Ch 5: the Integumentary system

ESC-2050-52, Human Anatomy, Dr. Farnell

what makes up the integumentary system

skin, hair, nails

What are the 5 functions of the integumentary system?

1. protection

2. sensation

3. temperature regulation

4. vitamin D production

5. excretion of waste products

6. (self expression)

how does the Skin protect the body?

protects against:

abrasion, UV light, and microorganism entry

How does the Hair protect the body?

protects against:

abrasion and UV light

How do nails protect the body?

act as shields for the ends of the digets

What does the skin sense?

heat, cold, touch, pressure, pain

How does the skin help with temperature regulation?

controls heat loss via dilation/ constriction of blood vessels

contains sweat glands

How does the skin produce Vitamin D?

UV light stimulates a precursor molecule, the molecule is modified by the liver and kidneys, which turn it into vitamin D

vitamin D increases calcium uptake

UV light also stimulates Keratinocytes within the epidermis to produce Keratin, which helps form the protective layer

How does the skin excrete waste products?

sweat excretes NaCl, Urea, ammonia, lactic acid, and electrolytes

How much does the skin weigh on average?

What percentage of the body is that?

About how many feet is that?

11-23 lbs

7-15%

21 ft²

What is the order of the Major skin layers?

1. Epidermis

2. Dermis

3. Subcutaneous (hypodermis)

What makes up the epidermis?

5 layers of DEAD stratified squamous cells

and

Keratinocytes, Melanocytes, Langerhans cells, Merkel cells

What is the primary function of the Epidermis?

protection against abrasions and dehydration

What does the epidermis NOT contain?

blood vessels = no blood suply = dead cells

What do Keratinocytes do?

produce a protein, Keratin, that makes cells stronger and hold things together. Also contribute to waterproofing. More and more are dead as they move toward the surface of the skin.

What do Melanocytes do?

produce melanin for skin color, protect against UV light

found within the stratum basale

What do Langerhans cells do? What do they contain?

help with immune function

contain Macrophage which kill/ eat foreign invader microorganisms and stimulate other immune cells to help

found within stratum spinosum

What do Merkel cells do?

detect light touch and superficial pressure

(are the free nerve endings in the dermis)

found within the stratum basale and below

What are the 5 strata/ sublayers of the Epidermis? Come Lets Get Sun Burned

How many sublayers do each of the Strata contain?

Corneum (25+ layers)

Lucidum (3-5)

Granulosum (3-5)

Spinosum (8-10)

Basale (1)

What is the function of the Stratum Corneum? What does it contain?

waterproofing and protect against abrasion/ penetration

25+ layers of dead keratinized cells

What is the function of the Stratum Lucidum?

What does it contain?

to build up Thick Skin (calluses) (only present in thick skin areas)

3-5 layers of flat, dead, keratinocytes

What is the function of the Stratum Granulosum?

What does it contain?

Contain 3-5 layers of Lamellated bodies (fat/ lipids) for waterproofing

after this level keratinocytes die off

What is the function of the Stratum Spinosum?

What does it contain?

UV protection, Melanin is transferred from melanocytes to Keratinocytes and accumulates on the “sunny side” to protect the nucleus of each cell

Melanin granules and Langerhans cells are preasent

What is the function of the Stratum Basale?

What does it contain?

acts at the base layer of the epidermis, provides structural strength to the epidermis.

contains Desmosomes in between the cells to add strength, consists of a single row of youngest keratinocytes

How often to cells in the Stratum Basale undergo mitosis?

approx every 19 days

How long does it take for the daughter cells of the Stratum Basale to move all the way to the Stratum Corneum?

40-56 days

What is the function of the Dermis?

What does the dermis contain?

nutrient and waste exchange with living cells of the epidermis

collagen, elastic, and reticular fibers; smooth muscle; hair follicles; free nerve endings; sensory receptors; fibroblasts, adipocytes, macrophages

What are the specific cells of the Dermis? What do they do?

Fibroblasts → builds up connective tissue

Adipocytes → fat cells

Macrophages → immune cells

What do the free nerve endings in the Dermis detect?

pain, itch, tickle, temperature

What are the sensory receptors in the Dermis?

What do they do?

Pacinian corpuscles → detect deep pressure

Missner corpuscles → two point dissemination (feeling two points at the same time)

Ruffini end organs → detect touch, pressure

What are the two sublayers of the Dermis?

Papillary Layer (superficial)

Reticular Layer (deep)

What is the function of the Papillary layer of the Dermis?

What does it contain?

to contain the blood vessels and supply the epidermis with blood

contains friction ridges (finger prints), loose connective tissue, and dermal papillae (the hills that go into the epidermis)

What is the main function of the Reticular sublayer of the Dermis?

main layer, connects/ holds together the materials in the Dermis

contains dense and irregular elastic connective tissues (like collagen, protein, etc)

What layer of the skin is the BULK of the skin?

the dermis

What is the Subcutaneous layer NOT considered?

part of the skin (it is just lumped into this category)

What is the main function of the Subcutaneous layer of the skin?

What does it contain?

attaches skin to underlying structures (bone, muscle, etc), a shock absorber, and insulates

Contains mostly adipose and connective tissue

The Subcutaneous layer contains what fraction of the body’s stored fat?

½

Injection that goes into the dermis, skin is taut, needle is held at a shallow angle

Intradermal injection

injection enteres the subcutaneous layer, skin is pinched, it is a short needle at a slight angle

Subcutaneous injection

enters into the muscle tissue, needle is perpendicular to the skin (no angle)

intramuscular injection

what type of hair covers fetus’?

Lanugo

What type of hair is short, fine, and unpigmented (peach fuzz)

Vellus

What type of hair is on the scalp, eyelids, eyebrows and is corse, thick, and colored; usually occurs after puberty?

Terminal

What is the site of hair formation?

the hair bulb

What part of the hair runs from the dermis to epidermis?

the follicle

There are three layers of hair made of dead, keratinized epithelia cells, what are they?

Medula → soft keratin, 2 cell layers thick

Cortex → hard keratin, bulk of hair

Cuticle → hard keratin, 1 layer thick

What is the name of the smooth muscles that cause hair to “stand on end” and produce “goose bumps”?

erector pili

What are Sebaceous Glands?

Where are they found?

What do they look like?

What do they produce?

Alveolar glands,

Within the Dermis layer, found everywhere except for the palms and soles, attached to the hair shaft (not directly to the surface of the skin)

Looks like small grape sacs,

Produce sebum

What is the function of Sebum?

soften skin, prevent dehydration by lubricating hair/skin, inhibits body bacteria = immune function

(stimulated by antogens)

What are the two types of Sweat Glands?

Eccrine

Apocrine

What are Eccrine glands?

Where are they found?

What do they look like?

What do they produce?

Sweat glands,

Found on palms and soles, open directly to skin surface via pores

Coiled portion (produces wastes) and Tube portion (NaCl is reabsorbed) secrete with emotional stress (no temp regulation)

What are Apocrine glands?

Where are they found?

What do they look like?

What do they produce?

sweat glands

found in armpits and genitalia, open into the hair folicle

Coliled

produce pheromones, odor when in contact with bacteria (only active after puberty)

What are Mammary glands?

Where are they found?

What do they produce?

Modified apocrine sweat gland

Found in the female breast

Produce milk via prolactin signal during pregnancy

What are Ceruminous glands?

Where are they found?

What do they produce?

modified eccrine sweat glands

found in lining of external ear canal

secretes Cerumen (ear wax)

What is the function of Cerumen?

ear wax

protects ear from dehydration, insects, and foreign objects

the nail is an extension of what layer of the skin?

the epidermis, specifically the stratum corneum

What is Basal cell carcinoma?

What layer of the skin does it affect?

How treatable is it?

least malignant, most common

invades dermis and hypodermis

slow growing, cured by surgical excision, 99% success

what is Squamous Cell Carcinoma?

What layer of the skin does it affect?

How treatable is it?

arises from keratinocytes

affects stratum spinosum on scalp, ears, lower lip

grows rapidly, metastasis, cured by radiation or surgical removal, highly successful if treated early

what is Melanoma?

What layer of the skin does it affect?

How treatable is it?

cancer of melanocytes

most dangerous, likely to metastasize, resistant to chemo

chance of survival is poor if lesion is over 4 mm deep

What should you check for when evaluating for skin cancer? ABCDE

asymmetry

border

color

diameter

evolving

In a first degree burn what layer of skin is damaged?

What are the symptoms?

Only the epidermis

localized redness, swelling, and pain

In a second degree burn what layer of skin is damaged?

What are the symptoms?

epidermis, upper regions of dermis

mimic first degree burns with addition of blisters

In a second third burn what layer of skin is damaged?

What are the symptoms?

entire thickness of skin is damaged down to the underlying tissue

area appears gray-white, cherry red, or black; no initial edema or pain since nerve endings are destroyed