Human Nervous System Central Nervous System (CNS) -Brain and spinal cord - interneurones Peripheral...

Human Nervous System


Central Nervous System (CNS)-Brain and spinal cord- interneurones

Peripheral Nervous system (PNS)-Everything else (cranial and spinal nerves)-Sensory and motor neurons

Somatic Nervous System Autonomic Nervous System- Voluntary - Involuntary- Input from sense organs - Input from internal receptors- Output to skeletal muscles - Output to smooth muscles and glands

Sympathetic Motor System Parasympathetic Motor System-`Fight or Flight` response - Relaxing responses- Neurotransmitter: Noradrenaline - Neurotransmitter: Acetylcholine- `Adrenergic System` - `Cholinergic System`


Parts of Nervous System:

I- Central Nervous system

* Brain

* Spinal Cord

II- Peripheral Nervous System:

* Cranial Nerves

* Spinal Nerves


Parts of Nervous

System:


* Brain

* Spinal Cord


Parts of Nervous

System:


* Cranial Nerves

* Spinal Nerves



Brain

• Is the primary center for regulation and coordination of body

activities.

• Each portion of the Brain controls different aspects of body

function.

• The Brain is organized so that the left side of the Brain

controls the right side of the body and the right side of the

Brain controls the left side of the body


Parts of the Brain

1. Forebrain

2. Midbrain

3. Hindbrain


Spinal cord

• Spinal cord carries all the

nerves that affect the limbs and

lower portion of the body.

• It is the pathway for impulses

going to and from the Brain.


Cerebrospinal Fluid (CSF)

• CSF flows throughout the Brain and the spinal cord

• Its primary function is to cushion these organs from shock and injury.


Parts of Nervous System:


* Cranial Nerves

* Spinal Nerves

• The cranial nerves are arranged in 12 pairs, so the two nerves on a pair are identical in function and structure.

• These nerves serve both sensory and motor functions.


The 12 Cranial Nerves

•The cranial nerves are generally named for the area or function they serve

and are identified with Roman numerals.1. I - Olfactory

2. II - Optic

3. III - Oculomotor

4. IV - Trochlear

5. V - Trigeminal

6. VI - Abducens

7. VII - Facial

8. VIII - Auditory

9. IX - Glossopharyngeal

10. X - Vagus

11. XI - Accessory

12. XII - Hypoglassal



* Cranial Nerves

* Spinal Nerves

1. Cervical nerves

2. Thoracic nerves

3. Lumbar nerves

4. Sacral nerves


Structure of the Nervous system

• The basic cells of the nervous system are the Neurons

• They are composed of a cell body and neural process (nerve fibers)

Types of nerve cells

1. Sensory neurons

2. Motor neurons



1. Sensory neuron:

* Afferent Neuron– Moving away from a central organ or point.

* Relays messages from receptors to the Brain or Spinal cord.



2. Motor neuron:

* Efferent Neuron– Moving towards a central organ or point.

* Relays messages from the Brain or Spinal cord to the muscles and organs.


Interneuron (relay neurone):

* Relays messages from sensory neurone to motor neurone

* Make up the Brain and Spinal cord


Synapses

• Is the space between two neurons or between a neuron and a receptor organ.

Neurotransmitter

• Is a chemical substance that makes it possible for the impulse to jump across the synapse from one neuron to another.


Schwann cells

• Most neurons have many companion cells called Schwann cells, which wrap

their cell membrane around the axon many times in a spiral to form a thick

insulating lipid layer called the Myelin sheath.


Myelin sheath

-Is the white protective covering of some nerves.


Myelin sheath

*If the nerve is covered with myelin it is referred to as the white matter.

*If the nerve is NOT covered with protective myelin sheath is called gray matter

which makes up the gray matter of the Brain and spinal cord.



Central Nervous System (CNS)-Brain and spinal cord- interneurones

Peripheral Nervous system (PNS)-Everything else (cranial and spinal nerves)-Sensory and motor neurons

Somatic Nervous System Autonomic Nervous System- Voluntary - Involuntary- Input from sense organs - Input from internal receptors- Output to skeletal muscles - Output to smooth muscles and glands

Sympathetic Motor System Parasympathetic Motor System-`Fight or Flight` response - Rest and digest responses- Neurotransmitter: Noradrenaline - Neurotransmitter: Acetylcholine- `Adrenergic System` - `Cholinergic System`


- Most body organs are innervated

by two separate sets of motor

neurons;

• one from the sympathetic system

• one from the parasympathetic

system

- These neurones have opposite

(antagonistic) effects.


The Autonomic Nervous SystemStructureSympathetic StimulationParasympathetic StimulationIris (eye muscle)Pupil dilationPupil constriction

Salivary GlandsSaliva production reducedSaliva production increased

Oral/Nasal MucosaMucus production reducedMucus production increased

HeartHeart rate and force increasedHeart rate and force decreased

LungBronchial muscle relaxedBronchial muscle contracted

StomachPeristalsis reducedGastric juice secreted; motility increased

Small IntestineMotility reducedDigestion increased

Large IntestineMotility reducedSecretions and motility increased

LiverIncreased conversion ofglycogen to glucose

KidneyDecreased urine secretionIncreased urine secretion

Adrenal medullaNorepinephrine andepinephrine secreted

BladderWall relaxedSphincter closed

Wall contractedSphincter relaxed


• It should be noted that the autonomic nervous system is always

working. It is NOT ONLY active during "fight or flight" or "rest

and digest" situations. Rather, the autonomic nervous system

acts to maintain normal internal functions and works with the

somatic nervous system.

Human Nervous System Central Nervous System (CNS) -Brain and spinal cord - interneurones Peripheral...

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