By: Emma Friedman and Jearicamarie Dodge
Period 3
Function of the System
 The nervous system allows us to sense our
surroundings, bringing inside and outside
information to our brain and spinal cord to
interpret.
 The three main functions of the nervous
system are the:
• Sensory function
• Integrative function
• Motor function
The Neuron
The main parts of a neuron are the:
•Cell body- The nucleus (and the
nucleolus) lie within the cell body,
along with chromatophilic substance.
There are also various organelles in the
body such as mitochondria.
•Dendrites- Dendrites are the main
receptors of the neuron and
communicate with other neurons’
axons.
•Tubular- The areas of the tubular not
covered by Schwann cells are referred
to as Nodes of Raniver.
•Axon- Axons communicate with other
neurons and extend from the axonal
hillcock.
oUnmyelinated axons appear as gray
matter, myelinated as white matter.
There are extensions at the end of the
axon that do the communicating.
The Synapse
When two neurons
communicate, the
junction is called a
synapse.
•The two neurons are
separated by the
synaptic cleft
•The neuron carrying
the impulse is the
presynaptic neuron,
and the receiver the
postsynaptic neuron.
Synapses and
Neurotransmitters
Neurotransmitters are
the biochemicals that
carry out synaptic
transmission.
•The synaptic vesicles
that lie within the
synaptic knobs on the
ends of axons release
the neurotransmitters,
which then travel
across the synaptic
cleft.
The Central Nervous System
 The central nervous system includes the
brain and the spinal cord, which connects
to the brainstem.
The Brain
Major Aspects of the Brain
 Cerebrum
 Ventricles and Cerebrospinal Fluid
 Dicencephalon
 Brainstem
 Cerebellum
The Cerebrum
The Cerebrum
The lobes of the cerebrum:
 Frontal lobe
 Parietal lobe
 Temporal lobe
 Occipital lobe
 Insula
Function of the Cerebrum
 The cerebrum performs many high-level functions.
• The motor areas are in the frontal lobes, and its tissue
consists of pyramidal cells, which send impulses to
skeletal muscle fibers.
• Sensory areas are in various lobes and interpret
information from sensory receptors, thus producing
sensations or feelings.
• Association areas are also in various lobes, and connect
with other brain structures. They deal with things like
memory, reasoning, and judgment.
Ventricles and Cerebrospinal Fluid
Diencephalon
 The thalamus and hypothalamus lie within the
diencephalon.
 The thalamus receives and sends to the cortex sensory
impulses except for smell.
 The hypothalamus regulates many visceral activities,
which maintains homeostasis. It also links the
endocrine to the nervous system.
 The other structures in the diencephalon make up the
limbic system, which modifies a person’s behavior and
emotions based on their outside situation.
Brainstem
Brainstem Parts and Functions
 The brainstem is composed of the midbrain, pons, medulla
•
•
•
•
oblongata, and reticular formation.
Midbrain: Contains bundles of myelinated axons that join
the brainstem to the spinal cord and the brain.
Pons: A small sphere that transmits impulses from the
cerebrum to cerebellum
Medulla Oblongata: All nerve fibers from the brain to
spinal cord run through it, as it is part of the fourth
ventricle.
Reticular formation: Is a network of nerve fibers
scattered throughout the brainstem, which arouses the
otherwise “sleeping” cortex.
Cerebellum
 The cerebellum communicates with the rest of the
CNS by way of cerebellar peduncles.
 It’s main function is to integrate sensory information
in relation to body position and movement of skeletal
muscles.
Peripheral Nervous System
 The peripheral nervous system is divided into the
autonomic and somatic nervous systems.
 The system includes the cranial and spinal nerves.
 The CNS consists of the brain and spinal cord, and the
PNS of the body’s nerves.
The Autonomic Nervous System
 The autonomic nervous system is the part of the PNS
that functions independently.
 It’s function is to regulate the actions of muscles and
glands, as well as heart rate and blood pressure,
breathing rate, body temperature, and maintaining
homeostasis in general.
Sympathetic and Parasympathetic
Divisions
Sympathetic Level:
• Its fibers originate in the gray matter of the spinal cord. The
axons exit through ventral roots of spinal nerves
• Once they have left the spinal nerves, the fibers form
paravertebral ganglia.
Parasympathetic Level:
• Its fibers originate in the brainstem.
• They proceed outward in cranial/sacral nerves in order to
reach ganglia.
• The postganglionic fibers extend to certain muscles in
viscera.
Somatic Senses
 Touch and pressure senses: Their receptors are free
nerve endings in epithelial tissue, Meissner’s
corpuscles that sense extremely light touch, and
Pacinian corpuscles, which respond to deep pressure.
 Temperature senses: There are warm and cold
receptors of free nerve endings.
 Sense of pain: Free nerve endings dispersed
throughout the body (excluding the brain) sense pain.
According to referred pain, visceral pain often feels as
though it is occurring in a different area of the body.
Smell and Taste
Similar Both sensations must adapt very quickly to the
environment
 For both senses, substances must dissolve in liquid to
cause a stimulation
 Just as the nose has hairs, taste hairs extend from each
taste pore, and both types are major receptors
Different Despite their many similarities, smell impulses are
eventually sent to the temporal lobes, and taste impulses
to the parietal lobe.
Diseases and Disorders
 Parkinson's: The disease often occurs after age 50, when
the nerve cells that make dopamine slowly die. Dopamine
controls muscle movement, and the person therefore can
lose simple abilities like blinking and swallowing.
 Alzheimer's: It’s a form of dementia that progressively
becomes worse. It often first appears as forgetfulness, but
can lead to loss of cognitive skills.
 Multiple Sclerosis: It is caused by damage to the myelin
sheath, which exposes nerve cells that can slow down or
stop. There are various symptoms, some of which are loss
of balance, tremors, and loss of coordination.
Sources
 http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH00
01762/
 http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH00
01767/
 http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH00
01747/
 All pictures were taken from Hole’s Essentials of
Human Anatomy and Physiology; McGraw-Hill Higher
Education