Integumentary System (LAB)

integumentary system consists of

• skin

• hair

• nails

• glands

two types of glands

• eccrine (sweat) glands

• sebaceous (oil) gland

2 regions of the skin

• epidermis

• dermis

epidermis

superficial region

is the epidermis vascular or avascular?

avascular

what is the epidermis made of?

keratinized, stratified squamous epithelium

dermis

deep to the epidermis

is the dermis vascular or avascular?

vascular

dermis is made of

mostly dense irregular connective tissue and a thin layer of areolar tissue

hypodermis

subcutaneous layer, deep to the skin

the hypodermis is made of

mostly adipose tissue that absorbs shock and insulates

hypodermis function

anchors skin to underlying structures

cells in the epidermis

• keratinocytes

• melanocytes

• dendritic (Langerham) cells

• Merkel (tactile) cells

Keratinocytes function

produce fibrous keratin-protein that gives skin its protective properties

keratinocytes are tightly connected by

desmosomes

melanocytes function

produce pigment melanin, which is packed into melanosomes

melanosomes are transferred to

keratinocytes where they protect nuclei from UV damage

melanocytes

spider-shaped cells located in deepest epidermis

merkel cells

associated with sensory receptors that sense light touch

dendritic cells

star-shaped macrophages that patrol deep epidermis

dendritic cells are key activators of the

immune system

epidermis is made of __ layers

4 or 5

how many layers does thick skin have

five

how many layers does thin skin have?

four

where is thick skin found

high abrasion areas like the hands and feet

deepest layer of the epidermis

stratum Basale

how many layers is the stratum Basale

one

what types of cells are in the stratum Basale

cuboidal/low columnar, desmosomes, and hemidesmosomes

the stratum Basale has high __ activity

mitotic

second deepest layer of the epidermis

stratum spinosum

how many layers does stratum spinosum have

several layers

third deepest layer of the epidermis

stratum granulosum

stratum granulosum number of cell layers

3-5 layers

stratum granulosum types of granules

• keratohyalin granules

• membrane-coated lamellar granules

keratohyalin granules

large, not membrane-bound, very basophilic, and have bundles of keratin

stratum lucidum

second layer of epidermis in thick skin only

The stratum lucidum has cells filled with

keratin

stratum lucidum cells connect in

squames

stratum lucidum has a disrupted

nucleus and organelles

top layer of epidermis

stratum corneum

stratum corneum layer thickness

varies in thickness

stratum corneum cells

flat and desicated

cells in the dermis

fibroblasts, macrophages, and occasionally mast cells and white blood cells

how many layers is the dermis made of

two

two layers of the dermis

• papillary

• reticular

papillary layer of the dermis consists of what tissues

areolar connective tissue with loose, interlacing collagen and elastic fibers and blood vessels

superficial layer of the dermis

papillary layer

loose fibers in the papillary layer of the dermis allow

phagocytes to patrol for microorganisms

dermal papillae

superficial region of the dermis that sends fingerlike projections up into the epidermis

projections of the dermal papillae contain

• capillary loops

• free nerve endings

• touch receptors

reticular layer of the dermis

deep layer

how much of the dermis does the reticular layer make up

about 80%

what kind of tissue is the reticular layer of the dermis made of

dense irregular with many elastic and collagen fibers

cutaneous plexus

network of blood vessels between the reticular layer and the hypodermis

the extracellular matrix of the reticular layer of the dermis contains pockets of

adipose tissue

hair

flexible strands of dead, keratinized cells

hair is produced by

hair folicles

hair contains __ keratin

hard

hair pigments are made by __ in hair follicles

melanocytes

hair shaft

area that extends above the scalp, where keratinization is complete

hair root

area of hair within the scalp where keratinization is still going on

hair follicle extends from the epidermal surface to the

dermis

hair bulb

expanded area at the deep end of the hair follicle

hair papilla

dermal tissue containing a knot of capillaries that supplies nutrients to growing hair

arrector pili

small band of smooth muscle attached to the follicle (responsible for goosebumps)

wall of the hair follicle is composed of

• peripheral connective tissue sheath

• glassy membrane

• external and internal root sheath

most numerous type of gland

eccrine sweat glands

eccrine sweat glands are abundant on

palms, soles, and forehead

eccrine sweat glands function in __ regulated by the sympathetic nervous system

thermoregulation

apocrine sweat glands

secrete viscous milky or yellowish sweat that contains fatty substances and proteins

apocrine sweat glands are confined to

axillary and anogenital areas

which sweat gland is larger

apocrine

which sweat gland empties into hair follicles

apocrine

sebaceous glands are widely distributed except in

thick skin of palms and soles

most sebaceous glands develop from and secrete into

hair follicles

sebum

oily holocrine secretion