INTEGUMENTARY SYSTEMChapter 4

BODY MEMBRANES Cover surface Line body cavities Form protective sheets around organs

2 major categories: 1. epithelial membranes 2. connective tissue membranes

EPITHELIAL MEMBRANES Cutaneous membrane(skin) Mucous membranes Serous membranes

Even though we call them epithelial- they are not only composed of epithelial tissue They are epithelial tissue and connective

tissue

CUTANEOUS MEMBRANE Skin

Superficial epidermis is composed of a keratinizing stratified squamous epithelium

Underlying dermis is dense fibrous connective tissue

Exposed to the air and is a dry membrane

MUCOUS MEMBRANE Composed of epithelium rest on a loose connective tissue

membrane called lamina pretrial

Lines all body cavities that are open to the exterior

Ex: lines the hollow organs of the respiratory system, digestive system, urinary system, and reproductive tracts

Most contained stratified squamous epithelium or simple columnar epithelium.

Wet or moist membranes that are bathed in secretions

Adapted for absorption or secretion.

SEROUS MEMBRANES Serosa membrane

Composed of a layer of simple squamous epithelium resting on a thin layer or areolar connective tissue.

Line body cavities that are closed to the exterior.

Occur in pairs Parietal layer lines a specific portion of the wall of the ventral

body cavity Parietal layer folds on itself and forms the visceral layer Visceral layer- cover the outside of the organs in the cavity

SEROUS MEMBRANES Serous layers are separated by a thin, clear fluid called

serous fluid

Serous fluid is secreted by membranes

Serous fluid allows organs to slide easily across the cavity walls of one another without friction as they carry out routine functions.

Serosa lining abdominal cavity- peritoneum Serosa around the lungs- pleura Serosa around the heart- pericardium

CONNECTIVE TISSUE MEMBRANES Composed of soft areolar connective

tissue Contain no epithelial cells at all Line fibrous capsules of surrounding

joints Provide a smooth surface between

joints Secrete lubricating fluid Line small sacs of connective tissue

called bursae and tubelike tendon sheaths

BASIC SKIN FUNCTIONS Keeps water and precious molecules in. Keeps water and bacteria out. The capillary network and sweat glands offer

regulation of heat loss. Insulates and cushions the deeper organs. Protects the entire body from mechanical damage

and UV radiation. Houses our cutaneous sensory receptors. (part of the

nervous system)

STRUCTURE OF THE SKIN The skin is composed of two kinds of tissue1. Stratified Squamous Epithelium makes up the

EPIDERMIS. (This epithelium is capable of keratinizing.)

2. Dense Connective Tissue makes up the DERMIS. These two layers are firmly connected .

A layer of Adipose Tissue lies beneath the skin and is called the subcutaneous tissue, or HYPODERMIS. It connects the skin to underlying organs

EPIDERMIS The epidermis is composed of 5 layers which are

avascular called strata.

The cells of the epidermis are keratinocytes – they produce the fibrous protein keratin.

The deepest layer of the epidermis is the STRATUM BASALE, which is the only layer that receives nourishment by diffusion from the dermis.

The Stratum Basale undergoes constant division, pushing new cells upward to become part of the next layer.

LAYERS OF THE EPIDERMIS5. STRATUM BASALE

4. STRATUM SPINOSUM3. STRATUM GRANULOSUM

2. STRATUM LUCIDUM1. STRATUM CORNEUM

The cells become flatter and increasingly full of keratin as they move away from the dermis.

The accumulation of water repellent keratin, and increasing distance form the blood and nutrient supply ultimately kills the cells.

DERMIS The dermis is a strong stretchy envelope that helps

hold your body together. It varies in thickness in different locations of the body.

LAYERS OF THE DERMIS1. Papillary Layer2. Reticular Layer

The papillary layer lies just below the epidermis. It is uneven and has fingerlike projections from its superior surface called DERMAL PAPILLAE. The Dermal Papillae contains small blood vessels called capillary loops, pain receptors, and touch receptors.

The reticular layer is the deepest layer of the skin. It contains blood vessels, sweat and oil glands, and pressure receptors.

Collagen and Elastic fibers are found throughout the dermis and are responsible for its toughness.

SKIN COLOR Amount and kind (yellow, reddish brown, or

black) of melanin in the epidermis

Amount of carotene deposited in the stratum corneum and subcutaneous tissue Carotene is orange-yellow pigment found in carrots

and other yellow-orange vegetables

Amount of oxygen bound to hemoglobin in the dermal blood vessels.

SKIN APPENDAGES 1. Cutaneous Glands (Sebaceous Glands and Sweat

Glands) 2. Hair and Hair Follicles 3. Nails

SKIN APPENDAGES1 Cutaneous Glands

The cutaneous glands are all exocrine glands that secrete their secretions to the skins surface via ducts. They fall into 2 groups:

A. SEBACEOUS GLANDS B. SWEAT GLANDS

SEBACEOUS GLANDS A. Sebaceous Glands (oil glands) – their ducts

usually empty into a hair follicle, but some open directly onto the skin. These glands produce SEBUM. ( a mixture of an oily substance and fragmented cells)

Sebum keeps the skin soft and moist and prevents the hair from becoming brittle. It contains chemicals that kill bacteria.

SWEAT GLANDS B. Sweat glands – are found all over the body, there

are two main types.1. Eccrine Glands produce SWEAT which reaches the

skins surface via a duct called a PORE. Eccrine glands are an important and highly efficient

factor in heat regulation. They are supplied with nerve endings which sense internal and external temps.

2. Apocrine Glands Usually confined to the axillary and genital areas.

SKIN APPENDAGES2. Hair and Hair Follicles

Today hairs only serve a few minor functions (eyelashes, nose hairs)

A HAIR is flexible epithelial structure produced by a HAIR FOLLICLE

The part of the hair enclosed in the follicle is called the ROOT.

Each hair consists of a central core called the MEDULLA surrounded by a bulky CORTEX which is surrounded by the CUTICLE.

SKIN APPENDAGES3. Nails

Nails are a scale like modification of the epidermis that is similar to a hoof or claw of other animals.

Nails have a free edge, a body, and a root which imbedded in the skin

They are transparent and nearly colorless but appear pink because of the blood supply in the dermis below.

HOMEOSTATIC IMBALANCE Overexposure to the sun The appearance of aging skin Bed Sores Blushing- Turning Blue Acne Allergies and Infections Burns Cancer

HOMEOSTATIC IMBALANCES OF SKIN Infections and allergies Burns Skin cancer

ATHLETES FOOT Itchy, red, peeling condition of the skin

Appears between the toes

Results from a fungus infection

Tinea pedis

BOILS AND CARBUNCLES Inflammation of hair follicles and

sebaceous glands

Common in dorsal neck

Carbuncles- composite boils typically caused by a bacteria infection

COLD SORES Fever blisters

Small, fluid-filled blisters that itch and sting

Caused by a herpes simplex infection

Virus localizes in a cutaneous nerve where it remains dormant until activated by emotions upset, fever, or UV radiation

Usually occur around the lips and oral mucosa of the mouth

CONTACT DERMATITIS Itching, redness, swelling of the skin

Progressing to blistering

Caused by exposure of the skin to chemicals that provoke allergic responses in sensitive individuals

IMPETIGO Pink, water-filled, raised lesions (commonly

around the mouth and nose)

Develop a yellow crust and eventually rupture

Caused by a highly contageous staphlycoccus infection

Common in elementary school-ages children

PSORASIS Chronic condition

Characterized by reddened epidermal lesions covered with dry, silvery scales

May be disfiguring when severe

Cause is unknown: may be hereditary in some cases

Attacks often triggered by trauma, infection, hormonal changes, and stress

BURNS Skin is only as thick as a paper towel

When skin is severely damages, nearly every body system suffers

Metabolism accelerates or may be impaired Changes in the immune system occur Cardiovascular system may falter

Burn- tissue damage and cell death caused by intense heat, electricity, UV radiation (sunburn), certain chemicals (such acids)

BURNS When skin is burned and its cells destroyed,

two life-threatening problems result.

1. body loses its prescious supply of fluids containing proteins and electrolytes as these seem from the burned surfaces

2. dehydration and electrolyte imbalance follow- this can lead to a shutdown of kidneys and circulatory shock

RULE OF THE NINES Divides the body into 11 areas, each county

for 9 percent of the total body surface area

Additional 1% is accounted for by the area surrounding the genitals

Volume of fluid lost can be estimated indirectly by determining how much of the body surface is burned by using this rule.

DEVELOPMENTAL ASPECTS OF SKIN AND BODY MEMBRANES During the fifth and sixth month of fetal development the

infant is covered with a downy type of hair called lanugo.

Lanugo has usually been shed by birth.

When a baby is born the skin is covered with vernix caseosa White, cheesy-looking substance Produced by sebacous glands Protects the baby’s skin while it is floating in water-filled sac

inside the bother Newborn skin is very thin and you can see blood vessels through

it

DEVELOPMENTAL ASPECTS OF SKIN AND BODY MEMBRANES Milia- white spots that appear on the baby’s nose and

forehead Accumulations in the sebaceous glands Usually disappear by 3 weeks after birth

During adolescence skin and hair become more oily Sebaceous glands are activated Acne may appear Acne usually subsides in early adulthood and skin reaches

optimal appearance when we are in our 20s and 30s.

Visual changes appear in skin as we are exposed to sun, wind, abrasion, chemicals, and other irritants

DEVELOPMENTAL ASPECTS OF SKIN AND BODY MEMBRANES

When skin pores become clogged with pollutants and bacteria pimples, scales, and various kinds of dermatitis(skin inflammation) become visible.

During old age: Amount of subcutaneous tissue decreases which leads

to intolerance to cold Skin becomes dry Thinning skin make it more susceptible to bruising and

other types of injuries Sunlight causes loss of elasticity

DEVELOPMENTAL ASPECTS OF SKIN AND BODY MEMBRANES

Hair loses its luster as we age

By age 50 the number of hair follicles has dropped by 1/3

A bald man is not really hairless – he does have hairs in the bald area The hair follicles have begun to degerate Hairs are colorless and very tiny These hairs are called vellus