CH5: Integumentary System Flashcards
Functions of the integumentary system
Helps the body maintain its temperature
Converts inactive vitamin D to its active form
Provides sensory information
Helps maintain homeostasis in a number of ways
Stores blood
Absorbs and excretes substances
What parts of the body are included in the integumentary system and what is its function:
Has a wide variety of
skin, hair, oil and
sweat glands, nails, and sensory receptors
Structure of epidermis vs dermis
Epidermis consists of epithelial tissue and is avascular and is thinner, while dermis contains irregular connective tissue made of collagen and elastic fibers and is vascular
BOOYAKASHA
4 type of cells in epidermis
Keratinocytes: Most abundant (85%), produce keratin for tissue protection and lamellar granules produce waterproof sealant and preventing materials from leaving through the skin
Melanocytes: Produce melanin pigment, a yellow-red or brown-black pigment that contributes to skin color and absorbs damaging ultraviolet (UV) light.
Langerhans cell/Dendritic cells: Arise from red bone marrow and migrate to the epidermis, where they constitute about 5% of the epidermal cells. They participate in immune responses mounted against microbes that invade the skin, and are easily damaged by UV light. Their role in the immune response is to help other cells of the immune system recognize an invading microbe and destroy it.
Tactile epithelial cells (Merkel cell): Only about 2% of epidermal cells, They are located in the deepest layer of the epidermis, where they make contact with the flattened process of a sensory neuron (nerve cell), called a non encapsulated sensory corpuscle or Merkel disc. Tactile epithelial cells and their associated nonencapsulated sensory corpuscles detect touch sensations
Layers in thin and thick skin and their structure
The stratum basale: Deepest layer, composed of single row of cuboidal or columnar keratinocytes. Also contain melanocytes, and tactile epithelial cells. Cell divsion occurs most prominently here, and they move upwards..
The stratum spinosum: Eight to ten rows of many- sided keratinocytes with bundles of keratin intermediate filaments; contains projections of melanocytes and dendritic cells.
The stratum granulosum: Three to five rows of flattened keratinocytes, in which organelles are beginning to degenerate; cells contain the protein keratohyalin (converts keratin intermediate filaments into keratin) and lamellar granules (release lipid- rich, water-repellent secretion).
The stratum lucidum (only present in thick skin): Present only in skin of palms, palmar surfaces of digits, soles and plantar surfaces of toes. Consists of four to six rows of clear, flat dead keratinocytes with large amounts of keratin
The stratum corneum: Few to 50 or more rows of dead, flat keratinocytes that contain mostly keratin, that randomly/continuously slough off
They get samples at crime scenes from dead skin cells
Two constituents of the dermis
Papillary dermis: Superficial portion of dermis (about one- fifth); consists of areolar connective tissue with thin collagen and fine elastic fibers; contains dermal ridges that house blood capillaries, tactile corpuscles, and free nerve endings.
Reticular dermis: Deeper portion of dermis (about four- fifths); consists of dense irregular connective tissue with bundles of thick collagen and some coarse elastic fibers. Spaces between fibers contain some adipose cells, hair follicles, nerves, sebaceous glands, and sudoriferous glands
How melanocytes work
Melanocytes function in the stratum basale through organelles called melanosomes. Here, they synthesize melanin from the amino acid tyrosine, facilitated by the enzyme tyrosinase. UV ilight increases tyrosinase activity
What is albinism and what is vitiligo?
Albinism is the inherited inability to produce melanin,causing full or partial loss of pigment in the hair, skin and eye colour
Vitiligo is irregular patches of skin pigmentation that occurs due to some loss in melanocytes there, which occurs due to immune system malfunction, where antibodies begin attakcing melanocytes.
Describe the structure and function of hair
Function: hair on the head guards the scalp from injury and the sun’s rays. It also decreases heat loss from the scalp. Eyebrows and eyelashes protect the eyes from foreign particles, similar to the way hair in the nostrils and in the external acoustic meatus defends those structures. Touch receptors (hair root plexuses) associated with hair follicles are activated whenever a hair is moved even slightly. Thus, hairs also function in sensing light touch
Anatomy: Hair is composed of dead keratinized epidermal cells and extracellular protein
The shaft: above the skin surface
The follicle: Below the level of the skin. A sac or tube that surrounds the hair root, extending into the dermis.
The root: Penetrates into skin, with the epithelial root sheath and dermal root sheath
Describe the stages of hair growth
Growth stage: Cells of matrix divide added to the base of hair root. As new cells from the hair matrix are added to the base of the hair root, existing cells of the hair root are pushed upward and the hair grows longer
Regression stage: Hairmoves away from blood supply in papillary (part of hair system containing blood vessels) and follicle atrophies (no more growth)
Resting stage: – Old hair root falls out and new growth begins
After the resting stage, a new growth stage begins. Scalp hair is in the growth stage for 2 to 6 years, the regression stage for 2 to 3 weeks, and the resting stage for about 3 months. At any time, about 85% of scalp hairs are in the growth stage. Visible hair is dead, but until the hair is pushed out of its follicle by a new hair, portions of its root within the scalp are alive.
Differences in skin glands
Sebaceous (oil) glands are glands that secrete sebum, an which is a mixture of triglycerides, proteins, cholesterol and inorganic salts. This substance coats the surface of hairs and helps keep them from drying and becoming brittle. Sebum also prevents excessive evaporation of water from the skin, keeps the skin soft and pliable, and inhibits the growth of some (but not all) bacteria. Sebaceous glands become active during puberty, and are located in the dermis. These glands are absent in thick skin but common in the penis, vaginal areas, face and neck.
Sudoriferous glands are sweat glands, which are divided into two types: apocrine and eccrine
Eccrine glands are more common, found in the forehead, palms and soles. Secretion occurs in the reticular dermis onto the epidermis and mainly water with contains small ions like NaCl, ammonia, urea, lactic acid, etc. This occurs to regulate body temperature, (thermoregulation) but is also onset by emotional stress.
Apocrine glands are less common and found in hairier areas, like the armpits, groins and beared areas of the face. They have the same secretion as eccrine glands plus lipids and proteins. Secretions occur in the lower part of the reticular dermis onto hair follicles, and occur during stress and sexual excitement. Onset during puberty
Ceruminous glands are modified sweat glands located in the ear canal, secreting in the subcutaneous tissue onto the surface of ear canal. They secrete cerumen, or earwax, which impede entrance of foreign bodies into the ear canal, waterproof ear canal and prevent microbes from entering cells. Onset soon after birth
Parts of nails
Free edge: Visible portion of nails (white part)
Nail bed/plate: Visible portion of nails (pink part)
Hyponychium: Junction of nail and skin at top of fingertip
Nail root: Part of nail encapsulated in fold of skin
Eponychium/Cuticle: Layer of epidermis which secures proximal end of nail to skin
Portion of epithelium proximal to nail root where divison of keratnocytes occurs
Functions of skin (6)
Thermoregulation: Skin is responsible for regulating the temperature of the body. Vasodilation increases the diameter of blood vessels to allow more heat to reach the surface while vasoconstriction does otherwise. Sweating also releases heat and lowers body temperature
Blood reservoir: The skin (mainly the dermis) can hold up to 8-10% of a body’s blood when at rest
Protection: Macromolecules synthesized by the skin help protect the body
- Keratin
- Lipids released by lamellar granules
- Sebum
- Acidic sweat
- Melanin
- Macrophages
Cutaneous sensations: Thermal receptors detect heat, tactile epithelial cells detect touch and pain receptors detect pain
Exretion and absorption of products, important for transdermal drug administration
Synthesis of vitmain D: Ultraviolet rays activate the precursor molecule(calcitriol) that allows vitamin D to be made
Vitamin D aids in the absorption of calcium from foods in the gastrointestinal tract (important for muscle contraction and bones)
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Phases of deep wound healing
Inflammatory phase: CLot forms
Migratory phase: CLot becomes scab
Proliferative phase: Epithelial cells begin to to regrow under scab
Maturation phase: Scab falls off when epidermis is restored
IM PaM
Age associated changes
Wrinkles: Fat in the deeper layers of your skin diminishes. This causes loose, saggy skin and more-pronounced lines and crevices
Dehydration and cracking
Sweat production decreases
The numbers of functional melanocytes decrease which results in gray hair and atypical skin pigmentation
Subcutaneous fat is lost and skin thickness decreases
Nails may become more brittle
