ap lecture ch 6 integument system

functions of the skin

protection

prevention

temperature regulation

hormonal and immune Functions

sensory perception

how many layers does the skin have?

2 - epidermis, dermis

epidermis

first layer of the skin

avascular

nourished by blood capillaries in dermis

the epidermis is composed of..

stratified squamos keratinized epithelium

the epidermis has ___ layers in thick skin and ___ layers in thin skin

5, 4

dermis

second layer of the skin

composed of connective tissue

2 layers

the dermis houses…

glands, hairs, and sensory receptors

hypodermis

the subcanteous layer

composed of adipose tissue

Stratum corneum - 1st layer of epidermis

composed of dead keratinzed cells

makes skin water resistant

protects against invasion

Stratum lucidum - 2nd layer of epidermis

found only in thick skin such as the palm or sole

2-5 layers of dead cells

filled with eleidin (keratin protein)

transparent layer

Stratum granulosum - 3rd layer of epidermis

cells are in process of keratinization

contain granules of keratohyalin protein

Stratum spinosum - 4th layer of epidermis

thickest layer

made up of living cells

cells interconnected by desomsomes

Stratum basale (or germinativum) - 5th layer of epidermis

consists of living cells

basal cells are attached lies on top of dermal papillae

determine the pattern of the epidermal ridge (fingerprints)

contains Merkel or Tactile cells

Basal cells

form the bottom most layer of epidermis

Keratinocytes

dead cells forming top layers of the skin

Melanocytes

gives skin pigment aka its color

Dendritic or Langerhans cells

cells recognize foreign invaders and alert the immune system to fight the pathogen

originate in bone marrow

Merkel or Tactile cells

located in the stratum basale

sensitive to light touch

Skin pigmentation

Melanin, carotene and hemoglobin cause skin color

Papillary layer 

made up of areolar connective tissue

provide nutrients to the epidermis

Reticular layer 

hickest layer of skin underneath the papillary layer

made up of dense irregular connective

Free edge

Part of the nail that has grown beyond the nail body

Hyponychium

Tissue underneath the free edge of the nail

Nail folds

folds of skin covering the lateral edges of the nail

Nail body

Part of the nail which is attached to the underlying skin

made up of dead, keratinized cells

Nail root

Part of the nail covered with the epidermis

lies close to the periosteum

Nail bed

Part of stratum basale on which lies the nail body

Nail matrix

Part of the nail root covered with stratum basale

where the nail grows

Eponychium (cuticle)

Part of stratum corneum that grows over the exposed part of the nail at the base

Lunula

crescent shaped pale region at the base of the nail