04: Integumentary System

Functions, characterists, layers of epidermis, layers of dermis, hypodermis, glands of skin, conditions of skin, burns, cancers, nail construction, hair construction, ageing effect on system

What does the system protect against

dehydration

microorganisms

UV rays

organ damage

How much sweat is lost per day

1 pint

Why do microorganisms die on our skin

Due to its slightly acidic nature (4-6)

What protects the skin from UV rays

Melanin pigment from melanocytes

How does the body regulate for hot temperatures

Dilation of BV that bring blood to the surface instead of being internal

Sweat glands release more sweat to evaporate heat loss

How does the body regulate for cold temperatures

Constriction of BV that keep the blood more internal

Hair puffs up to make goosebumps

What are other functions of Integumentary

• Blood Reservoir (dermis is highly vascularized)

• Excretion (Sweat)

• Sensation (Neuroepithelial tissue)

• Vitamin D Synthesis

Characterizes of Skin

Largest organ (1.5-2 meters long and 0.5-4mm thick)

15% body mass

Continuous w/ mucous membrane

Cutaneous Membrane Layer = epidermis and dermis

Subcutaneous layer = hypodermis

Characteristics of Epidermis

First layer of skin

Avascular

90% are filled with keratin (keratinocytes)

• waxy waterproofed

5 Layers

Forms Nails, Hairs, Glands

Stratum Germinativum/Basal

Closest to the dermis

where mitosis of keratinocytes take place, millions of them begin to push to the surface

Stratum Spinosum

Cells are spiny-shaped

Stratum Granulosum

Spiders have granulosum and look visually grainy

Stratum Lucidum

Looks clear/transparent/lucid

Is the first layer of dead cells

Only present in thick skin (hands and feet) for extra waterproofing

Stratum Corneum

Cornified corneocytes or horn cells

Different structure than all other skin cells

Are almost waterless with no nuclei

Peeled surface skin

Desmosomes

Linking cells that link skin cells (dead or alive) together

the reason skin peels off in sheets

What is the lifespan of skin cells

25-45 days

What cells contribute to skin color

Melanocytes, Carotin, Blood

Melanocytes

Arms deposit pigment to surrounding cells, pigment creates a hat over DNA to sheild from sun rays

Does the number of melanocytes increase in those with darker skin?

No, humans have the same number of melanocytes, there are other genetic factors that lead to skin color differences

Carotin

Gives the orange/yellow color

Hypercartonemia

Excess amounts of Carotin, similar to jaundice

Blood

Gives skin the redness

Cyanosis

Purple/cyan color of skin when those are low in O2

Vitiligo

Genetic Autoimmune Disorder where WBC attack melanocytes leading to depigmentation

Does Albinism effect just skin?

No, it can also affect hair and eyes, but melanocytes aren’t the sole contributing factor to eye and hair color

Albinism

Genetic disorder with various genetic mutations as causes

Pigment is not produced by melanocytes

the need for increased external skin protection (hats, long sleeves, ect)

Basal Cell Carcinoma

Mainly on the face/arms and arises from stratum basal layer

Rarely metastasizes

Squamous Cell Carcinoma

Arises from stratum spinosum

Faster growing, cells divide as they produce keratin

Some metastasizes into dermis first

Melanoma

Most dangerous, aries from melanocytes

What is the chance of survival of Melanoma is not metastasized

90%

What is the chance of survival of Melanoma is metastasized

14%

Dermis

Deeper skin layer divided into 2, uneven, layers

Epidermis is connected to dermis via ridges

Papillary Layer

Superficial layer made from areolar connective tissue

forms dermal papillae, finger prints,

Houses capillary loops and neurons (sensation)

Reticular Layer

Deeper, thicker layer made from dense irregular connective tissue

location of most skin organs

fibers show preferences in direction via skin folds

What causes wrinkle lines

weakened elastic fibers

Hypodermis

Subcutaneous layer/membrane made of adipose connective tissue

connects skin to organs by being the outermost wrapping of internal organs

First Degree Burns

Reach only the epidermis

opens BV to increase redness and sensitivity

Accessory organs are not effected

Second Degree Burns

Epidermis and superfically dermis are burned

Blisters and pain w some oozing due to nervous tissue

Most organs are unaffected

Third Degree Burns

All layers are damaged, may reach bone

Has a chared appearance

Organs are damaged, no pain (receptors are burned)

Glands are made of what type of tissue

Simple cuboidal

Ducts are made of what tissue

Stratified cuboidal

Nails

Modified epidermis split into three regions (root, plate, and free edge)

Nail Function

increase sensitivity and protect/waterproof the surface

Hair

Made up of follicle + sebaceous gland + pili muscle

Arrector Pili

activated by cold/nerves

when active, oil is squeezed out and hair strands stand erect creating small bumps (goosebumps)

What is effected when aging

Epidermis becomes dry due to reduced glandular activity

• causes overheating of body and reduced repair and vitamin d production

Reduced blood supply

thinned dermis = wrinkles and saggy skin

reduced fat and hair (thinned) due to sex hormones

Fewer melanocytes