BIO-50B Lab Practical I

What are the main components of a neuron?

• Cell Bodies/Soma

• Dendrites

• Axons

What is a Graded Potential? Which part of the Neuron detects it?

• Graded Potential: a change in a neuron’s membrane potential (carrying in magnitude based on the strength of the stimulus).

• Dendrites

What is an Action Potential? Which part of the Neuron detects it?

• Action Potential: a rapid, large, and all-or-nothing electrical signal that travels along the length of a neuron, allowing it to communicate with other neurons, muscles, or glands.

• Axon Hillock

What are the main structural classes of neurons?

• Multipolar

• Bipolar

• Unipolar

Where are multipolar neurons usually found (CNS/PNS)? Is this a structural or functional neural classification?

• CNS (Brain & Spinal Cord)

• Structural

Where are bipolar neurons usually found (CNS/PNS)? Is this a structural or functional neural classification?

• PNS: Retina, Olfactory Mucosa, & Cochlea

• Structural

Where are unipolar neurons usually found (CNS/PNS)? Is this a structural or functional neural classification?

• PNS: Dorsal Root Ganglia, Cranial Nerve Ganglia

• Structural

What are the main functional classes of neurons?

• Sensory

• Motor

• Interneurons

Where are sensory neurons usually found (CNS/PNS)? Are they afferent or efferent? Is this a structural or functional neural classification?

• PNS

  • Dorsal Root Ganglia, Cranial Merve Ganglia

• Afferent

• Almost all are unipolar.

• Functional

Where are motor neurons usually found (CNS/PNS)? Are they afferent or efferent? Is this a structural or functional neural classification?

• CNS

• Efferent

• Multipolar

• Functional

Where are interneurons neurons usually found (CNS/PNS)? Is this a structural or functional neural classification?

• Lie between sensory and motor neurons.

• Most are entirely within the CNS.

• Functional

List the different types of Glia? Which ones are in the CNS? PNS?

• Central Nervous System

  • Oligodendrocytes

  • Ependymal

  • Astrocytes

  • Microglia

• Peripheral Nervous System

  • Schwann Cells

  • Satelite Cells

List the role of the following cell and state whether it is found in the CNS or PNS: Oligodendrocytes.

• Produce Myelin Sheath

• CNS

List the role of the following cell and state whether it is found in the CNS or PNS: Ependymal.

• Line the central cavities of the brain and spinal cord; involved on the production and circulation of CSF.

• CNS

List the role of the following cell and state whether it is found in the CNS or PNS: Astrocytes.

• Most abundant, versatile, and highly branched of glial cells that cling to neurons, synaptic endings and capillaries.

• CNS

List the role of the following cell and state whether it is found in the CNS or PNS: Microglial Cells.

• Cells that touch and monitor neurons, migrate toward injured neurons and phagocytize microorganisms and neuronal debris.

• CNS

List the role of the following cell and state whether it is found in the CNS or PNS: Schwann Cells.

• Similar function to oligodendrocytes of CNS.

• Located in PNS

List the role of the following cell and state whether it is found in the CNS or PNS: Satellite Cells.

• Similar function to astrocytes of CNS.

• Located in PNS

Define: Synapse

The functional connection between a neuron and the cell it is signaling.

Can a pre-synaptic cell be a neuron, muscle, or gland cell? What about post-synaptic cells?

A pre-synaptic cell is typically a neuron, but it can sometimes be a muscle cell or gland cell.

A post-synaptic cell can be a neuron, muscle cell, or gland cell, depending on the synapse type.

State the function: Cell Body/Soma/Cyton

Synthesize proteins, membranes, and chemicals.

State the function: Dendrite

Conduct a graded impulse toward the cell body/soma when stimulated.

State the function: Nissl Body

What is it composed of?

• Composition: Rough ER

• Function: Protein Modification

State the function: Nucleus

Store Genetic Information

State the function: Axon Hillock

Triggers action potentials (APs).

State the function: Axon

Carry electricals from neurons to other cells.

State the function: Myelin Sheath

Increase AP conduction speed.

State the function: Shwann cell

Produce Myelin Sheath (PNS)

State the location and function: Node of Ranvier

• Location: Small gaps between myelin sheath.

• Function: Speed up the transmission of impulses by allowing them to jump from one to the next.

State the location and function: Axolemma

• Location: The outer covering/cell membrane of an axon.

• Function: Helps send signals and maintain axon’s environment.

State the location and function: Axon Collateral

Extensions from the main axon.

State the function: Axon Terminal

Send information to next cell.

State the function: Vesicles

Transport Substances

What are the three general steps of neuronal processing?

• Sensory Input

• Integration

• Motor Response

What types of neurons are present in the following step of neural processing: Sensory Input? Is this step involved in the CNS or PNS?

• Sensory Neurons

• PNS

What types of neurons are present in the following step of neural processing: Integration? Is this step involved in the CNS or PNS?

• Interneurons

• CNS

What types of neurons are present in the following step of neural processing: Motor Output? Is this step involved in the CNS or PNS?

• Motor Neurons

• PNS

Define: White Matter

Is this located in the CNS or PNS?

• Regions of brain and spinal cord with dense collections of myelinated fibers.

• Location: CNS

Define: Gray Matter

Is this located in the CNS or PNS?

• Mostly neuron cell bodies and unmyelinated fibers.

• Location: CNS

Define: Fascicle

What connective tissue wraps around it? What is inside it?

A bundle of nerve fibers (axons) that are grouped together within a nerve.

It is wrapped by perineurium; the fascicle contains axons of sensory, motor, and autonomic neurons, which transmit signals to and from the CNS.

Are blood vessels inside or outside a fascicle?

Outside

What is the space that Spinal Nerves pass through in the Vertebral Column?

Intervertebral Foramen

Do spinal nerves have motor axons, sensory axons, or both?

Both

True/False - Parts from a single neuron can be present in BOTH the CNS and the PNS.

True

True/False - Interneurons are present in BOTH the CNS and the PNS.

False

Fill in the blank: Spinal nerves are formed by ___ and ___ roots.

• Dorsal

• Ventral

Select the best answer choice: In terms of function, spinal nerves are classified as ___?

A. Sensory

B. Motor

C. Both/Mixed

D. None of the above

C. Both/Mixed (Sensory & Motor)

List the cranial nerves in order.

• Olfactory Nerve

• Optic Nerve Nerve

• Oculomotor Nerve

• Trochlear Nerve

• Trigeminal Nerve

• Abducens Nerve

• Facial Nerve

• Vestibulocochlear Nerve

• Glossopharyngeal Nerve

• Vagus Nerve

• Accessory Nerve

• Hypoglossal Nerve

State the Cranial Nerve name nemonic

Oh Oh Oh To Touch And Feel Very Green Vegetables At Home

Olfactory Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• I (1)

• Sensory (S)

• Inferior Temporal Lobe; Smell

• No

Optic Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• II (2)

• Sensory (S)

• Occipital Lobe; Vision

• No

Oculomotor Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• III (3)

• Motor

• Target:

  • Superior Rectus

  • Medical Rectus

  • Inferior Rectus

  • Inferior Oblique

• Function: Eyeball Movement

• Yes—-Parasympathetic: Pupil Dilation/Contractions

Trochlear Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• IV (4)

• Motor

• Superior Oblique; Eyeball Movement

• No

Trigeminal Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Auntonomic Function (Yes/No)

• V (5)

• Subdivisions:

  • Ophthalmic

    • Sensory: Face

    • Motor: Mastication

    • Muscles Innervated: Masseter

  • Maxillary

    • Sensory

  • Mandibular

    • Both

• No

Abducens Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• VI (6)

• Motor

• Lateral Rectus; Lateral Eye Movement

• No

Facial Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• VII (7)

• Both

  • Sensory: Taste Buds

  • Motor: Facial Muscles

• Yes—-Parasympathetic: Tear Ducts & Savillary Glands

Vestibulocochlear Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Auntonomic Function (Yes/No)

• VIII (8)

• Sensory

• Cochlea; Balance & Hearing

• No

Glossopharyngeal Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• IX (9)

• Both

  • Sensory: Taste

  • Motor: Swallowing

• Yes—-Parasympathetic: Savillary Glands

Vagus Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• X (10)

• Both

  • Sensory:

    • Thoracic & Abdominal Viscera

    • Aortic Arch (Blood Pressure)

    • Breathing

  • Motor: Pharynx

• Yes—-Parasympathetic: Gag Reflec, Rest & Digest

Accessory Nerve

List:

• Roman Numeral/Number

• Functional Class (S, M, or B)

• Target (Supply) & Function

• Autonomic Function (Yes/No)

• XI (11)

• Both

  • Sensory: Proprioception of Muscles

  • Motor: Contractions

*Innervates TRAPEZIUS & STERNOCLEIDOMASTOID

• No

Hypoglossal Nerve

List:

• Roman Numeral/Number

• Functional Class (S, N, or B)

• Target (Supply) & Function

• Auntonomic Function (Yes/No)

• XII (12)

• Both

  • Sensory: Proprioception of Tongue

  • Motor: Tongue

• No

List the CN that have autonomic (i.e Parasympathetic) functions.

• CN 3: Oculomoter - Pupil Dilation

• CN 7: Facial - Lacrimal Glands, Submandibulary & Sublingual Salivary Glands

• CN 9: Glossopharyngeal - Salivary Glands

• CN 10: Vagus - Gag Reflex

How many cranial nerves are involved in the movement of eyeballs? Which specific muscles are innervated by these nerves?

• CN 3 - Oculomoter

  • Superior Rectus

  • Medical Rectus

  • Inferior Rectus

  • Inferior Oblique

• CN 4 - Trochlear

  • Superior Oblique

• CN 6 - Abducens

  • Lateral Rectus

What part of sensory neurons detect stimuli?

Sensory neurons have specialized structures at their dendrites, called receptors, that are sensitive to specific types of stimuli.

Remember: “Stimulus-gated ion channels are on dendrites of sensory neurons.”

Remember: Sensory Neurons detect specific changes in their environment (aka STIMULI).

Do sensory receptor neurons detect external Stimuli? Do they detect internal stimuli?

They detect BOTH!

If the neurophysiology is generally the same, then what makes sensory receptor neurons different?

1) Different “stimulus-” gated ion channels that induce the graded potential on the dendrites.

2) Different dendrite and neuron morphologies.

What are the three ways we can classify a sensory receptor neuron?

• Location/Gross Anatomy

• Structural Complexity/Cell Anatomy

• Stimulus Type/Phsyiology

Touch on the location/gross anatomy classification of sensory receptor neurons.

• Where in the body they function.

• General Senses v. Special Senses

Where are sensory receptors for general senses found? List the subtypes/subclasses of stimuli detected by general senses.

• In Skin or Internal Tissues (usually not in specialized sensory organs).

• Subtypes:

  • Touch

  • Pressure

  • Temperature

  • Pain

Where are sensory receptors for special senses found? List the subtypes/subclasses of stimuli detected by special senses.

• In Head/Specialized Sensory Organs

  • *Specialized sensory organs include eyes, nose, ear, tongue, etc.

• Subtypes:

  • Vision

  • Hearing

  • Eqillibrium

  • Smell

  • Taste

Touch on the structural complexity/cell anatomy classification of sensory receptor neurons.

• Their morphological features.

• Can range from simple to complex.

True/False - Simple nonencapsulated nerve endings and complex/specialized nerve endings are usually a part of general senses; simple encapsulated nerve endings are usually a part of special senses.

False

Explanation: Simple nonencapsulated nerve endings and simple encapsulated nerve endings are usually a part of general senses; complex, specialized nerve endings are usually a part of special senses.

Define: Interoceptors

What types of stimuli do they usually detect?

Sense INTERNAL Stimuli

Define: Exteroceptors

What types of stimuli do they usually detect?

Sense OUTSIDE Stimuli

Define: Proprioceptors

What types of stimuli do they usually detect?

• Sensitve to stimuli inside the body.

Touch on the stimulus type/physiology classification of sensory receptor neurons.

• The type of stimulus they detect.

List subtypes/subclasses of stimuli detected by interoreceptors?

• Chemoreceptors

• Mechanoreceptors

• Thermoreceptors

List subtypes/subclasses of stimuli detected by extoreceptors.

• Chemoreceptors

• Mechanoreceptors

• Thermoreceptors

• Photoreceptors

What type of stimuli do chemoreceptors usually detect? Where are these receptors found?

• Respond to stimuli when a specific chemical binds to gated channels, opening them up and depolarizing the membrane.

• Found:

  • General Senses: Blood Glucose, Toxins in Interstitial Fluid, Ions in CSF, etc

  • Special Senses: Tongue (Taste) & Nose (Smell)

What type of stimuli do mechanoreceptors usually detect? Where are these receptors found?

• Mechanical Force Stimuli

• Found:

  • General Senses:

  • Special Senses: Ear (Hearing & Equilibrium)

What type of stimuli do thermoreceptors usually detect? Where are these receptors found?

• Temperature Change Stimuli

What type of stimuli do nociceptors usually detect? Where are these receptors found?

• Damagung Srimulus w/Pain

  • Ex:

    • Too Much Heat = Pain

    • Too Much Physical Strain = Pain

    • Too Much Chemical = Pain

Is vision a general sense or a special sense”?

Special Sense

How many cranial nerves serve structures of the eye? List them.

• Four

  • CN II - Optic

  • CN III - Oculomoter

  • CN IV - Trochlear

  • CN 6 - Abducens

Where are photoreceptors located in the eye?

Retina

Are photoreceptors located at the top or bottom of the neural nayer in Retina?

Bottom

What is the general order of signal relay, after light photons stimulate photoreceptors?

Photoreceptor —> Bipolar Cell —> Ganglion Cells (CNII-Optic Nerve)

What are rods? What do they detect? What are their general characteristics/functions?

• Def: A type of photoreceptor that is numerous, very sensitive, only has one type of visual pigment, and detects dim light.

• Functions:

  • Perceive Gray-Scale Images (no color-vision or sharp/high-resolution images).

What are cones? What do they detect? What are their general characteristics/functions?

• Def: A type of photoreceptor that contains detects bright light and contains three pigment types: red, blue, and green.

• Functions:

  • Perceive Sharp/High Resolution Color Images

What is the general cellular anatomy of photoreceptors?

Inner Segment & Outer Segment

Touch on important characteristics of the outer segment anatomy of photoreceptors.

• Light-Recieving Region

• Contains visual pigments that change shape when they absorb light.

How often do photoreceptors (rods and cones) regernarte their outer segment? Why?

Every 24 hours due to intense light exposure.