nervous system

Question 1

Describe the organization of the nervous system (or draw the organization chart of the nervous system)

Question 2

Describe the three main functions of the nervous system.

Answer 2

1. To receive information/stimuli from the external
   and internal environment by sensory nerves
2. To analyse and integrate these stimuli from the
   sensory pathway by Central Nervous System
   (CNS
   - Brain and spinal cord)
3. Initiate response of effector (such as muscle
   contraction) by sending signal via motor
   nerves

Question 3

what is cns made up of and what does it do

Answer 3

Made up of brain and
spinal cord
what it does: Acts as body’s
control center
* Coordinates body’s
activities
* Nerve Impulses
travel through the
neurons in your body
to reach the brain

Question 4

what is the PNS made up of

Answer 4

• Made up of all the nerves
  that carry messages to and
  from the CNS (transporters)

Question 5

Divisions of PNS - Sensory

Answer 5

Sensory (afferent) division
Nerves carrying information to the CNS
* Somatic (skin, muscle, joints) sensory nerves
carry sensory inputs from skin, muscle, joints,
are involved in the voluntary control of body
movements
* Visceral sensory nerves carry
sensory impulses (usually pain or reflex
sensations) from the internal organs, glands,
and blood vessels to the central nervous
system.

Question 6

Divisions of PNS - Motor

Answer 6

Motor (efferent) division:
Nerves carrying information FROM the CNS
Somatic Nervous System
- Voluntary
- Conducts impulses from CNS to skeletal muscles
Autonomic Nervous System (ANS)
- Involuntary
- Conducts impulses from CNS to cardiac muscles,
smooth muscles, and glands.
- ANS includes two divisions:
- Sympathetic Nervous System
- Parasympathetic Nervous System

Question 7

Divisions of PNS - Autonomic

Answer 7

Sympathetic Nervous System: controls
body in times of stress, such as the
secretion of adrenal
* Parasympathetic Nervous System:
controls body in times of rest (such as
sleep)
* Sym and Parasym nervous system
usually have opposite effects on the
same organ to balance the activity of the
organ

Question 8

Describe the difference between sensory and motor nervous system.

Question 9

Give at least 6 examples of the functions of sympathetic and parasympathetic nervous system

Answer 9

1.para: constrict pupils, symp: dilate pupils (think to see better)
2.para: slow heartbeat , symp: increased heartbeat
3.para: contrict airways, symp: relaxed airway (think for more air for running)
4.para: stimulate activity of stomach, symp: inhibit activity of stomach
5.para: stimulate activity of intestine , symp: inhibit activity of intestine
6. para: contract bladder, symp: relax bladder (no time to pee)

Question 10

Describe the structure of a neuron

Answer 10

Neurons are composed of
- One or more dendrons or dendrites, -
branch like tiny trees and carry nerve
impulses towards the cell body
- With large surface area to receive signals
to the cell body
- A cell body (containing the nucleus)
- An axon – carry the nerve impulse
away from the cell body
- single, long process in each neuron,
conduct signal away from cell body to
other neurons

Question 11

What are the major glial cells in PNS and CNS that form myelin sheaths around the axons?

Answer 11

pns: schwann cells (look like swarma wrap)
cns: oligodendrocytes (little ball-o)

Question 12

What is a node of Ranvier?

Answer 12

The gaps between adjacent glial cells is called Nodes of Ranvier.

Question 13

why myelin can help to speed up the signal transduction through the axon?

Answer 13

• Myelin is an insulating layer, which helps to actually conduct
  signals through the axon at a much faster speed than
  unmyelinated axons

Question 14

function of glia cells

Answer 14

support, nourish and
protect neurons like “glue”

Question 15

what is the myelin sheath

Answer 15

Cell membrane of glial
cells tightly wrap around
the axon to form a
covering of axon called “Myelin Sheath” * Oligodendrocytes in CNS * Schwann cells in PNS

Question 16

What are grey matter and white matter

Answer 16

gray matter: unmyelinated
axon terminals
* Dendrites
* Cell Bodies
white matter: Consists of
– Myelinated axons (myelin made up of fat-> white)

Question 17

Action Potential

Answer 17

An action potential is the electrical signal that
allows nerve impulses to propagate along the axon of a neuron.

tells impulse to move)

Question 18

The process of generating an action potential involves
several membrane mechanisms:

Answer 18

1) Resting Membrane Potential
2) Depolarization
3) Rising Phase
4) Repolarization
5) Hyperpolarization

Question 19

what happens during resting membrane potential

Answer 19

Neurons have a resting membrane
potential, which means there is a voltage
difference across their cell membrane
when they are not actively sending
signals.
* At rest, the inside of the neuron is
negatively charged relative to the outside.
* This resting membrane potential is
typically around -70 millivolts (mV).
The voltage difference between the 2 sides of
cell membrane in a neuron is largely due to
distribution of different ions on the 2 sides of membrane. There are ion channels located at
the cell membrane
* Ions such as sodium, potassium flow through the ion channels

Question 20

what happens during depolarization

Answer 20

• When a neuron receives a strong enough stimulus (e.g., from a
  neighbouring neuron), it can cause a temporary increase in
  permeability to sodium ions (Na+).
• Sodium channels in the cell membrane open, allowing Na+ to
  rush into the neuron.
• This influx of positive charge causes the inside of the neuron to
  become less negative, a state called depolarization.
• Depolarisation leads to the excitation (activation) of the
  neuron.

Question 21

what happens during rising phase

Answer 21

The rapid influx of positively charged sodium
ions leads to a sharp rise in the membrane
potential, reversing the polarity of the neuron’s
membrane.
* The inside becomes positively charged relative
to the outside, creating the action potential
(AP).
* Depolarized/excited neurons generate the
electrical impulse, traveling along the axon.
* AP is mainly due to the flow of Na+ into the cell

Question 22

what happens during repolarization

Answer 22

After reaching its peak (around +30 mV to +40 mV), the
voltage-gated sodium channels start to close, and
voltage-gated potassium channels begin to open.
* The efflux of potassium ions (K+) repolarizes the
membrane, bringing it back to its negative resting
potential.

Question 23

what happens during hyperpolarization

Answer 23

In some neurons, the efflux of potassium ions can
briefly cause the membrane potential to become more
negative than the resting potential.
* This phase is called hyperpolarization, and it is usually
short-lived. (potassium channels close slowly, too many potassium ions flow out causing it to be more negative than its suppose to me)

Question 24

How the signal is passed between two neurons

Answer 24

When an action potential reaches the
axon terminal
* Neurotransmitters (NT) are released
from axon terminal
* NTs are molecules generated by a neuron.
* The receptors on the dendrite of the next
neuron are stimulated by the NT,
* leading to the excitation of next neuron
* A new AP would be generated in the next
neuron

Question 25

Describe the two different types of neurotransmitters

Answer 25

Excitatory neurotransmitters
* Usually cause an influx of sodium so that the
neurons will be depolarized (make inside of cell
more positive)
* Inhibitory neurotransmitters (no impulse transmitted)
* Cause entry of chloride ions which lead to
hyperpolarization (make inside of cell more
negative)

Question 26

Give at least one example of excitatory neurotransmitters and inhibitory neurotransmitters each

Answer 26

excitatory NT: dopamine, serotonin
inhibitory NT: GABA

Question 27

What are the four main parts of the brain and what are the structures under each part?

Answer 27

A. Cerebrum
(cerebral cortex)
* B. Diencephalon
* Thalamus
* Hypothalamus
* C. Brain Stem
* Midbrain
* Pons
* Medulla oblongata
* D. Cerebellum

Question 28

List the five major functional regions/areas of the brain cortex and understand their functions. (smavh) (cerebrum cortex)

Answer 28

Sensory areas
* receive somatic sensory information from
different part of body
* Motor areas
* initiate/coordinate motor activity in muscles
* Auditory areas
* receive hearing information from ears
* Visual areas
* Receive visual information from eyes
* Higher functional areas (eg.
prefrontal cortex)
* solving the complex tasks

Question 29

function of cerebrum

Answer 29

Controls conscious activities, intelligence, memory, language,
muscles.

Question 30

function of cerebellum

Answer 30

Area of the brain responsible for coordination of movement, balance, posture

Question 31

function of the brain stem

Answer 31

Consists of the medulla
oblongata, pons and midbrain
* Brain stem is responsible for
vital life functions such as
breathing, heartbeat, and
blood pressure

Question 32

function of diencephalon

Answer 32

Relay station between brain stem and
cerebrum
* Thalamus - acts as a relay station for sensory
inputs to the cerebrum
* Hypothalamus - interface between the
nervous system and the endocrine system

Question 33

Correctly label the following structure in a brain picture: cerebrum, cerebellum, brain stem, Pons, medulla oblongata, hypothalamus

Question 34

How is CNS protected?

Answer 34

Brains and spinal cord are protected by Cranium (bones of brain) Vertebral column and Meninges

Question 35

describe the three layers of meninges membrane.

Answer 35

Three layers of
membrane (surface to
depth)
covers brain and spinal cord
* Dura mater (doublelayered external
covering below the bone
of skull)
* Arachnoid layer
(middle Web-like layer)
* Pia mater: Internal layer
(blue)

Question 36

What is the composition of CSF?

Answer 36

similar to blood
plasma

Question 37

Where does CSF circulate?

Answer 37

in brain ventricles and spinal
cavity in arachnoid space (space below the
arachnoid layer)

Question 38

What are the functions of CSF?

Answer 38

The primary function of CSF is to cushion the brain
within the skull and serve as a shock absorber for the
central nervous system
* CSF also circulates nutrients and chemicals, removes
waste products from the brain and spinal cord

Question 39

The number, name and function of each of the 12 cranial nerve

Answer 39

I olfactory- smell
II optic -sight
III oculomotor -moves eye, pupil
IV trochlear- moves eye
V trigeminal -face sensation
VI abducens- moves eye
VII facial -moves face, salivate
VIII vestibulocochlear- hearing, balance
IX glossopharyngeal -tastes, swallow
X vagus -heart rate, digestion
XI accessory -moves head
XII hypoglossal -moves tongue

Question 40

Describe the structure of a spinal cord

Answer 40

The spinal cord consists of well-organized nerve fibres running in
tracts.
* Its uniform structure extends throughout its entire length, with outer
white matter surrounding the central grey matter.
* Additionally, it is enveloped by the meninges and surrounded by
cerebrospinal fluid (CSF), which also flows within the central canal.
In a transverse section, the grey matter
displays a distinctive butterfly shape.
The ventral horns stand out, housing the
cell bodies of the large motor neurons,
whereas the dorsal horns house the cell
bodies of the comparatively smaller
sensory neurons.
The white matter contains a greater
proportion of myelin and consists of
ascending tracts of sensory fibres and
descending motor tracts

Question 41

Reflex

Answer 41

• A reflex is an involuntary and nearly instantaneous movement
  (response) to a stimulus (suddenly pulling back your finger from
  hot object)
• A reflex is made possible by neural pathways called reflex arcs
  which are organized at spinal cord level without involvement of
  brain
• Reflex protects the body against potential damage by its fast
  response, due to the short neuronal circuit involved

Question 42

What are the neuronal circuit involved in reflex (what is a reflex arc)?

Answer 42

Receptor (nerve endings in the skin)
* Sensory neuron
* Spinal cord
* Motor neuron
* Effector (muscles)