1.1 – Introduction to Anatomy, Physiology, and the Nervous System
○ Receives, processes, and sends information.
○ Coordinates and controls all body systems.
● Nervous tissue carries electrical impulses between body parts — the “wiring” of the
body.
1. Central Nervous System (CNS)
● Includes: Brain + Spinal Cord.
● Protected by: Skull and vertebrae.
○ Processes information.
○ Sends and receives impulses to/from the PNS.
● Structures:
○ Nuclei: Collections of neuron cell bodies inside the CNS.
○ Tracts: Bundles of axons inside the CNS.
2. Peripheral Nervous System (PNS)
● Includes: All nerves outside the brain and spinal cord.
● Subdivisions:
○ Cranial Nerves – Emerge from the brainstem (innervate head, face, neck).
○ Spinal Nerves – Branch from the spinal cord (innervate trunk and limbs).
● Structures:
○ Ganglia: Collections of cell bodies outside the CNS.
○ Nerves: Bundles of axons in the PNS.
● Function: Connects all parts of the body to the CNS.
,1.2 – Neurons
Neuron Basics
● Neurons are nerve cells that conduct electrical impulses and transmit information
throughout the body.
● Do not undergo mitosis → cannot divide or regenerate.
● Lifespan: Can last a person’s entire lifetime.
● Highly dependent on oxygen — die within minutes without it.
Part Description / Function
Cell Body (Soma) Contains the nucleus and organelles; synthesizes all nerve cell products
(e.g., neurotransmitters). Cannot divide (no centrioles).
Dendrites Short, branched extensions that receive impulses from other neurons
and carry them toward the cell body.
Axon Single, long projection that conducts impulses away from the cell body
to axon terminals. Can be up to 3 feet long. Depends on cell body for
proteins.
Axon Terminals Ends of the axon; contain secretory vesicles with neurotransmitters.
Neurotransmitters Chemicals that transmit signals across the synapse from one neuron to
another.
Synapse The gap between two neurons — neurons never touch.
, Structural Classification Structure Location / Function
of Neurons
Multipolar 1 axon + many dendrites Motor neurons; most common type.
Bipolar 1 axon + 1 dendrite Found in retina (vision) and olfactory
system (smell).
Unipolar 1 process that splits into 2 Sensory neurons of the PNS.
(Pseudounipolar) branches
Functional Classification of Neurons
, Type Direction of Function / Notes
Impulse
Sensory (Afferent) From PNS → Carry sensory input (e.g., touch, pain) from
CNS receptors to CNS; usually unipolar.
Interneurons Within CNS Connect sensory and motor neurons; multipolar.
(Association)
Motor (Efferent) From CNS → Carry commands to muscles or glands; multipolar.
PNS
1.3 Neuroglial Cells in the Peripheral Nervous System (PNS)
Cell Type Structure / Function
Schwann Cells Form the myelin sheath — a white, fatty layer wrapped around axons.
Insulate the axon and speed up nerve impulses. Found only in the PNS.
Myelin Sheath Increases conduction speed of impulses by insulating axons from each
other.
Nodes of Ranvier Gaps between Schwann cells. Impulses “jump” from node to node —
called saltatory conduction, which makes transmission faster.
Satellite Cells Surround the cell bodies of PNS neurons (in ganglia). Help regulate and
stabilize the environment of the neuron cell body.
○ Receives, processes, and sends information.
○ Coordinates and controls all body systems.
● Nervous tissue carries electrical impulses between body parts — the “wiring” of the
body.
1. Central Nervous System (CNS)
● Includes: Brain + Spinal Cord.
● Protected by: Skull and vertebrae.
○ Processes information.
○ Sends and receives impulses to/from the PNS.
● Structures:
○ Nuclei: Collections of neuron cell bodies inside the CNS.
○ Tracts: Bundles of axons inside the CNS.
2. Peripheral Nervous System (PNS)
● Includes: All nerves outside the brain and spinal cord.
● Subdivisions:
○ Cranial Nerves – Emerge from the brainstem (innervate head, face, neck).
○ Spinal Nerves – Branch from the spinal cord (innervate trunk and limbs).
● Structures:
○ Ganglia: Collections of cell bodies outside the CNS.
○ Nerves: Bundles of axons in the PNS.
● Function: Connects all parts of the body to the CNS.
,1.2 – Neurons
Neuron Basics
● Neurons are nerve cells that conduct electrical impulses and transmit information
throughout the body.
● Do not undergo mitosis → cannot divide or regenerate.
● Lifespan: Can last a person’s entire lifetime.
● Highly dependent on oxygen — die within minutes without it.
Part Description / Function
Cell Body (Soma) Contains the nucleus and organelles; synthesizes all nerve cell products
(e.g., neurotransmitters). Cannot divide (no centrioles).
Dendrites Short, branched extensions that receive impulses from other neurons
and carry them toward the cell body.
Axon Single, long projection that conducts impulses away from the cell body
to axon terminals. Can be up to 3 feet long. Depends on cell body for
proteins.
Axon Terminals Ends of the axon; contain secretory vesicles with neurotransmitters.
Neurotransmitters Chemicals that transmit signals across the synapse from one neuron to
another.
Synapse The gap between two neurons — neurons never touch.
, Structural Classification Structure Location / Function
of Neurons
Multipolar 1 axon + many dendrites Motor neurons; most common type.
Bipolar 1 axon + 1 dendrite Found in retina (vision) and olfactory
system (smell).
Unipolar 1 process that splits into 2 Sensory neurons of the PNS.
(Pseudounipolar) branches
Functional Classification of Neurons
, Type Direction of Function / Notes
Impulse
Sensory (Afferent) From PNS → Carry sensory input (e.g., touch, pain) from
CNS receptors to CNS; usually unipolar.
Interneurons Within CNS Connect sensory and motor neurons; multipolar.
(Association)
Motor (Efferent) From CNS → Carry commands to muscles or glands; multipolar.
PNS
1.3 Neuroglial Cells in the Peripheral Nervous System (PNS)
Cell Type Structure / Function
Schwann Cells Form the myelin sheath — a white, fatty layer wrapped around axons.
Insulate the axon and speed up nerve impulses. Found only in the PNS.
Myelin Sheath Increases conduction speed of impulses by insulating axons from each
other.
Nodes of Ranvier Gaps between Schwann cells. Impulses “jump” from node to node —
called saltatory conduction, which makes transmission faster.
Satellite Cells Surround the cell bodies of PNS neurons (in ganglia). Help regulate and
stabilize the environment of the neuron cell body.
