Integumentary System Ch 6 Notes (Part 2 Dermis)

What pigments are associated with brownish-black hair?

eumelanin

What is sebum?

helps keep hair and skin soft, pliable and waterproof.

What pigments are associated with albino hair?

none - this type of hair has no pigments (has no melanin).

What pigments are associated with reddish-yellow hair?

pheomelanin

What are eccrine glands?

A type of sweat gland, they respond throughout life to body temperature elevated by environmental heat or physical exercise. They produce profuse sweat on forehead, neck, and back.

What are sweat glands and what do they do?

Also called sudoriferous glands, they are exocrine glands that are widespread in the skin. Each gland consists of a tiny tube that originates as a ball-shaped coil in the deeper dermis or superficial subcutaneous layer. The coiled portion of the gland is closed at its deep end and is lined with sweat-secreting epithelial cells. In short, sweat glands secrete sweat!

What layer of the skin is the hair follicle made of?

Extends from the surface into the dermis and contains the hair root.

How are tattoos made and how are they removed? Why do they not disappear?

Tattoos are created by very fine needles injecting ink into the DERMIS (not epidermis). Dermis cells DON'T SHED, so that is why tattoos don't slough off and disappear (like epidermis cells do).

What is hair?

a derivative of the epidermis (created by multiplication of cells at the follicle base which grow downward into dermis thus creating papilla cells which then push upward and become keratinized). consists of two distinct parts: the follicle and the hair shaft. The follicle is the essential unit for the generation of hair. The hair shaft consists of a cortex and cuticle cells, and a medulla for some types of hairs.

What are apocrine glands and how are they different than eccrine glands?

Another type of sweat gland, these glands, become active at puberty. They differ from eccrine glands in that they secrete when a person is emotionally upset, frightened, in pain or sexually aroused. They are mostly in axillary regions and groin, and their ducts open into hair follicles. The gland secretions smell as they are metabolized by skin bacteria.

What is the name and role of smooth muscle in the dermis?

Arrector pili muscle

How does the skin play a role in a negative feedback loop? Describe the steps of the negative feedback loop.

Background: Heat is a product of cellular metabolism; the more active cells of body are the major heat producers. These cells include skeletal and cardiac muscle cells and certain gland cells such as the liver. Negative Feedback Loop (when body overheated): As body temp rises (like from physical exercise), nerve impulses tell skin and other organs to release heat. Blood carries that heat away. The warmed blood reaches the hypothalamus that controls the body's temperature set point, tells dermal blood vessels to relax/dilate. As the vessels dilate, more blood enters them and some of the heat the blood carries escapes to the outside. At the same time that the skin loses heat, the nervous system stimulates the eccrine sweat glands to become active and to release sweat onto the skin surface. As this fluid evaporates (going from liquid to gas), it carries heat away from the surface, cooling the skin further. Negative Feedback Loop (when body underheated): If too much heat is lost and body temp drops (like in cold environment), the brain triggers different responses in the skin structures. Muscles in the walls of dermal blood vessels are stimulated to contract; this decreases the flow of heat-carrying blood through the skin and helps reduce heat loss. Also, the sweat glands remain inactive, decreasing heat loss by evaporation. If body temperature continues to drop , the nervous system may stimulate muscle fibers in the skeletal muscles throughout the day to contract slightly. This action requires an increase in the rate of cellular respiration and produces heat as a by-product. If this response does not raise body temperature to normal, small groups of muscles may contract rhythmically with greater force, and the person begins to shiver, generating more heat.

Explain how bed sores or pressure ulcers are formed. Include a picture to help explain.

Bed sores occur when blood flow to the epidermis is blocked, killing the epidermal cells. The tissue breaks down (necrosis) and a pressure ulcer (bedsore) appears.

What factors affect fingerprints?

Fingerprints are made from epidermal ridges between epidermis and dermis where conical projections of dermis (dermal papillae) extend into. Fingerprints are made from these undulations of the skin. Genes determine the pattern but ultimately the pattern can change slightly when fetus presses against uterine wall. So identical twins don't have identical fingerprints.

What layer of the skin does the hair follicle tap into for nutrients?

From dermal blood vessels in a projection of connective tissue at the deep end of the follicle.

What determines hair color?

Genes -- by directing the type and amount of pigment that epidermal melanocytes produce.

What's a hair follicle?

Group of epidermal cells at the base of a tubelike depression.

What accessory structures are found in the dermis?

The dermis contains accessory structures including hair follicles, sebaceous (oil-producing) glands, and sweat glands.

What are the three parts of a nail?

Nail Plate (overlies surface of nail bed) Nail Bed (surface of skin at tips of fingers/toes; made of specialized epithelial cells) Lunula (whitish/thickened half-moon area on base nail plate; covers most actively growing area)

What is the difference between nerve cell processes that are called motor processes vs. sensory processes?

Sensory processes carry impulses away from specialized sensory receptors (i.e. touch receptors in the dermis) to the brain or spinal cord. Motor processes carry impulses OUT from the brain or spinal cord to dermal muscles and glands.

What is a sebaceous gland and what does it do?

contains groups of specialized epithelial cells and is usually associated with hair follicles. They are holocrine glands that secrete an oily mixture of fatty material and cellular debris called sebum through small ducts in the hair follicles.