Histo lab 6

The integument

Consists of the skin and accessory structures such as hair, glands, and nails.

•Protection

•Sensation 

•Vitamin D Production 

•Temperature Regulation 

•Excretion

Functions of the integument

Epidermis
Dermis

•Two Major Tissue Layers:

Epidermis

most supericial layer, made of epithelial tissue, provides protection

Dermis

Below the epidermis, made of dense connective tissue, provides structural strength

Subcutaneous tissue

•Also called hypodermis, it's a connective tissue layer beneath the skin.

•Connects the skin to underlying muscle or bone but is not part of the skin.

hypodermis

Sjubcutaneous tissue is also called the

Epidermis

•Made of stratified squamous epithelium; deepest layers undergo mitosis.

•New cells push older cells to the surface, where they flake off.

•Functions: Prevents water loss, resists abrasion, and provides protection.

•Cells fill with keratin, becoming rigid and durable.

•Dead, keratinized cells form a protective outer layer.

10–20 times

The dermis is ____ thicker than the epidermis

Stratum basale

Stratum spinosum

Stratum granolosum

Stratum lucidum

Stratum corneum

•Epidermal Layers (Strata) from Deepest to Superficial:

Stratum basale

•Cuboidal/columnar cells undergo mitosis; one cell remains, the other moves upward.

Stratum spinosum

•Cells flatten and accumulate lamellar bodies (lipid-filled vesicles).

Stratum granulosum

•Flat, diamond-shaped cells; accumulate keratin, release lipids, and die.

Stratum lucidum

Present only in thick skin (e.g., palms, soles).

Stratum corneum

Outermost layer of dead, keratinized cells; abrasion-resistant barrier.

hemidesmosomes

The stratum basale, also known as stratum germinativum, is separated from the dermis by the basement membrane (basal lamina) and attached to it by

keratinocytes
melanocytes

The cells in this layer are cuboidal to columnar, mitotically active stem cells that constantly produce ____, this layer also contains

8-10 layers

how many cell layers in startum spinosum

prickle cell layer

the stratum spinosum is also called the

dendritic cells

what cells can be found in the stratum spinosum

3-5 cell layers

the stratum granulosum has how many layers

keratohyaline

____ granules contain keratin precursors that aggregate, cross-link, and form bundles

lamellar

granules contain the glycolipids secreted to the cell surfaces, functioning as an adhesive to maintain cellular cohesion

2-3 cell layers

the stratum lucidum has how many cell layers

eleidin

, a transformation product of keratohyalin.

20 to 30 cell layers

the stratum corneum has how many cell layers

defensins

Dead keratinocytes release ___

Hair

•is found on most of the body except the palms, soles, lips, nipples, parts of the genitalia, and distal fingers and toes.

Hair bulb

•is the expanded base of the root, resting on the hair papilla, which supplies nutrients through blood vessels.

hard cortex

•Hair consists of a _____ surrounding a softer medulla, and is covered by the cuticle, which holds it in the follicle.

goose bump

Contraction of the arrector pili causes the hair to become more perpendicular to the skin’s surface, or to “stand on end,” and it produces a raised area of skin called a

nail

•are made of dead stratum corneum cells containing a hard type of keratin.

nail body

•is the visible part, while the nail root is covered by skin.

The cuticle (eponychium)

•is a layer of stratum corneum extending onto the nail body.

the nail matrix

is the thick epithelial tissue at the nail root that produces most of the nail.

the nail bed

•is located beneath the nail, distal to the matrix.

lunula

•is the crescent-shaped, whitish area visible at the base of the nail.

Sebaceous gland

•Simple, branched acinar glands

•Connected to hair follicles

•Produce sebum (oily, lipid-rich substance)Released by holocrine secretion

•Lubricates hair and skin, Prevents drying & Protects against bacteria

Sebum

the sebaceous gland produces what?

Eccrine sweat gland

•Simple, coiled, tubular glands

•Release sweat by merocrine secretion

•Found all over the body, especially in palms and soles

•Sweat composition: Mostly water with some salts

•Ducts open onto the skin surface

mostly water with salt

Sweat composition

Secretory part

Eccrine sweat gland

generally more pale-staining than the ducts; consists of an unusual stratified cuboidal epithelium with three cell types:

Clear cells
Dark cells
Myoepithelial cells

•Secretory part: generally more pale-staining than the ducts; consists of an unusual stratified cuboidal epithelium with three cell types:

Clear cells

•pale staining; located on the basal lamina; produce the sweat; have abundant mitochondria and microvilli to provide large surface areas.

Dark cells

filled with strongly eosinophilic granules; line most of the lumen and do not contact the basal lamina; granules undergo merocrine secretion

Myoepithelial cells

on the basal lamina contract to move the watery secretion into the duct

Apocrine sweat gland

•Simple, coiled, tubular glands

•Secretory components have much wider lumens than eccrine glands

•consist of simple cuboidal, eosinophilic cells with numerous secretory granules that also undergo exocytosis.

•Produce thick secretion rich in organic substances

merocrine secretion
holocrine

•Apocrine sweat glands

Secrete primarily by ___ secretion, with some ___ secretion

armpits and genitalia

Apocrine sweta glands can be found in

Dermis

•Made of dense collagenous connective tissue with fibroblasts, adipocytes, and macrophages.

•Contains nerves, hair follicles, smooth muscles, glands, and lymphatic vessels.

Dermal papillae

•Projections into the epidermis containing blood vessels.

•Supply nutrients, remove waste, and regulate temperature.

•In hands, feet, and fingertips, they form friction ridges (fingerprints & footprints) for better grip.

Pacinian corpuscle in thick skin

•Found deep in the dermis (thick skin) and subcutaneous tissue

•Ovoid shape, contains an elongated central myelinated axon (2b, 9b)Axon is surrounded by concentric lamellae (2a, 9a) made of compact collagen fibers

•Connective tissue capsule (2c, 9c) forms the outer layer

•Contains lymph-like fluid between lamellae

•In transverse section, resembles a sliced onion

•Sensory receptors for: Pressure, Vibration & Touch

•Arteriovenous Anastomoses (AVAs)

•Direct connections between arteries and veins, bypassing capillaries

•Found in numerous tissues

•Functions: Regulate blood pressure, Control blood flow, Regulate body temperature, Conserve body heat

Glomus

•A more complex arteriovenous shunt

•Highly coiled arteriovenous vessel

•Surrounded by collagenous connective tissue

•Location: Fingertips, External ear, Other peripheral areas exposed to cold temperatures