3. Functions of nervous system
Types of nervous system
Difference between CNS & ANS
Neuron
CNS
Brain
Spinal cord
PNS
ANS
Disorders of NS
References
4. 1. Communication and coordination
Adapt and respond to changes from both
inside and outside the body
2. Site of reasoning- your brain
5. Neuron- basic
structural unit of the
nervous system
Dendrites- carry
impulses towards
the cell
Axon-carry
impulses away from
the cell
Myelin sheath
6. Nerves are made of many nerve cells
Afferent-sensory nerves-- carry message to
brain
Efferent-motor neurons-- carry message
from brain to muscle
Intercalated neuron- these are found
between sensory & motor neurons and form
links in the pathways of nerves
Synapse:-the point at which the nerve impulse
passes from one to another is called synapse.
7. Various chemicals(Neurohumoral) known as
“Transmitters” are secreted in the synapse &
are involved in the transmission of information
across the synapse.
Important neurohumoral or chemical transmitters
are:-
i)Acetylcholine
ii)Adrenaline
iii)Noradrenaline
Since they transmit nerve impulses, they are
called as transmitters.
9. 1. Brain
A. Mass of nerve tissue
B. Protected by
membranes & the
cranium or skull
C. Cerebrum/ forebrain -
largest part of brain.
Responsible for
reasoning, thought,
memory, speech,
sensation, etc.
Further divided into
lobes; occipital,
parietal, temporal and
frontal
10. D. Cerebellum/Hind brain -
responsible for muscle
coordination
E. Midbrain
Responsible for:
conducting impulses
between brain parts
certain eye reflexes
F. Brain stem/medulla
oblongata- most basic
functions; respiration,
swallowing, blood pressure.
Lower part (medulla oblongata)
is continuous with spinal cord
11. G. Pons
Responsible for:
conducting messages to other parts of the
brain
Reflex actions such as chewing, production of
saliva
12. 2. Spinal cord-
Goes down back of
body from Medulla
Oblongata
Surrounded and
protected by
vertebrae
Responsible for
reflex actions
Carries sensory and
motor messages
13. 3. Meninges
Consists of 3 membranes
Covers and protects the brain and spinal cord
Three Membranes
Dura mater
thick, tough outer layer
Arachnoid membrane
middle delicate web like layer
Pia mater
inner most layer with blood vessels to nourish the
nerves
14. 4. Ventricles
Four hallow spaces located in the middle of the brain.
Connected to each other
Filled with fluid called cerebrospinal fluid
1.Right & left lateral ventricles
2.third ventricle
3.fourth ventricle
Function-To produce CSF
Cerebrospinal Fluid
Circulates continuously
Serves as shock absorber to protect brain and spinal cord
Carries nutrients to parts of brain and spinal cord
helps remove metabolic products & wastes
after circulation, absorbed into the blood vessels of the dura
mater.
15. Composition of CSF
It is clear, Slightly alkaline fluid with a specific gravity of
1.005 & consists of :- Water, amino acids, glucose,
mineral salts and urea, creatinine in small amounts .
The normal hydrostatic pressure of CSF is about 130 mm
of water (10 mm of Hg).
Functions of CSF
It supports & protects the delicate structures of brain and
spinal cord.
It maintains uniform pressure around these delicate
structures.
It acts as a cushion and shock absorber for the brain &
spinal cord.
It keeps the brain & spinal cord moist as there may be an
interchange of substances between the fluid & nerve cells.
16. Functions of spinal cord
It is the means of connection between peripheral organs & the brain.
Reflex action- is the automatic motor response given by the
spinal cord to the sensory stimulus without involving brain
in action. Most of reflex actions are protective in nature. are the part of
defense mechanism of the body.
Simple reflex arc has the following components
A sensory neuron
Connector neuron
Motor neuron
Important reflex actions are
The quick closing of an eyelid, if the eye is touched or when something
threatens to touch it.
The sudden withdrawal of the hand if the fingers touch something hot.
The quick recovery of the balance of the body to prevent falling after a
slip.
A sudden coughing attack, if a crumb is inhaled.
17. Somatic system
12 pairs cranial nerves
arising from Brain
31 pairs spinal nerves
arising from spinal cord.
Autonomic
Sympathetic
Fight or flight
Parasympathetic
18. Sympathetic Nervous
System
Parasympathetic
Nervous System
Increases heart rate Decrease heart rate
Increase respiratory rate Decrease respiratory rate
Increase Blood Pressure Decrease Blood Pressure
Decrease digestive system
activity
Increase digestive system
activity
19. We use the modal verb “Can” to express
that we know how to do something.
The negative form is “can’t” or “cannot”
(more formal).
“Can” and “can’t” are always followed by a
verb in the infinitive.