Special Senses & Sensation

Special Senses

• Special senses are how the body receives stimuli and information from the environment.
• Special senses include touch, smell, taste, vision, and hearing.

Sensation

• Sensation is a feeling resulting from something contacting or happening to the body.
• Sensation involves four steps: reception, transduction, encoding, and perception.
• Reception is the first step in sensation.
• Transduction is converting a sensory signal into an electrical signal for the brain; this occurs at the sensory receptor.
• Encoding involves the stimulus's type, location, duration, and relative intensity, sensory information is encoded and transmitted.
• Perception is an individual's interpretation of a sensation, taking place in the brain.

Touch

• Touch is also referred to as somatosensorial.
• Touch is the sensation perceived from the skin, mucous membranes, limbs, and joints.
• Touch occurs over the exterior and internal locations of the body.

Smell

• Smell is also called olfaction.
• Smell provides the sense of odor.
• Smell occurs through the nose.

Taste

• Taste is also called gustation.
• Taste combines smell, texture, and temperature, plus sensations distinguished by the tongue.
• The tongue has tiny bumps known as papillae.
• Thousands of taste buds and sensory receptors cover the papillae.
• Taste provides a passageway for air into the body

Vision

• Vision occurs when light focuses on photoreceptors in the retina.
• The retina translates visual messages to the brain.
• The cornea, pupil, and lens work together for visual processing.

Hearing

• Hearing is the discernment of sound by the ears and brain, taking place within the ear and its structures.
• The ear is divided into the outer, middle, and inner ear.

Root Words and Definitions

• blephar/o: eyelid
• cor/o: pupil
• lent/o: lens
• opt: eye
• ot/o: ear
• ton/o: tone; tension

Prefixes and Definitions

• auditor-: hearing
• dys-: difficult
• pupill-: pupil
• scler-: hardening
• tympano-: relationship to the eardrum
• xer-: dry

Suffixes and Definitions

• -geusia: sense of taste
• -ician: specialist
• -ism: condition
• -opia: sight; vision
• -plasty: surgical repair
• -y: pertaining to
• -al: pertaining to
• -ist: one who specializes
• -itis: inflammation
• -oma: tumor
• -opsy: view of
• -osis: condition

Morphemes and Definitions

• dys-: difficult
• -guesia: sense of taste
• exo-: out
• trop: turn
• -ia: condition
• gloss: tongue
• -itis: inflammation
• ichthy: fish
• -osis: condition
• psor/a: itch
• -iasis: condition
• sclero-: hardening
• derm/a: skin
• xero-: dry

Diseases/Conditions

• Dysgeusia: A taste disorder where all foods taste sour, sweet, bitter, or metallic.
• Exotropia: A condition in which the eye turns outward.
• Glossitis: A condition resulting in swollen, inflamed or discolored tongue.
• Ichthyosis: A disorder that causes dry, thickened skin which appears scaly and rough.
• Psoriasis: A condition causing scaly skin that may swell or feel hot.
• Scleroderma: A condition characterized by the hardening and tightening of the skin.
• Xeroderma: Dry skin, resulting in roughness, tightness, flaking, and scaling of the skin.

The Integumentary System

• The integumentary system is layers of skin and tissue, forming the body's external surface; functions include protection, sensory reception, and temperature regulation.
• It is associated with the morphemes integument/o and -ary.
• It consists of the body's skin and accessory structures.

Skin

• Skin is the main component of the integumentary system containing three layers.
• The layers are the epidermis, dermis, and hypodermis.

Epidermis

• The epidermis consists of the outer layer of the skin.
• Epidermis does not contain blood vessels.
• The epidermis is composed of four to five layers of epithelial skin cells.
• Epidermis cells include keratinocytes, melanocytes, Merkel cells, basal cells, and Langerhans cells.

Dermis

• The dermis is considered the "core" of the integumentary system.
• The dermis contains blood vessels, lymph vessels, and nerves; accessory structures, and the papillary layer.

Hypodermis

• The hypodermis is the deepest layer of the skin.
• It attaches the skin to the muscle and bone.
• The hypodermis contains adipose tissue (fat cells).
• The hypodermis stores fat, energy, and nutrients; it provides insulation and cushioning.

Skin Pigmentation

• Skin pigmentation is determined by melanin (found in epidermis), carotene (found in dermis), and hemoglobin (found in blood capillaries in the dermis).

Accessory Structures

• Accessory structures support integumentary system functions.
• Hair originates in the dermis and grows through the epidermis to the skin surface, made of dead, keratinized cells, and provides support, protection, touch stimuli, and thermoregulation.
• Hair structure consists of the follicle, shaft, root, bulb, and arrector pili.
• Nails are structures on the epidermis of fingers and toes, entirely composed of keratin, providing support and protection.
• Sudoriferous glands produce sweat to cool the body, originate in the dermis, and project through the epidermis to a small opening.
• Sebaceous glands are oil glands that lubricate and waterproof the skin and hair, connected to hair follicles in the dermis and produce/excrete sebum onto the skin's surface.

Root Words for Integumentary System

• aden/o: gland
• derm/a/o: skin
• follicul/o: little bag
• melan/o: black
• rhytid/o: wrinkle
• seb/o: oil

Prefixes for Integumentary System

• hypo-: under
• intra-: within
• photo-: light
• sub-: below
• thermo-: hot, heat
• xantho-: yellow

Suffixes for Integumentary System

• -al: pertaining to
• -ist: one who specializes
• -itis: inflammation
• -oma: tumor
• -opsy: view of
• -osis: condition