Download Nervous System Guided Notes

Nervous System Guided Notes
Name:___________________ Class:______
Do Now
Which “fact” is false?
1) All body functions are controlled and regulated by the nervous system
2) There are more neurons in the brain then there are stars in the Milky Way galaxy
3) The left side of the body is controlled by the right side of the brain and vice-versa
4) The brain reaches maturity at around 25 years of age.
Nervous System Functions
The nervous system has three major functions:
1.
2.
3.
1) _____________________________ – the body gathers information, or _________________________ from the
internal or external environment
Ex) seeing a bright light
2) _____________________________– the body processes information and makes a decision about what should be
done
Example: “decision” to initiate flight – or- fight response
3) _______________________________– the body activates muscles or glands to effect a response.
Example: moving your arm to grab a chip
Which function(s) are demonstrated in these examples?
 You hear a buzzing sound.

You weigh the pros and cons of two different universities, and make a choice.

You move your leg

You touch a hot stove and jerk your hand back.
Nervous System Organization
Structurally, the nervous system is organized into
 The _______________________________________, which consists of the brain and spinal cord, and which acts
to integrate (interpret & issue instructions for) stimuli

The ________________________________________, which consists of all the nerves outside the brain and
spinal cord. These receive stimuli and effect responses in muscles and glands.
The peripheral nervous system can be further divided into:
1) _______________________________or sensory neurons
- bring stimuli to CNS
-- affect the body by internal or external information
2) _______________________________or motor neurons
-- cause muscles or glands to respond
-- effect a change / response
Mneumonic : A (afferent)
comes before E (efferent) –
must have sensory stimuli
before you can have a
response
The efferent / motor neurons can be further divided into:
1) _______________________________
- neurons that control
skeletal muscles
- mostly voluntary
2) ____________________________________
-- neurons that control smooth and cardiac muscle and glands
- involuntary
Determine which parts of the nervous system are involved in these:
You hear a buzzing sound.
You weigh the pros and cons of two different universities, and make a choice.
You move your leg
You touch a hot stove and jerk your hand back.
Neuroglia
All nervous tissue cells _______________________________ are known as neuroglia, or glial cells. Neuroglia
means “nerve glue”.
CNS Neuroglia
__________________________________ (star-cell)
 __________________________________________________



protect neurons from harmful materials.
“blood brain barrier”
Control flow of blood through brain (what is measured in MRI)
 __________________________________________________
 change shape
 release calcium and ‘glial transmitters’; uptaking ions and neurotransmitters
 Digest waste
 Moderate the behavior of neurons
____________________________________________________
 Shaped like astrocytes, but smaller, and don’t connect neurons to blood vessels
 ________________________________________________________________________

___________________________________________________
 Line the cavities of the brain and the spinal cord
 ________________________________________________________________________
______________________________________________________
 ______________________________________________________________________
______________________________________________________________________
 Each oligodendrocyte wraps around the axons of several neurons
 Allow for efficient nerve impulse propagation
PNS Neuroglia
___________________________

__________________________________
__________________________________

Many Schwann cells per neuron

Give peripheral neurons some ability to
regenerate
______________________________________________

_____________________________________________________________________

Function not fully understood – may have similar function as astrocytes??
Think, Pair, Share
 Identify the two PNS glial cells, determine which cells in the CNS have similar function, and describe
the similarities and differences in each pair of cells.

Identify two similarities and one difference between astrocytes and microglia

Explain the location and function of ependymal cells
Neuron Anatomy
The ________________________ contains the nucleus and organelles
•
_________________________ is rough ER
•
_________________________ are intermediate filaments
_______________________________ carry information.
•
•
______________________________________________________________________________
_____________________________________________________.
•
__________________________________________________________________
_________________________________________________________________.
•
There may be 100’s of dendrites, but only 1 or 2 axons.
•
The end of the axon branches into 100’s or 1000’s of axon terminals
___________________________ wrap around most PNS axons, forming the myelin sheath.
•
____________________________ are gaps in the myelin sheath / spaces between Schwann cells.
Nerve Impulses and Reflexes
Irritability and Conductivity
Individual neurons have two major functional properties: irritability and conductivity.

Irritability = ability to ________________________________________ and _____________________________
______________________________________

Conductivity = ability to _______________________________________ to other neurons, muscles, or glands.
Irritability
What types of stimulus trigger nerve impulses?

______________________________________________________________ (e.g. touch, temperature, pressure,
tension, sight, hearing, chemical)

All ___________________________ (interneurons, motor neurons) ___________________________________
released by other neurons
What is a nerve impulse?

A quick switch in ___________________________________________________________________________
that travels all the way along the axon of the neuron

Occurs due to flow of ions across the membrane

All – or – nothing
Resting Potential


Neurons at rest have an ____________________________________ across the cell membrane, known as the
resting potential.
The resting potential is approximately -70mV.
The resting potential is maintained by:

__________________________________________________ (3 Na+ pumped out for every 2 K+ pumped in)

___________________________________________________ (K+ can diffuse back out to some degree)

________________________________ (- ions) within cell
Action Potential

An action potential involves the rapid depolarization and repolarization of the membrane.
Steps of an Action Potential
1) When a stimulus is applied to a nerve, _________________________, allowing Na+ to diffuse in.
2) Once a threshold is reached, _________________________, causing _________________ of the membrane.
When the membrane is depolarized, the inside of the membrane is ______________________ than the outside.
3) Membrane _____________________ occurs when Na+ gates close and K+ gates open, allowing net ___________
_______________________ outside. Repolarization ________________________________
___________________ (more negatively charged inside)
4) The K+ gates close and the resting potential is maintained by the Na+ / K+ pump
Turn and Talk

At rest, what ions are most abundant outside the cell, and which are most abundant inside the cell?

Which side of the membrane is more negative at rest?

Describe how the movement of ions causes

Depolarization

Repolarization
Nerve Impulse Propagation
The nerve impulse moves along the axon.
The change in voltage of one area triggers the depolarization of the next area.
Repolarization follows immediately.
In myelinated neurons the impulse “jumps” from node to node,
rather than traveling the whole length of the axon – makes the impulse
transmission much more efficient.
Conductivity
Synapses
•
•
The __________________________________________________________________ is called a synapse
Chemicals called _______________________________ carry the nerve impulse across the synapse.
Steps of synaptic transmission
1. The nerve impulse reaches the axon terminal.
2. Ca+ gates open, allowing Ca+ into the axon.
3. The Ca+ causes vesicles containing neurotransmitters to empty into the synapse
4. The neurotransmitters diffuse across the synaptic cleft and binds with receptors of the next neuron.
5. Na+ channels open in the dendrites of the post-synaptic neuron
6. Post-synaptic neuron depolarizes
7. Remaining neurotransmitter is broken down.
Brain Structure and Function
The brain is divided into four main regions:

_________________________

_________________________

_________________________

_________________________
Cerebrum


Largest region
Responsible for _______________________________________________:
◦ speech
◦ memory
◦ reasoning
◦ emotion
◦ consciousness
◦ interpretation of sensation
◦ voluntary movement
 Divided into left and right hemispheres
 Wrinkled texture
◦ Raised areas called ___________________
◦ Shallow grooves called ____________________
Deep groves called _______________________
The outer part of the cerebrum – called the
_________________________________________-is composed of gray matter


Gray matter = ________________________
____________________________________

This is where thought, sensation, etc. occur

The inner part of the cerebrum is mostly
white matter

White matter = ______________________
____________________________________

This is the connection between different
regions of the brain
The _________________________________________ is one especially important area of white matter – it’s the
connection between the two cerebral hemispheres
Diencephalon structure
The diencephalon consists of three parts:

__________________________

__________________________ (completely enclosed by thalamus)

__________________________

Regulation of autonomic functions, including
◦ __________________________________
◦
__________________________________
◦
__________________________________

_____________________________________________________

_____________________________– emotional / visceral brain (sex, food, thirst, pain, pleasure)
Brain Stem
The brain stem consists of three parts



______________________________
______________________________
______________________________
Controls many autonomic functions, including:



_______________________________
_______________________________
_______________________________
Allows passage of nerve fibers between brain and spinal cord
Cerebellum


Back of the brain, beneath cerebrum
Like cerebrum, it has
o Two hemispheres
o Wrinkled surface
o Outer cortex made of gray matter outside
Functions:


_______________________________________________________
________________________________________________________
Questions
Following a stroke, a person develops the symptoms listed below. In each case, which part of the brain was
injured?


Ataxia (an inability to coordinate muscular movement)
Drooping left side of face
Cerebrospinal Fluid

Fluid that surrounds and protects brain and spinal cord

Produced by the _________________________ from blood plasma, and drains back into the blood

Some diseases can be diagnosed by examining CSF collected during a spinal tap
Which glial cells are involved with CSF? What do they do?
Blood brain barrier

Protects the brain from toxins, most drugs, and fluctuations in other chemicals such as ions

Two major barriers
◦
___________________________________________
◦
___________________________ which control flow ofmaterials from blood vessels to neurons
Why is the blood brain barrier necessary?
Does the blood brain barrier block the passage of alcohol?
Brain Injuries and Parasympathetic vs Sympathetic Divisions
Traumatic Brain Injury
 Leading cause of accidental death among all people in US
○ 1.7 million experience TBI each year…
… causing ~52,000 deaths each year
 Leading cause of all death and disability among US children
○ ~500,000 children visit ER with TBI each year
Causes of Brain Injury
 ___________________ & _______________________ are leading causes
 Sports-related are grouped in the struck/by against
 Important to understand that the damage is caused not just by the blow, but also by the brain
______________________________________________________________________________
Concussion –
 Mild injury (though still serious)
 _______________________________________________ (such as severing of connections between
neurons)
 Symptoms
 Dizziness, nausea, inability to concentrate, memory difficulties, sensitivity to light or sound,
mood changes, sleep changes
 Treatment
 _________________________________________________________________
 VERY IMPORTANT TO PREVENT SECONDARY IMPACT!
Contusion –
 Localized tissue bruising / destruction
 Often occurs with _______________________________ (extensive bleeding in the brain)
 Often causes __________________________________________ (brain swelling), which can be fatal if
the pressure isn’t relieved
 Symptoms
 Same as concussion, but more often include __________________________________,
___________________________, ______________________________
 Can be seen on MRI / CT
 More likely to cause permanent loss of function or death
Misconception alert!
 A contusion is not simply a more severe concussion. You can have a concussion, or a contusion, or
both.
Cerebrovascular Accident (aka stroke)
 3rd leading cause of death in US
 ________________________________
due to clot or bleeding in the brain
 Brain tissue dies due to lack of oxygen
 Treatment involves restoring blood flow
through ______________________,
blood thinners, shunts, etc.
 Long-term effects depend on location,
size/degree of blockage, and speed of
treatment
The scenario...
A semi-conscious young woman is brought to the hospital by friends after falling from a roof. She did not lose
consciousness immediately, and she was initially lucid. After a while, though, she became confused and then
unresponsive.
Questions
 What is a likely explanation for her condition?
 What test(s) would you do?
 What treatment(s) might be necessary?
 What is her prognosis?
Misconception alert!
We are not usually in “sympathetic mode” or “parasympathetic mode” … rather, our body constantly uses the
two types of neurons to maintain homeostasis (e.g. raising or lowering heartbeat, increasing or decreasing
digestion, as needed).
If SD and PD are both motor neurons, connecting in many cases to the same organs, HOW do they create
opposite effects?