THE NERVOUS SYSTEM LECTURE NOTES
How information is received from the outside world and passed along to the entire body
CENTRAL NERVOUS SYSTEM (CNS): Main part of the nervous system, the “command
center”; consists of the brain, spinal cord, and brain stem (more detail in other lectures)
o SPINAL CORD:
Controls trunk and limb muscles
Carries vital information from the rest of the body into and out of the brain
Not only relays messages but can also initiate some involuntary
automatic behaviors (reflexes) – a signal only travels as far as the spinal
cord, spinal cord initiates action, brain is notified later
The patellar reflex test at doctors’ offices (tapping the knee and
kicking in response)
The grasp reflex (stroking a baby’s hand causes them to close
their fingers in a grasp)
Pulling away from something hot automatically, and processing
being burned after the fact
PERIPHERAL NERVOUS SYSTEM (PNS): All the nerves outside of the brain and spinal
cord; links brain and spinal cord to the body’s sense receptors, muscles, and glands;
made up of scout-like sensory motor neurons that carry messages to the periphery of
the body
o SOMATIC NEROUS SYSTEM (SOMA = BODY): Also known as the voluntary
nervous system; like a two-way street, first carries sensory information to the
brain and spinal cord and then carries messages from the CNS to the skeletal
muscles
Controls all things we are aware of and can consciously influence, such
as moving the arms and legs or other parts
Also associated with reflexes
o AUTONOMIC NERVOUS SYTEM: Like an autopilot, operates automatically;
mediates an organism’s responses to stress as well as various kinds of
vegetative functions
Responsible for involuntary tasks like heat rate, digestion, pupil dilation,
breathing, etc. (Stress response can impact these actions)
Can be further divided into subsystems, sympathetic and
parasympathetic; the two systems are like children on a seesaw:
function in opposition but ultimately complementary
SYMPATHETIC NERVOUS SYSTEM: Kicks in when stressed to
mobilize bodily resources to respond to the stressor; associated
with fight or flight (winds you up, depletes bodily resources)
o Organizes the body to meet emergencies
o Concerned with getting more oxygenated blood and
energy to skeletal muscles
o Shuts down trivial functions (stops digestive and
eliminative processes) to prioritize energy being put into
How information is received from the outside world and passed along to the entire body
CENTRAL NERVOUS SYSTEM (CNS): Main part of the nervous system, the “command
center”; consists of the brain, spinal cord, and brain stem (more detail in other lectures)
o SPINAL CORD:
Controls trunk and limb muscles
Carries vital information from the rest of the body into and out of the brain
Not only relays messages but can also initiate some involuntary
automatic behaviors (reflexes) – a signal only travels as far as the spinal
cord, spinal cord initiates action, brain is notified later
The patellar reflex test at doctors’ offices (tapping the knee and
kicking in response)
The grasp reflex (stroking a baby’s hand causes them to close
their fingers in a grasp)
Pulling away from something hot automatically, and processing
being burned after the fact
PERIPHERAL NERVOUS SYSTEM (PNS): All the nerves outside of the brain and spinal
cord; links brain and spinal cord to the body’s sense receptors, muscles, and glands;
made up of scout-like sensory motor neurons that carry messages to the periphery of
the body
o SOMATIC NEROUS SYSTEM (SOMA = BODY): Also known as the voluntary
nervous system; like a two-way street, first carries sensory information to the
brain and spinal cord and then carries messages from the CNS to the skeletal
muscles
Controls all things we are aware of and can consciously influence, such
as moving the arms and legs or other parts
Also associated with reflexes
o AUTONOMIC NERVOUS SYTEM: Like an autopilot, operates automatically;
mediates an organism’s responses to stress as well as various kinds of
vegetative functions
Responsible for involuntary tasks like heat rate, digestion, pupil dilation,
breathing, etc. (Stress response can impact these actions)
Can be further divided into subsystems, sympathetic and
parasympathetic; the two systems are like children on a seesaw:
function in opposition but ultimately complementary
SYMPATHETIC NERVOUS SYSTEM: Kicks in when stressed to
mobilize bodily resources to respond to the stressor; associated
with fight or flight (winds you up, depletes bodily resources)
o Organizes the body to meet emergencies
o Concerned with getting more oxygenated blood and
energy to skeletal muscles
o Shuts down trivial functions (stops digestive and
eliminative processes) to prioritize energy being put into
