ANALEC [NERVOUS SYSTEM] - MIDTERMS

Give the functions of the Nervous System.

1. Sensory Input

2. Integration

3. Motor Output

Sensory Input

Gathering information; to monitor changes occurring inside and outside the body (changes = stimuli).

Integration

To process and interpret sensory input and decide if action is needed.

Motor Output

A response to integrated stimuli; the response activates muscles or glands.

Central Nervous System (CNS)

Structural Classification of the:

• Brain

• Spinal cord

Peripheral Nervous System (PNS)

Structural Classification of the:

• Nerves outside the brain and spinal cord

Sensory (Afferent) Division

Nerve fibers that carry information TO THE central nervous system.

Motor (Efferent) Division

Nerve fibers that carry impulses AWAY FROM the central nervous system.

How many subdivisions does the Motor (Efferent) Division have?

2

Somatic Nervous System

Voluntary

Autonomic Nervous System

Involuntary

Astrocytes

• Abundant, star-shaped cells

• Brace neurons

• Form barrier between capillaries and neurons

• Control the chemical environment of the brain (CNS)

Microglia (CNS)

• Spider-like phagocytes

• Dispose of debris

Ependymal Cells (CNS)

• Line cavities of the brain and spinal cord

• Circulate cerebrospinal fluid

Oligodendrocytes (CNS)

Produce myelin sheath around nerve fibers in the central nervous system.

Neuroglia…

Divide

Neurons…

Do not divide

Most brain tumors are…

“Gliomas”

Most brain tumors involve the…

Neuroglia cells

Give the support cells of the PNS.

• Satellite Cells

• Schwann Cells

The support cells of the PNS that protect neuron cell bodies.

Satellite Cells

The support cells of the PNS that form myelin sheath in the peripheral nervous system.

Schwann Cells

Neurons = ?

Nerve Cells

Neurons

Cells specialized to transmit messages

What are the major regions of neurons?

• Cell Body

• Processes

Cell Body

Nucleus and metabolic center of the cell.

Processes

Fibers that extend from the cell body (dendrites and axons).

The cell body includes…

• Nucleus

• Large nucleolus

Dendrites

Conduct impulses TOWARD the cell body.

Axons

Conduct impulses AWAY FROM the cell body (only 1!)

The axons end in…

Axonal Terminals

Axonal Terminals

These contain vesicles with neurotransmitters.

Axonal Terminals

These are separated from the next neuron by a gap.

Synaptic Cleft

Gap between adjacent neurons.

Synapse

Junction between the nerves.

Schwann Cells

These PRODUCE myelin sheaths in JELLY-ROLL like fashion.

Nodes of Ranvier

These are the GAPS in the myelin sheath ALONG THE AXON.

In Multiple Scleroses, the myelin sheath is…

Destroyed

The myelin sheath hardens to a tissue called the…

Scleroses

What type of disease is Multiple Scleroses considered?

Autoimmune Disease

Where are neuron cells mostly located?

Central Nervous System (CNS)

Gray Matter

Cell bodies and unmylenated fibers.

Nuclei

Clusters of cell bodies within the white matter of the central nervous system.

Ganglia

Collections of cell bodies outside the central nervous system.

Proprioceptors

Detect stretch or tension.

Association Neurons

Interneurons

Interneurons (Association Neurons)

Found in neural pathways in the central nervous system.

Interneurons (Association Neurons)

Connect sensory and motor neurons

Multipolar Neurons

Many extensions from the cell body.

Multipolar Neurons

• STRUCTURE: One axon, many dendrites

• LOCATION: Central Nervous System (CNS)

• FUNCTION: Motor neurons and interneurons (integration and output)

• EXAMPLE: Spinal Motor Neurons, Pyramidal Cells

Bipolar Neurons

One axon and one dendrite.

Bipolar Neurons

• STRUCTURE: One axon and one dendrite

• LOCATION: Special Sense Organs

• FUNCTION: Sensory (special senses)

• EXAMPLE: Retina (eye), olfactory epithelium (smell), cochlea (ear)

Unipolar Neurons

Have a short single process leaving the cell body.

Unipolar Neurons

• STRUCTURE: Single process; splits into peripheral and central branches

• LOCATION: Peripheral Nervous System (PNS - dorsal root ganglia)

• FUNCTION: Sensory (general senses)

• EXAMPLE: Touch, pain, temperature receptors

Irritability

Respond to stimuli.

Conductivity

Transmit an impulse.

The plasma membrane at rest is…

Polarized

Fewer ________ ___ are inside the cell than outside the cell.

Positive Ions

Depolarization

A stimulus depolarizes the neuron’s membrane.

A depolarized membrane allows ______ (___) to flow inside the membrane.

Sodium (Na+)

The exchange of ions initiates an…?

Action potential in the neuron.

If the action potential (nerve impulse) starts…

It is propagated over the entire axon.

_________ ____ rush out of the neuron after sodium ions rush in, which repolarizes the membrane.

Potassium Ions

The ______-_________ pump restores the original configuration (though this action requires ATP).

Sodium-potassium

The _______ continues to move toward the cell body.

Impulse

Impulses travel faster when fibers have a ______ ______.

Myelin Sheath

Impulses are able to cross the _______ to another nerve.

Synapse

________________ is released from a nerve’s axon terminal.

Neurotransmitter

The dendrite of the next neuron has _________ that are stimulated by the neurotransmitter.

Receptors

An ______ _________ is a started in the dendrite.

Action Potential

Reflex

Rapid, predictable, and involuntary responses to stimuli.

Reflex Arc

Direct route from a sensory neuron, to an interneuron, to an effector.

Reflex

Rapid, predictable, and involuntary responses to stimuli.

Autonomic Reflexes

• Smooth muscle regulation

• Heart and blood pressure regulation

• Regulation of glands

• Digestive system regulation
  
  

Somatic Reflexes

• Activation of skeletal muscles

Central Nervous System (CNS)

• Develops from the embryonic neural tube

• The neural tube becomes the brain and spinal cord

• The opening of the neural tube becomes the ventricles
  - Four chambers within the brain
  - Filled with cerebrospinal fluid

Regions of the Brain

• Cerebral hemispheres

• Diencephalon

• Brain stem

• Cerebellum

Cerebral Hemispheres

• LOCATION: Largest, uppermost part of the brain

• MAIN STRUCTURES: Cerebral cortex (gray matter), white matter, basal nuclei

• KEY FUNCTIONS: Conscious thought, memory, reasoning, emotions, voluntary movement, sensory perception
  
  

Diencephalon

• LOCATION: Between the cerebral hemispheres and brain stem

• MAIN STRUCTURES: Thalamus, Hypothalamus, Epithalamus (pineal gland)

• KEY FUNCTIONS: Sensory relay, hormone control, homeostasis, sleep-wake regulation
  

Brain Stem

• LOCATION: Connects brain to spinal cord

• MAIN STRUCTURES: Midbrain, Pons, Medulla oblongata

• KEY FUNCTIONS: Vital functions (breathing, heart rate, blood pressure), reflexes, communication pathway

Cerebellum

• LOCATION: Below occipital lobes, behind the brain stem

• MAIN STRUCTURES: Cerbellar hemispheres, vermis

• KEY FUNCTIONS: Balance, posture, coordination of movement, motor learning

Cerebral Hemispheres (Cerebrum)

• Paired (left and right) superior parts of the brain

• Include more than half of the brain mass

• The surface is made of ridges (gyri) and grooves (sulci)

Fissures (Deep Grooves)

Divide the cerebrum into lobes.

Surface Lobes of the Cerebrum

• Frontal lobe

• Parietal lobe

• Occipital lobe

• Temporal lobe

Frontal Lobe

• Voluntary movement (motor control)

• Planning, reasoning, decision-making

• Problem-solving and judgement

• Speech production (Broca’s area)

• Personality and emotional regulation

Parietal Lobe

• Processing sensory information (touch, pressure, pain, temperature)

• Spatial orientation and body awareness

• Understanding language (together with temporal lobe)

Temporal Lobe

• Hearing and auditory processing

• Memory and learning

• Language comprehension (Wernicke’s area)

• Emotional association

Occipital Lobe

• Vision (visual processing, recognition of shapes, colors, movement)

Insula (Hidden Lobe)

• Taste perception

• Visceral sensation (internal organ awareness)

• Emotional experience

• Integrating sensory with emotional responses
  
  

Somatic Sensory Area

Receives impulses from the body’s sensory receptors.

Primary Motor Area

Sends impulses to skeletal muscles.

Cerebral Areas Involved in Special Senses

• Gustatory (taste)

• Visual

• Auditory

• Olfactory
  
  

Interpretation Areas of the Cerebrum

• Speech/language region (Broca’s area)

• Language comprehension region (Wernicke’s area)

• General interpretation area (Gnostic area)

Broca’s Area

Speech/language region.

Wernicke’s Area

Language comprehension region.

Gnostic Area

General interpretation area.

Gray Matter

• Outer layer of the cerebrum

• Composed mostly of neuron cell bodies

White Matter

• Fiber tracts inside the gray matter

• EXAMPLE: corpus callosum connects hemispheres

Basal Nuclei

• Internal islands of gray matter

• Regulates voluntary motor activities by modifying info sent to the motor cortex

• PROBLEMS = ie unable to control muscles, spastic, jerky

• Involved in Huntington’s and Parkinson’s Disease
  
  

Diencephalon

• Sits on top of the brain stem

• Enclosed by the cerebral hemispheres

• Made of three parts
  - Thalamus
  - Hypothalamus
  - Epithalamus