Anatomy and Physiology: Chapter 15

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Questions and Answers

What is sensation?

Arriving information

What is perception?

The conscious awareness of a sensation

What are the five special senses?

Olfaction (smell), Vision (sight), Gustation (taste), Equilibrium (balance), Hearing

What is transduction?

The translation process of a sensory receptor detecting a stimulus and translating it into an action potential that can be conducted to the CNS Signup and view all the answers

What are free nerve endings?

The branching tips of dendrites Signup and view all the answers

What is a labeled line?

The link between a peripheral receptor and cortical neuron Signup and view all the answers

What are tonic receptors?

Sensory neurons that are always active Signup and view all the answers

What are phasic receptors?

Receptors that provide information about the intensity and rate of change of a stimulus Signup and view all the answers

What is adaptation in sensory receptors?

A reduction in sensitivity in the presence of a constant stimulus Signup and view all the answers

Is a tonic receptor a fast-adapting receptor or a slow-adapting receptor and why?

Slow-adapting receptor because they show little peripheral adaptations Signup and view all the answers

Where are nociceptors most common?

Superficial portions of the skin, in joint capsules, within the periostea of bones, and around the walls of blood vessels Signup and view all the answers

What may nociceptors be sensitive to?

Extreme temperatures, Mechanical damage, Dissolved chemicals Signup and view all the answers

What two types of axons carry painful sensations? Briefly describe the type of pain it carries.

Type A fibers - Fast pain/prickling pain; Type C fibers - Slow pain/burning and aching pain Signup and view all the answers

Are nociceptors tonic or phasic receptors?

Tonic Signup and view all the answers

Where are thermoreceptors located?

The dermis, skeletal muscles, liver, and in the hypothalamus Signup and view all the answers

Are thermoreceptors tonic or phasic receptors?

Phasic Signup and view all the answers

What are mechanoreceptors?

Sensitive to stimuli that distort their plasma membranes Signup and view all the answers

What are the three classes of mechanoreceptors?

Tactile receptors, Baroreceptors, Proprioceptors Signup and view all the answers

What are fine touch and pressure receptors?

Provides detailed information about a source of stimulation, including its exact location, shape, size, texture, and movement Signup and view all the answers

What are crude touch and pressure receptors?

Provides poor localization and give little additional information about the stimulus Signup and view all the answers

What are the six types of tactile receptors in the skin?

Free nerve endings, Root hair plexus, Merkel cells and tactile discs, Tactile corpuscle, Lamellated corpuscle, Ruffini corpuscle Signup and view all the answers

What are the three major groups of proprioceptors?

Muscle spindles, Golgi tendon organs, Receptors in joint capsules Signup and view all the answers

What are chemoreceptors?

Responds only to water-soluble and lipid-soluble substances that are dissolved in body fluids Signup and view all the answers

What is a first-order neuron?

A sensory neuron that delivers sensations to the CNS Signup and view all the answers

What are the three major somatic sensory pathways?

The spinothalamic pathway, Posterior column pathway, Spinocerebellar pathway Signup and view all the answers

What does the spinothalamic pathway carry?

Sensations of poorly localized touch, pressure, pain, and temperature Signup and view all the answers

What does the posterior column pathway carry?

Sensations of precise touch and vibrations, and proprioception Signup and view all the answers

What does the spinocerebellar pathway convey?

Information about muscle, tendon, and joint positions from the spine to the cerebellum Signup and view all the answers

What are the spinal tracts involved with the posterior column pathway?

Left and right fasciculus gracilis, Left and right fasciculus cuneatus Signup and view all the answers

What is decussation?

The crossing of an axon from the left side to the right side and vice versa Signup and view all the answers

What is the corticospinal pathway?

(AKA pyramidal system) Provides voluntary control over skeletal muscles Signup and view all the answers

What do corticobulbar tracts provide?

Conscious control over skeletal muscles that move the eye, jaw, and face, and some muscles of the neck and pharynx Signup and view all the answers

What is the function of the medial pathway?

Helps control gross movements of the trunk and proximal limb muscles Signup and view all the answers

What is the function of the lateral pathway?

Helps control the distal limbs that perform more precise movements Signup and view all the answers

What are the three tracts in the medial pathway?

Vestibulospinal tracts, Tectospinal tracts, Reticulospinal tracts Signup and view all the answers

What is the function of the vestibulospinal tracts?

Subconscious regulation of balance and muscle tone Signup and view all the answers

What is the function of the tectospinal tracts?

Subconscious regulation of eye, head, neck, and upper limb position in response to visual and auditory stimuli Signup and view all the answers

What is the function of the reticulospinal tracts?

Subconscious regulation of reflex activity Signup and view all the answers

What is the function of the rubrospinal tracts?

Subconscious regulation of upper limb muscle tone and movement Signup and view all the answers

Study Notes

Sensation and Perception

Sensation refers to the incoming information detected by sensory receptors.
Perception is the conscious awareness and interpretation of those sensations.

Special Senses

The five special senses are olfaction (smell), vision (sight), gustation (taste), equilibrium (balance), and hearing.

Sensory Processes

Transduction is the process by which sensory receptors convert a stimulus into an action potential for the central nervous system (CNS).
Free nerve endings are the branching tips of sensory neuron dendrites, involved in detecting various stimuli.
A labeled line connects peripheral receptors to specific neurons in the brain, ensuring the correct interpretation of sensory information.

Receptor Types

Tonic receptors are sensory neurons that remain consistently active and respond slowly to stimuli (slow-adapting).
Phasic receptors provide information about the intensity and rate of change of a stimulus and adapt quickly (fast-adapting).
Adaptation describes decreased sensitivity to a constant stimulus over time.

Receptors by Function

Exteroceptors gather information from the external environment.
Proprioceptors monitor the position of skeletal muscles and joints.
Interoceptors track conditions within visceral organs.

Classification of Receptors

Four main types of receptors based on stimulus type:
- Nociceptors: respond to pain
- Thermoreceptors: respond to temperature
- Mechanoreceptors: respond to physical distortion
- Chemoreceptors: respond to chemical concentration

Nociceptors

Most abundant in skin, joint capsules, periosteum of bones, and blood vessel walls.
Sensitive to extreme temperatures, mechanical damage, and certain dissolved chemicals.
Pain signals are carried by Type A fibers (fast, prickling pain) and Type C fibers (slow, burning pain).
Nociceptors are classified as tonic receptors due to their persistent activation.

Thermoreceptors

Found in the dermis, skeletal muscles, liver, and hypothalamus.
Classified as phasic receptors, responding to changes in temperature.

Mechanoreceptors

Sensitive to stimuli that cause physical changes in their membrane structure.
Three classes:
- Tactile receptors: detect touch, pressure, and vibration.
- Baroreceptors: monitor pressure changes within blood vessels and organs.
- Proprioceptors: sense joint and muscle positions.

Touch and Pressure Receptors

Fine touch and pressure receptors provide detailed information about stimulus characteristics.
Crude touch and pressure receptors offer poor localization and limited detail about the stimulus.
Six types of tactile receptors:
- Free nerve endings: alert to touch and pressure.
- Root hair plexus: detects movements across skin.
- Merkel cells and tactile discs: sensitive to fine touch and pressure.
- Tactile corpuscles: respond to fine touch, pressure, and low frequency vibration.
- Lamellated corpuscles: sensitive to deep pressure.
- Ruffini corpuscles: respond to skin pressure and distortion.

Proprioceptors

Three key groups:
- Muscle spindles: monitor skeletal muscle length and trigger reflex actions.
- Golgi tendon organs: respond to tendon tension during muscle contraction.
- Receptors in joint capsules: detect joint pressure, tension, and movement.

Chemoreceptors

Respond exclusively to substances that are dissolved in body fluids, both water-soluble and lipid-soluble.

Sensory Pathways

First-order neurons transmit sensory information to the CNS.
Major somatic sensory pathways:
- Spinothalamic pathway: carries poorly localized touch, pressure, pain, and temperature sensations.
- Posterior column pathway: transmits precise touch, vibrations, and proprioceptive information.
- Spinocerebellar pathway: conveys position information from muscles, tendons, and joints.

Spinal Tracts

Posterior column pathway consists of fasciculus gracilis and fasciculus cuneatus.
Decussation refers to the cross-over of axons between left and right sides of the body.

Motor Pathways

Corticospinal pathway: voluntary control over skeletal muscles.
Corticobulbar tracts: control of muscles in the face, neck, and pharynx.
Medial pathway: regulates gross movements of the trunk and proximal limbs.
Lateral pathway: manages precise movements of distal limbs.

Medial Pathway Tracts

Three tracts include vestibulospinal, tectospinal, and reticulospinal tracts.
Vestibulospinal tracts: regulate balance and muscle tone subconsciously.
Tectospinal tracts: position control related to visual and auditory stimuli.
Reticulospinal tracts: manage reflex activities subconsciously.

Rubrospinal Tracts

Subconsciously regulate muscle tone and movement of the upper limbs.

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Test your knowledge on key concepts from Chapter 15 of Anatomy and Physiology. This quiz includes terms related to sensation, perception, and the five special senses. Ideal for students looking to reinforce their understanding of sensory processes.