The Skin & Body Membrane

sheets of tissue

Function:

covers and lubricate body

line body cavities

form protective sheets around body organs

Types:

epithelial membrane

connective membrane

subcutaneous

just under the skin

dermal

on top of the skin

integument

the skin when it is considered as a body organ

integumentary system

the skin when it is considered as a body system

function of the integument

regulation of body temp.

protects body tissues from injury

acts as a physical barrier to prevent germs from entering the body

aids in vitamin D synthesis

elimination of waste products

provides for sensations; touch, pressure, warmth and cold

provides protection from UV light

permits the absorption certain drugs and other chemicals

cutaneous

What kind of membrane is the skin?

epithelial membrane

consists of:

epithelial & connective tissue

each component represents a main division of the skin

epidermis

consists entirely of stratified squamous epithelium

consists of subdivisions which are represented by layers of cells making up the SSE

dermis

composed of connective tissue containing collagen and elastic protein fibers; also contains blood vessels, nerves, glands and hair follicles

hyodermis

AKA. subcutaneous layer/ superficial fascia

NOT a division of the skin

connects the dermis to underlying bones and muscles

composed of areolar and adipose connective tissue

hypodermic injection/needle

avascular

Is the division of the epidermis vascular or avascular?

stratum germinative

germinating layer; made up of cells attached to the basal lamina which is very mitotically active & replaces cells lost in the upper layers

stem cells

What are the cells in the stratum basal referred to as?

stratum spinosum

spiny layer; consists of the next several layers of cells; cells begin to shrink; mitotically active of the cells slows

corneum

lucidum (thick skin)

granulosum

spinosum

stratum basal

What are the layers of the epidermis?

stratum basal

What is the most nourished epidermal layer b/c of the nutrients diffusing it from the dermis?

stratum granulosum

granular layer; 1-3 cell layers; mitotic activity stops; cells begin to manufacture the protein keratohyalin

stratum lucidum

clear layer; present only in thick skin; keratohyalin leads to production of the protein eleidin; cells are densely packed and flattened and do not contain nuclei

eleidin

product of the amino acid complex; not alive; deposited in form of the minute granulars

stratum corneum

horny layer

outermost division

20-30 cells layers

comprises 75% of the epidermal thickness

plasma membrane thickens- reduces permeability and water loss

eleidin is converted to keratin- a very strong waterproof protein

25-45 days

How long does it take for a totally new epidermis?

bacteria & viruses from blood

What does the corneum prevent?

stratum corneum

Where is keratin abundant in?

stratum corneum

What layer is replaced by a deeper layer?

epidermal ridges

deep layers of the epidermis which extend into dermis below

contain nerve receptors that provide sensitivity to change

melanocytes

pigment cells that are squeezed between the cells of the S. germinativum; manufactures the inclusion melanin

melanin

produces skin tone; provides protection from UV light

Merkel’ cells

large, oval cells located in the S. basal

associated with touch (have sensory nerve endings)

associated with a highly malignant skin tumor

Langerhans cells

macrophages used in the body’s defense against microorganisms

located primarily in the S. spinosum

dermis

(deep layer); composed of connective tissue containing collagen and elastin protein fibers; contains blood vessels, nerves, glands, and hair follicles

lamellar corpuscle

deep pressure receptors gets activated when their is deep pressure

papillary region

superficial region characterized by papillae

papillae

fingerlike projections located between the epidermal ridges; uneven peg-like projections

reticular layer

the deep layer of connective tissue that contains both collagen and elastic fibers

hypodermis

not a division of skin

connects dermis to underlying bones and muscles

composed of areolar and adipose connective tissue

hair

consists of the fibrous protein keratin; vellus, intermediate, terminal, lanugo

vellus

peach fuss

intermediate

hair of the arms and legs

terminal

heavy, dark hair (head, eyebrows, and eyelashes)

lanugo

the very fine hair that covers a newborn infant- shed shortly after birth

shaft

the visible portion above the skin surface

root

portion below the skin surface

follicle

the socket which surrounds the hair; consists of stratified squamous epithelium

bulb

an onion-shaped swelling located at the base of the hair

papilla

the indentation at the bottom of the follicle; it contains blood vessels and nerves

matrix

a layer of germ cells that produce new hairs

medulla

the soft, flexible center of the hair; contains soft keratin (cross-section)

cortex

a region of hard keratin that surrounds the medulla; gives the hair stiffness (cross-section)

cuticle

a layer of hard keratin that coats the hair (cross-section)

arrector pili muscle

smooth muscle in the dermis that is attached to both the hair follicle and skin

its contraction causes “goosebumps” and hair to stand up

connect each side of the hair follicle to the dermal tissue

sebaceous glands

produce sebum, oil /holocrine glands, found everywhere except the the palms of hands and soles of feet

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

sebum

mixture of oily substances fragmented cells

lubricate that keeps the skin soft and moist and prevents the hair from becoming brittle

contains chemical that kill bacteria present on the skin surface

sebaceous follicles

ducts that lead to pores in the skin

sudoriferous glands

secrete sweat/perspiration; apocrine and eccrine

apocrine

ducts empty into hair follicles

are largely confined to the axillary (armpit) and genital areas

plays a minimum role in thermoregulation

secretion contains fatty acids and proteins

activated by nerve fibers during pain and stress

eccrine

produce sweat

highly important and efficient part of the body’s heat-regulating equipment

supplied with nerve endings that cause them to secrete sweat when the external/body temperature is high

open directly to pores

2-5 million

eccrine glands

What do these functions describe?

cool the surface of the skin to reduce body temperature

excretion of water and electrolytes

apocrine glands

What does this describe?

coiled, tubular glands that secrete a sticky, cloudy and potentially odorous perspiration into hair follicles

nails

hard plates of tightly packed keratinized cells

clear

cover the dorsal surface of the last phalanges of fingers and toes

protect the ends of fingers and toes

body

the visible portion of the nail

root

an epidermal fold that is not visible from the surface

nail bed

the area of the epidermis covered by by the nail body

eponychium

cuticle- a region of stratum corneum covering the nail body near the root

lunula

a pale, crescent-shaped area near the root

hyponychium

an area of thickened stratum corneum beneath the free edge of the nail

thermoregulation

refers to the body’s ability to maintain a homeostatic balance between heat production and heat loss

hypothalmus

the body’s thermostat (inter brain; diencephalon)

set to 36.5 degrees C to 37.8 degrees C

maintained via heat loss and heating mechanisms

heat promoting

Is vasoconstriction a heat promoting or loss mechanism?

heat loss

Is vasodilation a heat promoting or loss mechanism?

vasoconstriction

sweat glands close

shivering (muscle contract)

reduces speed of heat loss

goosebumps & hair stand on end

blood vessel size reduces

vasodilation

sweat glands open

allows for water to come to surface of skin and evaporate

opening of blood vessels (expands the lumen)

above normal

Does this describe temp. above/below normal:

sweat glands activated, pores open

increased blood flow to skin

allows for evaporation

below normal

Does this describe temp. above/below normal:

sweat glands inactivated

pores closed

decreased blood flow to skin

1. heat
2. radiation
3. electric shock
4. chemical agents (acids & bases)

What are the 4 reasons for a burn?

partial thickness

first degree burns

second degree burns

full thickness

third degree burns

head= 4.5%

arms= 4.5%

truck= 18%

legs= 9%

perineum= 1%

Explain rule of 9s

first degree burns

affect only the epidermis

red, tender, dry, absent of blisters'

mild sunburn

scaring does not occur

2-3 days of discomfort

second degree burns

affect epidermis and parts of the dermis

red, blistered, painful, possible swelling, may be moist

liquid burns, severe sunburn

third degree burns

affect the epidermis and all of the dermis; often also involves hypodermis

appears white or charred

no pain

chemical or electrical burns

nerve endings are destroyed

Why do 3rd degree burns have no pain?

sufficient epithelial cells still present regeneration of epithelium can occur

How is infection prevented for 2nd degree burns?

wounds

injuries that result in an internal or external break in the skin

incision

a clean precise cut

glass, knife, papercut, scapel

laceration

similar to incision, but has jagged edges

splitting skin, rock, picked scab, animal bite, knocking body

abrasion

epidermis is rubbed or scrapped away; exposing knee with blood vessels

rug/brush burn, skinned knee

puncture

an object pierces the skin with little bleeding

nail, splinter

avulsion

a portion of the skin is ripped or torn away

blisters

contusion

a cluster of broken capillaries caused by a blunt blow of the skin

bruise

tumors

neoplasm- new and abnormal growth of tissues

out of control rapid mitotic division when an unnecessary that have undergone some type of mutation

benign

tumor remain localized as discrete mass, rarely fatal

malignant

tumor that is invasive and metastasizes, fatal

referred to as cancer

metastasizes

move to other sites

basal cell carcinoma

squamous cell carcinoma

malignant melanoma

What are the most common types of skin cancer?

basal cell carcinoma

located: basal cells in the stratum germinativum

causes: chronic exposure to sunlight, UV will disrupt/mutate the DNA

areas affected: face, neck, scalp, shoulders, ears

warning signs: open sore, reddish patch, shiny bump, pink growth, scar-like area

squamous cell carcinoma

located: squamous cells of the epidermis

causes: chronic exposure to sunlight

areas affected: face, neck, bald scalp, shoulders, arms, back, sometimes trunk

warning signs: wart-like growth, persistent scaly red patch open sore that bleeds and crusts for weeks

desquamation

loss of dead squamous cells

malignant melanoma

location: melanocytes

causes: chronic exposure to sunlight

areas affected: legs, trunk, arms, scalp in men

warning signs: small brown/black (or larger) multicolored patches; plaques or nodules with an irregular outline; many arise from pre-existing moles

asymmetry

half of the mole does not match the other half