1B Integumentary System

Integumentary system: system of body composed of the _______ and the underlying _________

skin; subcutaneous tissue

What percent of the total body weight does the skin comprise?

15

Functions of skin

1. protection of underlying tissues

2. site of sensory receptors

3. regulation of body temperature

4. Salt and water excretion

5. formation of vitamin D

2 layers of skin

epidermis; dermis

thickest skin

back (1/2 cm)

thinnest skin

Eyelids (1/2 mm)

epidermis composed of

stratified squamous keratinized epithelium

epidermis is vascular or avascular?

avascular

does the epidermis have nerves

yes

layers of epidermis

stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum

stratum basale

base layer of epidermis where cell division takes place

stratum spinosum

epidermal layer where cells are tightly bound together

stratum granulosum

epidermal layer where cells become waterproof and continue to break down

stratum lucidum

epidermal layer where precursor for keratin is laid down, cells flatten and appear clear, no nucleus

stratum corneum

outer layer of epidermis, provides a protective layer that is waterproof and hard; thickest on palms and hands and soles of feet

epidermal layer where mitosis occurs

stratum basale

as cells move toward surface of epidermis...

they become dead, water resistant and filled with keratin

how many days for cell to go from birth to slough

30

what layer of skin regenerates

epidermis

melanocytes

produce melanin; found in deep layers

dermis

deep to epidermis

structures found in dermis

blood vessels, nerves, hair follicles and sweat glands

epidermis makes up what percent of skin

20%

dermis makes up what percent of skin

80%

superficial papillary layer of dermis

bumps that extend into epidermis that contain tactile receptor

recticular layer

contains collagen fibers laid down in multiple directions to resist 3 dimensional stress

subcutaneous tissue

composed of loose connective tissue and adipose cells

structures of subcutaneous tissues

blood vessels and nerves, some sensory receptors

adipose tissue is more abundant in

females

adipose tissue function

provide insulation, conserve body heat and shock absorber

The hair follicle originates in which layer of the skin?

epidermis

when hair follicle becomes inactive,

the hair becomes lost

hairs form by cells undergoing mitosis at

papilla of hair follicle

sebaceous glands

produce oil (sebum)

Where do sebaceous glands typically empty their contents into?

hair follicle

arrector pilorus

smooth muscles that attach to hair follicle and dermal-epidermal junction

sweat glands

secretion part in dermis and their ducts passing through epidermis to open at PORES

what does sweat contain

water, salt, ammonia

nails are composed of

keratin