Skin and Body Membranes

Body membranes

Cover surface, line body cavities, and form protective sheets around organs

Epithelial and Connective tissue membrane

Types of Body membranes

Epithelial membranes

Covering and Lining

Includes cutaneous, mucous, and serous membranes

Composed of epithelial layer + Connective tissue

Cutaneous, Mucous, and Serous membrane

Types of Epithelial membrane

Cutaneous Membrane

Composed of the superficial epidermis and underlying dermis

Stratified squamous epi + dense CT

Exposed to air and is dry

Skin

Example of Cutaneous membrane

Mucous membrane

Composed of epithelium resting on a loose CT (Lamina propria)

Lines of body cavities that open to the exterior

Either stratified squamous or stratified columnar

Digestive and respiratory system

Example of Mucous Membrane

Serous membrane

Composed of a simple layer of simple squamous epithelium resting on a thin layer or areolar CT

Line body cavities that are CLOSED to the exterior )except for the dorsal body cavity and joint cavities)

Parietal and Visceral

Serous membrane occurs in: ___ and ____

Serous fluid

Clear fluid that fills the serous membrane

Peritoneum, Pleurae, and pericardia

The 3 location where we can find Serous membrane

Peritoneum

Serosa lining the abdominal cavity and its organs

Pleurae

Membranes surroundings the lungs

Pericardia

Membrane around the heart

Connective tissue membrane

Encapsulate organs and line movable joints

Synovial membrane

Formed solely from connective tissue

Synovial membrane

Composed of loose areolar connective tissue and contain no epithelial cells

Lines the fibrous capsules surroundings joint

Bursae

Synovial membrane line the small sacs of connective tissue called _______

Tendon sheaths

Synovial membrane line the tube like ______

Integumentary system

Composed of skin and its appendages

Contributes to homeostasis

Allows an organism to sense stimuli

Most exposed to infection, disease, and injury

Dermatology

The skin

Also known as cutaneous membrane

Covers the external surface of the body

Epidermis and Dermis

Two types Tissues found in the skin

Epidermis

Superficial, thinner portion

Composed of keratinize strat, squamous epithelium

Avascular

Keratinocytes, Melanocytes, Intraepidermal macrophages, and Tactile epithelial cells

Four principal types of cells in Epidermis

Keratinocytes

Arranged in four to five layers

Produce lamellar granules

Product is Keratin

Melanocyte

Long and slender projections

Produces pigment melanin

Melanin

A yellow-red or brown-black pigment that contributes to skin color and absorbs UV radiation

Intraepidermal macrophages

Arise from red bone marrow and migrate to the epidermis

Participate in Immune response

Langerhans cell

Cell of the Intraepidermal macrophages

Tactile Epithelial Cell or Merkel cells

Located in the deepest layer of the epidermis

Detect touch sensations

Stratum basale, spinosum, granulosum, lucidum, and corneum

5 layers of epidermis

Stratum Basale

Deepest layer of the epidermis

Single row of cuboidal or columnar keratinocytes

Also known as Stratum germinativum

Stratum Spinosum

Superficial to the stratum basale

Consists of numerous keratinocytes

Arrangements provide both strength and flexibility to the skin Langerhans cells are present

Stratum Granulosum

Middle layer with cells contain “grains”

No longer produced but are becoming more apparent due to organelle regression

Stratum Lucidum

Clear layer

Present only in the thick skin areas

Four to six layers of flattened, clear, dead keratinocytes that contain large amounts of keratin and thickened plasma membranes.

Stratum Corneum

25-30 layers of flattened dead keratinocytes

Cells are extremely thin, flat, plasma membrane-enclosed packages of keratin

Cells overlap one another like scales

Dermis

Second layer, deeper

Composed of dense irregular connective tissue containing collagen and elastic fibers

Has the ability to stretch and recoil easily

Vascular

Much thicker

Fibroblasts, Macrophages, and Adipocytes

Principal type of cells in Dermis

Papillary region and Reticular region

Division of Dermis into 2 region

Papillary region

Superficial layer

Contain collagen and fine elastic fibers

Surface area greatly increased by dermal papillae

Reticular Region

Attached to subQ layer

Contains bundle of thick collage fibers, scattered fibroblasts, and macrophages

Contains blood vessels, glands, and lamellar corpuscles

Cyanotic

Bluish

Blood not picking up an adequate amount of O2 from the lungs

Jaundice

Yellow

Build up of bilirubin in the skin

Indicates liver disease

Erythema

Red

Engorgement of capillaries in the dermis due to skin injury, heat, infection, inflammation, or allergic reaction

Pallor

Paleness

Shock and Anemia

Loss of decrease of blood flow to the skin

Albinism

Inherited inability of an individual to produce melanin

Results in problem with vision and skin to burn on overexposure to sunlight

Vitiligo

Partial or complete loss of melanocytes from patches of skin

Related to an immune system malfunction in which antibodies attack the melanocytes

Skin Appendages

Hair, Skin Glands, and Nails

Develop from the embryonic epidermis

Holds several important functions

Hair

Present on most skin surfaces except the palms, palmar surfaces of the finger, the soles, and the plantar surface of the feet.

Scalp, eyebrows, axillae, and around the external genitalia

Offers limited protection

Hair anatomy

Composed of columns of dead keratinized epidermal cells

Hair Shaft

Superficial to hair root

Hair Root

Deep to the shaft

Medulla, Cortex, and Cuticle

Three concentric layers of cells

Cutaneous glands

All exocrine glands that release their secretions to the skin surface via ducts

Sebaceous, Swear, and Ceruminous Glands

3 cutaneous glands

Sebaceous Glands

Oil glands

Simple, branched acinar glands

Some are connected to hair follicles

Sudoriferous glands

Three to four million

Sweat glands

These glands release sweat into hair follicles or onto the skin surface through pores

Eccrine and Apocrine

2 types of sudoriferous glands

Eccrine Sweat Glands

Found all over the body

Secretory portions is located mostly in deep dermis

Excretory duct projects through the dermis and epidermis and ends as a pore at the surface of the dermis

Apocrine Sweat Glands

Simple, coiled, tubular glands that have larger ducts and lumens

Formed mainly in the skin of the axilla, groin, areolae of the breasts, bearded regions of the face in adult males

Ceruminous glands

Modified sweat glands in the external ear \

Produces a waxy lubricating secretion

Athletes foot

An itchy, red, peeling condition of the skin between the toes, resulting from an infection witht he fungus Tinea pedis

Boils

Furuncles and carbuncles

Caused by inflammation of hair follicles and surrounding tissues

Boils often caused by bacterium Staphylococcus aureus

Cold Sores

Fever blisters

Small fluid-filled blisters that itch and sting, caused by human herpesvirus 1 infection

Impetigo

Develop a yellow crust and eventually rupture

Caused by highly contagious Staphylococcus spp or Streptococcus spp. infections

Squamous cell carcinoma, Basal cell carcinoma, and Malignant melanoma

Types of Skin cancer

Squamous Cell Carcinoma

Arises from the cells of the stratum spinosum

The lesions appear as scarly, reddened papule that gradually form shallow ulcers with firm, raised borders.

Basal cell Carcinoma

The least malignant and most common skin cancer

Cells that altered the production of keratin, no longer honor the boundary between epidermis and dermis

Malignant melanoma

Cancer of melanocytes

Arises from accumulated DNA damage in a skin cell and usually appears as a spreading brown-to-black patch that metastasizes rapidly to surrounding lymph and blood vessels