Gross A&P Chapter 6

• Protects against infection

• Protects against water loss (keratin)

• Houses sensory organs

• Protects against UV rays (melanin)

• Blood reservoir (blood vessels)

• Absorption and secretion

• Production of vitamin D

• Regulation of body temperature

Functions of the Integumentary System

Epidermis

Dermis

Hypodermis/Subcutaneous layer

Main Layers of the Skin

Epidermis

• Thinner layer

• Superficial layer

• Stratified squamous epithelium

• Resist abrasion

• Prevents water loss (keratin)

• Lacks blood vessels

Calluses

extra layers of Cells with keratin

Dermis

• Deep to the epidermis

• Two different types of connective tissues

• Thicker layer

• Attached to subcutaneous tissues

• underneath

Layers of the Epidermis

Basale, Spinosum, Granulosum, Lucidum, Corneum,

Basale

• Deepest layer

• Single row of cuboidal or columnar cells that divide and grow

• Includes melanocytes

Spinosum

• Many layers of cells with large, oval nuclei

• Developing fibers of keratin

• Cells start to become flattened

Granulosum

• 3-5 layers of flattened granular cells with

• shriveled nuclei (dying)

• Shrunken fibers of keratin

Lucidum

• Only in soles of feet and palms of hands*

• Cells appear clear – nuclei, organelles, and cell

• membranes are no longer visible

Corneum

• Superficial layer (dead cells covered with keratin)

• Many layers of keratinized, flattened dead cells

• Flakes off as new skin grows from underneath

• Waterproof

Melanocytes

• Secrete melanin

• Gives skin its coloring

• Protective functions

Phagocytes that engulf foreign material and microbes

Langerhan’s Cells

Sensory receptor for light touch

Merkel Cells

• Hair follicles

• Nerve endings

• Sensory receptors

• Glands

• Blood vessels

• Lymphatic vessels

What does the dermis layer contain?

Papillary layer, reticular layer

Layers of the Dermis

Papillary Layer

• Thinner, superficial layer of dermis

• Areolar connective tissue

• Papilla on superior surface

• Finger-like projections

Reticular Layer

• Deeper layer of dermis

• Dense irregular connective tissue

Subcutaneous Tissue

• Superficial to fascia

• Deep to the dermis

• Not part of the skin

• Areolar connective issue

• Bind dermis to underlying tissues

• Contains adipose tissue

• Stores fat

• Subcutaneous injections (aiming past skin layer but not into belly fat)

• Not officially part of skin

Nail root

Nail body/plate - growing on top of nail bed

Nail bed

Lunula - area of growth

Free edge - any portion of nail plate that hangs off the edge of the finger

Cuticle - skin that overlaps bottom portion of nail (soft tissue connection point

Parts of the Nail

Keratinized Cells (dead cells)

Nails are made of what?

epithelial tissue

What kind of Tissue is hair made of?

Hair root - beneath the skin,Hair bulb

hair shaft - above the skin

Two main parts of hair

Medulla – innermost layer, core of hair

Cortex – middle layer, varies in thickness (thick v.s. thin hair)

Cuticle – outermost layer

Three hair tissue layers

Hair

• Not present on palms, soles, lips, nipples, and

• parts of the reproductive organs

• follicle surrounds the root

• grows out of a follicle from the matrix

• Growth cycle

• 2-6 years of growth

• 2-3 months before new growth

• Color is produced by melanocytes in the Bulb

Arrector pili muscle

• attaches to follicles

• gives us goosebumps

• Ability to pull up on hair standing up providing an extra layer of insulation

Sebaceous Glands

• Produce sebum

• Secrete substances into the hair follicle for transport to the skin surface

  • Conditions skin and hair

• Not found in palms of hands or soles of feet

• Can cause acne (trapping of oil

Merocrine

• Most numerous on the forehead, neck, back

• Open directly to the skin surface

• Secretes watery sweat with salts and wastes

• Respond to heat changes

• What we think of as Sweat glands

Apocrine

Open into hair follicles

Become active at puberty

Most numerous in axillary and genital regions

Secretes mixture of oil and water (bridge btw sebaceous and merocrine glands)

Causes body odor (reacts with whatever is on the skin)

Respond to emotions, pain, and arousal

Mechanoreceptors, Chemoreceptors, Thermoreceptors, Photoreceptors, Nocireceptors, Exteroreceptors, Intereceptors, Proprioreceptors

Main Types of Sensory Receptors

Mechanoreceptors

Touch and Pressure (mechanical forces)

Chemoreceptors

Touch and Taste

Thermoreceptors

Temperature

Photoreceptors

Vision

Nocireceptors

pain (generally follow up when a sensation has gone too far)

Exteroreceptors

exterior of the body

Interceptors

Viscera

Prorpioceptors

joints and tendons

Sensory Receptors in Skin

Pacnian corpuscles, ruffni endings, free nerve endings, root hair plexus, proprioceptors, golgi tendon organ

Pacnian corpuscles

• Laminated corpuscles

• Deep areas of the dermis

• General pressure and vibrations

Ruffni endings

• Middle areas of the dermis

• General pressure and vibrations

Free nerve endings

• Throughout dermis

• Pain and temperature

Root hair plexus

• Located on hair follicles

• Free nerve endings wrapped

• around hair follicles

• Detects movement of the hair

Proprioceptors (skin)

• Muscle spindle

• Dendrites wrapped around specialized muscle fibers

• Monitors skeletal muscle length

• Triggers stretch reflex

Golgi tendon organ

• Dendrites wrapped around collagen fibers

• Located in joints

• Monitors tendon stretching

• Resist stretch of tendon (happens with heavy lifting)

What is Heat?

the production of cellular metabolism

Majority of heat is produced by what?

Cardiac and Skeletal Muscles

What in the brain controls body temperature?

hypothalamus

How to dermal blood vessels release heat?

they dilate to allow more blood to enter so that its heat can be released

How is primary means of body heat lost?

radiation

3 means of heat loss

conduction, convection, evaporation

What is Conduction?

• Heat moves from the body directly into cooler objects in contact with its Surface

• Continues to

  Equilibrium

• Ex. Laying on the cold floor

What is Convection?

• Circulation of air over a warm surface

• Body loses heat to the

  air around it and that

  air moves away

• Replaced with

  cooler air

• Ex. Ceiling fan, blowing cold air

What is evaporation?

• Nervous system stimulates sweat glands to release Sweat

• Sweat evaporates, carrying heat away

What happens when body temperature decreases?

• Smooth muscles in the walls of the dermal blood vessels contract when

• body temperature drops

• This reduces the flow of blood that is carrying heat

• Sweat glands become inactive

• Nervous system will cause muscle contractions to increase cellular respiration in an attempt to produce heat

What is hyperthermia?

• Body temperature is too high

• Skin becomes dry, hot, flushed

• Person can become dizzy, weak, nauseous, with a headache and rapid pulse

What is hypothermia?

• Body temperature is too low

• Begins with shivering and feeling cold

• Progresses to mental confusion, lethargy, loss of reflexes, loss of consciousness, and shut down of major organ

Cyanosis

Blue to skin, lack of blood oxygen flow

Jaundice

Yellow tint to skin, liver problems

Psoriasis

• Chronic skin disease

• Cells in the epidermis divide 7x more than usual

• Excess cells accumulate into silvery scales

How does the body react to cuts?

1. Blood vessels break to release blood to form a clot

2. Scab formation

3. Epithelial cells proliferate

When do granulomas occur?

when the wound is so big the scab doesn’t cover it

1st Degree Burn

• Superficial, partial- thickness burn

• A little swelling, peeling, only top layer

• Inflamed, warm, and red

• Mild edema

• Mild peeling

• Only injuring epidermis

• Healing: a few days – 2 weeks

• Ex. Suburn

2nd Degree Burn

• Deep, partial-thickness burn

• Epidermis is affected and some of the dermis

• Destroy some epidermis and some dermis

• Blisters form

• Tissues will be dark red to white

• Healing time varies

• Usually occurs due to exposure to hot objects, hot liquids, flames, or burning clothing

3rd Degree Burn

• Full-thickness burn

• Destroys epidermis, dermis, and accessory structures of the skin

• Tissue is dry and leathery

• Usually occurs due to immersion in hot liquids, prolonged exposure to hot objects, flames, or corrosive chemicals

• Usually requires grafting

2 types of grafting

Autograft, Allograft

Autograft

• Removing a thin layer of skin from an unburned region of the body and transplanting it to the injured area

 

• Used when there are areas of the body available

 

• Creates a second site for healing

Allograft

• Skin from a cadaver is used

 

• Temporary covering that shrinks the wound and helps prevent infections and preserve deeper tissues

 

• Used when there is not skin available

 

• Rejection can be a concern

When do bed sores form?

when the blood supply is cut off

most common ulcers in skin

diabetic foot ulcers, bed sores

4 stages of Ulcers

Stage 1

• Redness of surface

• bruise like

• skin still in tact

 

Stage 2

• Partial through the dermis

 

Stage 3

• All the way through the dermis

• Can see muscle or tendon

 

Stage 4

• Can see the muscle and bone as well as damage to them