THE CENTRAL NERVOUS system in science lab

Central nervous system in the body

1. THE CENTRAL NERVOUS
•The central nervous system is so named
because it integrates information it receives
from, and coordinates and influences the
activity of, all parts of the bodies.
•Some co-ordination is brought about by
chemicals produced by glands in the
endocrine system.

2. TYPES OF NERVE CELLS(NEURONES)
•The central nervous system and the nerves
are made up of nerve cells, called neurones.
•The motor neurones carry impulse from the
CNS to muscles and glands.
•The sensory neurones carry impluses from the
sense organs to CNS
•The inter neurones are neither sensory nor
motor but make connections to other
neurones inside the CNS

3. •Neurons have special structures that allow
them to send signals rapidly and precisely to
other cells.
•They send these signals in the form of
electrochemical waves traveling along thin
fibers called axons, which cause chemicals
called neurotransmitters to be released at
junctions called synapses.

4. NEURONES ARE SPECIALISED
•They are long to carry signals from one part of
the body to another.
•They have many branched nerve endings or
dendrites to collect and pass on signals
•Many neurons are wrapped in a layer of fat and
protein, the myelin sheath which insulates cells
from each other and allows the impulses to travel
faster.
•Neurones are usually grouped together in
bundles called nerves

5. THREE DIFFERENT PARTS OF THE
NEURON
•There are three different parts of the neuron:
•the cell body
•dendrites
•axon
•Cell body of a neuron
•The cell body is like any other cell with a
nucleus or control center.
 

6. •Dendrites
•The cell body has several highly branched,
thick extensions that appear like cables and
are called dendrites.
  The exception is a
sensory neuron that has a single, long
dendrite instead of many dendrites.
  Motor
neurons have multiple thick dendrites. The
dendrite's function is to carry a nerve impulse
into the cell body.

7. •Axon
•An axon is a long, thin process that carries
impulses away from the cell body to another
neuron or tissue.
  There is usually only one axon
per neuron.
 
•Myelin Sheath
•The neuron is covered with the Myelin Sheath or
Schwann Cells. These are white segmented
covering around axons and dendrites of many
peripheral neurons

8. •The PNS consists mainly of nerves, which are
enclosed bundles of the long fibers or axons,
that connect the CNS to every other part of
the body. The PNS includes motor neurons,
mediating voluntary movement.

9. •; the autonomic nervous system, comprising
the sympathetic nervous system and the
parasympathetic nervous system, which
regulate involuntary functions, and the enteric
nervous system, which functions to control
the gastrointestinal system.

10. •The parasympathetic nervous system (PSNS,
or occasionally PNS) is one of the two main
divisions of the autonomic nervous
system(ANS). The ANS is responsible for
regulation of internal organs and glands,
which occurs unconsciously.

11. •The parasympathetic system is responsible for
stimulation of "rest-and-digest" or "feed and
breed" activities that occur when the body is
at rest, especially after eating, including sexual
arousal, salivation, lacrimation (tears),
urination, digestion and defecation.

12. •Its action is described as being
complementary to that of one of the other
main branches of the ANS, the sympathetic
nervous system, which is responsible for
stimulating activities associated with the fight-
or-flight response.

13. •Sympathetic and parasympathetic divisions
typically function in opposition to each other.
This natural opposition is better understood
as complementary in nature rather than
antagonistic. For an analogy, one may think of
the sympathetic division as the police
responders and the parasympathetic division
as the court system.

14. •The sympathetic division typically functions in
actions requiring quick responses. The
parasympathetic division functions with
actions that do not require immediate
reaction. A useful acronym to summarize the
functions of the parasympathetic nervous
system is SLUDD (salivation, lacrimation,
urination, digestion and defecation).

15. Parasympathetic Nervous
System
Sympathetic Nervous System
Constriction of pupils Dilation of pupils
Stimulation of secretion of
saliva
Inhibition of secretion of saliva
Decreases the heart rate,
thus, causing
a drop in the blood
pressure
Increases the heart rate,
thus,
causing an increase in the
blood pressure

16. Constricts the bronchi and
thus, decreasing the
diameter of airway
Dilates the bronchi, thus,
increasing the diameter of
airway
Stimulates activity of
digestive system, like
stimulation of peristalsis
Inhibits activity of the
digestive system, like
inhibition of peristalsis
Stimulates gallbladder
secretions
Decreases gallbladder
secretions
Contracts urinary bladderRelaxes urinary bladder
Relaxes rectum Contracts rectum

17. SYNAPSES

18. •Neurotransmitter: A chemical that is released
from a nerve cell which thereby transmits an
impulse from a nerve cell to another nerve,
muscle, organ, or other tissue. A
neurotransmitter is a messenger of neurologic
information from one cell to another.