Chapter 5 - The Integumentary System Flashcards
Which layer of skin is the outermost protective shield of the body?
the epidermis
What is the epidermis composed of?
epithelial cells
What makes up the bulb of the skin?
dermis
What is dermis composed of?
It is a tough, leathery layer composed mostly of fibrous connective tissue
How much does your skin weight?
9-11 lbs
T or F. Only the epidermis is vascularized
False. Only the DERMIS is vascularized. Nutrients reach the epidermis by diffusing trough the tissue fluid from blood vessels in the dermis.
What is the function of the hypodermis? (aka superficial fascia)
Besides storing fat (adipose tissue) it anchors the skin to the underlying structures. It is technically not part of the skin but shares it’s protective functions. It thickens markedly when a person gains weight!!
Structurally, _____ is a keratinized stratified squamous epithelium consisting of 4 distinct cell types and 4 or 5 distinct layers.
epidermis
Name the 4 types of cells populating the epidermis.
KMDT
Keratinocytes
Melanocytes
Dendritic cells
Tactile Cells
What fibrous protein helps give epidermis its protective properties?
keratin
Most epidermal cells are what type?
Keratinocytes. Their chief role is to produce keratin.
Keratinocytes arise from the deepest part of the epidermis from a cell layer called?
Stratum basale
T or F. By the time keratinocytes reach the skins surface they are dead.
T
Found in the deepest layer of the epidermis and synthesize the pigment melanin. Spider shaped.
Melanocytes
As melanin’s made, it accumulates in membrane-bound granules called?
melanosomes. These melanin granules accumulate on the superficial or “sunny” side of the keratinocyte nucleus forming a pigment shield that protects the nucleus from damaging effects of UV radiation
Star shaped cells who arise from bone marrow and migrate to the epidermis.
Dendritic cells. Aka Langerhans cells.
What do dendritic cells do?
they ingest foreign substances and are key activators of our immune system.
What type of cells are present at the epidermal-dermal junction and allow us to feel things through a dislike sensory nerve ending?
Tactile Cells. Aka Merkel cells.
Name the 5 layers (strata) of thick skin.
From deep to superficial: Stratum basal, Stratum spinosum, Stratum granulosum, Stratum lucidum and Stratum corneum.
Which of the 5 layers (strata) is missing in thin skin?
Stratum lucidum. And the other strata are thinner.
Where is the thickest skin in the body located?
upper back
The deepest epidermal layer, attached to the underlying dermis. Consists of a single layer of constantly renewing stem cells which represent the youngest keratinocytes.
Stratum basale (basal layer). Aka stratum germinativum (“germinating” layer)
10-25% of the cells in the stratum basal are?
melanocytes
The second epidermis layer is several cell layers thick and its cells are known as “prickle” cells that look like they have a spine. Keratinocytes, melanin granules and dendritic cells are abundant in this layer.
Stratum Spinosum
In this layer, the process of keratinization begins. (Cells fill with the protein keratin)
Stratum Granulosum (3rd strata)
As keratinocytes keratinize, they flatten and accumulate two types of granules. What are they and what do they do?
Keratohyaline granules help form keratin in the upper layers of the epidermis. Lamellar granules contain a water-resistant glycolipid and are a major factor in slowing water loss across the epidermis
Visible only in thick skin, this layer forms a translucent band just above the stratum granulosum. Consists of 2-3 rows of clear, flat, dead keratinocytes.
Stratum Lucidum
Outermost epidermal layer that accounts for 3/4 of the epidermal thickness. (20-30 cell layers thick)
Stratum Corneum.
Keratin and the thickened plasma membrane of its cells protect skin against abrasion and penetration, and the glycolipid bw its cells nearly waterproofs this layer.
The second major skin region, the dermis, is composed of what?
Strong, flexible connective tissue
Dermis cells are typical of those found in any connective tissue proper and include? (4)
Fibroblasts, macrophages, occasional mast cells and white blood cells
What 2 layers make up the dermis?
Papillary and reticular.
The thin superficial layer made up of areolar connective tissue in which fine interlacing collagen and elastic fibers form a loosely woven mat, heavily invested with small blood vessels makes up which later of the dermis?
the Papillary layer. This connective tissue is very loose and allows phagocytes and other defensive cells to wander around looking for bacteria
On the surface of the papillary layer are peg like projections that indent the overlying epidermis called?
Dermal papillae. These contain capillary loops or house free nerve endings and touch receptors called tactile or Meissner’s corpuscles.
The papillae lie atop large mounds and cause the overlying epidermis to form ______ _______. These are assumed to enhance the gripping ability of the fingers and feet like tire treads help grip the road.
Friction ridges. These patterns are unique to each of us. (identifying people with fingerprints)
The deeper layer of the dermis that accounts for about 80% of the thickness?
Reticular layer
What is the reticular layer composed of?
Course, irregularly arranged, dense fibrous connective tissue.
The network of blood vessels that nourished the dermis and lies between it and the hypodermic is called?
Cutaneous plexus
What Within the reticular layer are externally invisible lines important to surgeons and why?
Cleavage lines. If an incision is made parallel to these lines the skin gapes less and heals more rapidly.
The deep creases on our palms, wrists, fingers, soles and toes are called ___? What’s their purpose?
Flexure lines. Since the skin cannot slide easily to accommodate joint movement in such regions, the dermis folds and deep skin creases form.
What 3 pigments contribute to skin color?
melanin, carotene and hemoglobin
What is the only pigment MADE in the skin?
melanin
What is melanin and what it it made of?
It is a polymer man of tyrosine amino acids.
Melanin has two forms and they range in color from ____ to ____?
reddish yellow to brownish black.
When we expose our skin to sunlight, keratinocytes secrete chemicals that stimulate melanocytes. What does this in turn do?
Prolonged sun exposure causes substantial melanin buildup, which helps protect the DNA of viable skin cells from UV radiation by absorbing the rays and dissipating the energy as heat. By the melanin synthesis speeding up, there seems to be a faster repair rate of DNA that has suffered photo damage and tanning occurs.
The yellowish tinge of Asian people can be attributed to?
Carotene (yellow to orange pigment found in some plant products such as carrots)
Explain the pinkish hue of fair skinned people.
Caucasian skin contains only small amounts of melanin. The epidermis is nearly transparent allowing hemoglobin, the red blood cells circulating through dermal capillaries, to show through.
When hemoglobin is portly oxygenated, both the blood and skin of Caucasians appear blue. This condition is called?
Cyanosis. Happens during heart failure and severe respiratory disorders. In dark skinned persons, look at their mucous membranes and nail beds (sites where the red cast of oxygenated blood is normally visible)
Red skin may indicate? (5)
Embarrassment (blushing), fever, hypertension, inflammation or allergy.
Pallor or blanching may indicate?
Fear, anger or other emotional stress. Pale can also signify anemia or low blood pressure.
Jaundice or yellow cast may indicate?
Liver disorder. Yellow bile pigments accumulate in the blood and are deposited in body tissues. Liver cells secrete bile pigments called BILIRUBIN.
What does bronzing of the skin indicate (bronzing or metallic appearance)?
Addison’s disease. The adrenal cortex produces inadequate amounts of its steroid hormones; also a sign of pituitary gland tumors
What happens when you get a bruise?
blood escapes from the circulation and gets clotted beneath the skin. These clotted blood masses are called hematomas or “blood swelling”
Name the 5 “skin appendages” that all play a unique role in maintaining body homeostasis
hair, hair follicles, nails, sweat glands, sebaceous glands
Main purpose of our hair?
to sense insects before they bite us. On our head to guard against physical trauma, heat loss and sunlight. (pity the bald man)
How does the hard keratin of hairs (pili) and nails differ from the soft keratin of skin?
It is tougher and more durable and its individual cells do not flake off
The body hair of children and adult females is called?
vellus hair
The coarser, longer hair of the eyebrows and scalp is called?
terminal hair
Excessive hairiness as a result of an adrenal glam or ovarian tumor secreting large amounts of androgens is called?
hirsutism
