Nervous System 1 (Basic mechanisms)

Question 1

Stimulus

Answer 1

Any internal or external environmental change

to which an organism responds

Question 2

Examples of stimuli

Answer 2

Light, sound, taste

touch —> pressure, temperature, chemicals

Question 3

PNS

Answer 3

Conducts nerve impulses to and from CNS
12 pairs of cranial nerves
31 pairs of spinal nerves

Question 4

Receptors

Answer 4

Detect stimulus

Convert into nerve impulse

Question 5

Function of CNS in geeneral process of reaction

Answer 5

Process and integrate information

Question 6

Effectors and 2 examples

Answer 6

Organs that respond to stimuli physically when given information “command” from CNS
e.g.) muscles and glands

Question 7

Neurons

Answer 7

• Nerve cells
• Conduct nerve impulses from one part of body to another
• Structural units of the nervous system

Question 8

Neuroglia and function

Answer 8

Nerve cell glue
Connective tissue

Function: Nourishment and support

Question 9

Cell body consists of

Answer 9

Porminent nucleas
Dark granule
Cytoplasm

Question 10

Nissl granules

Answer 10

Rich in RNA

Involved in protein synthesis

Question 11

Nerve fibres

Answer 11

Outgrowths of neurons

-Axons and dendrites

Question 12

Terminal branches

Answer 12

Formed by axon
Bunched branches
Synaptic knobs at tips

Question 13

Schwann cells

Answer 13

Specialized cells
Spirally coil or wrap themselves around axon
Form myelin sheath (‘exude’ fatty protein myelin from cell membrane)

Question 14

Myelin sheath and functions

Answer 14

White fatty tissue

Functions:

• insulates
• accelerates the transmission of nerve impulses

Question 15

Nodes of Ranvier and function

Answer 15

Gaps between adjacent Schwann cells

Function: accelerate transmission of nerve impulses from one node to another

Question 16

Neurilemma and function

Answer 16

Outermost membrane of myelin sheath

Function: Essential for repair/regeneration of damaged neurons

Question 17

Unmyelinated fibres

Answer 17

Not surrounded by a myelin sheath

Cannot be repaired or regenerated (applies to myelinated axons of CNS)

Question 18

3 types of structural classification of neurons and short definition

Answer 18

1. Unipolar
   One outgrowth that branches into two

2.Bipolar
2 outgrowths: Dendrite and axon
Rare in adult humans (ear, eye retina, nose)

3.Multipolar
Many outgorwths - dandrites
1 axon

Question 19

3 types of functional classification of neurons and short definition

Answer 19

1. Sensory neuron
Afferent neurons (conduct impulses TOWARDS CNS)

2.Motor neuron
Efferent neuron(conduct impulses FROM CNS)

3.Interneuron
connector neuron
INSIDE CNS

Question 20

Synaptic cleft

Answer 20

Small gap
That separates successive neurons
Ensures that neurons are never in direct contact with one another.

Question 21

Synapse

Answer 21

Physiological / functional connection

Formed in synaptic cleft

Question 22

Why are impulses termed electrochemical impulses

Answer 22

Electrical: Electric signal transmitted along neurons
Chemical: carried across synapse via a chemical

Question 23

What do synaptic vesicles do at the synapse

Answer 23

Carry neurotransmitters
Nerve impulses cause them to burst at surface
Release neurotransmitter into synaptic cleft

Question 24

Pre-synaptic membrane

vice versa for post

Answer 24

Borders synaptic knob on axon side of synaptic cleft

opp: on dendrite side

Question 25

Name 2 neurotransmitters

Answer 25

Serotonin | Acetylcholine

Question 26

Purpose of mitochondria in synaptic knob

Answer 26

Supply energy for transmission

Question 27

Significance of synapses | Give 3

Answer 27

1. (1D) Ensure all stimuli move in one direction Neurotransmitter can only be released/accepted by only one side 2. (Target organs) Can affect more than one organ with a single stimuli 3. (Overload) Synapse filters out insignificant (feet) and weak stimuli,

Question 28

Where nerves located... exception?

Answer 28

Most nerves protected deep in body tissue Exception: funny bone Exposed ulnar nerve ---> peculiar tingling sensation tingeling

Question 29

Endoneruium

Answer 29

Thin layer connective tissue | Separates and surrounds individual nerve fibres

Question 30

perineurium

Answer 30

Bundles of nerve fibres that are bound together with no connective motion

Question 31

Epineruem

Answer 31

Dense sheathe of connective tissue | Surround number of nerve bundles to form a single nerve

Question 32

purpose of blood vessels

Answer 32

Provide fibre, oxygen, nutrients | Remove waste done by blood system

Question 33

Discuss difference in terms of myelin sheath of motor and sensory neurons

Answer 33

Sensory : Myelin sheath on both dendrite and axon | Motor : Myelin sheath only on axon

Question 34

DIscuss polarity of the 3 different types of neurons

Answer 34

Sensory : Unipolar (mostly) | Motor and inter: multlipolar