The Dermis

Where is the dermis located? What tissues are in the dermis? What layers are found in the dermis? What are some of the characteristics?

The Skin is an important body system, used mainly for protection. The skin is made up of three parts; the epidermis, the dermis, and hypodermis. The dermis is the second layer located beneath the epidermis. It contains two layers itself; the papillary and reticular layers. They contain nerve endings, blood vessels, oil glands, sweat glands, collagen and elastin fibers.


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Blood vessels which supply nutrients and oxygen to the skin, take away cell waste and cell products.
Functions:
  • Transport the vitamin D produced in the skin back and body
  • Nerve endings are extremely important and it would not be good to live without them.
  • The dermis layer contains pain and touch receptors that transmit sensations of pain, itch, pressure and temperature to the brain for interpretation.
  • They cause shivering (involuntary contraction and relaxation of muscles) to generate body heat.

    • Apocrine glands are specialized sweat glands that can be found only in the armpits and pubic region. These glands secrete a milky sweat that encourages the growth of the bacteria responsible for body odor.
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Apocrine Gland

    • Eccrine glands are sweat glands found over the entire body. These glands regulate body temperature sweating or bringing water to the pores where it evaporates and reduces temperature to keep cool.
eccrine_gland.jpg


Sebaceous or oil glands, are attached to hair follicles and can be found everywhere on the body except for the palms of the hands and the soles of the feet. It’s a tube-shaped strand that surrounds the part of the hair that is in the dermis. Sebaceous glands secrete oil that helps keep the skin smooth and supple. Hair follicles contain oil glands, which nourishes the hair. The oil also helps waterproof the skin and protects against bacteria.

The dermis is held together by a protein called collagen, made by fibroblasts. Fibroblasts are skin cells that give the skin its strength.

  • Collagen is a tough, insoluble protein found throughout the body in the connective tissues that hold muscles and organs together.
  • Elastin fiber is a similar protein. Its the substance that allows the skin to spring back into place when stretched and keeps the skin flexible.


Collagen and Elastin Fibers
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The dermis is composed of two layers: The papillary layer closest to the epithelium and the reticular layer underneath the papillary layer.

The upper layer of the dermis is the papillary layer. The papillary layer supplies nutrients to select layers of the epidermis and regulates temperature. It contains a thin arrangement of collagen fibers. The muscles are sometimes constricted and expanded and are in control the amount of blood that flows through the skin depending if the body is hot or cold. Controlling the body’s senses are free nerve endings and touch receptors (Meissner's corpuscles).

The lower, reticular layer, is thicker and made of thick collagen fibers that are arranged parallel to the surface of the skin. The reticular layer is denser than the papillary layer. It also strengthens the skin, providing structure and elasticity. It supports other parts of the skin, such as hair follicles, sweat glands, and sebaceous glands. Collagen helps to keep the skin hydrated when binded with water.

Layers of the Dermis

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Between fiber spaces are a small amount of:
  • adipose tissue
  • hair follicles
  • nerves
  • oil glands and ducts of sweat glands

There are different cell types found in the dermis.
They are:
  • fibroblasts
  • macrophages
  • sometimes mast cells or white blood cells.

Its matrix is heavily full with collagen, elastin, and reticular fibers. The dermis is supplied with nerve fibers, blood vessels, and lymphatic vessels. Included in the dermis are hair follicles, as well as oil and sweat glands but are made from epidermal tissue.

Collagen fibers have enormous tensile strength and provide the skin with strength and toughness. Their bundles are small in the upper or papillary dermis, and form thicker bundles in the deeper or reticular dermis.
Elastin is a type of fiber that provides the properties of elasticity to the skin.


  • Mast cells: These contain granules packed with different chemicals, released when the cell is disturbed.
MAST CELLS HE 40.JPG

  • Vascular smooth muscle cells: These allow blood vessels to contract and dilate, required to control body temperature.



  • Specialized muscle cells: myoepithelial cells are found around sweat glands and contract to secrete sweat.


  • Fibroblasts. These are cells that produce and deposit collagen and other elements of the dermis as required for growth or to repair wounds.


  • Immune cells. The function of tissue macrophages is to remove and digest bad material known as phagocytosis.



Fingerprints info

Definition: A fingerprint is an impression of the friction ridges on all parts of the finger.


A friction ridge is a raised portion of the epidermis on the palm or fingers and toes. These epidermal ridges serve to amplify vibrations when fingertips brush across an uneven surface. It sends signals to the brain back to sensory nerves. Fingerprints are classified by general shape, (arch, loop, or whorl) position within the finger, and relative size. Fingerprints begin forming during the 12th week of gestation, and cannot repair itself back to the way it was.

Arch Whorl Loop
Arch.gif whorl-189x197-1.jpg Loop_2A-167x202.jpg

There are two methods of classifying fingerprints:

1. Henry Classification

2. NCIC Classification


Fingerprinting gives investigators a practically flawless means of nailing murders, thieves and law abusers. Latent fingerprints are not visible to the naked eye and therefore can be found anywhere in the crime scene without the criminal even realizing it.
























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tissue, a small amount of adipose, hair follicles, nerves, and oil. "integumentary system." Augusta Technical College. N.p., n.d. Web. 22 Oct. 2012. <http://www.augustatech.edu/anatomy/chapter5.html>.