INTEGUMENTARY SYSTEM

Chapter 4 Notes

I. I. Classification of Body Classification of Body MembranesMembranes

• The four major types of membranes are:The four major types of membranes are:

A. Synovial MembraneA. Synovial Membrane

B. Serous MembraneB. Serous Membrane

C. Mucous MembraneC. Mucous Membrane

D. Cutaneous MembraneD. Cutaneous Membrane

A. Synovial MembraneA. Synovial Membrane

• Lines the joint cavities between the ends of bones at freely movable joints.

• Secretes a thick, colorless synovial fluid which lubricates and cushions the ends of bones within the joint.

B. Serous MembraneB. Serous Membrane

Lines ventral body cavities that lack openings to the outside.

Secrete a watery fluid called serous fluid which helps lubricate the surfaces of the membrane.

Found in the inner lining of the thorax and abdomen. They also cover the organs within these cavities.

B. B. Serous MembraneSerous Membrane

• Examples: Peritoneum Examples: Peritoneum (abdominal cavity), (abdominal cavity), Pleura (lungs), Pleura (lungs), Pericardium (heart)Pericardium (heart)

• Serious membrane, Serious membrane, shown in red, shown in red, line line ventral body cavities ventral body cavities that are closed to the that are closed to the exterior.exterior.

C. Mucous MembraneC. Mucous Membrane

• Lines the cavities and tubes that open to the outside of the body.

• Usually wet or moist membrane that functions in absorption and secretion

• Generally found in the oral and nasal cavities and the tubes of the digestive, respiratory, urinary, and reproductive systems.

C. MucousC. Mucous MembraneMembrane

• The mucous The mucous membrane, shown in membrane, shown in blue, blue, lines body lines body cavities that are open cavities that are open to the exteriorto the exterior..

D. Cutaneous MembraneD. Cutaneous Membrane

• An organ of the An organ of the integumentary system integumentary system and is commonly and is commonly called the skin.called the skin.

• The cutaneous The cutaneous membrane is exposed membrane is exposed to the air and is a dry to the air and is a dry membrane.membrane.

• Two parts: epidermis Two parts: epidermis and dermisand dermis

II. Integumentary SystemII. Integumentary System

• Consists of the cutaneous membrane (skin) and its Consists of the cutaneous membrane (skin) and its accessory organs.accessory organs.

• ““Integument” means covering.Integument” means covering.• Weighs about six pounds.Weighs about six pounds.• As you age your skin loses its elasticity and thins. As you age your skin loses its elasticity and thins.

The thinning process allows the skin to be bruised The thinning process allows the skin to be bruised and damaged easier. The loss of elasticity causes and damaged easier. The loss of elasticity causes wrinkles and sagging to occur.wrinkles and sagging to occur.

A. Functions

1. Protection from: Physical damage - I.S. is a physical barrier that contains

keratin, which toughens cells, and pressure receptors, which alerts the nervous system to possible damage.

Bacterial damage - I.S. also has skin secretions that are acidic to inhibit bacterial growth.

Ultraviolet radiation - Melanin provides protection from sun damage.

Thermal damage - Contains heat/cold/pain receptors Desiccation - Skin contains waterproofing substances

including keratin.

A. Functions

2. Regulates Body Temperature: Heat Loss - When the body temperature rises above

normal, the dermal blood vessels dilate which allows blood to rush into skin capillary beds. The nervous system then activates sweat glands which acts as a cooling system.

Heat Retention - When the body temperature drops below normal, the dermal blood vessels constrict and sweat glands become inactive.

A. Functions

3. Excretion: The integumentary system excretes urea (wastes), salts,

and water as sweat.

4. Sensory Reception: Along with the nervous system, the skin is embedded

with sensory receptors that provide us with information about our external environment.

B. Structure of Skin

1. Epidermis Outer portion of skin and is made up of

stratified squamous epithelium. Avascular - no blood supply of its own. Capable of keratinization, which means to

harden and waterproof the cells in this layer. It is composed of five layers called strata:

1. Epidermis

A) Stratum Basale - Cells are constantly undergoing cell division in this layer. Millions are produced daily. Cells in this layer also contain melanin which protects the cells from the sun. This melanin is what causes the tanning effect on our skin. As cells are being produced, the older cells move away and become part of the more superficial layers. FYI - Freckles, Moles, and Skin Cancer

1. Epidermis

B. Stratum Spinosum and Granulosum - The cells in these layers become flatter, keratinize and die.

C. Stratum Lucidum - This is the next layer of skin. This layer is the outer layer of skin where there is no hair.

D. Stratum Coneum - The outermost layer of skin everywhere else on the body. It is about 8 cell layers thick. The cells at the surface continually flake off. We have totally new skin about every 25-35 days.

B. Structure of Skin

2. Dermis Made up of dense connective tissue that lies

underneath and connected to the epidermis. It is our “hide” (bags, belts). It is extremely strong and stretchy. Made up of three layers: Papillary, Reticular,

and Subcutaneous tissue. FYI - Blisters

2. Dermis

A) Papillary - this layer furnish nutrients and houses pain receptors. It also contains the dermal papillae which forms patterns called finger prints.

B) Reticular - which is the deepest layer. It contains blood vessels, sweat and oil glands.

C) Subcutaneous tissue - AKA hypodermis. It is essentially adipose tissue. It is not actually part of the skin, but it does anchor the skin to underlying organs.

III. Accessory Organs of the Skin

A. Hair and hair follicles - each hair develops from epidermal cells at the base of a hair follicle.

Just like skin, hair is dead cells that have gone under keratinization.

The root is the section of the hair hidden in the follicle. The shaft is the part you see.

A bundle of smooth muscles cells called arrector pili is attached to each hair follicle.

Hair color is determined by melanin.

III. Accessory Organs of the Skin

B. Sebaceous Glands - Oil glands are found all over the skin and are considered an exocrine gland.

Their ducts usually empty into a hair follicle, but some open directly onto the skin.

The secretions from these glands are called Sebum. It is a mixture of oily substances and fragmented cells. Sebum is a lubricant to keep skin soft and helps prevent hairs from becoming brittle. Sebum also waterproofs the skin and contains chemicals that help kill bacteria.

FYI - Acne

III. Accessory Organs

C. Sweat Glands - AKA sudoriferous glands; this is a type of exocrine glands. We have about 2.5 million per person. There are two types:

Eccrine glands are far more numerous and produces sweat. Sweat is primarily water and some salt, vitamin C, metabolic wastes, and lactic acid. Eccrine glands function in responding to an elevated body temperature.

Apocrine glands are confined to the axillary and genital areas. Apocrine glands responds to emotional stress. Their secretions contains fatty acids and proteins. Their function is not yet known, but they are activated by nerve fibers during pain, stress and during sexual foreplay.

Homeostatic Imbalances of SkinA. Infections and Allergies

Athletes Foot Boils and Carbuncles Cold Sores Contact Dermatitis Impetigo Psoriasis

B. BurnsC. Skin Cancer

Basal Cell Carcinoma Squamous Cell Carcinoma Malignant Melanoma