)
Low light intensity

A
  • Radial muscles in the iris contract, become shorter, & pull the pupils, making it wider.
  • Circular muscles relax.
  • Wider pupil = more light can enter eye, clear image is formed at retina.
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11
Q

Iris reflex (pupil reflex)
High light intensity

A
  • Circular muscles in the iris contract, causing the pupil to get smaller.
  • Radial muscles relax.
  • Smaller pupil = less light can enter eye, protecting retina from damage.
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12
Q

Looking at nearby objects:

A
  • Ciliary muscles contract, suspensory ligaments slackened.
  • Lens become more fat
  • This increases the amount by which it refracts light.
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13
Q

Looking at distant objects:

A
  • Ciliary muscles relax, suspensory ligaments pulled tight.
  • Lens pulled thin.
  • This refracts light by a smaller amount.
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14
Q

2 types of receptors in retina, function of them, distribution

A

Rods
* Sensitive to dim lights
* Allows us to see in dim light, only in black & white.
* Distributed around the edge of retina except blind spot & fovea.

Cones
* Sensitive to light of diff colors/bright light (red, green, blue)
* Gives color vision.
* Most located in fovea; tightly packed together

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