The Nervous System
1. Central Nervous System (CNS)
Is like the CPU of a computer
It controls, regulates, integrates every function
of your body
It Consist of:
a. Nerve Cells – basic communication unit of
the brain and SC
b. Brain
c. Spinal Cord
2. Peripheral Nervous System (PNS)
Is like the cables of a computer
It transmits/distributes electrical impulses
The PNS include sensory receptors, sensory
and motor neurons:
a. Sensory PNS – Afferent Pathway
Afferent - “upward movement” or
ascending movement going to the
brain”
Transmits signals from the skin (i. e.
pain), muscles, and internal organs to
the brain.
Example: If you sense a hot/warm
surface it goes through the afferent
pathway
b. Motor PNS – Efferent Pathway
Efferent– meaning “effect” – The peripheral nervous system includes sensory
downward movement or descending receptors, sensory neurons, and motor neurons.
from the brain Sensory receptors are activated by a stimulus
It sends commands from the brain to (change in the internal or external environment).
the body to control the muscles The stimulus is converted to an electronic signal
(locomotion) and to supervise the and transmitted to a sensory neuron. Sensory
autonomic nervous system, which is neurons connect sensory receptors to the CNS. The
in charge of controlling the heart, CNS processes the signal, and transmits a message
intestines and other organs. back to an effector organ (an organ that responds to
Further divided into 2: a nerve impulse from the CNS) through a motor
a. It Consist of: neuron.
b. Somatic – voluntary NS
Soma = prefix for muscles, thus the target is our muscles, skeletons
ligaments and tendons
Voluntary meaning = conscious, under your will
c. Autonomic – involuntary NS (ANS)
you cannot see it but it is working, doing its job
Example: Visceral organs like your heart is constantly pumping.
Further divided into 2:
a. Sympathetic NS
is activated during stress
Fight/Flight response
b. Parasympathetic NS
Is activated during rest and relaxation
, a. Spinal Nerves (SN) – 31 pairs
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
b. Cranial Nerves (CN) – 12 pairs
NERVE CELL
2 Types of Nerve Cell:
a. Neuroglia (“Nerve Glue”)
A supporting cell
it is non-functioning as far as transmitting impulses is concerned
b. Neuron (the “star”)
Is the functional unit of the nerve cell (NC)
It transmits and relays impulses and messages
Neuroglia
1. Astrocytes (letter B) – star-shaped
Cell body
Capillaries
It is connected to your neuron (cell body) and the other part to your capillaries
It’s function is part of your “blood-brain-barrier”:
only certain substances or nutrients can enter your cell body
harmful substances are off limits
it maintains the chemical environment of your neuron
acts like a regulator
2. Microglia (letter D)
Acts as phagocytes, eating the harmful substances in the cell
3. Ependymal (letter A)
Is like the “cushion” in your neuron
It is located in the crevices of your
neuron
, 4. Oligodendrocyte (letter C)
Forms part of myelin sheath (the axon’s insulator)
In the CNS the oligodendrocyte cells form part of the myelin sheath, while in the PNS the Schwann
cells form part of myelin sheath
Oligodendrocytes = does not regenerate
Schwann cells = may regenerate
Neuron
The neuron consists of:
1.) Cell Body Nodes of
* Center of activity Ranvier
* Metabolic process of
the neuron
2.) Dendrites
* The impulses carried by
the dendrites are
moving towards the cell Axon
body terminals
(clubbed-
3.) Axon shaped)
* The impulses carried by the axon are moving away from the cell body
* A = away
* 1 axon per neuron
4.) Axon Terminal Junction
* at the axon terminal (at the end of the neuron)
5.) Nodes of Ranvier
* it allows for the impulses to have staltutory leaps
6.) Synapse
means “gap”
it is where chemicals (neurotransmitters) are stored
The Brain
The brain (also called encephalon) has 4 major parts:
1) Cerebrum
* Has 2 hemispheres the left & right hemispheres
* Joined by the corpus callosum
* Each hemisphere has 4 lobes:
a. Frontal Lobe (pinaka bright)
The largest lobe
Responsible for: * Anything Intellectual
Judgment
Abstract thinking contains the BROCA’S area which is said to
Memory storage be responsible for the MOTOR part of
Behavior articulated SPEECH (expressive speech)
Emotions Aphasia = absence of speech
Artistic traits Broca’s Aphasia is deficit in speech production
Right hemisphere – left sided weakness, impulsiveness & poor judgment
Left hemisphere – aphasia
b. Temporal Lobe
It controls, regulates and integrates hearing or reception of sound
Auditory reception
1. Central Nervous System (CNS)
Is like the CPU of a computer
It controls, regulates, integrates every function
of your body
It Consist of:
a. Nerve Cells – basic communication unit of
the brain and SC
b. Brain
c. Spinal Cord
2. Peripheral Nervous System (PNS)
Is like the cables of a computer
It transmits/distributes electrical impulses
The PNS include sensory receptors, sensory
and motor neurons:
a. Sensory PNS – Afferent Pathway
Afferent - “upward movement” or
ascending movement going to the
brain”
Transmits signals from the skin (i. e.
pain), muscles, and internal organs to
the brain.
Example: If you sense a hot/warm
surface it goes through the afferent
pathway
b. Motor PNS – Efferent Pathway
Efferent– meaning “effect” – The peripheral nervous system includes sensory
downward movement or descending receptors, sensory neurons, and motor neurons.
from the brain Sensory receptors are activated by a stimulus
It sends commands from the brain to (change in the internal or external environment).
the body to control the muscles The stimulus is converted to an electronic signal
(locomotion) and to supervise the and transmitted to a sensory neuron. Sensory
autonomic nervous system, which is neurons connect sensory receptors to the CNS. The
in charge of controlling the heart, CNS processes the signal, and transmits a message
intestines and other organs. back to an effector organ (an organ that responds to
Further divided into 2: a nerve impulse from the CNS) through a motor
a. It Consist of: neuron.
b. Somatic – voluntary NS
Soma = prefix for muscles, thus the target is our muscles, skeletons
ligaments and tendons
Voluntary meaning = conscious, under your will
c. Autonomic – involuntary NS (ANS)
you cannot see it but it is working, doing its job
Example: Visceral organs like your heart is constantly pumping.
Further divided into 2:
a. Sympathetic NS
is activated during stress
Fight/Flight response
b. Parasympathetic NS
Is activated during rest and relaxation
, a. Spinal Nerves (SN) – 31 pairs
8 Cervical
12 Thoracic
5 Lumbar
5 Sacral
1 Coccygeal
b. Cranial Nerves (CN) – 12 pairs
NERVE CELL
2 Types of Nerve Cell:
a. Neuroglia (“Nerve Glue”)
A supporting cell
it is non-functioning as far as transmitting impulses is concerned
b. Neuron (the “star”)
Is the functional unit of the nerve cell (NC)
It transmits and relays impulses and messages
Neuroglia
1. Astrocytes (letter B) – star-shaped
Cell body
Capillaries
It is connected to your neuron (cell body) and the other part to your capillaries
It’s function is part of your “blood-brain-barrier”:
only certain substances or nutrients can enter your cell body
harmful substances are off limits
it maintains the chemical environment of your neuron
acts like a regulator
2. Microglia (letter D)
Acts as phagocytes, eating the harmful substances in the cell
3. Ependymal (letter A)
Is like the “cushion” in your neuron
It is located in the crevices of your
neuron
, 4. Oligodendrocyte (letter C)
Forms part of myelin sheath (the axon’s insulator)
In the CNS the oligodendrocyte cells form part of the myelin sheath, while in the PNS the Schwann
cells form part of myelin sheath
Oligodendrocytes = does not regenerate
Schwann cells = may regenerate
Neuron
The neuron consists of:
1.) Cell Body Nodes of
* Center of activity Ranvier
* Metabolic process of
the neuron
2.) Dendrites
* The impulses carried by
the dendrites are
moving towards the cell Axon
body terminals
(clubbed-
3.) Axon shaped)
* The impulses carried by the axon are moving away from the cell body
* A = away
* 1 axon per neuron
4.) Axon Terminal Junction
* at the axon terminal (at the end of the neuron)
5.) Nodes of Ranvier
* it allows for the impulses to have staltutory leaps
6.) Synapse
means “gap”
it is where chemicals (neurotransmitters) are stored
The Brain
The brain (also called encephalon) has 4 major parts:
1) Cerebrum
* Has 2 hemispheres the left & right hemispheres
* Joined by the corpus callosum
* Each hemisphere has 4 lobes:
a. Frontal Lobe (pinaka bright)
The largest lobe
Responsible for: * Anything Intellectual
Judgment
Abstract thinking contains the BROCA’S area which is said to
Memory storage be responsible for the MOTOR part of
Behavior articulated SPEECH (expressive speech)
Emotions Aphasia = absence of speech
Artistic traits Broca’s Aphasia is deficit in speech production
Right hemisphere – left sided weakness, impulsiveness & poor judgment
Left hemisphere – aphasia
b. Temporal Lobe
It controls, regulates and integrates hearing or reception of sound
Auditory reception
