Integumentary System - Chapter 6 Anatomy

Organs

Organs

Body structures composed of two or more different tissues that perform specific functions

Which is the largest organ in the body?

Skin

Accessory structures of the skin

Hair, nails, glands, and sensory receptors

How does skin act

A barrier between internal environment and the external environment

Epidermis

Thin, outer layer of stratified squamous epithelium

Dermis

Thicker, inner layer of connective tissue, blood vessels, smooth muscle, and nervous tissue

Basement membrane seperates what

Epidermis from dermis, and anchors these layers together

Where is the subcutaneous layer (hypodermis)

Layer underneath dermis

What does subcutaneous layer consist of?

Areolar and adipose tissue

Function of the subcutaneous layer (hypodermis)

Binds skin to underlying tissue, but not part of the skin

How does adipose tissue function?

Insultes to conserve body heat

What is the epidermis made of?

Stratified squamous epithelium

Characteristic of epidermis

Lacks blood vessels, consist of 4 layers in most areas, but 5 layers in thick skin

Another name for stratum basale

Stratum germinativum

Characteristics of stratum basale

Deepest layer; consist of dividing cells; well-nourished by dermal blood vessels

Describe the process of cells migrating toward skin surface

Basal cells divide, older cells, called keratinocytes will migrate outward. They will then harden, dehydrate, and die, in a process called keratinization

First layer of the epidermis

Stratum corneum

Second layer of the epidermis

Stratum granulosum

Third layer of epidermis

Stratum spinosum

Fourth layer of epidermis

Stratum basale

Fifth layer of epidermis (only in thick skin)

Stratum lucidum

Characteristics of stratum corneum

Outermost layer; dead, flattened, keratinized cells; these are continually being shed from the outer skin surface

Characteristics of stratum lucidum

Layer between stratum granulosum and the stratum corneum, which is found only in the thick skin of the palms and soles

Why is the epidermis important?

Protects against water loss, mechnical injury, chemicals, and microorganisms

Where are melanocytes found?

Deepest layer of epidermis and in dermis

What do melanocytes produce?

Melanin

Function of melanin

Protects DNA of skin cells against damaging effects of UV radiation from the sun

Cytocrine secretion

Melanin is trasferred from extensions of the melanocytes to other neaby cells with this process

Eumelanin

Brownish-black

Pheomelanin

Reddish-yellow, found in areas such as lips

What do all people have in common

Same number of melanocytes

Factors that go into skin color

Genetically determined, amount of melanin the melanocytes produce, environmental, and physiological

Describe genetic differences in skin color

Results from differing amounts of melanin produced, and in the size and distribution of melanin granules

How does skin get darker

Exposure to sunlight, UV light from sun lamps, X-rays, all are due to an increase in melanin production

What skin color is associated with well-oxygenated blood

Pinkish color, due to hemoglobin

What skin color is associated with poorly-oxygenated blood

Blue, due to deep red tone of the hemoglobin; called cyanosis

How can you get yellowish skin color

Eating too many orange foods with carotene, or from jaundice due to liver disease

Function of dermis

Binds the epidermis to underlying tissue

Epidermal ridges

Extend down toward dermis; border between epidermis and dermis is uneven because of this

Dermal papillae

Extends upward toward epidermis; also a border between epidermis and dermis to make it uneven

How are fingerprints formed

Genetically determined pattern of friction ridges formed by dermal papillae

What consists of the dermis

Areolar and dense connective tissue, with collagen and elastic fibers within a gel-like ground substance

What do dermal blood vessels do

Carry nutrients to upper layers of skin, to help regulate body temp.

What does the dermis contain?

Nerve fibers, sensory receptors, hair follicles, sebaceous glands, and sweat glands

Function of nails

Protective coverings over the ends of fingers and toes

What do nails consist of

Nail plate overlying a layer of skin surface, called the nail bed

Lanula

Half-moon-shaped structure at base of nail plate; most actively growing region of the nail root

Location of hair

Nearly all regions of skin except palms, soles, lips, nipples, and portions of external genitalia

Hair follicle

Hair develops from epithelial stem cells at the base of a tube-like depression

Location of hair follicle

Dips down into the dermis or sometimes the subcutaneous layer

Hair bulb

Deepest part of the hair root

What is hair composed of

Dead, keratinized epithelial cells

Albinism (white)

Genetic lack of melanin

Gray hair

Mixture of pigmented and unpigmented

Describe the process of goose bumps

Bundle of smooth muscle cells, called arrector pili muscle, attaches to each hair follicle; contracts in response to cold temperature or emotional upset

Sebaceous glands

Holocrine glands; entire cells filled with secretion are released; associated with hair follicles

Subum

Oily substance that is secreted; waterproofs and moisturizes the hair shaft and skiin

Sweat (sudoriferous) glands

Merocrine glands; secretions exit via exocytosis; ther are two types

Eccrine

Merocrine glands that respond to body temperature; more abundant type; many found on forehead, neck, back

Apocrine

Becomes active at puberty; respond to fear, emotional upset, pain, or sexual arousal; most numerous in axilla and groin; sweat contains proteins and fats that produce body odor

Ceruminous glands

Secrete wax in the ear canal, to trap dust and pathogens

Mammary glands

Secrete milk to nourish a baby; all mother mammals have this

Function of skin

Protective covering underlying tissues; prevents substances and pathogenic microorganisms from entering body; house sensory receptors; helps in process for making vitamin D; body temperature regulation, sweat gland activation; vasodilation or vasoconstriction of dermal blood vessels; healing of wounds

Why is it important to keep body at proper temperature? (97-99 F)

Vital to maintaining metabolic reaction rates

What helps with temperature regulation

The skin and the hypothalaus controlling the process

What do active cells play in for body temp. regulation

The heart and skeletal muscle, and the liver, produce heat

Inflmmation

Blood vessels dilate and become more permeable, causing tissues to become red and swollen, body’s normal response to injury

Function of dilated blood vessels

Bring in fluids, oxygen, nutrients, and imune cells to aid in healing

How are superficial cuts filled

By reproducing epithelial cells

Describe process of healing a deep wound

Forms blood clot from released blood; blood cut and dried tissue fluids form a scab to cover wound; phagocytic cells remove debris and dead cells; damaged tissue is replaced and the scab falls off; extensive collagen fiber production can make an elevated area of a scar

Describe process of granulations

New branch of blood vessels grows into the area, vessel accompanied by a cluter of fibroblasts that begin producing collagen fibers and repairing the wound; blood vessels are reabsorbed and fibroblasts leave, which leaves a scar of collagen fibers