A&P Sensations and General Sensation

Sensation

Our conscious/subconscious awareness of changes in the internal/external environment

Perception

The conscious interpretation of sensation

Transduction

The conversion of the stimulus into a graded potential

Translation

Conscious sensations and perceptions are integrated into the cerebral cortex

Modality

Each sensation feels differently than others, despite sensory impulses feeling the same

Projection

The brain projecting a sensation back to the point of simulation

Afterimages

When a sensation persists after a stimulus is removed

Adaptation

When a stimulus persists, and the sensation diminishes or eventually disappears

The 2 sensory modalities

General senses: Simatic and visceral senses

Special senses: Vision, hearing, equilibrium, smell, and taste

Receptor density

Areas of the body that are more sensitive, due to having more receptors

Ex: Fingertips, lips, and tongue

What part of the brain is responsible for the translation of somatic sensations?

The postcentral gyrus of the prefrontal cortex

What are the 5 tactile sensations?

Touch

Pressure

Vibration

Itch

Tickle

Receptors location

The skin or subcutaneous layer

Meissner’s corpuscles

Encapsulated dendrites located in the upper dermis of hairless skin. Adapts rapidly

Ex: Fingertips, lips, n!pples, soles of feet

Hair root plexus

Free nerve endings wrapped around hair follicles.

Adapts rapidly

Detects a bug on your skin

Merkel’s Discs

Flattened free nerve endings in the stratum basale of the epidermis. Slowly adapting

Found in fingertips, hands, lips, and external genitals.

Ruffini’s corpuscles

Encapsulated receptors deep in the dermis, ligaments, and tendons. Sensitive to digit and limb stretching.

Adapt slowly.

Crude touch

Vibration

Results from rapid, repetitive stimuli of certain tactile receptors

Itch

Results from free nerve ending stimulation

Tickle

Only when the stimulus is applied to someone else

Free nerve endings

Receptors for the thermal sensations

Specialized mechanoreceptors

Proprioceptors involved in these sensations

Where are propriceotors located?

Muscles, tendons, joints, and the inner ear

Muscle spindles

Monitors the length of speed and contraction

Golgi tendon organs

Proprioceptors located in the muscle tendons near junctions with muscle fibers.

Monitors tendon tension and impacts tendon reflexes

What type of nerves are nociceptors?

Free nerve endings

Fast pain pathway

Medium diameter myelinated fibers

Translates into a sharp, localized type of pain

Slow pain pathway

Small diameter, unmyelinated fibers

Dull, aching, deeper type of pain

Referred pain

When an area of the body is in pain, it may refer to pain/issues in a different area

Gate mechanism

A stimulus is applied to/near the area of damage

Central inhibition

The brain releases chemicals that block the release of neurotransmitters used by pain passageways. Assists in fight/flight situations