Anatomy & Physiology L3Integumentary System

Integumentary System

I. Overview: General structure: composed of epidermis and a dermis, separated by a basement membrane with a subcutaneous layer underneath

                                                            

General Function: (5) 1.protective covering 2.regulate body temp 3.houses sensory receptors 4.synthesizes various

chemicals 5.excretes wastes

II. Epidermis layer

Layers (5) of avascular stratified squamous tissue

1. stratum corneum: composed of dead epidermal cells, fully keratanized (most superficial)

2. stratum lucidium: in the thickened skin of palms and soles. Contains transparent protein resembling keratin.

3. stratum granulosum: contain granules in the cell’s cytoplasm which die and become keratinized.

4. stratum spinosum: a thick layer of tiny fibers in the cytoplasm (spiny when pulled apart)

5. stratum basale: (basal layer) cells undergoing mitosis

Keratinization:

Strands of tough, fibrous, waterproof keratin proteins are synthesized and stored in cells causing hardening.

epidermal cells undergo process: keratinization, as they are “pushed” towards the surface

Mitotic rate is normally EQUAL to that of those cells lost

Mitotic rate INCREASES when friction occurs causing:

1. calluses on hands and feet2. corns (keratinized masses on

toes)

Overall Fxn: Protect underlying tissues against:

Water loss (*Wrinkly fingers) Mechanical injury Affects of harmful chemicals /

pathogens

Melanocytes

: Melanocytes Structures lying deep in the epidermis Produce melanin: fxn is to protect

underlying cells from UV light Cytocrine secretion: the transfer of

granules of melanin into nearby epidermal cells.

Melanocytes

                                                            

III Dermal layer

Layer of loose connective tissue binding epidermis to underlying tissues, such as muscles, adipose, etc

Composed mainly of collagen & elastin: Avg. thickness: 1-2 mm.

0.5 on eyelids, 3mm soles of feet

Contains: muscle fibers, nerve endings, and blood supply

Basic fxn: 1. blood vessels supply

nutrients to all skin cells 2. regulate body temp.

Nervous tissue scattered throughout the dermis Some carrying impulses to muscles /

glands of the skin Some associated with various sensory

receptors in the skin

Fingerprints

Specialized structure: Dermal papillae

Uneven ridges formed during fetal development

NO TWO sets are exactly alike!

IV Extension of Dermis, also called hypodermis/ 3rd layer)

Subcutaneous layer composed mainly of loose connective and adipose

Layer containing majority of dermal blood vessels

Therefore fxn: insulates= conserves body heat and impedes entrance of heat from outside

Types of injections:

1. IM (Intramuscularly)EX: vaccinations 2. SubQ (subcutaneously) EX: insulin 3. Intradermally EX: TB test 4. Transdermally EX: birth control,

smoking patch, pain patches

V Accessory organs of the skin

1. Hair follicles: hair found almost all areas of the body each hair develops at base called:

follicle as newly formed cells develop and

grow, older cells “pushed” towards surface and keratinize: called hair shaft

                                                            

hair color genetically determined bundle of smooth muscle and one

or more sebaceous glands attached to each hair follicle: arrector pili muscle

2. Sebacious glands:

glands that secrete sebum, helping to keep skin and hair soft and waterproof

In some regions, open directly to the skin surface:

1. lips 2. corners of mouth 3. external reproductive parts

None found on

Palms Soles

3. Nails:

-protective covers on the ends of fingers and toes (tactile)

-undergo keratinization

4. Sweat glands:primary fx=cool body

Excretes wastes located in nearly all areas of the skin Each gland consists of a coiled tube,

lined with sweat secreting epithelial cells

Sweat is primarily composed of water, also containing salt and urea

                                                            

Types of sweat glands (3)

Apocrine: respond to emotional stress

Eccrine:respond to elevated body temp.

Specialized apocrine:1. ceruminous gland-secretes earwax2. Mammary glands-secretes milk

V. Regulation of Body Temperature

Normal or core body temp, is about 98.6 F, 37 C)

Heat Production and loss Heat is by- product of cellular

respiration

Heat

Lost to outside environment by the following ways: Evaporation Conduction Convection Radiation*#1 way to cool body

Hyperthermia vs. Hypothermia

Problems with temperature regulation

Humidity due to saturation EX:hyperthermia- sweat

glands activated but cannot evaporate sweat r/t hot humid day. Body temp. rises

At risk age groups for Temperature related condition

1. Very young2. Very old3. Very thin

VI. Skin Color

Melanin: Primary skin pigment. All humans have same concentration of melanocytes. Skin color is due to amt. of melanin sent to the epidermis.

Genetics: each person inherits genes for melanin production.

Environment: sunlight, uv light, x-ray

Causes: existing melanin to darken and stimulate additional melanin production

VII. Physiological factors

1. Oxygen content in blood. Normal / to high: red blood causes

pinkish look to skin Insufficient (Too low): ↓02= bluish

(cyanosis)

2. Additional skin pigmentation carotene: in subcut. Causes

yellowish look (Asian) 3. Variety of diseases EX: Jaundice- infants or adults

with liver disease.

VIII. Response to injuries

Inflammation: Is a response to injury in which:

Blood vessels dilate Membrane permeability increases Benefits of Inflammation are: aid in

healing by providing additional nutrients and 02 to tissue

IX. Burns

1st degree burn

Epidermis ONLY affected

Redness and burning

EX: sunburn

Epidermal (1st degree) burn

2nd degree burn

Damage to both the epidermis and dermis

Damage not enough to PREVENT healing

Dermal (2nd degree) burn

Deep dermal (2nd degree) burn

3rd Degree burn ENTIRE

epidermis, dermis, and accessory organs destroyed

Tissue death

Sub-dermal (3rd degree) burn

Skin graft

Common disorders of the Feet

Skin disorders of the feetsuch as Callus, Athlete's foot

and Plantar Warts

                   

Athlete's Foot(right down)

                       

    

Tinea pedis

Acne

Contact dermatitis

Moles are harmless skin growths that may be flat or protruding. They vary in color from pink flesh tones to dark brown or black.

Pediculosis

Decubitus pressure ulcer (Bed sore)

Where do pressure ulcers form?

Where bone causes the greatest force on the skin and tissue.

For bedridden persons, most pressure ulcers form on the lower back below the waist (sacrum), the hip bone (trochanter), and heels.

Diabetic Ulcer

Pathophysiology: diabetic foot ulceration

Neuropathy

Sensory

Loss of protective sensation

Motor

Abnormal foot biomechanics

Autonomic

Reduced skin compliance

and lubrication

Ulceration

InfectionInfectionVascular insufficienc

y

Eczema

Quick Quiz: 2 pts each

1. Name 3 of the, at least 8 fx’s of integ. system

2 . List and describe the 3 layers of the skin

3. Name/describe top 2 ways we lose body heat

4. Describe keratin and keratinocytes 5. Describe the relationship between

skin color and melanin

Quick Quiz: cont

6. Describe what a sebacious gland is/does

7. Describe what a sweat gland is/does 8. What does Vit D have to do with skin? 9 . Discuss the differences in 1st,2nd, 3rd

degree burns 10. Discuss two factors that can

influence diabetic ulcers and pressure ulcers