6.4: Repair and Regeneration of the Integumentary System

By the _______ week, the _____ ________ and friction ridges form.

21st Stratum corneum

a vascular connective tissue that initially forms in a healing wound.

Granulation tissue

During the embryonic period the mesoderm becomes:

Mesenchyme; developing in to the components of the dermis at about eleven weeks.

What week do nails form?

Tenth week of development; fingernails reach the tips at about 32 weeks, toenails reach the tips at about 36 weeks.

Is this the third or fourth step in healing damaged skin? The cut blood vessels regenerate and grow in the wound. A soft mass deep in the wound becomes granulation tissue. Macrophages within the wound begin to remove the clotted blood. Fibroblasts produce new collagen fibers in the region.

Third step

The _________ layer will form the stratum basale and all other epidermal layers.

basal

Repetitive mechanical stresses applied to the integument stimulate ______ activity in the stem cells of the stratum basale.

mitotic

Coats the skin of the fetus:

vernix caseosa

What is the dermis derived from?

Mesoderm

Name the two ways damaged tissues repair themselves.

Regeneration and Fibrosis

Replacement of damaged or dead cells with the same cell type.

Regeneration; restores organ function

Is this the 1st or 2nd step in healing damaged skin? A blood clot forms, temporarily patching the edges of the wound together and acting as a barrier to prevent the entry of pathogens into the body. Internal to the clot, macrophages and neutrophils (leukocytes) clean the wound of cellular debris.

Second step

During the _____ period, the ________ is eventually sloughed off; these cells then mix with sebum secreted by the _______ glands, producing a waterproof protective coating called the ______________

fetal periderm sebaceous vernix caseosa

Hair follicles begin to appear between 9 and 12 weeks of development as pockets of cells called _____ _____, invade the dermis from the overlying stratum basale.

hair buds

By the end of the seventh week of development, the _________ forms a layer of squamous epithelium that flattens and then becomes both a covering layer called the _______ and an underlying basal layer.

Ectoderm Periderm

What are integumentary system structures derived from?

Ectoderm (origin of the epidermis), mesoderm germ layers (origin of the dermis).

If an organ is [too] severely damages or its cells lack the capacity to divide, the body fills in the gap with scar tissue. What is this process called?

Fibrosis

Is this the first or second step in healing damaged skin? Cut blood vessels initiate bleeding into the wound. The blood brings clotting proteins, numerous leukocytes (white blood cells) and antibodies .

First step

When do integumentary systems not repair?

Following severe damage to the integument (hair follicles, exocrine glands, nerves, and the arrector pili muscle cells.

Is this the third or fourth step in healing damaged skin? Epithelial regeneration of the epidermis occurs due to division of epithelial cells at the edge of the wound. These new epithelial cells migrate over the wound, creeping internally to the now superficial remains of the clot (the scab). The connective tissue is replaced by fibrosis .

Fourth step