5.3: Papillary Dermis and Reticular Dermis

What does most dermal papillae contain?

capillary loops

What are the functions of friction ridges?

- may enhance our ability to grip certain kinds of surfaces. -contribute to our sense of touch by enhancing vibrations detected by the large lamellar corpuscles (receptors) in the dermis.

Cleavage lines

-represent separations between underlying collagen fiber bundles in the reticular dermis. -run circularly around the trunk and longitudinally in the limbs. -surgical incisions parallel to cleavage lines heal better than those made across them.

Homeostatic Imbalance 5.1 1. Extreme stretching of the skin can result in... 2.Give an example of stretching skin. 3. What can cause a blister? Also, give an example. 4. What is a blister?

1. tearing the dermis and leaving silvery white scars called striae (stretch marks) 2. A pregnant belly 3. Short-term but acute trauma. Ex: A burn or from repeated friction when wielding a hoe. 4. A fluid-filled pocket that separates the epidermal and dermal layers.

Stefan's front bike tire slipped on a patch of gravel as he rode to work. He needed five stitches to close the cut above his left eye. The split skin ran along a cleavage line. Is Stefan likely to have a major scar or is the wound likely to heal cleanly? Explain.

Because Stefan's wound runs along a cleavage line, it is likely to heal much more cleanly than it would if it ran perpendicular to the cleavage lines.

You have just gotten a paper cut. It is very painful, but it doesn't bleed. Has the cut penetrated into the dermis or just the epidermis?

Because there is no bleeding, the cut has penetrated into the avascular epidermis only.

What is the composition of the extracellular matrix of the reticular dermis?

Contains thick bundles of interlacing collagen fibers.

Light micrograph of the dermis. (Figure 5.3)

Dermis is the underlying layer of the epidermis and consists of 2 layers, the papillary (areolar connective tissue) and reticular (dense irregular connective tissue)

What are cleavage lines?

External invisible lines that tend to run longitudinally in the skin of the limbs and in circular patterns around the neck and trunk

Tactile epithelial cells and tactile corpuscles are the same structures. True or False

False, Tactile epithelial cells and tactile corpuscles are different structures.

What are flexure lines and where are they located?

Flexure lines are dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures. Location: the deep creases on your palms, wrists, fingers, soles, and toes.

How are friction ridge patterns determined and who are they unique to?

Friction ridge patterns are genetically determined and unique to each individual.

What is the role of the collagen fibers that are in the dermis?

Give skin strength and resiliency that prevent minor jabs and scrapes from penetrating the dermis.

In what region of the body does dermal papillae reside on top of larger mounds called dermal ridges?

In thick skin, such as the palms of the hands and soles of the feet,

What does sweat pores opening along friction ridges contribute?

It allows our fingertips to leave identifying films of sweat called fingerprints on almost anything we touch.

What happens as a result of the dermal papillae residing on top of larger mounds called dermal ridges?

It causes the overlying epidermis to form epidermal ridges

What is the matrix of the dermis and what is its function?

It's a semifluid matrix, embedded with fibers, binds the entire body together like a body stocking.

The Dermis consists of

Papillary Dermis and Reticular Dermis

What is dermal papillae?

Peglike projections that arise from the papillary dermis and indent the overlying epidermis.

What is the role of the elastic fibers that are in the dermis?

Provide the stretch-recoil properties of skin.

What forms cleavage (tension) lines in the skin?

Separations, or less dense regions, between the collagen fibers

What pores open along the crest of friction ridges on our finger tips?

Sweat pores

What is considered your "hide" and corresponds to animal hides used to make leather?

The dermis is known as the hide.

What is the the dermal vascular plexus and where is it located?

The network of blood vessels that nourishes the reticular dermis. Location: lies between the reticular dermis and the subcutaneous tissue.

What are the 2 layers of the dermis and where are they located?

The papillary and reticular, which lie next to one another along an indistinct boundary.

What type of tissue makes up the papillary and reticular dermis?

The papillary dermis consists of areolar connective tissue, and the reticular dermis consists of dense irregular connective tissue.

1. Name the tissue types composing the dermis.

The papillary dermis is composed of areolar connective tissue. The reticular dermis is composed of dense irregular connective tissue.

What is the papillary dermis?

The thin, superficial layer of the dermis that is composed of areolar connective tissue in which fine interlacing collagen and elastic fibers form a loosely woven mat with many small blood vessels.

Why are cleavage lines important to surgeons?

They are important because when an incision is made parallel to these lines, the skin gapes (opens up/widens) less and heals more readily.

Collagen fibers and elastic fibers are fond in both the papillary and reticular layer of the dermis. True or False

True

Friction ridges of fingertip

a. Sweat duct openings along the crests of friction ridges help make fingerprints. b. friction ridges consist of epidermal ridges that lie on top of dermal ridges.

The looseness of _______ connective tissue allows phagocytes and other defensive cells to wander freely as they patrol the area for bacteria that have penetrated the skin.

areolar

Dermal modifications result in characteristic skin markings such as...

cleavage lines, flexure lines, and friction ridges

The _____ fibers run in various planes, but most run parallel to the skin surface.

collagen

Since the skin cannot slide easily to accommodate joint movement in such regions, the _____ folds and deep skin creases form.

dermis

The ____ is made up of strong, flexible connective tissue

dermis (derm = skin)

The cells of the dermis are typical of those found in any connective tissue proper, so what are the cells?

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

Flexure lines

form where the dermis is closely attached to the underlying structures.

What are some of the things that other dermal papillae house (contain)?

free nerve endings (pain receptors) and touch receptors called tactile corpuscles or Meissner's corpuscles

As a collective of both skin ridges. What is dermal and epidermal referred to as

friction ridges

What is the reticular dermis named for ?

its network of collagen fibers (reticulum = network); the name does not imply any special abundance of reticular fibers.

2. List its major layers and describe the functions of each layer.

papillary dermis- formation of dermal papillae and friction ridges. reticular dermis- formation of cleavage (tension) lines and flexure lines. Both provide nutrients to the skin .

The deeper ______ dermis, accounting for about 80% of the thickness of the dermis, is coarse, dense irregular connective tissue

reticular