The Integumentary System

What is the superficial epidermis composed of?

(1) The epithelium (2) connective tissue

Fill in the blanks. Structurally, the _____(1)_____ epidermis is a _____(2)_____ _____(3)_____ epithelium consisting of _____(4)_____ distinct cell types and _____(5)_____ or _____(6)_____ distinct layers.

(1) avascular (2) stratified (3) squamous (4) four (5) four (6) five

What two granules compose the stratum granulosum?

(1) lamellar granules (2) keratohyaline

List functions of the skin.

(1) protects the entire body from abrasion, exposure to harmful chemicals, temperature extremes, and bacterial invasion (2) insulates and cushions the underlying body tissues (3) the hardened uppermost layer of the skin prevents water loss from the body surface (4) acts as an excretory system Ex. urea, salts, and water are lost through the skin pores in sweat (5) metabolic duties Ex. location of vitamin D synthesis (6) Location of sensory organs

Cells of the ___(1)___ and ___(2)___ are the only epidermal layers to receive adequate nourishment from the diffusion of nutrients from the dermis?

(1) stratum basale (basal layer) (2) stratum spinosum (spiny layer)

What are the two distinct regions of the skin?

(1) superficial epidermis composed of the (a) epithelium (b) and underlying connective tissue (2) the dermis

Why is the integument considered an organ system?

Because it consists of multiple organs, the skin and its accessory organs.

How are keratinocytes tightly connected to each other?

By desmosomes

The hypodermis is considered part of the skin. True or False.

False. The hypodermis is not considered part of the skin.

Occasional tactile epithelial cells are also present in the stratum basale. True or False.

True

What does the hypodermis primarily consist of?

adipose tissue

What are dendritic cells (aka Langerhans cells)?

arise from bone marrow and migrate to the epidermis and function to ingest foreign substances and play a key role in activating the immune response.

What is melanin?

brown-to-black pigment produced by melanocytes.

Where is thin skin found? Thick skin?

covers most of the body; hands and the soles of the feet

How many layers does the epidermis consist of in thin skin? In thick skin?

four; five

What are keratinocytes and what is their main function

keratin cells that produce keratin fibrils which is a fibrous protein that gives the epidermis its duability and protective capabilities.

What is the most abundant epidermal cell?

keratinocytes

What are tactile epithelial cells?

occasional spiky hemispheres that along with sensory nerve endings form sensitive touch receptors located a the epidermal-dermal junction.

What is the function of melanin?

provides a protective pigment umbrella over the nuclei of the cells in the deeper epidermal layers shielding their DNA from the damaging effects of ultraviolet radiation.

What are melanocytes?

spidery black cells that produce the brown-to-black pigment called melanin.

Epidermal layer whose cells appear spiky. Why?

startum spinosum (spiny layer); because when the tissue is prepared, the cells shrink, but their desosomes hold tight to adjacent cells.

Epidermal layer whose cells are constantly undergoing mitosis to form new cells.

stratum basale (basal layer)

Epidermal layer with a single row of cells immediately above the dermis.

stratum basale (basal layer)

Some 10-25% of the cells in this epidermal layer are melanocytes which thread their processes through this and adjacent layers of keratinocytes.

stratum basale (basal layer)

List the layers of the skin from deep to superficial.

stratum basale → stratum spinosum → stratum granulosum →stratum lucidum → stratum corneum

Layer of epidermis that is constantly being exfoliated and replaced by the division of deeper cells

stratum corneum (horny layer)

The outermost layer of the epidermis consisting of 20-30 layers of dead, scalelike keratinocytes.

stratum corneum (horny layer)

Another name for startum basale

stratum germinativum

At the upper boarder of this epidermal layer the cells are beginning to die.

stratum granulosum (granular layer)

Layer of epidermis that is thin and named for the abundant granules its cells contain.

stratum granulosum (granular layer)

Layer of epidermis present only in thick skin.

stratum lucidum (clear layer)

Layer of epidermis that is very thin and is a transparent band of flattened, dead keratinocytes with indistinct boundaries

stratum lucidum (clear layer)

This epidermal layer contains several layers of thick web-like bundles of intermediate filaments made of pre-keratin protein.

stratum spinosum (spiny layer)

What extra layer is found in thick skin?

the stratum

Where is the hypodermis?

the subcutaneous layer

What is the function of keratohyaline granules?

they help form keratin in the more superficial layers.

What is contained in the lamellar granules?

waterproofing glycolipid that is secreted into the extracellular space