The Nervous System Flashcards

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1
Q

The Central Nervous system

A

consisting of the brain and spinal cord

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2
Q

The peripheral nervous system

A

consisting of nerves that conduct nerve impulses from the brain to the spinal cord

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3
Q

How do humans respond to stimuli?

A
  • Receptors detect stimuli
  • nerve impulses are conducted along a network of nerve cells to the B and SPC
  • B and SPC process and integrate the information
  • is then conducted along a network of nerve cells from the B and SPC to the effectors(muscles, glands etc.)
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4
Q

Neurons

A

nervous tissue consisting of millions of nerve cells

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5
Q

FUNCTION OF NEURONS?

A

conduct nerve impulses from one part of body to another

structural units of the nervous system

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6
Q

Cell body (STRUCTURE OF NEURON)

A

Consists of:

  • cytoplasm
  • Nissl granules (rich in RNA involved in protein synthesis)
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7
Q

DENDRITES

A

Conduct nerve impulses TO the cell body

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8
Q

AXONS

A-away from cell body

A

conduct nerve impulses AWAY FROM the cell body

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9
Q

Synaptic knobs

A

Occur at the ends/tips of the axons called terminal branches

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10
Q

MYELIN SHEATH

A

This encloses the nerve fibers (axons and dendrites) and is formed by specialized cells called SCHWANN CELLS.

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11
Q

FUNCTION OF MYELIN SHEATH

A

insulates the nerve fibres and accelerates the transmission of nerve impulses

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12
Q

Neurilemma

A

the outermost layer of the myelin sheath and is essential for repair or regeneration of damaged neurons

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13
Q

Sensory/AFFERENT(same thing) neurons

A-afferent (A-away from receptors)

A

conducts impulses from the receptors TO the CNS

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14
Q

Motor/EFFERENT neurons

moTOr-to TOWARDS-to receptors

A

conduct nerve impulses FROM the CNS TO the receptors

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15
Q

Neurotransmitter

A

a chemical that is released in the synapse to conduct impulses from one neuron to the next (the axon to synaptic knobs)

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16
Q

How nerve impulses travel between neurons?

A

Each synaptic knob is filled with a neurotransmitter that is released into the synapse. The nerve impulses is conducted via the dendrite towards the cell body of the next neuron.

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17
Q

Significance of the synapse

A
  • neurotransmitter is only released from one side of the synapse to ensure the signal can only move in one direction
  • Insignificant stimuli are filtered out to prevent overloading of the brain
  • The synapse determines which stimuli will be transferred to the next neuron, if it is too weak the impulse is not transmitted to prevent overloading the CNS
18
Q

Autonomic Nervous System

A

conducts impulses from the CNS to the INVOLUNTARY MUSCLES and come GLANDS

19
Q

Somatic Nervous System

A

conducts impulses to the CNS to the INVOLUNTARY MUSCLES

20
Q

Sympathetic Division

A

prepares body for fast reactions like ‘fight or flight’ situations

21
Q

Parasympathetic Division

A

returns body to normal status (by the release of hormones so the body may remain in homeostasis)

22
Q

PIA MATER

Cerebral membranes

A

innermost membrane that is tightly wrapped around the brain and spinal cord
It is rich in blood vessels, providing oxygen and nutrients to the CNS

23
Q

DURA MATER

cerebral membrane

A

tough outermost membrane that lines the skull cavity and spinal cord

24
Q

ARACHNOID

cerebral membrane

A

membrane between pia and dura

between pia and arachnoid is a space filled with cerebrospinal fluid

25
Q

FUNCTIONS OF CEREBROSPINAL FLUID

A
  • acts as shock absorber
  • removes waste
  • prevents dehydration of neurons
  • maintains constant pressure around the CNS
26
Q

GREY MATTER

A
27
Q

WHITE MATTER

A
28
Q

Cerebrum (largest part pf brain)

A
  • responsible for all VOLUNTARY ACTIONS
  • interprets nerve impulses from sense organs
  • intelligence, imagination, emotions, planning and 5 senses
29
Q

Corpus Callosum (C-shaped between 2 halves of cerebrum)

A
  • conducts impulses between the two hemispheres of cerebrum

- forms bridge of communication between hemispheres to coordinate processes

30
Q

Cerebellum (situated below cerebrum)

A

-coordinates and controls all voluntary actions to make smooth precise movements possible
controls the muscle tone to maintain balance and posture

31
Q

Medulla Oblongata (extension of spinal cord)

A
  • transmits nerve impulses between brain and spinal cord

- controls involuntary functions (breathing, heartbeat, peristalsis, vomiting etc.)

32
Q

Spinal Cord

A

-enclosed and protected by 3 cerebral membranes
grey matter that make up H-shape on the inside
-Two grooves( dorsal root and ventral root), these enter and exit the spinal cord
-nerves enter and exit spinal cord between successive vertebrae
-nerves branch from PNS that connects to CNS to the rest of the body

33
Q

Dorsal Root

A

consists of sensory neurons conducting impulses from receptors to spinal cord
(occurs on thinner upper part of grey matter)

34
Q

Ventral root

A

consists of motor neurons conducting nerve impulses away from the spinal cord to effectors
(occurs on thicker lower part of grey matter)

35
Q

Ganglion

A

cell bodies of sensory and motor neurons occur in a swelling of the dorsal root and ventral root

36
Q

FUNCTIONS OF SPINAL CORD

A
  • provides a pathway for nerve impulses to and from the brain
  • ASCENDING TRACTS (spinal cord to brain)
  • DESCENDING TRACTS (brain via motor neurons to spinal cord)

-contains reflex centres that initiate actions

37
Q

REFLEX ACTION

A

a rapid, involuntary (automatic) response of an effector to a stimulus received by a receptor

38
Q

REFLEX ARC

A

A pathway along which nerve impulses are transmitted from a receptor to an effector to bring about a response to a stimulus during a reflex action

39
Q

The parts of a reflex arc include:

A
  • receptor(detects a stimulus and converts it into a nerve impulse)
  • sensory neuron
  • interneuron
  • Motor neuron
  • Effector
40
Q

Interneuron

A

serves as the reflex centre(where the nerve impulse is conducted across the synapse to the interneuron) in the grey matter of the spinal cord and conducts the nerve impulses from the sensory neuron to the motor neuron

41
Q

Functioning of a reflex arc

A
  1. The stimulus is detected by receptors and converted into a nerve impulse.
  2. The nerve impulse is transmitted along the sensory neuron through the dorsal root to the spinal cord.
  3. The impulse is transmitted from the sensory neuron to an interneuron in the spinal cord.
  4. The impulse is transmitted from the interneuron to a motor neuron in the spinal cord.
  5. The impulse exits the spinal cord through the ventral root and is transmitted along the axon of the motor neuron to the effector organs (muscle; this causes the muscles in the limb to contract).
  6. The hand pulls away from the stimulus quickly.
42
Q

Significance of the reflex arc

A
  • reflex action is rapid as to protect the hand from further injury
  • prevents overload of the higher centres of the brain as it is not a conscious response