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

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 legYou touch a hot stove and jerk your hand back.

Mneumonic : A (afferent) comes before E (efferent) – must have sensory stimuli before you can have a response

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

______________________________________________

_____________________________________________________________________

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

___________________________

____________________________________________________________________

Many Schwann cells per neuron

Give peripheral neurons some ability to regenerate

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

Cerebrum

Largest region Responsible for _______________________________________________:

◦ speech◦ memory

The brain is divided into four main regions:

_________________________

_________________________

_________________________

_________________________

◦ 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 _________________________________________ is one especially important area of white matter – it’s the connection between the two cerebral hemispheres

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

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 hemisphereso Wrinkled surfaceo 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 yearCauses 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)

The scenario...

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

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?