Nervous System for nursing students - GNM first year1.pptx

Nervous System for GNM I

1. Nervous system

2. * The nervous system

— It is an organ system containing a network of
specialized cells called NEURONS that coordinate
the action and transmit signals between different

parts of body.

3. The Nervous System

- The nervous system regulates the body's activities and
responses. It works by means of specialized cells called
neurons which transmit information in the form of nerve
impulses.

4. Functions of nervous system

— Orientation to and perception of the ever
changing internal and external environment

— Activation, control and co-ordination of all the
other body part

— Intelligence — conceptual thoughts:

* Highly intellectual function:
— Imagination, abstract, reasoning, creativity, predictions,
calculation and control of violence
— Exhibition of capacity of the nervous system to RECORD,
PROCESS, STORE and RELATE IMFORMATION RECEIVED and
ACTION taken for the experience and use it for future reaction
to environment change or situation

5. CELLS AND TISSUES OF THE
NERVOUS SYSTEM

6. Nervous Tissue Types
* Two types: Neurons and Neuroglia
* Neurons = nerve cells that conduct electrical signals

* Neuroglia = connective tissue that supports neurons

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cest

7. Structure of a Typical Neuron

Dendrite Axon terminal

Schwann cell

Nucleus Myelin sheath

8. Properties of neuron

* The neurons are working Nerve Cell
units of the nervous
system that generate and
transmit nerve impulses.

Dendrites

Nucleus

0% ; Cell Body
* 100 billion neurons in the

. ¡A Aron
brain N (with Myelin Sheath)

+ Each neuron consists of:
— Cell body
— Axon and dendrite

Axon Teminals
(Synaptic Bulbs)

Ranvier {\ A >
i}

Synapse À — Dendrite of Next Newron

9. Conductivity (transmit
impulse)

Excitability (initiate
impulse)

Stimulus

— Mechanical

— Electrical

— Chemical

Nerve Cell

(Neuron) Y 7 Dendrites
é Nucleus
sehvann oY Cell Body
> eels A
————— Axon
(with Myelin Sheath)
ge Axon Teminals
Nodesof VS (Synaptic Bulbs)
Ranvier LR
{Yi As

‘synapse’ 4 — Denttrite of Next Neuron

10. Cell body:

— Present at periphery in / Dendrites
the brain and in the
centre of the spinal cord

— Nuclei - in the CNS

— Ganglia — in the PNS

11. * Axon and dendrite:

— Are the branches which
extend from a tapered
portion of the cell body

— Aneuron has only ONE
axon, 100 cm long thin
cylindrical projections,

— Axon are found deep in
brain and in periphery in
spinal cord

— Nerve fibres: is a term used Dendiles y
for neuron process (axon
and dendrite)

12. Dendrite Axon Terminal

D Some

AXON

EE —

Node of Ranvicy
\

ee

= Insulated by myelin shea_. “= cone
It gives white colour to the nerve fiber.

© Has a series of Schwann cell plasma membrane
and also known as neurolenmna.

= There are tiny areas of exposed axolemma
between adjacent Schwann cells, called modes of
Ranvier.

© Nodes of Ranvier:

Assist in rapid transmission of nerve impulse.

(the speed of transmission of nerve impulse slower in
non-myelinated fibers.)

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13. Dendrite

Asingle neuron may receive nerve nerve impulses from different neurons
Internal Structures of a Multipolar Neuron

+ Structure:
- Finger-like
projections from cell

body
They are not
myelinated

« Function:

Receives nerve
impulse from
previous neuron.

14. * The nerve impulse or action potential

— Action potentials are electrochemical pulses that
transmit information along nerves.

— An action potential is a temporary change in electrical
potential of a neural cell membrane (the voltage
between the interior of the cell and the exterior) from
the resting potential.

— It involves a series of electrical and underlying
chemical changes that travel down the length of a
neuron.

— An action potential is a controlled, temporary shift in
the concentrations of charged molecules in the cell
that sweeps rapidly down a long, fiber-like projection
(axon).

Action potential - Dictionary definition of Action potential | Encyclopedia.com:

FREE online dictionary

16. Synapses and neurotransmitters

* Synapses: A SYNAPSE

— ajunction between
two nerve cells,
consisting of a
minute gap across
which impulses pass
by diffusion of a
neurotransmitter.

17. Neurotransmitter
A chemical substance which is an En
released at the end of a nerve

fibre by the arrival of a nerve " N
impulse and, by diffusing across. all I mM
the synapse or junction, effects ‘YY Bag AA e

the transfer of the impulse to
another nerve fibre, a muscle
fibre, or some other structure.
They maintain signals in the
nervous system by binding to

receptors on post- a» E

synaptic neurons and triggering

electrical impulses ‘ F
They also activate responses by }
effector organs (such as a;
contraction in muscles or

hormone release from endocrine Ws
glands) venta

19. Types of neurotransmitters

* Adrenaline

— Adrenaline is primarily a hormone released by the adrenal gland, but some
neurons may secrete it as a neurotransmitter

t increases heart rate and blood flow, leading to a physical boost and
heightened awareness

t is produced during stressful or exciting situations
+ Noradrenaline

n contrast to adrenaline, noradrenaline is predominantly a
neurotransmitter that is occasionally released as a hormone

t contracts blood vessels and increases blood flow, improving attention
and the speed at which responsive actions occur

* Dopamine

= It is primarily responsible for feelings of pleasure, but is also involved in
movement and motivation

— People tend to repeat behaviours that lead to dopamine release, leading to
addictions

— Abnormal dopamine secretion is common in specific movement disorders,
like Parkinson's disease

20. Serotonin
— Contributes to feelings of well-being and happiness

— Is affected by exercise and light exposure, and plays a role
in the sleep cycle and digestive system regulation

GABA

— Inhibits neuron firing in the CNS — high levels improve
focus whereas low levels cause anxiety

— Also contributes to motor control and vision
Acetylcholine
— Involved in thought, learning and memory within the brain

— Activates muscle contraction in the body and is also
associated with attention and awakening

21. « Glutamate
— Most common brain neurotransmitter
— Regulates development and creation of new nerve
pathways and hence is involved in learning and
memory
+ Endorphins

— Release is associated with feelings of euphoria and a
reduction in pain (body’s natural 'pain killers’)

— Released during exercise, excitement and sex

22. Types of Nerves

+ Anerve is a bundle
of nerve fibers held
together by layers of

connective tissue.

+ Nerves can be
sensory, motor, or
mixed, carrying both
sensory and motor
fibers.

23. * Sensory nerves / afferent nerve:
— Transmit sensory impulses from receptors in the skin,
sense organ, muscles, joints and viscera into the CNS
* Somatic cutaneous — pain, temperature, touch, vibrations, etc
« Special senses: of tases,smell
* Proprioceptor senses: vision, hearing and balance via cranial
nerves
* Motor / efferent nerve:
— Convey nerve impulses from CNS to effectors (muscles or
glands)
— Two types:
* Somatic nerves- skeletal muscles contraction

+ Autonomic nerves (parasympathetic and sympathetic):
contraction of smooth muscles, cardiac muscles, glands via cranial
and spinal nerves

+ Mixed nerve:
— out side the spinal cord, enclosed in same sheath.

24. + NEUROGLIA:

— Also known as glial cells
or glia means glue are
non-neuronal cells in the
CNS and the PNS.

— They act as glue to the
neurons

— They maintain
homeostasis, form
myelin, and provide
support and protection
for neurons.

Nervous Tissue Types
+ Two types: Neurons and Neuroglia
+ Neurons = nerve cells that conduct electrical signals

+ Neuroglia = connective tissue that supports neurons,

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1 un

25. * Functions of neuroglia

— Form myelin which wrap
around axon to speed
up electric impulse

— Provide nutrients to
neurons, including
oxygen

— Destroy pathogens

— provide a general
support structure on
which neurons can sit

26. * Types of neuroglia
— Astrocytes

— Oligodendrocytes
— Ependymal cells

— Microglia

27. * Astrocytes: (CNS)

— Astro means star, cytes
means cells- star shaped cells

— Form the part of blood brain
barrier (helps to prevent
undesirable substances from
entering the brain via blood
vessels)

— Provide nutrients

— Structural support

— Release and absorption of
ions and neurotransmitters
for improved modulation of
cell to cell communication
between neuron

— They maintain the proper

balance of K+ ion for Astrocyt neurog
generation of nerve impulses (a) uch mo pe RE po

— Repair of the neurons

28. * Oligodendrocytes
(CNS):

— Creates myelin sheaths
around the axons
neurons.

— These myelin sheaths
allows for action
potentials to travel down
the axon

29. * Microglia (CNS):

— Smallest of glial cells

— Derived from monocytes
(macrophages or WBC)

— Phagocytic in nature and
protect the CNS from
disease by engulfing,
invading microbes

— Clear away debris from
dead cells

— Help to reduce
inflammation through
release of anti
inflammatory chemical
signals

30. * Ependymal cells:

— Specialized cells that line
the cerebral ventricles
and central canal of the
spinal cord

— Funtions:

CSF production

Nutrient provision for

neurons

Filtration of harmful

substances

Neurotransmitter

distribution

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31. * Swachnn cells (PNS):

— Are wrapped around
some neuronal axons to
form the myelin sheath
in PNS

— Help to improve nerve
signal conduction

— Assist in nerve
regeneration and nerve
repair

— Antigen recognition by T
cells

32. * Satellite glial cells:

— Covers the surface of the
nerve cell bodies in
sensory, sympathetic
and parasympathetic
glaglia

— Act as a protective
cushion sheath

— Supply nutrients to
neurons

— Link to neurochemical

— Similar role to astrocytes

34. CENTRAL NERVOUS
SYSTEM(CNS)

BRAIN
receives and sends
out messages.

SPINAL CORD
connects the

brain to the rest |
of the body. Il!

Coordinating center | (AI
for incoming and A

outgoing information

PERIPHERAL
NERVOUS SYSTEM
(PNS)
CRANTAL NERVES

carry messages

> \ directly to and

N from the brain.

SPINAL NERVES
carry messages to
and from the spinal

cord,
Carry info. between
organs such as skin,

heart, eyes, ears and
the CNS.

35. CENTRAL NERVOUS

SYSTEM
- Brain ‘
* Relays
Spinal messages
cord « Processes
information
+ Analyzes

information

LPS ©2004 by Ap A Rs

36. The meninges are
the membranes
covering the brain
and spinal cord

Dura mater (2 layers)
Arachnoid
Pia mater

37. Skin

Periosteum

Dura mater
Arachnoid

Pia mater

38. + «Extradural Space
Epidura space

» Potential Space
between the

the

> Normally absent or very
minute space

39. « Ventricles:

— The irregular cavities inside the brain which
produces and maintains CSF
— There are four types of ventricles
+ Left and right ventricle
+ 3 ventricles
+ 4 ventricles

40. Interventricular
Lateral
foramen (of Monro) ventición

orien Posterior
en (occipital)
horn
Cerebral
aqueduct
Third ventricle

Inferior \ \ Fourth
(temporal) horn \ | ventricle

41. The Ventricular System of the Human Brain

Right Lateral
Ventricle Left Lateral

Central Part Ventricle

of Left Lateral
Ventricle

Third
Ventricle

Cerebral
Aqueduct

Choroid
Plexus
Fourth

Central Canal Ventricle

43. CSF Definition & Functions

CSF definition:
The liquid surrounding the brain and spinal cord

It flows in subarachnoid area (the space between the
arachnoid & pia matter)

Functions:

= Physical support & protection

= Provides a controlled chemical environment > nutrient
supply & waste removal

= Intra- & extracerebral transport: Neuroendocrine function

44. + Mechanism of csf formation

— Plasma is passively filtered across the choroidal
capillary endothelium
— Secretion of water and ions across the choroidal
epithelium
* Bicarbonate, chloride, and potassium ions, enter the
CSF via channels in the epithelial cellaical membranes

* Aquaporins provide for water movement to blance
osmotic gradients

45. ra

AR of CSF flow

Hydrocephalus

46. Flow of Cerebrospinal Fluid

(1) CSF is secreted by choroid gy Superior sagittal sinus
dd plexus in each lateral a === Subarachnoid
ventricle. ER space
CSF flows throu
interventricular
foramina into
third ventricle. J)

adds more CSF.

CSF flows down = = ventricle
cerebral aqueduct to . P 1 Cerebral
fourth ventricle. : | aqueduct
(5) Choroid plexus in fourth ¿— Lateral
ventricle adds more CSF. aperture

(6) CSF flows out two lateral apertures
and one median aperture.

(7) CSF fills subarachnoid space and aperture
bathes external surfaces of brain
and spinal cord. Central canal
(8) At arachnoid villi, CSF is resorbed of spinal cord

into venous blood of dural Subarachnoid
venous sinuses. space of spinal cord

47. Normal composition of CSF

Appearance : Clear ,Colorless

Lymphocytes :

1-5/H.P.F.

7.4

100 - 150 mi

450 - 500 pl

1.006 - 1.007
15 - 45 mg/dl
50-80 mg/dl

115 - 130 mmol /L

1.0 - 1.40 mmol/L

0,4 - 0.7 mmol/L

1.2 - 1.5 mmol/L

2.6 - 3.0 mmol/L

49. Function of the CSF :

Cushions & protects the CNS from trauma
Provides mechanical buoyancy & support for the brain

Serves as a reservoir & assists in the regulation of the
contents of the skull

Nourishes the CNS
Removes metabolites from the CNS

Serves as a pathway for pineal secretions to reach the
pituitary gland

50. * THE BRAIN

— Brain is a large organ weighing 1.4 kg. it lies within
the cranial cavity.

— The portion of the central nervous system that is
located within the skull. It functions as a primary
receiver, organizer, and distributor of information
for the body. It has a right half and a left half, each
of which is called a hemisphere.

51. » Parts of brain:

— Fore brain (procencephalon)
* Olfactory lobe
* Cerebrum
— Cerebral cortex (grey mater - cell body)
— Medulla (white mater - axon )
* Diencephalon
— Epithalamus
— Thalamus
— Hypothalamus
— Mid brain (Mecencepahalon)
* Tectum
— Superior coliculus
— Inferior coliculus

* Tegmentum

— Hind brain — cerebellum
* Pons BRAIN STEM
* Medulla oblongata

53. Fore brain

1. Olfactory lobe —
covered by cerebral
hemisphere

— Olfactory bulb (A)
— Olfactory tract (B)
* One pair
* Solid small structure
* Connected to
olfactory region of
temporal lobe
* Detection of smell

54. « Olfactory lobe Either
member of a pair
of lobes in the forebrain,
at the anterior end of the
cerebrum. They contain
the endings of
the olfactory nerves (the
first pair of cranial
nerves) and are
concerned with the
sense of smell

55. | Structure of the Cerebrum
L er cerebrum . The Cerebrumis the largest portion of

the brain. It is divided into two
hemispheres by the longitudinal fissure.
A deep ridge of nerve fibers called the
corpus callosum connects the two
halves.

The surface of the cerebrum has ridges,
or convolutions separated by grooves.

Ashallow groove is called a sulcus and
deep grooves are called fissures.

56. Cerebral Cortex - The outermost layer of gray
matter making up the superficial aspect of the
cerebrum.

57. Function of the cerebral cortex:

— Higher order functions: the mental activities
involved in memory, sense of responsibilities

— Sensory perception, including the perception of
pain, temperature, touch, sight, hearing, taste,
and smell

— Initiation and control of skeletal muscle
contraction and therefore voluntary movement

58. * Corpus collusum

— The corpus callosum is a
thick band
of nerve fibers that
divides the cerebral
cortex lobes into left and
right hemispheres. It
connects the left and
right sides of the brain
allowing for
communication between
both hemispheres.

— The corpus callosum
transfers motor, sensory,
and cognitive
information between the
brain hemispheres.

59. * Corpus Callosum Function

— The corpus callosum is the
largest fiber bundle in the
brain, containing nearly
200 million axons. It is
composed of white
matter fiber tracts known
as commissural fibers. It is
involved in several
functions of the body
including:

— Communication Between
Brain Hemispheres

— Eye Movement and Vision

— Maintaining the Balance of
Arousal and Attention

— Tactile Localization

60. + Lobes of the
cerebrum

61. Functions of the Cerebral Lobes

Frontal lobes Association areas carry on higher
intellectual processes for concentrating,
planning, complex problem solving, and
judging the consequences of behavior.
Motor areas control movements of
voluntary skeletal muscles.

Parietallobes Sensory areas provide sensations of
temperature, touch, pressure, and pain
involving the skin.

Association areas function in understanding
speech and in using words to express
thoughts and feelings.

Temporal lobes Sensory areas are responsible for hearing.
Association areas interpret sensory
experiences and remember visual scenes,
music, and other complex sensory patterns.

Occipital lobes Sensory areas are responsible for vision.

Association areas combine visual
images with other sensory experiences.

62. Functional areas of the cerebral cortex

—Motor area

—Sensory area

—Association areas

63. Motor area

A | aes

Primary motor area Frontal lobe Control skeletal muscles
immediately anterior to activity
the central sulcus

Motor speech (broca's Frontal lobe just above Muscle movements
area) the lateral sulcus needed for speech

64. Sensory area
fares tocation =| Funtion [|

Somatosensory area Immediately behind the pain, temperature,
centralsulcus pressure and touch,
awareness of muscular
movement and the
position of joints are

percieved.
Auditory area Immediately below the Hearing
lateral sulcus
Olfactory area Deep within the temporal Smell
loe
Taste area Lateral sulcus in the deep Taste

layers of the
somatosensory area

Visual area Behind the parieto- Vision
occipital sulcus

65. Associated areas

Premotor area Frontal lobe immedeately Coordinate movement eg
anterior to the motor area tying a lace or writing —
manual dexterity
Prefrontal area Extrends anteriorly from the Intellectual functions —

premotor area to include the perception and

remainder of the frontal area comprehension of the
passage of time, the avbility
to anticipate consequences
of the events and
management of emotion

Sensory speech (wernicke’s) | Temporal lobe adjacent to Spoken words are perceived,

area the parieto-occipitotemporal and comprehension and
area intelligence are based,
language based,
Perieto-occipitotemporal Behind the somatosensory Spatial awareness,
area area interpretation of written

language and the ability to
name objects

68. Blood supply to the brain

70. * Circulus arteriosus play a vital role in
maintaining a constant supply of oxygen and
glucose the brain

* The brain receives about 15% of the cardiac
output (750 ml) of blood per min

71. Venous drainage of the brain

73. Diencephalon
— Connects the
cereburm and the
midbrain
— Consists of :
* Thalamus
+ hypothalamus

74. Thalamus

-The brain’s sensory switchboard

« Directs messages to the sensory receiving
areas in the cortex

« Thalamus is Greek for “inner chamber”
* Sits on top of brainstem

Sensory receptors in the skin and viscera
send information about touch, pain and
temperature and inputs from the special
sense organs travel to the thalamus where
there is recognition and relays information to
the brain

75. Pneumonic for cranial nerves

* One Of Our Trained Teacher Asked For
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