Biology 12
Name: ________________________
The Nervous System (pp. 320-338)
Nervous Tissue
The nervous tissue has 2 main divisions:
1. ____________________________________ (CNS)

Consists of ________________ & _________________________
2. ____________________________________ (PNS)

Consists of ____________ that carry _______________________ messages to
the CNS & _________________ commands from the CNS to the
_______________ & _________________
The nervous system has 2 types of cells:
1. ___________________________ that transmit nerve impulses between parts of the nervous
system
2. ___________________________ that support & nourish neurons
There are 3 classes of neurons:
1. ________________________ neurons that take messages from sensory receptors to CNS

Sensory receptors detect changes in the ________________________
2. ________________________ that lie entirely within the CNS & receive input from
_____________________ neurons & other interneurons
3. ________________________ neurons that take messages from CNS to effectors in muscles
or glands
Neurons have 3 parts:
1. _________________________ that contains the nucleus & other organelles
2. _________________________ that receive signals from other neurons & send them to the
cell body
3. _________________________ that conduct nerve impulses away from the cell body toward
other neurons or target structures
Using Fig. 17.2 p. 319, draw & label a picture of a neuron.
Some axons are covered by a __________________________________. In the PNS, this covering is
formed by ________________ cells which wrap themselves around the axon many times. The myelin
sheath is interrupted and the gaps where there is no sheath is called ____________________________.
Functions of myelin:
1. An excellent ______________________________
2. Plays important role in nerve _________________________________
3. Speeds up nerve impulse
Long axons ______________ myelin sheaths, short axons _____________________ nor does the gray
matter in the CNS. The white matter of the CNS ________________ myelin sheaths.
Electrical potential difference between the outside & inside of an axon (a.k.a. voltage) is measured
using an _________________________.
When the axon is NOT conducting an impulse, its electrical potential difference is ________mV. The
inside of the axon is _________________ compared to the outside. This is called its ______________
potential.
The existence of this polarity is because of a difference in __________ distribution maintained by the
__________________________________________ pump. This pump actively moves _________ out
of the axon & _________ into the axon. This ensures that there is a greater concentration of _______
outside the axon & a greater concentration of ________ inside the axon.
An ________________________________ is a rapid change in polarity across the axomembrane.
Being an “all or nothing” phenomenon, the stimulus must cause the axomembrane to reach a
______________________ for an action potential to occur.
First, _______________ channels open allowing _________ to flow into the axon. The membrane’s
potential changes from _______mV to _______mV. This is _______________________________.
Second, _____________________ channels open allowing ______ to flow out of the axon. This
returns the action potential to __________mV. This is _____________________________.
Like a domino effect, each proceeding portion causes an ___________________________ in the next
portion of the axon. As soon as the action potential has moved on, the previous portion undergoes a
_________________________ period when the _________________ gates cannot open ensure the
impulse can only move forward.
Ion exchange can only occur at the nodes of __________________ meaning impulses move faster in
myelinated axons as the action potential will “jump” from node to node. This is called
_________________________________________.
At the end of every axon is a small swelling called an _________________________. This lies very
close to either a _____________________ or another neuron’s cell body. This region of close
proximity is called a ___________________________. The small gap is called a _________________
__________________. Transmission across the gap is carried out by __________________________.
When impulses reach the bulb, ___________ channels open up allowing _________ to enter the bulb.
This stimulates the synaptic _______________ containing neurotransmitters to merge with the
_______________________________ membrane, which releases the neurotransmitters into the
synaptic ______________. They diffuse across & bind with ____________________ proteins.
An excitatory neurotransmitter has a ___________________________ effect, which drives the neuron
closer to an action potential. An inhibitory neurotransmitter has a _____________________________
effect, which drives the neuron further from an action potential. __________________________ is the
summing up of inhibitory & excitatory signals.
At least __________ neurotransmitters have been identified including ________________________
(ACh) & _______________________________ (NE).
Neurotransmitters can be inactivated by ______________________ such as
___________________________________ (AChE) which breaks down acetylcholine or they can be
reabsorbed by the presynaptic membrane for _______________________________ or breakdown.
The Central Nervous System (CNS)
The ________________ and _____________________________ make up the CNS where
_____________________ info is received & ___________ control is initiated. Both are protected by
_________________. Both are wrapped in protective membranes called _____________________.
The space between the membranes is filled with _______________________________ fluid, which
cushions & protects. This fluid is also contained within the brain’s _________________________.
________________________ is an infection of the meninges & ___________________________ can
occur in infants whose excess cerebrospinal fluid is prevented from draining.
_______________________ protect the spinal cord. Spinal ____________________ project from the
spinal cord between the vertebrae. Intervertebral _________ separate vertebrae. The spinal cord is part
of the CNS but the spinal nerves are part of the ______________. The function of the spinal cord is to
provide a means of ___________________________ between the __________________ & the PNS.
Loss of sensation & loss of voluntary control is called ________________________. Another function
of the spinal cord is the center for _______________________ arcs.
_______________________ cause sensory receptors to send a nerve impulse to the spinal cord.
_______________________ in the spinal cord will integrate the data & send a signal to the
____________________ neurons. This will cause muscles to ______________________.
Use Fig. 17.7 to complete the following chart:
The Brain
The _________________________ (or telencephalon) is the ________________________ part of the
brain in humans. It _______________________ & _________________________ the activities of
other parts of the brain. It carries out higher thought processes required for __________________,
memory, language, & ______________________. The cerebrum is divided into left & right
________________________________________________________ connected by the corpus
callosum. Each hemisphere is divided into 4 lobes:
1. ____________________________

Movement

Higher intellect (Prefrontal area)

Motor speech (_________________ area)
2. ____________________________

Sensations

Taste
3. ____________________________

Hearing

Sensory speech (___________________ area)

Smell
4. ___________________________

Vision
The ________________________________ is a thin, highly convoluted outer layer of gray matter that
covers the cerebral hemispheres. It is responsible for sensation, voluntary ____________________
(motor), & conscious thought.
1. Voluntary movement: _________________________________ area is in the frontal lobe.
2. Sensation:

The _____________________________________ area is in the parietal lobe. It is
responsible for receiving ___________________ information from the skin & skeletal
muscles.

Primary visual area receives information from our __________ & is found in the
____________________ lobe.

Primary auditory area receives information from our ____________ & is found in the
____________________ lobe.

Primary taste area receives information from our _______________ & is found in the
____________________ lobe.
3. Conscious thought: develops at association areas where __________________ occurs

Somatosensory association area in the ________________________ lobe processes &
analyzes sensory information from skin & muscles

Visual association area in the _____________________ lobe processes & analyzes
visual information

Auditory association area in the ____________________lobe processes & analyzes
auditory information

Prefrontal area in the _____________________ lobe receives information from all other
association areas & uses this info to reason & plan actions
The ______________ matter consists of long myelinated axons organized into _____________.
Because the tracts cross over the medulla, the ___________ side of the cerebrum controls the
_______________ side of the body & vice versa. Tracts take ___________________ between the
different sensory, motor & association areas.
______________________________ ensures proper muscle movement. ______________________
disease & ______________________ disease are thought to be due to malfunction in this area.
The diencephalon contains the _______________________ & _______________________. The
hypothalamus helps maintain __________________________ by regulating hunger, ____________,
body ___________________, & water ______________________. It also controls the
_________________________ gland so serves as a link between the ______________________ &
__________________ systems. The thalamus receives all sensory input except ____________,
integrates the info, & sends it to the ____________________.
The ____________________ maintains __________________ & ___________________. It also
ensures smooth, _________________________ voluntary movements.
The brain stem consists of the midbrain, ___________, & ______________________________. The
midbrain acts as a _____________ station between the cerebrum & spinal cord or cerebellum &
contains _____________ centers. The pons forms a “_________________” between the cerebellum &
the rest of the CNS. It assists the medulla oblongata to regulate ______________ & also has
_______________ centers. The medulla oblongata has ______________ centers for regulating
_____________________, ______________________, blood pressure, vomiting, _______________,
sneezing, hiccupping, & ______________________.
Note: Sec. 17.3 The Limbic System & Higher Mental Functions is for interest sake. You will not be
tested on this section.
The Peripheral Nervous System (PNS)
The PNS is composed of ______________ & _________________. _________________ nerves
(fibers) carry info to the CNS & ______________ nerves (fibers) carry info away from the CNS.
_________________ are swellings associated with nerves that contain ___________ bodies. There are
______ pairs of cranial nerves & _________ pairs of spinal nerves. Cranial nerves take impulses to &
from the ___________ & spinal nerves take impulses to & from the _________________________.
The PNS is subdivided into the ____________________ & ________________________ systems. The
____________________ system serves the skin, skeletal muscles, & tendons. Some actions in this
system are ____________ (autonomic responses to stimuli).
In a reflex arc, sensory receptors generate _______________________________ that move along
sensory nerves. Sensory nerves pass the signal on to ______________________ in the spinal cord.
Interneurons synapse with __________________ neurons which send the nerve impulse to an
_______________________ which brings about a response to the stimulus. ______________ will not
be felt until the ______________ receives the information & interprets it. These involuntary reflexes
allow us the respond ___________________ to stimuli.
The autonomic system regulates the activity of ____________________ & ___________________
muscle and glands. It is divided into _________________________ & ________________________
branches. The two divisions function ______________________ & bring nerves to all internal
___________________.
Most nerves of the sympathetic division come from the ________________________ portion of the
spinal cord. It is especially important during ________________________ situations (“fight or flight”).
The parasympathetic division includes a few ___________________ nerves & nerves that come from
the ____________________ portion of the spinal cord. It promotes responses associated with a
____________________ state (“rest & digest”).
Organ
Eye
Digestion
Heart rate
Lung/bronchi
Neurotransmitter
Sympathetic Response
Parasympathetic Response