Somatic Nervous System (SNS)
NERVOUS SYSTEM ➔ Transmits action potentials from the
CNS to skeletal muscles.
Functions of the Nervous System
Autonomic Nervous System (ANS)
➔ Receiving sensory input. Sensory
➔ Transmits action potentials from the
receptors monitor numerous external
CNS to cardiac muscle, smooth muscle,
and internal stimuli.
and glands
➔ Integrating information. The brain and
➔ Divided into sympathetic and
spinal cord are the major organs for
parasympathetic divisions
processing sensory input and initiating
Sympathetic: prepares the body for
responses.
(emergency situations) intense physical activity
➔ Controlling muscles and glands.
(fight or flight response) ex: adrenaline rush
Nervous system controls the skeletal
Parasympathetic: relaxes the body and (body
muscle (responsible for the
at rest) inhibits/slows down many high energy
movements of the body), as well as
functions (rest and digest function) ex:
cardiac, smooth muscles, and glands.
regulating digestion
➔ Maintaining homeostasis. The nervous
system can stimulate or inhibit the
Enteric Nervous System
activities of other systems to help
➔ A special nervous system found only in
maintain homeostasis.
the digestive tract
➔ Establishing and maintaining mental
activity. The brain is the center of
Cells of the Nervous System
mental activity (consciousness,
Neurons (nerve cells)
memory, and thinking).
➔ Receive stimuli, conduct action
potentials, and transmit signals to
Division of the Nervous System
other neurons or effector organs
Central Nervous System (CNS)
3 Parts
➔ Brain and spinal cord
1. Cell body (soma): contains single
nucleus; contains the nucleus and
Peripheral Nervous System (PNS)
holds all of the general parts of the
➔ All nervous tissue outside CNS (nerves
cell.
and ganglia).
➔ Nucleus: source of info for gene
➔ Is the communication link b/w CNS
expression, surrounded by rough ER,
and the various parts of the body
Golgi apparatus, mitochondria
➔ Carries info to CNS and delivers
➔ Neurofilaments and microtubules
commands from the CNS to body
organize the cytoplasm into distinct
tissues that alter body cavities.
areas.
2. Dendrites: are short, often highly
Sensory division (Afferent [toward] division)
branching cytoplasmic extensions that
➔ Conducts action potentials from
are tapered from their bases at the
sensory receptors to the CNS
neuron cell body to their tips (is where
Sensory neurons: neurons that transmit action
a neuron receives input from other
potentials from the periphery to CNS
cells.)
3. Axon: a single long process extending
Motor division (Efferent [away] division)
from the neuron to the cell body.
➔ Conducts action potentials to effector
organs, such as muscles and glands
➔ Axon: a single long process extending
Motor neurons: neurons that transmit action
from the neuron to the cell body.
potentials toward the periphery
, ➔ Axon hillock: the area where the axon ➔ participate w/ the blood vessel
leaves the neuron cell body endothelium to form a permeability
➔ Axons of sensory neurons: conduct barrier called blood-brain barrier. help
APs towards the CNS limit damage to neutral tissues
➔ Axons of motor neurons: conduct APs Ependymal cells : line the cavities (ventricles
away from CNS and canals) in the brain that contains
➔ An axon may remain unbranched or cerebrospinal fluid
may branch to form collateral axons. Microglial: act in an immune cell of the CNS by
removing bacteria and cell debris.
Myelin sheath are highly specialized insulating Oligodendrocytes: provide an insulating
layer of cells that surrounds the axons material that surrounds axons.
Schwann cells: in the PNS, where glial cells are
Types of Neurons known, they provide insulating material around
1. Sensory neuron: carrying info to the axons.
CNS from the body
2. Motor neuron: sending info to the body Myelin Sheaths
from the CNS ➔ are specialized layers that wrap
3. Multipolar neurons - have many around the axons of some neurons,
dendrites and a single axon. (Neurons those neurons are termed, myelinated.
in the CNS and all motor neurons) ➔ Axons outside the CNS is myelinated
4. Bipolar neurons - have two processes: by Schwann cell, protects and
one dendrite and one axon. Located in insulated the fibers and increases
sensory organs (retina in the eye, nasal transmission of nerve impulses
cavity) ➔ Are formed by the cell processes of
5. Pseudo-unipolar neurons have a glial cells. Specifically,
single process extending from the cell oligodendrocytes in the CNS and
body, which divides into two processes Schwann cells in the PNS.
as short distance from the cell body. Myelin is an excellent insulator that prevents
➔ One process extends to the periphery, almost all ion movement across the cell
and the other extends to the CNS. membrane.
➔ The two extensions function as a single Nodes of Ranvier: gaps in the myelin sheath;
axon with small, dendrite-like sensory ion mvmnt can occur
receptors at the periphery. Multiple sclerosis is a disease of the myelin
Peripheral process: carry impulses from the sheath that causes loss of muscle function.
skin/organs to ganglion Unmyelinated axons
Central process: “” from the some to the CNS ➔ lack the myelin sheaths
➔ These axons rest in indentations of the
Glial cells (neuroglia) oligodendrocytes in the CNS and the
➔ are the supportive cells of the CNS and Schwann cells in the PNS.
PNS, they DO NOT conduct action ➔ A typical small nerve, which consists of
potentials and carry out different axons of multiple neurons, usually
functions that enhance neuron contains more unmyelinated axons
function than myelinated axons.
Astrocytes: serve as the major supporting cells
in the CNS. Organization of Nervous Tissue
can stimulate or inhibit the signaling activity of The nervous tissue varies in color due to the
nearby neurons. abundance or absence of myelinated axons; it
exists in gray and white matter.
NERVOUS SYSTEM ➔ Transmits action potentials from the
CNS to skeletal muscles.
Functions of the Nervous System
Autonomic Nervous System (ANS)
➔ Receiving sensory input. Sensory
➔ Transmits action potentials from the
receptors monitor numerous external
CNS to cardiac muscle, smooth muscle,
and internal stimuli.
and glands
➔ Integrating information. The brain and
➔ Divided into sympathetic and
spinal cord are the major organs for
parasympathetic divisions
processing sensory input and initiating
Sympathetic: prepares the body for
responses.
(emergency situations) intense physical activity
➔ Controlling muscles and glands.
(fight or flight response) ex: adrenaline rush
Nervous system controls the skeletal
Parasympathetic: relaxes the body and (body
muscle (responsible for the
at rest) inhibits/slows down many high energy
movements of the body), as well as
functions (rest and digest function) ex:
cardiac, smooth muscles, and glands.
regulating digestion
➔ Maintaining homeostasis. The nervous
system can stimulate or inhibit the
Enteric Nervous System
activities of other systems to help
➔ A special nervous system found only in
maintain homeostasis.
the digestive tract
➔ Establishing and maintaining mental
activity. The brain is the center of
Cells of the Nervous System
mental activity (consciousness,
Neurons (nerve cells)
memory, and thinking).
➔ Receive stimuli, conduct action
potentials, and transmit signals to
Division of the Nervous System
other neurons or effector organs
Central Nervous System (CNS)
3 Parts
➔ Brain and spinal cord
1. Cell body (soma): contains single
nucleus; contains the nucleus and
Peripheral Nervous System (PNS)
holds all of the general parts of the
➔ All nervous tissue outside CNS (nerves
cell.
and ganglia).
➔ Nucleus: source of info for gene
➔ Is the communication link b/w CNS
expression, surrounded by rough ER,
and the various parts of the body
Golgi apparatus, mitochondria
➔ Carries info to CNS and delivers
➔ Neurofilaments and microtubules
commands from the CNS to body
organize the cytoplasm into distinct
tissues that alter body cavities.
areas.
2. Dendrites: are short, often highly
Sensory division (Afferent [toward] division)
branching cytoplasmic extensions that
➔ Conducts action potentials from
are tapered from their bases at the
sensory receptors to the CNS
neuron cell body to their tips (is where
Sensory neurons: neurons that transmit action
a neuron receives input from other
potentials from the periphery to CNS
cells.)
3. Axon: a single long process extending
Motor division (Efferent [away] division)
from the neuron to the cell body.
➔ Conducts action potentials to effector
organs, such as muscles and glands
➔ Axon: a single long process extending
Motor neurons: neurons that transmit action
from the neuron to the cell body.
potentials toward the periphery
, ➔ Axon hillock: the area where the axon ➔ participate w/ the blood vessel
leaves the neuron cell body endothelium to form a permeability
➔ Axons of sensory neurons: conduct barrier called blood-brain barrier. help
APs towards the CNS limit damage to neutral tissues
➔ Axons of motor neurons: conduct APs Ependymal cells : line the cavities (ventricles
away from CNS and canals) in the brain that contains
➔ An axon may remain unbranched or cerebrospinal fluid
may branch to form collateral axons. Microglial: act in an immune cell of the CNS by
removing bacteria and cell debris.
Myelin sheath are highly specialized insulating Oligodendrocytes: provide an insulating
layer of cells that surrounds the axons material that surrounds axons.
Schwann cells: in the PNS, where glial cells are
Types of Neurons known, they provide insulating material around
1. Sensory neuron: carrying info to the axons.
CNS from the body
2. Motor neuron: sending info to the body Myelin Sheaths
from the CNS ➔ are specialized layers that wrap
3. Multipolar neurons - have many around the axons of some neurons,
dendrites and a single axon. (Neurons those neurons are termed, myelinated.
in the CNS and all motor neurons) ➔ Axons outside the CNS is myelinated
4. Bipolar neurons - have two processes: by Schwann cell, protects and
one dendrite and one axon. Located in insulated the fibers and increases
sensory organs (retina in the eye, nasal transmission of nerve impulses
cavity) ➔ Are formed by the cell processes of
5. Pseudo-unipolar neurons have a glial cells. Specifically,
single process extending from the cell oligodendrocytes in the CNS and
body, which divides into two processes Schwann cells in the PNS.
as short distance from the cell body. Myelin is an excellent insulator that prevents
➔ One process extends to the periphery, almost all ion movement across the cell
and the other extends to the CNS. membrane.
➔ The two extensions function as a single Nodes of Ranvier: gaps in the myelin sheath;
axon with small, dendrite-like sensory ion mvmnt can occur
receptors at the periphery. Multiple sclerosis is a disease of the myelin
Peripheral process: carry impulses from the sheath that causes loss of muscle function.
skin/organs to ganglion Unmyelinated axons
Central process: “” from the some to the CNS ➔ lack the myelin sheaths
➔ These axons rest in indentations of the
Glial cells (neuroglia) oligodendrocytes in the CNS and the
➔ are the supportive cells of the CNS and Schwann cells in the PNS.
PNS, they DO NOT conduct action ➔ A typical small nerve, which consists of
potentials and carry out different axons of multiple neurons, usually
functions that enhance neuron contains more unmyelinated axons
function than myelinated axons.
Astrocytes: serve as the major supporting cells
in the CNS. Organization of Nervous Tissue
can stimulate or inhibit the signaling activity of The nervous tissue varies in color due to the
nearby neurons. abundance or absence of myelinated axons; it
exists in gray and white matter.
