Integumentary System Skin & Membranes Anatomy and Physiology

Integument – Membrane Parts of the Integumentary System 1. Skin (cutaneous membrane) – dry, stratified epithelium over dense fibrous connective tissue 2. Mucous membranes – wet, simple or stratified epithelium over fibrous connective, line all cavities open to the outside, protect from infection and leakage

Parts of the Integumentary System Continued 2. Serous membranes – wet, simple epithelium over areolar, coating every cavity not open to the outside, double layered membrane with serous fluid in between the layers A> peritoneum – abdominal cavity B> pleura – around lungs C> pericardium – around heart D> meniges – around brain and spinal column

Parts continued 4. Synovial Membranes – wet, around joint cavities, only non-epithelial membrane – fibrous connective tissue that secretes synovial fluid to lessen impact of friction in joints.

Functions: Waterproofing (keeps water out and in) Synthesizes Vitamin D (allows Ca ++ Absorption) Protects internal structures from: UV rays Bacteria Heat, cold, chemical damage Temperature Control Through sweat glands Through blood vessel dilation and constriction Through subcutaneous fat layer for insulation

Structure of the Skin (Superficial to Deep) I. Epidermis (epithelium) A.Stratum Corneum (cornified layer) dead cells, keratinized, tough and waterproof B. Stratum Lucidum (clear layer) flat, full of keratin, dead or dying C. Stratum Granulosum (granular layer) some keratin and lipids D. Stratum Spinosum (Spiny layer) living with a little keratin E. Stratum Germinativum (Germinating layer or basal layer) living, only mitotic (growing) layer contain the melanoctyes that make melanin

SS SGR SC

↑ A B → C D ← → E ↑

As you go from deep to superficial the cells are becoming flatter, more keratin filled and less blood supply Cells start to die as go away from germinativum – starting to die at granulosum layer and entire corneum is dead

Melanocyte

Structure of Skin Continued II. Dermis –Dense fibrous connective tissue (collagen and elastin) –Good blood supply A.Papillary layer projects into the epidermis forming dermal papillae (forms ridges known as finger prints used for gripping) Pain and touch receptors

→ Pain or touch receptor

Structure Continued (Dermis) B. Reticular Layer (most of dermis) - Still dense fibrous with good blood supply Sebaceous glands (oil glands)– make sebum (oil & dead cells) softens skin and kills bacteria Sudoiferous glands (sweat glands) for temperature regulation Eccrine – water and salt – all over Appocrine – arm pits and groin – only start at puberty – secrete proteins, lipids with water and salt which bacteria feed off of making b.o. Pressure and temperature receptors C. Subcutaneous Layer (Fat) for insulation

Pacinian Corpusle(Pressure Receptor)

Hair Follicles Hair grows from epithelium which is an extension of the stratum germinativum – called the epidermal sheath (growth occurs from the hair bulb) Melanocytes are embedded in the hair bulb The hair itself has three parts: Cuticle – outside coat with overlapping cells Cortex – body of the hair Medulla – center of hair

Skin Cancer Basal Cell Carcinoma – cancer of the stratum germinativum or basal layer – usually doesn’t metastasize Squamous Cell Carcinoma – cancer of the stratum spinosum – metastasizes very slowly Melanoma – cancer of the melanocytes – most dangerous – metastasizes ABCD – method to recognize suspicious moles that could be a sign of melanoma A = asymmetry B = borders irregular C = color is different throughout D = diameter > 6mm

Burns First Degree – only epidermis damaged, appears red and swollen First Degree – only epidermis damaged, appears red and swollen Second Degree – epidermis and upper dermis damaged, red, painful, blisters Second Degree – epidermis and upper dermis damaged, red, painful, blisters Third Degree – through entire epidermis and dermis, white due to no blood or black from charring, no pain all of nerves destroyed >25% second degree is critical or >10 % third degree is critical Rule of 9’s