Peripheral Nervous System Anatomy Quiz

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Questions and Answers

What are the primary anatomical components of the peripheral nervous system (PNS)?

Autonomic and sensory systems

Cranial and spinal nerves (correct)

Cranial and peripheral nerves

Spinal nerves and sensory receptors

Which division of the PNS is responsible for sensory innervation?

Efferent division

Somatic division

Sympathetic division

Afferent division (correct)

What type of sensory stimuli do exteroceptors respond to?

Internal stimuli from organs

External stimuli for special and somatic senses (correct)

Visceral pain signals

Muscle tension and joint angles

How many pairs of cranial nerves are present in the human body?

12 pairs Signup and view all the answers

What kind of information do proprioceptors primarily provide?

Information about joint angles and muscle tension Signup and view all the answers

Which of the following is NOT a type of interoceptor?

Photoreceptor Signup and view all the answers

Which type of intervertebral disc abnormality can occur and could lead to spinal stenosis?

Herniated discs Signup and view all the answers

Which division of the autonomic nervous system is NOT recognized as part of the PNS?

Central nervous system Signup and view all the answers

What type of receptors primarily sense deep touch?

Pacinian corpuscles Signup and view all the answers

Which receptors are responsible for the sensation of a cold ice cube on your skin?

Thermoreceptors Signup and view all the answers

What type of adaptation do nociceptors exhibit?

Tonic adaptation Signup and view all the answers

Which of the following medications would reduce the activity of histamine in the body?

Antihistamines Signup and view all the answers

What happens to the ion channels in a receptor when it receives a stimulus?

They open, allowing sodium to enter. Signup and view all the answers

Which type of receptors are quick to adapt to stimuli?

Phasic receptors Signup and view all the answers

The receptor portion of tactile receptors is a modification of which neuron part?

Dendrite Signup and view all the answers

What do opiates chemically resemble in the brain?

Endorphins Signup and view all the answers

What is the purpose of a Snellen chart?

To measure visual acuity Signup and view all the answers

What does having 20/40 vision indicate about a person's eyesight?

They are myopic Signup and view all the answers

What does a prescription of -2.5 indicate?

The person is myopic Signup and view all the answers

What are the three layers of cells in the retina, in order from innermost to outermost?

Ganglion cell layer, bipolar cell layer, photoreceptor layer Signup and view all the answers

Where is the fovea centralis located?

In the center of the macula Signup and view all the answers

What is the main function of ganglion cells in the retina?

To fire action potentials and transmit signals Signup and view all the answers

What does the macula of the retina refer to?

An indentation in the retina Signup and view all the answers

Can diopters be directly converted into Snellen chart numbers?

No, they measure different aspects of vision Signup and view all the answers

What happens to rods when they are bleached?

They are unresponsive to photons. Signup and view all the answers

Which type of cells in the retina have receptors for neurotransmitters released during the bleaching of rods?

Bipolar cells Signup and view all the answers

What happens to retinal when it is exposed to light in rhodopsin?

It is converted into the trans conformation. Signup and view all the answers

Which process helps retinal return to its original conformation after light exposure?

Retinoid cycle Signup and view all the answers

What immediate effect does walking from a dark environment into bright light have on rods and cones?

Rods are bleached and cones become more active. Signup and view all the answers

What happens to the sensitivity of rods during dark adaptation?

Rods regenerate rhodopsin and regain sensitivity gradually. Signup and view all the answers

What is a likely reason for pirates to wear an eyepatch?

To keep one eye always dark-adapted. Signup and view all the answers

How long can it take for rods to recover fully in dark adaptation?

Up to 30 minutes Signup and view all the answers

What is the primary reason for the symptoms experienced during rapid ascent?

Rapid changes in air pressure Signup and view all the answers

Which maneuver can help alleviate pressure-related symptoms in the ear?

Yawning Signup and view all the answers

What fluid is contained in the scala media of the cochlea?

Endolymph Signup and view all the answers

What is the main function of the cochlea?

To convert sound vibrations into nerve impulses Signup and view all the answers

Which cells in the organ of Corti are primarily responsible for sending nerve impulses to the brain?

Inner hair cells Signup and view all the answers

What type of fluid do the scala vestibuli and scala tympani contain?

Perilymph Signup and view all the answers

Where is the organ of Corti located?

Within the cochlea Signup and view all the answers

Do outer hair cells in the organ of Corti have motile structures?

No, they are not motile Signup and view all the answers

Study Notes

### Peripheral Nervous System Anatomy

The PNS is comprised of the cranial and spinal nerves.
The PNS is functionally organized into two divisions: afferent and efferent.
The afferent division is responsible for sensory information, including:
- Somatosensory (touch, pressure, temperature, pain)
- Special Sensory (sight, hearing, taste, smell)
- Visceral Sensory (internal organ information)
The efferent division transmits motor commands and is comprised of:
- Somatic Motor (controls skeletal muscle)
- Autonomic Motor (controls smooth muscle, cardiac muscle, glands, and adipose tissue)
- The autonomic motor system further subdivides into the sympathetic, parasympathetic, and enteric nervous systems.

Sensory Receptors

Exteroceptors are sensory receptors that receive external stimuli from both special and somatic senses.
Proprioceptors provide the CNS with information about joint angle, muscle length, and muscle tension, ultimately giving information about limb position.
Interoceptors receive stimuli from internal organs, providing information about visceral sensations.

Cranial and Spinal Nerves

There are 12 pairs of cranial nerves, some of which are mixed (containing both sensory and motor fibers).
There are 31 pairs of spinal nerves.

Spinal Stenosis

Intervertebral disc abnormalities can lead to spinal stenosis:
- Deterioration: Weakening and breakdown of the disc
- Herniation: Protrusion of the disc material, potentially compressing nerves

Touch Receptors

Pacinian corpuscles detect deep touch.
Meissner's corpuscles and Merkel cells detect light touch.

Sensory Processing

Ipsilateral sensory information converges at the brainstem.
Contralateral sensory information converges at the spinal cord.

Receptor Types

Thermoreceptors detect temperature.
Chemoreceptors detect chemical stimuli (e.g., taste).
Nociceptors detect pain.
Mechanoreceptors detect pressure and movement.

Receptor Properties

Nociceptors are tonic, slowly adapting receptors.
Tactile receptors are phasic, quickly adapting receptors.
Odorant receptors are phasic.

Sensory Neuron Structure

Tactile receptors are modifications of a sensory neuron's dendrite.
Stimulus reception opens ion channels in the receptor, allowing sodium to enter and initiating an action potential at the neuron's initial segment.

Pain Modulation

NSAIDs (e.g., ibuprofen, aspirin) reduce prostaglandin activity.
Antihistamines (e.g., Benadryl) reduce histamine activity.
Capsaicin reduces substance P activity.
Opiates mimic the effects of the brain's natural opioids (endorphins).

Visual Acuity

A Snellen chart is used to measure visual acuity.
20/20 vision is considered "normal" vision. A person can read the smallest letters on the 20/20 line of a Snellen chart from 20 feet away.
20/40 vision indicates myopia (nearsightedness). A person can read the smallest letters on the 20/40 line from 20 feet away, while someone with 20/20 vision can read the same line from 40 feet away.
20/20 visual acuity does not mean perfect vision.

### Eyeglass Prescription

Eyeglass prescriptions are measured in diopters.
Diopters cannot be directly converted to Snellen chart values.
A prescription of -2.5 diopters indicates myopia.

### Retinal Structure

The retina has three layers:
- Ganglion cell layer (innermost)
- Bipolar cell layer (middle)
- Photoreceptor layer (outermost, containing rods and cones)
The macula is a retinal indentation off-center from the optic disc.
The fovea centralis is a region within the macula, containing a high concentration of cone photoreceptor cells.

Phototransduction

Ganglion cells are responsible for firing action potentials in response to light.
Light stimulates rhodopsin, leading to a conformational change in retinal from cis to trans.
"Bleaching" of rods occurs when opsin dissociates from retinal in rhodopsin, making rods unresponsive to photons.
Retinal is converted back to its original conformation via the retinoid cycle, mediated by pigmented epithelial cells of the retina.

### Light and Dark Adaptation

Light adaptation happens when transitioning from a dark environment to a bright environment, causing temporary dazzling.
Dark adaptation happens when transitioning from a bright environment to a dark environment, initially resulting in near blindness.
Over time, rhodopsin regenerates through the retinoid cycle, restoring rod sensitivity.

### Ear Structure

The inner ear contains a bony labyrinth and a membranous labyrinth.
Cochlea contains three chambers:
- Scala vestibuli (vestibular duct) - filled with perilymph
- Scala media (cochlear duct) - filled with endolymph
- Scala tympani (tympanic duct) - filled with perilymph
Membranes associated with these chambers:
- Vestibular membrane
- Tectorial membrane
- Basilar membrane

Organ of Corti

The organ of Corti is the sensory organ of audition, located within the cochlea.
It comprises:
- Tectorial membrane
- Outer hair cells
- Basilar membrane
- Inner hair cells
- Support cells
Inner hair cells fire nerve impulses in response to basilar membrane distortion.
Outer hair cells amplify basilar membrane vibrations by pushing on the tectorial membrane.
Stereocilia, found on hair cells, are not motile structures.

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Description

Test your knowledge on the anatomy and functions of the Peripheral Nervous System. This quiz covers the divisions of the PNS, sensory receptors, and their roles in transmitting information to and from the Central Nervous System. Prepare to dive into both afferent and efferent pathways of the nervous system.