Integumentary System Lecture Notes

Dermis

The dense irregular connective tissue layer beneath the epidermis, rich in collagen, containing blood vessels, nerves, sensory receptors, hair follicles, and glands.

Subcutaneous / Hypodermis / Superficial Fascia

The layer beneath the dermis, composed of loose connective tissue and adipose, functioning in energy storage, insulation, shock absorption, and anchoring the skin.

Stratum Corneum

The outermost epidermal layer, consisting of dead, keratin-filled cells that regularly slough off, providing the primary protective barrier.

Stratum Lucidum

An epidermal layer present only in thick skin (palms and soles), providing an additional layer of protection.

Stratum Granulosum

The epidermal layer where keratinization begins and cells start to die, accumulating lipid-filled granules.

Stratum Spinosum

The epidermal layer containing keratinocytes and Langerhans cells, which play a role in immune defense.

Protection (Skin Function)

The primary function of the skin to act as the body's first physical and microbial barrier, shielding deeper tissues from injury.

Thermoregulation (Skin Function)

The skin's role in regulating body temperature through mechanisms like vasodilation, vasoconstriction, and evaporative cooling via sweat.

Prevention of Desiccation (Skin Function)

The skin's ability, due to its keratinized surface, to limit water loss and maintain the stability of internal body fluids.

Ceruminous Glands

Modified apocrine glands located in the external ear canal that produce cerumen (ear wax) to trap debris and insects.

Cholecalciferol (Vit D
\,3)

The initial form of Vitamin D₃ synthesized in the skin when UV radiation converts a cholesterol-based compound.

Jaundice

A condition characterized by yellowing of the skin due to bilirubin accumulation, often observed in newborns.

Hair Follicle

The structure embedded in the dermis that surrounds the hair root, composed of epidermal and connective tissue sheaths, from which hair grows.

Hair Bulb

The enlargement at the base of the hair root, containing the living hair matrix and nourished by the papilla.

Dermal Papillae

Finger-like projections of the dermis that extend into the epidermis, containing capillary loops that supply nutrients to the epidermis.

Dermis

The dense irregular connective tissue layer beneath the epidermis, rich in collagen, containing blood vessels, nerves, sensory receptors, hair follicles, and glands.

Subcutaneous / Hypodermis / Superficial Fascia

The layer beneath the dermis, composed of loose connective tissue and adipose, functioning in energy storage, insulation, shock absorption, and anchoring the skin.

Stratum Corneum

The outermost epidermal layer, consisting of dead, keratin-filled cells that regularly slough off, providing the primary protective barrier.

Stratum Lucidum

An epidermal layer present only in thick skin (palms and soles), providing an additional layer of protection.

Stratum Granulosum

The epidermal layer where keratinization begins and cells start to die, accumulating lipid-filled granules.

Stratum Spinosum

The epidermal layer containing keratinocytes and Langerhans cells, which play a role in immune defense.

Protection (Skin Function)

The primary function of the skin to act as the body's first physical and microbial barrier, shielding deeper tissues from injury.

Thermoregulation (Skin Function)

The skin's role in regulating body temperature through mechanisms like vasodilation, vasoconstriction, and evaporative cooling via sweat.

Prevention of Desiccation (Skin Function)

The skin's ability, due to its keratinized surface, to limit water loss and maintain the stability of internal body fluids.

Ceruminous Glands

Modified apocrine glands located in the external ear canal that produce cerumen (ear wax) to trap debris and insects.

Cholecalciferol (Vit D

\1)

The initial form of Vitamin D₃ synthesized in the skin when UV radiation converts a cholesterol-based compound.

Jaundice

A condition characterized by yellowing of the skin due to bilirubin accumulation, often observed in newborns.

Hair Follicle

The structure embedded in the dermis that surrounds the hair root, composed of epidermal and connective tissue sheaths, from which hair grows.

Hair Bulb

The enlargement at the base of the hair root, containing the living hair matrix and nourished by the papilla.

Dermal Papillae

Finger-like projections of the dermis that extend into the epidermis, containing capillary loops that supply nutrients to the epidermis.

Epidermis

The outermost, avascular layer of the skin, primarily composed of keratinocytes, serving as the body's primary protective barrier.

Stratum Basale

The deepest layer of the epidermis, composed of a single row of cuboidal or columnar cells that continuously divide to produce new keratinocytes (also known as Stratum Germinativum).

Melanocytes

Specialized cells located in the stratum basale of the epidermis that produce melanin, the pigment responsible for skin and hair color.

Melanin

The dark brown to black pigment produced by melanocytes, giving skin and hair their color and protecting against UV radiation.

Sebaceous Glands

Glands found throughout the skin, except in palms and soles, that produce an oily substance called sebum, which lubricates the skin and hair.

Arrector Pili Muscle

Small muscles attached to hair follicles; their contraction causes hairs to stand upright, resulting in 'goosebumps' (piloerection).