NERVOUS SYSTEM TEST

Dendrite Description

• short and branched

• Receives signals from other neurons

• Carries messages towards cell body

Axon Description

• Long and single

• Sends signals to other neurons or muscles

• Carries messages away from the cell body

CNS parts

Brain and Spinal Cord

PNS parts

Cranial and Spinal Nerves

Schwann Cells

Cells in the PNS that wrap around axons to form the myelin sheath

What are the 4 types of CNS neuroglia cells

1. Astrocytes

2. Oligodendrocytes

3. Microglia

4. Ependymal

Astrocytes Functions

• support neurons

• maintain the blood brain barrier

• regulate nutrients and ions

Oligodendrocytes Functions

• form the myelin sheath

• insulate axons

• speed up signal transmission

Microglia Function

Remove debris and pathogens by phagocytosis

Ependymal Functions

• line the ventricles of the brain and spinal cord

• produce and circulate CSF

Somatic Nervous System

• Voluntary actions

• Moves skeletal muscles

• Conscious control

Autonomic Nervous System

• Controls involuntary actions

• Controls organs, glands, and smooth and cardiac muscles

• Unconscious control

What does the Sympathetic Nervous System do for us?

Fight or Flight

What does the Parasympathetic Nervous System do for us?

Rest and Relax

What are the 3 layers of the meninges?

1. Dura Mater

2. Arachnoid Mater

3. Pia Mater

Dura Mater function

Protects brain and spinal cord from injury

Arachnoid Mater function

Cushions brain by holding CSF

Pia Mater function

Sticks tightly to the brain and spinal cord, supplying nutrients and O2

What is the corpus callosum?

A thick band of nerve fibers that connects the left and right sides of the brain

What are the four main lobes of the cerebrum?

1. Frontal

2. Parietal

3. Occipital

4. Temporal

Frontal lobe functions

• thinking

• Decision making

• Personality

Parietal Lobe function

Sensations like touch, temperature, and pain

Temporal lobe function

Hearing

Occipital lobe function

Vision

What does Broca’s area do?

Help you produce speech

Precentral Gyrus function

Controls voluntary movement of body

Postcentral Gyrus function

Processes touch, pressure, pain, and temperature

Where is the Thalamus located

Deep inside the brain, just above the brain stem, in the center of the brain

Thalamus function

Sends sensory signals to the right part of the brain

Hypothalamus location

Just below the Thalamus in the brain, near the base of the brain

Hypothalamus function

Controls body functions like:

• hunger

• thirst

• body temperature

• sleep

• hormones

What are the parts of the brainstem?

• Midbrain

• Pins

• Medulla Oblongota

Medulla Oblongota functions

Heart Rate and Breathing

Limbic System

A group of brain structures that control emotions, memory, and behavior

Reticular Formation

A network of nerves in the brainstem that controls alertness and attention

What is the functional unit of the nervous system?

The Neuron

Dendrite

Short, branchlike parts of a neuron that recieves signals from other nerve cells and carry those signals toward the cell body.

Their main function is to collect info so the neuron can process it

Axon

Long, thin part of a neuron that carries electrical signals away from the cell body to other neurons, muscles, or glands

Axon Hillcock

Cone shaped area where the cell body of a neuron connects to the axon. It starts the action potential if the incoming signals are strong enough.

Nodes of Ranvier

Small gaps between the myelin sheath along an axon that speeds up nerve signal transmission by allowing the electrical signal to jump from one node to the next.

Nissl Bodies

Small, grainy structures found in the neuron’s cell body and dendrites. It makes proteins that the neurons need for growth, repair, and normal function.

Schwann Cells

Cells in the PNS that wrap around axons to form the myelin sheath. They insulate the axon and speed up nerve signal transmission.

Neurilemma

The outermost layer of a Schwann cell that surrounds a nerve fiber in the PNS. It protects the axon and help in nerve regeneration post injury.

Myelin Sheath

The fatty, insulating layer that wraps around an axon. It speeds up the transmission of nerve signals along the neuron.

Synaptic Knob (Axon Terminal)

The small, rounded end of an axon. It releases NT’s that carry the signal across the synapse to the next cell.

What are the parts of the central nervous system (CNS)?

• brain

• spinal cord

What are the parts of the peripheral nervous system (PNS)?

• cranial

• spinal nerves

What are the 2 functional parts of the PNS?

1. Sensory (Afferent)

2. Motor (Efferent)

What does the Sensory unit do?

Bring information towards the CNS

What does the Motor unit do?

Carry information away from the CNS

What are the 2 divisions of the Motor unit?

1. Somatic

2. Autonomic

What type of control is the Somatic Nervous System (SNS) of the Motor Unit?

Conscious

What type of control is the Autonomic Nervous System (ANS) of the Motor Unit?

Unconscious

Somatic Nervous System (SNS) effectors

Skeletal Muscle

Autonomic Nervous System (ANS) effectors

• Smooth Muscle

• Cardiac Muscle

• Glands

What are the 2 divisions of the Autonomic nervous system (ANS)?

1. Parasympathetic

2. Sympathetic

What is the Parasympathetic Nervous System?

• “Rest and Digest”

• Homeostasis

What is the Sympathetic Nervous System?

• “Fight or Flight”

• Energy Expending

Sympathetic Nervous System neurotransmitter

Acetylcholine (Ach)

Parasympathetic Nervous System neurotransmitter

Norepinepherine

Neuroglial cells function

Produce growth factors that nourish the neurons and remove ions and neurotransmitters between neurons to continue info transfer.

What do neuroglial cells do in embryo?

Guide neurons to position and may stimulate to specialize

What cells are in the PNS?

• Schwann Cells

• Satellite Cells

What cells are in the CNS?

• Astrocytes

• Oligodendrocytes

• Microglia

• Ependymal

What do Astrocytes look like?

Star-shaped

Where are astrocytes found?

Between neurons and blood vessels to provide support

What are the 7 functions of Astrocyte cells?

1. Plays important role in blood barrier

2. Most abundant / versatile

3. Aids metabolism

4. Mop up leaked sodium

5. Recapture and recycle neurotransmitters

6. Responds to injury in the brain tissue to form a special type of scar

7. Participate in informational processes in the brain

What do Oligodendrocytes look like?

They resemble astrocytes with fewer processes

What do Oligodendrocytes do?

Form myelin in brain and spinal cord, which speeds up impulses

What can Oligodendrocytes do regarding myelin?

A single Oligodendrocyte can provide myelin for multiple neuron axons

What do Microglia look like?

Small with fewer processes

Microglia functions (2)

1. Help support neurons

2. Phagocytic against bacteria to cellular debris

Where are Microglia located?

They are scattered in the CNS

When do Microglia increase in number?

When brain or spinal cord is inflammed

Why are Microglia important?

Because cells of our immune system are denied access to the CNS

What do Ependymal cells look like?

Columnar or cuboidal with cilia

Where are Ependymal cells found?

They form the inner lining of central canal and cover inside spaces in the brain called ventricles

What do Ependymal cells do?

Help ventricles regulate composition of cerebralspinofluid (CFS)

What is step 1 of the transmission of nerve impulses?

Resting Potential

What is step 2 of the transmission of nerve impulses?

Threshold Reached

What is step 3 of the transmission of nerve impulses?

Depolarization

What is step 4 of the transmission of nerve impulses?

Repolarization

What is step 5 of the transmission of nerve impulses?

Hyperpolarizzation

What is step 6 of the transmission of nerve impulses?

Return to Resting Potential

Resting Potential

• Neuron is at –70 mV

• Inside is negative, outside positive

• Sodium–potassium pump maintains this

Threshold Reached

• A stimulus brings the neuron to about –55 mV

• This is the minimum needed to trigger an impulse

Depolarization

• Sodium (Na⁺) channels open

• Na⁺ rushes in

• Inside becomes positive

• Membrane potential rises to about +30 mV

Repolarization

• Sodium channels close

• Potassium (K⁺) channels open

• K⁺ flows out

• Membrane potential drops back toward –70 mV

Hyperpolarization

• K⁺ keeps leaving briefly

• The neuron becomes more negative than resting

Return to resting potential?

• Sodium–potassium pump restores balance

• Neuron returns to –70 mV

• Ready for the next impulse

Where are Meninges located?

Between bone and soft tissue of brain and spinal cord

What are the 3 layers of the Meninges

1. Dura mater

2. Arachnoid Mater

3. Pia Mater

Dura Mater location

Outermost layer

What is Dura Mater made of?

Tough, white dense CT

What are Dura Mater channels?

Dural Sinuses

Arachnoid Mater (Middle Layer) description

Thin, web-like membrane that lacks blood vessels

What does the Subarachnoid Space do?

Absorb forces before they reach the brain

Subarachnoid Space description

• located below Arachnoid Mater

• contains CSF

Pia Mater description

Thin, contains many nerves and blood vessels

Pia Mater function

Helps nourish brain cells and spinal cord