Anatomy Chapter 5 Integumentary System

Front 1

Describe the hypodermis. WHy is it also called the superficial fascia? What functions does it share with the skin?

Back 1

The hypodermis/superficial fascia (b/c it is superficial to the tough connective tissue wrapping - fascia - of the skeletal muscles) is the subcutaneous tissue just deep to the skin. Not part of the skin but does share some of its protective functions. Consists mostly of adipose tissue.

Front 2

Describe how the hypodermis stores fat and how this effects it.

Back 2

The hypodermis stores fat and anchors the skin to the underlying structures like muscles. Its fatty composition also makes it able to act as a shock absorber and insulator. The hypodermis thickens markedly with weight gain.

Front 3

What are the four cell types of the epidermis?

Back 3

keratinocyes, melanocytes, epidermal dendritic cells, and tactile cells.

Front 4

What is the chief role of the keratinocytes? Where are they located?

Back 4

Keratinocyes chief role is to produce keratin, which is the fibrous protein that helps give the epidermis its protective properties.
Keratinocytes are tightly connected by desmosomes and are in the deepest layer of the epidermis, the stratum basale.

Front 5

Why do keratinocytes undergo almost continuous mitosis? WHere is keratin formation accelerated?

Back 5

They undergo almost continuous mitosis becuase of a peptide called epidermal growth factor; as cells are pushed upward by new cells, they make the keratin so dominant. Keratinocyes are dead by the time they reach the surface of the skin.Millions rub off every day.Keratin formation si accelerated in areas like the hands and feet because they are regularly subjected to friction.

Front 6

What are melanocytes? Where are they found? WHere do they accumulate?

Back 6

Melanocytes are spider shaped epithelial cells that synthesize melanin. Found in deepest layers of the epidermis. Melanin is accumulated in melanosomes. Melanosomes are moved along actin filaments by motor proteins to the ends of the melanocyte's processes (its 'spider arms'). Melanin granules accumulate on the superficial side of the keratinocyte nucleus, protecting the nucleus from UV radiation.

Front 7

Describe Epidermal dendritic cells. What is their other name?

Back 7

Epidermal dendritic cells arise from bone marrow and migrate to the epidermis. They are also called Langerhans cells after a German anatomist. They ingest foreign substances and are key activators of our immune system. Their slender processes form an almost continuous network around the surrounding keratinocytes.

Front 8

Describe Tactile (Merkel) cells. What is each cell associated with?

Back 8

Tactile (Merkel) cells are at the epidermal-dermal function. Each tactile cell is intimately associated with a disclike sensory nerve ending which forms a tactile or Merkel disc. They function as sensory receptors for touch.

Front 9

What are the five layers of the epidermis?

Back 9

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

Front 10

Where is the stratum basale and what does it consist of?

Back 10

Stratum Basale is the deepest epidermal layer, attached to the underlying dermis. Consists of a single row of columnar/cuboidal stem cells, a continually renewing cell population. 10-25% of cells in the stratum basale are melanocytes, and occasional tactile cells are in this layer.

Front 11

Describe the keratinocyte mitosis process in the stratum basale.

Back 11

Keratinocytes divide by mitosis every 19 days. Each time a cell divides, one daughter cell is pushed to the cell layer above to begin the process of becoming a mature keratinocyte; the other daughter cell remains in the stratum basale to continue making new cells that will become keratinocytes.

Front 12

Describe the stratum spinosum. What is this layer composed of?

Back 12

Stratum Spinosum is 8-10 multisided cell layers thick. Limited cell division occurs here. The upward push of cells tends to flatten their appearance. These cells contain a weblike system of pre-keratin filaments . Scattered among the keratinocyes are melanin granules and epidermal dendritic cells, which are most abundant in this layer. More keratin fibers and lamellar bodies are found.

Front 13

Describe the stratum granulosum.

Back 13

Stratum Granulosum consists of 3-5 cell layers in which the process of keratinization (cells fill with protein keratin) begins. The cells flatten and acquire a diamond shape.

Front 14

What do keratohyaline granules, lamellar granules and keratinocytes do in the stratum granulosum?

Back 14

Keratohyaline granules help form keratin in upper layers. Lamellar granules contain glycolipid and are a major factor in slowing water loss across the epidermis. Keratinocytes begin "toughening up" in this layer. The most superficial layers contain cells that are getting ready to die.

Front 15

Describe the stratum lucidum?

Back 15

Stratum Lucidum consists of two or three rows of dead keratinocytes. The gummy substance of the keratohyaline granules clings to the keratin filaments of the cells which causes them to group together in large parallel arrays. It is only visible in thick skin. The cells are somewhat transparent.

Front 16

Describe the stratum corneum? How thick is it? What happens when cells contain soft keratin versus hard keratin?

Back 16

Stratum Corneum is 20-30 cell layers thick accounting for up to 3/4 of the epidermal thickness. Keratin protects the skin against abrasion and penetration. If the cells contain soft keratin the the cells will desquamate (skin). If the cells contain hard keratin then the cells do not desquamate (nails). The lamellar bodies release the lipids reducing permeability.

Front 17

What do the glycolipid and the lamellar bodies do in the stratum corneum?

Back 17

The glycolipid between its cells nearly waterproofs this layer. It renders the body relatively insensitive to biological, chemical, and physical assaults. All this from a layer of dead skin cells. The lamellar bodies release the lipids reducing permeability

Front 18

Describe the dermis. What does it contain? What are its two layers?

Back 18

The dermis is made of strong, flexible connective tissue. It is richly supplied with nerve fibers, blood vessels, and lymphatic vessels. The major portions of hair follicles, oil glands and sweat glands reside in the dermis though they are derived from epidermal tissue. It provides most of the structural strength of the skin. It has two layers: the papillary and reticular.

Front 19

Describe the papillary layer. What does it do? WHat is it made of?

Back 19

The papillary layer is the thin superficial layer. It supplies epidermis with nutrients, removes waste, and regulates body temperature. It is made from areolar connective tissue that is heavily invested with small blood vessels. Contains phagocytes and other defensive cells that wander freely, patrolling the area for bacteria that breached the skin. Also contains dermal papillae that indent the epidermis.

Front 20

Describe the dermal papillae and what they do.

Back 20

The dermal papillae contain capillary loops or free nerve endings and touch receptors. On the palms of hands and soles of feets the dermal papillae lie atop dermal ridges which cause the epidermis to form epidermal ridges which is how we get finger prints or "friction ridges". These also enhance gripping ability.

Front 21

Describe the reticular layer. What is it made of?

Back 21

The reticular layer accounts for 80% of dermal thickness. It is made of dense fibrous connective tissue. A network of blood vessels nourishes the layer and lies between it and the hypodermis. Also contains pockets of adipose cells and thick bundles of interlacing collagen fibers, most of which run parallel to the skin surface. Collagen keeps skin hydrated by binding water, and elastic fibers provide the stretching properties of skin. Flexure lines occur at or near joints to accommodate joint movement. Also visible on wrists, fingers, soles and toes.

Front 22

The reticular layer contains cleavage lines. Describe how these are formed and what they do. Also describe flexure lines.

Back 22

Separations or less dense regions between these regions form cleavage lines in the skin. These externally visible lines tend to run longitudinally in the sking of the head and limbs and in circular patterns around the neck and trunk.

Front 23

Describe thick skin and thin skin. How are they different?

Back 23

•Refers to number of epidermal layers and not to total thickness
•Thick skin – has all 5 epithelial layers, found in areas of high friction, contains no hairs, papillae are in parallel curving ridges (finger prints)
•Thin skin – more flexible than thick, has fewer layers of cells, papillae are separated so there are no ridges, all hair is found here

Front 24

How do melanocytes and melanin work together to produce skin color? What else contributes to skin color?

Back 24

•Melanocytes – produce melanin (pigment), found between the stratum basale and spinosum
•Melanin is phagocytized from melanocytes by keratinocytes.
–This distribution of melanin helps to give skin its overall color.
–Uneven distribution gives rise to variations in skin color such as freckles.
•Additionally, the presence of hemoglobin and carotene add to the skin’s color.

Front 25

What are hair's functions? What does it consist of? What are the three layers of hair?

Back 25

Functions – sensory, prevent heat loss, protection, and filtration.
•Consists mostly of dead hard keratinized cells making them tougher and less likely to slough off than epidermal cells.
The three layers are medulla, cortex, and cuticle.

Front 26

Describe the three layers of hair.

Back 26

Medulla is the central core consisting of large cells with air spaces between them. This layer is absent in fine hair.
–Cortex surrounds the medulla and is made from several layers of flattened cells.
–Cuticle is the outermost layer formed from a single layer of overlapping cells. The shingle-like arrangement keeps hairs from matting together.

Front 27

Describe how texture is related to hair shape.

Back 27

Texture largely depends on shaft shape:
–Flat produces kinky hair.
–Oval produces silky and wavy hair.
–Round produces straight and coarse hair.

Front 28

Describe the three layers of the hair follicle.

Back 28

The hair follicle lies below the skin level and consist of three layers (from external to internal):
–Connective tissue root sheath (attaches hair follicle to adjacent skin)
–Outer basement membrane called the glassy membrane.
–Next is the external epithelial root sheath.
–Innermost is the internal epithelial root sheath that produces hair in the area of the hair bulb.

Front 29

Describe how hair growth and hair loss occur.

Back 29

Hair growth occurs during the growth phase with hair cells reproducing, keratinizing, fusing together and being pushed towards the surface.
•Hair loss occurs shortly after the resting phase with a new hair pushing out the old. (Various areas of the body have different timing for growth and resting phases.)

Front 30

Describe vellus hair, terminal hair, and hirsutism.

Back 30

Vellus hair is very fine and pale occurring on children and faces of females.
•Terminal hair is darker and coarser appearing in the axillary and pubic regions of adults, and also adult male facial regions.
•Hirsutism is overproduction of hair.

Front 31

Describe the different parts of nails.

Back 31

–Hard keratinized cells produced at the nail matrix. Pale region referred to as lunula.
–Nail body is overlapped by folds of skin.
•Proximal fold is the eponychium (cuticle).
•Lateral folds are on the lateral borders of the nail. (Hang nails occur here.)
–Nail bed – extension of the nail matrix used for nail attachment.
–Hyponychium is at the free edge of the nail.

Front 32

What is arrector pili?

Back 32

smooth muscle that cause hair to stand up and goose bumps to form.

Front 33

Name the different glands in skin and what they do.

Back 33

Eccrine sweat produce sweat
–Apocrine sweat produce fatty sweat in axillary and anogenital regions
–Ceruminous produce cerumen (earwax)
–Mammary produce milk
–Sebaceous produce sebum (oil)