Unit 3 Anatomy - Integumentary System

epidermis

outermost/most superficial layer of skin

dermis

middle layer of skin composed of dense, fibrous connective tissue

hypodermis/subcutaneous layer

deepest layer of skin, not technically a part of the skin

keratinocytes

cells that produce keratin

melanocyte

produce melanin (pigment/skin color)

melanosome

organelles that store and transport melanin

stratum corneum

outermost layer of epidermis; dead, keratinized cells; very flat and exposed to surface

stratum basale

deepest layer of epidermis; attached to basement membrane; cells are actively dividing/replacing; attached by hemidesmosomes

papillary region

superficial part of dermis that contains loose connective tissue w/ elastic fibers; contains dermal papillae (fingerprints); highly vascular, supports epidermis, contains capillaries/nerve support

reticular region

deeper portion of dermis that contains dense connective tissue and collagen/elastic fibers; contains hair follicles and sweat glands

carotene

gives skin yellow-orange pigment, precursor to vitamin A, accumulates in epidermal cells

melanin

UV light stimulates activity within melanosomes which increases melanin production; determines skin/eye color

hemoglobin

gives skin bright red color when oxygenated

albinism

lack of functional melanocytes, creates very light skin and hair

vitiligo

melanocytes die off slowly overtime, causes certain parts of skin to be lighter

root

anchors hair to skin

shaft

visible portion of hair

arrector pili muscle

tiny muscle connected to each hair follicle; causes goosebumps

eccrine gland

merocrine gland (cells intact); major sweat gland; covers most of the body; unscented; for temperature regulation

apocrine gland

sweat gland that begins to function during puberty; located in genital/armpit areas; scented; portion of cell pinches during secretion

sebaceous gland

oil gland; located everywhere except palms/soles; produces sebum to keep skin/hair soft; has chemicals that kill bacteria

ceruminous gland

glands of external ear; produces earwax

mammary gland

milk producing; only functional in women; modified sweat glands

nail body

visible portion of nail

free edge

part of nail not attached to skin

nail root

non visible portion of nail, located very close to bone

lunula

little moon of nail

epidermal wound healing

for superficial wounds only, doesn’t take long to heal

deep wound healing

when wound extends into dermis/hypodermis

first degree burn

affects epidermis only; mild pain; heals in less than a week

second degree burn

involves epidermis and dermis; hair follicles/glands typically unaffected; some blistering/swelling; takes 1-2 weeks to heal and can scar

third degree burn

most severe burn; affects all layers of skin; initially not painfully as nerve endings are destroyed; can’t heal on its own

What are general characteristics and functions of the skin/integumentary system?

• protection

• temperature control

• prevents dehydration

• help maintain homeostasis

What is the composition of the hypodermis?

fat, connective tissue

What is the function of the hypodermis?

stabilizes the position of skin to underlying tissues; shock absorber; reduces heat loss

Where is the skin the thickest and why?

dermis - for more protection

What are the layers of the epidermis?

• stratum corneum

• stratum lucidum

• stratum granulosum

• stratum spinosum

• stratum germinatium

• stratum basale

What is the tissue composition of the layers of the dermis?

papillary layer - loose connective tissue

reticular layer - dense connective tissue (more protection)

What gives the skin color and how?

melanin - melanocytes produce melanin; when UV hits skin it releases melanin to protect it from radiation

Discuss the distribution of body hair and what causes it.

warmth, more hair on head, arms and legs

How does hair grow?

from the follicle, dead cells are pushing out, they are keratinized

Discuss the composition and growth of nails.

grows from inside out; dead cells that are keratinized

How does the skin perform thermoregulation?

sweating and shivering

vasoconstriction - done when cold, vessels contract and produce heat

vasodilation - done when hot, vessels expand to move blood quicker and produce less heat by not contracting

What happens to skin as we age?

loses collagen fibers, which causes wrinkles and sagging

hypertrophic scar

due to an over-production of collagen fibers where a wound has healed; does not extend beyond the boundaries of the would

keloid scar

over production of fibroblasts ; extends beyond boundaries of the wound

This layer of the dermis is composed of dense irregular connective tissue

reticular layer

The smooth muscle associated with a hair follicle is called ________

arrector pilli

These cells produce a brown pigment when stimulated by UV rays

melanocytes

This subsection of the layer of the dermis is responsible for fingerprints

papillary layer

A burn that goes through the epidermis and most of the dermis

partial thickness/2nd degree burn

The stratum basale connects to dermis by the way of this structure

basement membrane

This stratum of the epidermis is made up of layers of dead keratinocytes

stratum corneum

This is one non-connective tissue found in the dermis

smooth muscle tissue

Burns of the skin are measured by this

rule of nines

The protein found in hair and nails

keratin

This layer of skin has no blood vessels

epidermis

Hair and nails are modifications of this tissue type

epithelial tissue

Mitosis occurs primarily in this stratum of the epidermis

stratum basale