ZOOLOGY 100 NOTES (1).mid

INTEGUMENTARY SYSTEMOUTLINE

I. FUNCTIONSII. INVERTEBRATE I.S.

III. VERTEBRATE I.S.IV. SOME MEDICAL CONDITIONS ASSOCIATED WITH THE INTEGUMENTARY SYSTEM IN HUMANSV. OTHER STRUCTURES IN THE SKIN

VI. SKIN DISORDERS IN HUMANS

OBJECTIVES:1. Know the functions of the integumentary system.2. Differentiate the integument of invertebrate to vertebrate3. Identify some medical conditions associated with the integumentary system4. Enumerate other structures that can be found in the skin and some skin disorders in humans5. Realize the importance of taking good care of the skin, and the body as a whole (mind, body, and spirit)

What is i.s.?How important is the i.s. to the living organisms?

THE INTEGUMENTARY SYSTEM• the SKIN & skin derivatives (consisting of the nails and the hair), is the outer covering of the body.• the human body’s largest organ• Integument comes from L. word which means “to cover” • FUNCTIONS:

A. important function: PROTECTION; 1. as a barrier against infection and injury2. regulates body temperature ( applicable only to homoeiothermic animals)3. removes waste products from the body4. against the UV rays from the sun5. produces vitamin DB. COVERINGC. SECRETION (cutaneous glands)D. EXCRETION OF METABOLIC WASTES (cutaneous gland)

• FUNCTIONS: E. SENSATION (nerve endings and tactile cells)

- serves as a gateway through which the sensations (HEAT, COLD, PRESSURE) are transmitted to the nervous system

F. RESPIRATIONExample: frog’s skin (highly impregnated with blood vessels) = accessory organ

G. ABSORPTIONExample: frog = stratum corneum is thin, allowing entrance of water

• HOMOIEOTHERMIC ANIMALS are WARM-BLOODED animals: those with a regulated body temperature because of their heat-conserving bodyExamples: aves & mammals

• POIKILOTHERMIC ANIMALS are COLD-BLOODED animals: whose body temperature closely follows that of their environment

THE INVERTEBRATE INTEGUMENT• PROTOZOA: animals with delicate cell membrane

Ex: Amoeba with firm and elastic pellicle; Ex: Paramecium• ALL MULTICELLULAR ANIMALS ARE PROVIDED the EPIDERMAL TISSUE (EPIDERMIS): Coelenterata,

Platyhelminthes, Annelida, Nemathelminthes, Arthropoda and Mollusca • The EPIDERMIS in INVERTEBRATES:

- single layer of cells found in animals with a soft body (Coelenterata)- contains delicate non-cellular CUTICLE secreted by the epidermis (Earthworm, Annelida)- contains RESISTANT CUTICLE in flukes, tapeworm (Platyhelminthes) and roundworms like Ascaris

(Nemathelminthes)- secretes protective external skeleton (CHITIN) in insects and shrimps (Arthropoda); or SHELLS in

snails and bivalves (Mollusca). Terrestrial arthropods have a CUTICLE with a thin layer of WAX that prevents the loss of body fluids.

THE VERTEBRATE INTEGUMENT• 2 principal parts: EPIDERMIS and DERMIS

1. EPIDERMIS:- outer, thinner but stratified layer of the skin- ectodermal in origin- many sheets of flattened, scaly epithelial cells.- most of the cells undergo rapid cell division (mitosis), thus

- producing new cells that push older cells to the surface of the skin.- older cells become Flattened, Lose their Cellular Contents and begin making KERATIN (tough

fibrous protein that forms the basic structure of the hair, nails and calluses; In animals it forms cow horns, reptile scales, bird feathers, and porcupine quills)

KERATIN:- KERATINCYTES (the Keratin-producing Cells): die and form a TOUGH, FLEXIBLE WATERPROOF

COVERING ON THE SURFACE OF THE SKIN. Our thickest Epidermis in on the palms and soles- these DEAD CELLS IS SHED OR WASHED AWAY ONCE EVERY 14 TO 28 DAYS.

- derivatives: hairs, nails, claws, scutes, hoofs, beaks and bills, horny scales (reptiles and birds), feathers, spines, enamel of the teeth, glands, horns (hollow and true horns of ruminants)

1. EPIDERMIS:

- contains, MELANOCYTES (cells that produce MELANIN, dark brown pigment LIGHT SKINNED & DARK SKINNED PEOPLE = same # , the difference is caused by the amount of

MELANIN produced & distributed; w/c depend on the ff. FACTORS:1. Heredity 2. Length of Time the Skin is Exposed to Ultraviolet Radiation (Tanning).

MELANIN: important for protection, by absorption of Ultraviolet Radiation from the sun, which can Damage DNA in Skin Cells and lead to deadly forms of Skin Cancer

such as MELANOMA CANCER. WHY THERE IS NO BLEEDING WHEN THE SKIN IS LIGHTLY SCRATCHED?

2. DERMIS (the TRUE SKIN):- inner, thicker layer of the skin composed of living cells- mostly connective tissues fibers, smooth muscles, blood vessels, hair follicles, glands and sensory

nerve endings (especially TACTILE CORPUSCLES – nerve endings responding to tactile, thermal and pain stimuli)- mesodermal in origin- derivatives: scales of fishes, antlers (horns of deer), dentine, bony plates- helps to control our body temperature:

A. On a cold day: the body needs to conserve heat, the Blood Vessels in the Dermis NARROW. B. On hot days: the Blood Vessels WIDEN, warming the skin and increasing heat loss.

- 2 major types of GLANDS:1. SWEAT GLANDS2. SEBACEOUS, OR OIL GLANDS

WHY DO SEBUM NEEDS TO COAT OUR SKIN & THE SHAFTS OF OUR HAIR?WHAT HAPPENS WHEN THE DUCTS OF OUR SEBACEOUS/OIL GLANDS BECOME CLOGGED WITH EXCESS SEBUM, DEAD CELLS, & BACTERIA?

2. DERMIS (the TRUE SKIN) 2 GLANDS: - PASS through the Epidermis and RELEASE THEIR PRODUCTS AT THE SURFACE OF THE SKIN.

1. SWEAT GLANDS produce SWEAT (watery secretions, containing salt, water) 2. SEBACEOUS GLANDS (OIL GLANDS) produce SEBUM (oily secretion, that spreads along the

skin and keeps the keratin rich epidermis flexible & waterproof) - production of Sebum is controlled by Hormones. - connected by Tiny Ducts (Exocrine Glands) to Hair Follicles.- Sebum coats the surface of the skin and the shafts of hair preventing excess water

loss and lubricating and softening the Skin and Hair- ACNE (skin disorder) results when the Ducts of Oil Glands become clogged with

excessive amounts of Sebum, Dead Cells, and Bacteria

WHAT ARE SOME MEDICAL CONDITIONS ASSOCIATED WITH THE SKIN/INTEGUMENT?WHAT HAPPENS WHEN THE DIFFERENT LAYERS OF THE SKIN ARE BURNED?WHY IS THE THIRD DEGREE BURN CONSIDERED LIFE-THREATENING?

SOME MEDICAL CONDITIONS ASSOCIATED WITH THE SKIN/INTEGUMENT• BLISTER: When the skin of the foot may be subject to friction, separating layers of Epidermis, or

separate the Epidermis from the Dermis, and tissue fluid may collect • CALLUS: If the skin is subjected to pressure, the rate of mitosis will increase and create a thicker

Epidermis• BURNS : caused by flames, hot water/steam, sunlight, electricity, corrosive chemicals

- SEVERITY (ranges: minor – fatal)- CLASSIFICATION (based on extent of damage): 1. FIRST-DEGREE BUR: superficial epidermis affected

- painful, not blistered; death of Epidermal Cells. 2. SECOND-DEGREE BURN: deep epidermal layers affected

- have inflammation, blisters, & often painful 3. THIRD DEGREE BURN: entire epidermis is affected/charred or burned away, extending into the

dermis- not painful if the receptors in the dermis have been destroyed- potential life-threatening due to loss of skin

-w/o natural barrier, living tissue exposed is susceptible to infection & dehydration

What are other structures found in the skin?OTHER STRUCTURES present in the SKIN:1. CELL TYPES2. HAIR3. NAIL4. GLANDS5. BLOOD SUPPLY

four principal cells that compose the epidermis: 1. Keratinocytes: 90% of all epidermal cells.

- produce KERATIN (a protein mixture) that helps waterproof and protect the skin. 2. Melanocytes: 8% of all epidermal cells.

- produce MELANIN (group of pigments responsible for skin, hair and eye color) 3. Langerhans cells: arise from the bone marrow and migrate to the epidermis.

- play an important role in the immune response. 4. Merkel cells: located in the deepest regions of the epidermis and are associated with sensory neurons and are thought to function in the sensation of touch.

Hair Structure - divided into:1. shaft - protrudes above the surface of the skin 2. Root - beneath the surface of the skin.

a. Hair bulb – the base of the root that is expanded - A hair is composed of numerous columns of dead yet keratinized cells held tightly together in three concentric layers:

1) medulla 2) cortex 3) Cuticle.

HAIR: produced by cells at the base of the hair follicles- large columns of dead cells that have been filled with keratin- protects and insulates the body- may grow for several years and fall out

Hair Follicles: tubelike pockets of Epidermal Cells that extend into the Dermis. - w/c are in close contact w/ sebaceous glands

Hair root: is where rapid growth of hair happens, causing hair to grow longer

What GIVES THE NAIL ITS PINKISH APPEARANCE?HOW FAST DO NAILS GROW? WhICH PART OF THE BODY HAS THE FASTEST GROWTH OF NAILS?

NAILS: grow from Nail matrix/nail root (area of rapidly dividing cells)

Nail matrix: located near the tips of the fingers and toes • During Cell division, the Cells fill with Keratin and produce a tough, strong platelike nail that covers

and Protects the tips of the fingers and toes. • Nails rest on a Bed of tissue filled with Blood Vessels, giving the nails a Pinkish Color. • Nails grow at a rate of 0.5 to 1.2 mm per day, with fingernails growing faster than toenails.

Nail Structure • Nails are plates of hard, tightly packed keratinized cells of epidermis. • three principal parts:

1. Nail body: visible portion of the nail. 2. Free edge: extend past the distal end of the digit.

3. Nail root:buried underneath a fold of skin.

Other structures associated with the nail: 1. Lunula: whitish semilunar area of the proximal end of the nail body. 2. Eponychium: the cuticle;narrow band of epidermis which extends from the lateral border of

the nail wall. 3. Nail matrix: Epithelial tissue deep to the nail root where actual nail growth occurs.

Glands additional infos: two major glands of the skin

1. SEBACEOUS GLANDS:- located in the dermis and are connected to hair follicles.

- Are also located on the lips, eyelids and genitalia 2. SWEAT GLANDS:

- 3-4 million in the human body- types (based on structure and location):a. ECCRINE/MEROCRINE GLANDS:

- most common type: numerous on palms of hands, & sole of the feet- simple coiled tubular glands that opens directly onto the surface of the skin through sweat

pores. b. APOCRINE:

- coiled tubular glands that usually opens into hair follicles superficial to the opening of sebaceous glands.

- in axillae, genitalia, & anus

Blood Supply • limited to the capillary plexus of the dermis & hypodermis. • A subcapillary network of veins drains the capillary system. • Lymphatic vessels of the skin arise in the dermis and drain into larger hypodermic branches.

SKIN DISORDERS IN HUMANS• Acne (AK-nee): Disorder in which hair follicles of the skin become clogged and infected.• Athlete's foot: Common fungus infection in which the skin between the toes becomes itchy and sore,

cracking and peeling away.• Basal cell carcinoma (BAY-sal CELL car-si-NO-ma): Skin cancer that affects the basal cells in the

epidermis.• Carcinoma (car-si-NO-ma): Cancerous tumor of the skin, mucous membrane, or similar tissue of the

body.• Dermatitis (der-ma-TIE-tis): Any inflammation of the skin.• Malignant melanoma (ma-LIG-nant mel-ah-NO-ma): Cancer of melanocytes; the most serious type of

skin cancer.• Psoriasis (so-RYE-ah-sis): Chronic skin disease characterized by reddened lesions covered with dry,

silvery scales.• Seborrheic dermatitis (seh-beh-REE-ik der-ma-TIE-tis): Commonly called seborrhea, a disease of the

skin characterized by scaly lesions usually on the scalp, hairline, and face.• Squamous cell carcinoma (SKWA-mus CELL carsi-NO-ma): Skin cancer affecting the cells of the second

deepest layer of the epidermis.• Vitiligo (vit-i-LIE-go): Skin disorder in which the loss of melanocytes results in patches of smooth, milky

white skin.• Warts: Small growths caused by a viral infection of the skin or mucous membrane.

ACNE• marked by pimples on the face, chest, and back. • can strike people at any age, acne usually begins at puberty and worsens during adolescence.• At puberty, increased levels of androgens (male hormones) cause the

sebaceous glands to secrete an excessive amount of sebum into hair follicles, combines with dead, sticky skin cells to form a hard plug that blocks the follicle that the bacteria (that normally lives on the skin) invades the blocked follicle.

• Treatment: depends on the condition (mild, moderate, or severe). The goal is to reduce sebum production, remove dead skin cells, and kill skin bacteria. In very mild cases, keeping the skin clean by washing with a mild soap is recommended. In other cases, medications applied directly to the skin or taken orally may be prescribed in combination with gentle cleansing.

ATHLETE’S FOOT: tinea pedis• common fungus infection in which the skin between the toes becomes itchy and sore, cracking and

peeling away. • infection causing fungi grow well in warm, damp areas (in and around swimming pools, showers, and

locker rooms or areas commonly used by athletes).• The fungi live exclusively on dead body tissue (hair, the outer layer of skin, and nails). • It is known that sweaty feet, tight shoes, and the failure to dry feet well after swimming or bathing all

contribute to the growth of the fungus.• Symptoms: itchy, sore skin on the toes, with scaling, cracking, inflammation, and blisters.

- If the blisters break, raw patches of tissue may be exposed. - If the infection spreads, itching and burning may increase.

• Treatment:- Simple cases: antifungal creams or sprays.- In more severe cases: oral antifungal medication

DERMITITIS• any inflammation of the skin.• EXAMPLE: (characterized: pink or red rash that itches).

contact dermatitis - allergic reaction to something that irritates the skin.- appears within forty-eight hours after touching or brushing against a

substance to which the skin is sensitive. - Chemical irritants: chlorine, cleaners, detergents and soaps, fabric

softeners, perfumes, glues, and topical medications (those applied on the skin). - TREATMENT: medicated creams or ointments and oral antihistamines

and antibiotics.

WHY DO YOU NEED TO TAKE GOOD CARE OF YOUR SKIN?HOW IMPORTANT IS TAKING GOOD CARE OF YOUR WHOLE BODY?