Integumentary System HST I

Integumentary system (Skin) Considered to be both: (a) Membrane – covers the body (b) Organ – contains several types of tissue – Largest organ in body - covering (c) 3,000 square inches – About (d) 15% total body weight

Tissue: 3 layers of tissue 1. (e) Epidermis – outermost layer of skin (f) NO blood vessels or nerve cells (avascular) 2. (g) Dermis – corium or “true skin” Includes: – Elastic connective tissue – Blood vessels – Lymph vessels – Nerves – Involuntary muscle – Sweat and oil glands – Hair follicles

Tissue: 3.(h) Subcutaneous layer (hypodermis) – the innermost layer Made of: Elastic and fibrous connective tissue Adipose (fatty) tissue Connects the skin to underlying muscles

Fingerprints? The top layer of the dermis has ridges which form lines or striations on the skin which give us our unique fingerprints

Major Organs/Structures Skin Sweat and oil glands Nails Hair

Two Main Types of Glands 1.(i) Sudoriferous (sweat) glands Sweat eliminated by these glands contains water, salts, and some body wastes Sweat is odorless until it interacts with bacteria on the skin Perspiration (sweating) removes excess water from the body and cools the body

Two Main Types of Glands 2.(j) Sebaceous (oil) glands Usually open onto hair follicles Produce sebum (oil) which keeps skin and hair from becoming dry and brittle Slightly acidic nature helps prevent infection Oil glands plugged with dirt and oil result in blackheads or pimples.

Hair Consists of a root (which grows in a hollow tube called a (k) follicle) A (l) hair shaft – Helps protect the body – Covers all body surfaces except the palms of the hands and the soles of the foot

(m) Alopecia (baldness) Genetically inherited Males (and some females) Permanent loss of hair of the scalp

Nails Protect the fingers and toes from injury Made of (n) dead, keratinized epithelial cells Formed in the nail bed If lost, nails will regrow if the nail bed is not damaged

Functions of Skin: 1.(o) Protection –barrier against UV rays and infection, and helps prevent dehydration 2.(p) Sensory perception – nerves help the body respond to pain, pressure, temperature, and touch sensations 3.(q) Body temperature regulation when blood vessels in the skin (r) dilate (get larger) – excess heat can escape when blood vessels (s) constrict (get smaller) – heat is retained

Functions of Skin: 4.(t) Storage – tissue temporarily stores fat, glucose, water, vitamins, and salts; adipose (fatty) tissue is a source of energy 5.(u) Absorption – certain substances are absorbed through the skin, such as medicine and nicotine patches; medication patches are (v) transdermal 6.(w) Excretion – eliminates salt, waste, excess water and heat through perspiration 7.(x) Production – skin helps produce vitamin D using UV rays

Pigmentation: Basic skin color is inherited – (y)Melanin – brownish-black pigment produced in the epidermis Everyone has the same number of (z) melanocytes but genes determine the amount of melanin produced Freckles are small concentrated areas of melanin – (aa)Albino – absence of color pigments in the skin Skin has pinkish tint Hair is pale yellow or white Eyes lack pigment; are red; very sensitive to light

Abnormal Pigmentation: (bb) Erythema – reddish color that can be caused by burns or a congestion of blood in the vessels (cc) Jaundice – yellow discoloration; indicates bile in the blood resulting from liver and gallbladder disease; also seen in diseases that involve destruction of RBC (dd) Cyanosis – bluish discoloration caused by insufficient oxygen; associated with heart, lung, and circulatory diseases or disorders (ee) Chronic poisoning – may cause gray or brown skin discoloration

Skin Eruptions: (ff) Macules – flat spots on the skin, such as freckles (gg) Papules – firm, raised areas such as pimples and the eruptions seen in some stages of chickenpox and syphilis (hh) Vesicles – blisters, or fluid- filled sacs, such as those seen in chickenpox

Skin Eruptions: (ii) Pustules – pus- filled sacs such as those seen in acne, or pimples (jj) Crusts – areas of dried pus and blood, commonly called scabs

Skin Eruptions: (kk) Wheals – itchy, elevated areas with an irregular shape; hives and insect bites are examples (ll) Ulcer – a deep loss of skin surface that may extend into the dermis; may cause periodic bleeding and the formation of scars

Diseases and Abnormal Conditions: (ss) Eczema – noncontagious, inflammatory skin disorder caused by allergens or irritants

Diseases and Abnormal Conditions: (tt) Psoriasis – chronic, noncontagious skin disease with periods of (uu) exacerbations (symptoms present) and (vv) remission (decrease or disappearance of symptoms) (ww) Ringworm – highly contagious fungal infection of the skin or scalp