Module 5
Descriptive word stems
- Blasts: create the matrix (ex: osteoblast builds bone )- Cytes: maintain the matrix of a mature cell (ex: chondrocyte maintain cartilage cell - it is a mature cartilage cell)- Clasts: break the matrix down for remodeling (ex: osteoclasts break down bone)
Heat exchange in the skin page 156
1) Blood vessel dilation results in increased blood flow toward the surface of the skin. 2) Increased blood flow beneath the epidermis results in increased heat loss (gold arrows). 3) Blood vessel constriction results in decreased blood flow toward the surface of the skin. 4) Decreased blood flow beneath the epidermis results in decreased heat loss.
Page 133 inflammatory response
1) Chemical mediators released: A splinter in the skin causes damage and introduces bacteria. Chemical mediators of inflammation are released or activated in injured tissues and adjacent blood vessels. Some blood vessels rupture, causing bleeding. 2) Tissue swelling: Chemical mediators cause capillaries to dilate and the skin to become red. Chemical mediators also increase capillary permeability, and fluid leaves the capillaries, producing swelling (arrows). 3) Recruitment of immune cells: White blood cells (e.g., neutrophils) leave the dilated blood vessels and move to the site of bacterial infection, where they begin to phagocytize bacteria and other debris.
Tissue repair page 134
1) Clot forms: Fresh wound cuts through the epithelium (epidermis) and underlying connective tissue (dermis), and a clot forms. 2) Epithelial cells grow into wound: Approximately 1 week after the injury, a scab is present, and epithelium (new epidermis) is growing into the wound. 3) Formation of granulation tissue: Approximately 2 weeks after the injury, the epithelium has grown completely into the wound, and fibroblasts have formed granulation tissue. 4) Formation of connective tissue scar: Approximately 1 month after the injury, the wound has completely closed, the scab has been sloughed, and the granulation tissue is being replaced by new connective tissue
Figure 5.4 Melanin transfer to keratinocytes (pg 146)
1) Melanosomes are produced by the Golgi apparatus of the melanocyte. 2) Melanosomes move into melanocyte cell processes. 3) Epithelial cells phagocytize the tips of the melanocyte cell processes. 4) The melanosomes, which were produced inside the melanocytes, have been transferred to epithelial cells and are now inside them.
Figure 5.3 epidermal layers and keratinization Page 146
5) Stratum Corneum : In the stratum corneum, the dead cells have a hard protein envelope, contain keratin, and are surrounded by lipids. 4) Stratum Lucidum : In the stratum lucidum, the cells are dead and contain dispersed keratohyalin. 3) Stratum Granulosum : In the stratum granulosum, keratohyalin granules accumulate, and a hard protein envelope forms beneath the plasma membrane; lamellar bodies release lipids; cells die. 2) Stratum Spinosum : In the stratum spinosum, keratin fibers and lamellar bodies accumulate. 1) Stratum Basale : In the stratum basale, cells divide by mitosis, and some of the newly formed cells become the cells of the more superficial strata.
Figure 5.6 cleavage lines page 149
An incision made across cleavage lines can gap, increasing the time needed for healing and resulting in increased scar tissue formation. An incision made parallel to cleavage lines results in less gapping, faster healing, and less scar tissue. The orientation of collagen fibers produces cleavage lines, or tension lines, in the skin.
Regulation of body temperaure
An increase in body temperature causes the blood to become warmer, warmer blood stimulates receptors in the brain (the hypothalamus) - then the hypothalamus will stimulate the dermal blood vessels to dilate and the sweat glands to secrete
Subcutaneous tissue
Deep to skin Consists of loose connective tissue with collagen and elastic fibers Cells of the subcutaneous tissue: Fibroblasts, adipose tissue, macrophages The subcutaneous tissue is also called the hypodermis or the superficial fascia (fascia means connective tissue) This layer contains about one half of the body's adipose tissue - this adipose tissue functions as an energy source, insulation, padding
Vitamin D production
Begins in skin; aids in Ca2+ absorption. Vitamin D (calcitriol): hormone. Stimulates uptake of Ca2+ and PO42- from intestines Promotes Ca2+ and PO42- release from bones Reduces Ca2+ loss from kidneys. Increases blood Ca2+ levels. Functions of Ca2+: bone formation, growth, repair clotting nerve and muscle function. 7-dehydrocholesterol converts to cholecalciferol when exposed to UV radiation. Cholecalciferol released to blood and modified in the liver and kidneys to form calcitriol (the active vitamin D). People in cold climates and those who cover the body can be deficient, but calcitriol can be absorbed through intestinal wall. Sources: dairy, liver, egg yolks, supplements.
Skin color
Blood circulating through the skin Imparts a reddish hue which is increased during inflammation Skin looks redder after exercise because the blood is brought to superficial muscles Cyanosis: blue color caused by decrease in blood oxygen content - it is less red so it appears blueish
Burns
Burns involved inflicting damage to different layers of the skin First degree is the mildest - then second degree then third degree First degree burns involves the epidermis Second degree burn goes down into the dermis - the dermis is there to hold things - so when you damage the dermis you will likely produce blisters - because the matrix and fluid of the dermis was damaged and leaves which forms a blister - takes longer to recover Third degree burns - aka full thickness burn - the burn reaches the subcutaneous tissue - if you have a full thickness burn you lose a major layer of protection and it is very difficult to treat - high risk of dehydration
Cleavage (tension) lines and striae
Cleavage (tension) lines: elastic and collagen fibers oriented in some directions more than in others Important in surgery If incision is parallel to lines, there is less gapping, faster healing, less scar tissue If skin is overstretched, striae (stretch marks) occur - these are collagen fibers that have been stretched beyond their ability to come back IF you go against the fibers there is a lot of tension in the incision which will cause the wound to heal slower
Glands of the skin page 152
Duct of apocrine sweat gland Hair follicle Hair bulb Apocrine sweat gland Duct of eccrine sweat glands Sweat pores Sebaceous gland Arrector pili (smooth muscle) Eccrine sweat gland
Hair color
Hair color is caused by varying amounts, types of melanin Melanin can be black-brown or red Due primarily to melanin which is formed in the hair bulb Hair pigments produce the varying shades of color Dark hair (black-brown shades) are produced by eumelanin Light hair (blonde-red shades) are produced by Pheomelanin Color variations result from differing concentrations Graying hair is caused by decrease of pigment cause by an inability of melanocytes to produce melanin White hair results from the leakage of air into the hair shaft Red hair is produced as a result of the iron containing pigment trichosiderin (an amino acid?)
Table 5.1 page 144 in txt (165 pdf)
Epidermis - Superficial part of skin; stratified squamous epithelium; composed of four or five strata - Prevents water loss and the entry of chemicals and microorganisms; protects against abrasion and harmful effects of ultraviolet light; produces vitamin D; gives rise to hair, nails, and glands Stratum corneum - Most superficial stratum of the epidermis; 25 or more layers of dead squamous cells - Provides structural strength due to keratin within cells; prevents water loss due to lipids surrounding cells; sloughing off of most superficial cells resists abrasion Stratum lucidum - Three to five layers of dead cells; appears transparent; present in thick skin, absent in most thin skin - Disperses keratohyalin around keratin fibers Stratum granulosum - Two to five layers of flattened, diamond-shaped cells - Produces keratohyalin granules; lamellar bodies release lipids from cells; cells die Stratum spinosum A total of 8-10 layers of many-sided cells Produces keratin fibers; lamellar bodies form inside keratinocytes Stratum basale - Deepest stratum of the epidermis; single layer of cuboidal or columnar cells; basement membrane of the epidermis attaches to the dermis - Produces cells of the most superficial strata; melanocytes produce and contribute melanin, which protects against ultraviolet light Dermis - Deep part of skin; connective tissue composed of two layers - Is responsible for the structural strength and flexibility of the skin; the epidermis exchanges gases, nutrients, and waste products with blood vessels in the dermis Papillary layer - Papillae project toward the epidermis; loose connective tissue - Brings blood vessels close to the epidermis; dermal papillae form fingerprints and footprints Reticular layer - Mat of collagen and elastic fibers; dense irregular connective tissue - Is the main fibrous layer of the dermis; strong in many directions; forms cleavage lines Subcutaneous tissue - Not part of the skin; loose connective tissue with abundant deposits of adipose tissue - Attaches the dermis to underlying structures; adipose tissue provides energy storage, insulation, and padding; blood vessels and nerves from the subcutaneous tissue supply the dermis
Figure 5.2 Dermis and epidermis page 145
Epidermis Dermal papilla Epidermis Papillary layer of dermis Papilla Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Dermal papilla extending into the epidermis
Nail page 154
Free edge Nail body Nail groove Nail fold Lunula Cuticle Nail root Nail fold Nail body Nail groove Epidermis Bone Bone Nail root (under the skin) Cuticle Nail body Nail bed Free edge Epidermis Hyponychium Nail Matrix
Dermis
Giver structural strength - it is connective tissue with many fibers, fibroblasts, and macrophages - some adipocytes and blood vessels Important things are in the dermis because it has the strength Contains nerves, blood vessels, hair follicles, smooth muscles, glands, and lymphatic vessels Sensory functions: pain, itch, tickle, temperature, touch, pressure, two-point discrimination The ends of the nerve can be in the epithelial tissue but the body of the nerve will be in the connective tissue layer
Hair structure
Hair follicle Dermal root sheath: part of the dermis that surrounds the epithelial root sheath (sheath=covering) Epithelial root sheath with internal and external parts: - Internal part contains stratum basale that may remain after injury and supply source of new epidermis - When hair is pulled out, the internal part comes out and is visible as a white bulb Hair bulb Internal matrix is the source of hair Dermis projects into bulb and is the blood supply Hair grows from the epidermis into the dermis Sebum is the fluid that makes hair pliable
Hair structure : hair growth
Hair growth occurs in cycles There are growth and resting stages Growth: Growth will happen at the base of the follicle - cells are added at the base and hair elongates - the average rate is .3mm/day Rest: The hair is not actively growing, it is being held in place - Follicle shortens and holds hair in place - rest, then hair falls our of follicle and new hair begins Regular hair loss means that hair is being replaced (because hair growth begins underneath a old hair follicle) Permanent hair loss: pattern baldness most common cause Muscles: Arrector pili - a type of smooth muscle - Muscle contraction causes hair to "stand on end" - Skin pushed up by movement of hair follicle
Page 151 hair follicle
Hair shaft (above skin surface) Hair root (below skin surface) Hair bulb (base of hair root) Artery Vein Adipose tissue Medulla Cortex Cuticle Arrector pili (smooth muscle) Sebaceous gland Dermal root sheath External epithelial root sheath Internal epithelial root sheath Matrix Hair papilla Hair follicle Hair
Sebaceous Glands
Holocrine type gland (death of secretory cells) Oily secretion Prevents drying and may inhibit bacteria Most of the sebum is secreted into a hair follicle Exceptions: lip, meilbomain glands of eyelids, genitalia
Rule of 9s page 157
In an adult, surface areas can be estimated using the rule of nines: Each major area of the body is 9%, or a multiple of 9%, of the total body surface area. (b) In infants and children, the head represents a larger proportion of surface area, so the rule of nines is not as accurate, as can be seen in this depiction of a 5-year-old child Head 15% Upper limb 9% Trunk 16% (front or back) Genitalia 1% Lower limb 17% Head 9% Upper limb 9% Trunk 18% (front or back) Genitalia 1% Lower limb 18%
Epidermal cells - Cell types
Keratinocytes: most cells - they produce keratin for strength - keratin is a protein that spreads out in the cell and gives it strength Melanocytes: melanin cell - contribute to skin color - melanin is produced by these cells and then transferred to keratinocytes - all people have the same number of melanocytes Merkel's cells: they are a nervous cell - they are there to detect light touch and superficial pressure Desquamate cells: cells of the deeper layers undergo mitosis, as they move toward the surface older cells slough off Keratinization involves keratinocytes: it is the process that as cells move outward through the layers they fill with keratin, die, and serve as a layer that resists abrasion and forms a permeability layer - Keratin helps repel water - as the cell is filled with keratin more and more it interferes with the cells metabolic abilities which is ultimately why the cells die
Hair types
Lanugo hairs (lana means wool): Fifth or sixth month or fetal development - the fine hair that covers the fetus and is usually shed prior to birth - helps with conserving body heat of the fetus Vallus hair (fleece): IT replaces Laungo hair - a colorless, small hair covering almost the entire body Terminal hairs - clearly visible hair - course visible hair seen on eyebrows, scalp, eyelashes, and after puberty in axillary and genital regions and facial area of the male
Responds to tissue damage or with an immune reponse
Manifestations: Redness, heat, swelling, pain, and disturbed function Chemical mediators include histamine and prostaglandins - stimulate pain receptor and increase blood vessel permeability as well as movement of white blood cells to the affected area
Page 151 hair follicle 2
Medulla Cortex Cuticle Hair Dermal root sheath External epithelial root sheath Internal epithelial root sheath Melanocyte Stratum basale Basement membrane Hair Hair follicle Hair Papilla Matrix (growth zone)
Skin color - melanin
Melanin is produced by melanocytes Melanocytes have processes that reach up and around other cells - these are used to distribute melanin to cells in the deep layer of the tissue The cells with melanin in them appear darker when they reach the surface
Pigments of epidermis
Melanin: provides protection against UV light Group of chemicals derived from amino acid tyrosine - colored brown to black and maybe yellowish or reddish Melanocytes: cells that produce melanin - processes extend between keratinocytes Albinism: deficiency or absence of pigment - Production determined by genetics, hormones, and exposure to light Carotene: Yellow pigment - from vegetables - Accumulates in stratum corneum, in adipose cells of dermis and in subcutaneous tissue (found in carrots and squash)
Nails
Nail body: stratum corneum - the nail is a downgrowth into the epidermis Cuticle or Eponychium is corneum superficial to nail body Hyponychium is the corneum beneath the free edge Matrix and the nail bed: cells that give rise to the nail Nail root: extends underneath the surfce Growth: Grows continuously unlike hair - Fingernails grow .5-1.2 mm/day; faster than toenails
Sebum
PLays an important role in keeping the hair supple
Two layers of the dermis
Papillary: Superficial 1/5 (outer layer) - Areolar connective tissue with lots of elastic fibers - dermal papillae, capillary beds - Fingerprints - whorls of ridges - touch receptors (Meissner's), free nerve endings sense pain - Areolar means loose, this layer is more fluid Reticular: Deep 4/5 (inner layer) - dense irregular connective tissue - collagen and elastic fibers - some adipose, hair follicles, nerves, oil glands, ducts of sweat glands, and heat sensors
Physiology of the integumentary system: sensation
Sensation: Pressure, temperature, pain, heat, cold, touch, movement of hair Temperature regulation: sweating and radiation - sweat causes evaporative cooling - arterioles in the dermis change diameter as temperature changes causing more or less blood to flow through the dermis (dilate to get rid of heat and constrict to keep heat)
Skin repair
Primary union: edges of wound are close together - wound fills with blood - clot forms: fibrin threads start to contract and pull edges together - scab - inflammatory response; pus forms as white blood cells die - granulation tissue replaces clot, delicate connective tissue composed of fibroblasts, collagen fibers, capillaries - Scar: formed from granulation tissue; tissue turns from red to white as capillaries are forced out Secondary union: edge of wounds are not closed; greater chance of infection - clot may not close the gap - inflammatory response is greater - wound contraction occurs leading to greater scarring
Physiology of the integumentary system
Protection Against abrasion, sloughing off of bacteria as desquamation occurs - when you wash your hands you are washing off the outer layer of cells as well as the dirt Against microorganisms and other foreign substances. Glandular secretions bacteriostatic and skin contains cells of the immune system. Melanin against UV radiation Hair on head is insulator and protection against light, and from abrasion - Eyebrows keep sweat out of the eyes; eyelashes protect eyes from foreign objects. Hair in nose and ear against dust, bugs, etc. Nails protect ends of digits, self defense Acts as barrier to diffusion of water
Body heat is lost due to
Radiation: heat moves from warm area to cooler surrounding area Conduction: heat moves from warmer area to colder object by touch Convection: air moving over or around a warmer area becomes warmer and takes that warmth away Evaporation: involves water molecules changing from a liquid to a gas and moving away from the warmer area - this is what happens when you sweat - works better on a dry day than a humid day
Excretion of the integumentary system
Removal of waste products from the body Sweat is made of water, salt, urea, ammonia, and uric acid Its excretion is insignificant when compared to the kidneys
page 143 in txt
Sebaceous gland Arrector pili (smooth muscle) Hair follicle Vein Artery Adipose tissue Nerve Sweat gland Epidermis Skin Dermis Subcutaneous tissue (hypodermis) Hairs
Skin - the skin can also be called the cutis (or cutus)
Skin is made up of two layers: epidermis and dermis Epidermis is the superficial layer of epithelial tissue Dermis is the deep layer of connective tissue - important for structural strength Subcutaneous tissue is underneath the dermis - it is not part of the skin - it is loose connective tissue that connects skin to underlying structures
Mammary glands: modified apocrine sweat glands
Stimulated by estrogen
Epidermal strata - multiple layers from bottom to top
Stratum basale (aka germinitivum): deepest portion of the epidermis and it is a single layer - high metabolic activity and cells become keratinized - associated with the basement membrane - reproduction is high Stratum spinosum (spiny layer): Limited cell division - desmosomes - lamellar bodies and additional keratin fibers (keratin is extending into fibers) - when you look at this layer in a microscope the cells kind of look spiny Stratum granulosum (granular layer): contains keratohyalin - in superficial layers the nucleus and other organelles degenerate and die - when you look at this layer under a microscope these cells look grainy (look like a bunch of dots in the cell) - death finally begins to occur in this layer Stratum lucidum: Thin, clear zone - found only in palms and soles - This layer only occurs in two areas of the body (palms of hands and soles of feet) - so this layer allows these two layers to be the thickest areas of epidermis - a "clear" layer Stratum corneum (corny layer): Most superficial layer - consists of cornified dead cells
Overview of Functions of the integumentary system
Structures: Skin, hair, nails, and glands Functions: Protection (skin is the first line of protection), Sensation (nerve endings - in the connective tissue), Temperature regulation (sweat glands), Vitamin D production (the catalyst of this process is the sun hitting the skin), Excretion (perspiration), Immunity (ability to protect against foreign substances)
Skin color is determined by
The amount of blood, pigments, oxygenation level of the blood 3 factors: pigments (dark pigment) , blood circulating through the skin (red color), and thickness of the stratum corneum
Pigment facts
The amount of melanin produced can result in skin color from pale yellow to black The number of melanocytes is 1000-2000 per mm^2 does not vary among races - all people have the same number of melanocytes - but there are genetic differences in peoples ability to produce melanin by the melanocytes that results in different skin colors (genetic differences in melanin production results in different skin colors) - how active are the melanocytes An inherited inability to produce melanin results in a condition called Albinism where the pigment is absent in hair, eyes, and skin - the eyes of the individual will appear pink - people with this condition are called albinos
Epidermis is epithelial tissue (particularly stratified squamous tissue)
The epidermis is avascular - meaning it does not have blood vessels - it is nourished by diffusion from capillaries of the papillary layer of the dermis - there are no capillaries in the epidermis The epidermis is composed of cells arranged into layers or strata Separated from dermis by the basement membrane - the basement membrane is an "avascular glue"
Accessory skin structures: hair
The hair follicle is mainly supported by the dermis Hair is found everywhere on the human body except the palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes Shaft protrudes above skin surface The root is located below the surface - base of root is the hair bulb The hair has 3 concentric layers: - Medulla (central axis) - Cortex (forms bulk of hair) - Cuticle (forms hair surface) Downgrowth of the epidermis - the hair follicle is a downgrowth of the epithelium
The integumentary system is not just the skin
The skin consists of the dermis and epidermis Everything below the skin is the subcutaneous region There are nerves and glands and muscles also involved in the integumentary system
Effects of aging
The skin is more easily damaged because the epidermis thins and the amount of collagen decreases Skin infections are more likely because there is more space in the skin Wrinkling occurs due to decrease in elastic fibers - as the papillary regions start to weaken the epidermis start to fall into the dermis Decrease blood supply causes poor ability to regulate body temperature Functioning melanocytes decrease or increase causing age spots - some dark pigmented and some light pigmented areas Sunlight ages skin more rapidly
Epidermal Ridges and Grooves
The skin of the hands and feet are marked by a series of ridges and grooves They are produced by the dermal papillae which push up the epidermis Can be on the palms, fingers, soles, and toes Unique to each individual - they reflect the arrangement of the papillae Ducts of sweat glands open on the ridges and "fingerprints" are left when a smooth object is touched Functionally these ridges increase the grip of the hand and foot by increasing friction
Ceruminous glands: modified merocrine sweat glands, external auditory meatus
These glands make wax Earwax (cerumen) composed of a combination of sebum and secretion from ceruminous Function - in combination with hairs, it prevents dirt and insects from entering the ears - also keeps eardrum supple
Thick and thin skin
Thick skin: - has all 5 epithelial strata - Thick skin will be found in areas subject to pressure or friction - palms of hands, fingertips, soles of feet - fingerprints and footprints are the Papillae of underlying dermis in parallel rows; the function of the ridges serve to increase friction; it is easier to grasp things Thin skin: - more flexible than thick skin - covers the majority of the body - hair grows on areas of thin skin Callus is an increase in the number of layers of stratum corneum; when this occurs over bony prominence a corn forms
Sweat glands aka sudoriferous glands
Two types traditionally called apocrine and merocrine glands, but apocrine may secrete in a merocrine or holocrine fashion Merocrine or eccrine are the most common: - simple coiled tubular glands - opens directly onto the surface of the skin - have own pores - the coiled part is in the dermis, duct exiting through the epidermis - Produce isotonic fluid (water and NaCl but also excretory because sweat includes ammonia, urea, uric acid and lactic acid) - As fluid moves through a duct NaCl is moved by active transport back into the body - final product is hypoosmotic (hypertonic) = sweat - numerous in palms and soles - absent from margin of lips, labia, minora, tips of penis, clitoris) Apocrine sweat glands: - active at puberty - compound coiled tubular, usually open into hair follicles - Secretion = organic compounds that are odorless but when acted upon by bacteria it may become odiferous (smells) - Found in axillae, genitalia (external labia, scrotum), around anus
Papillary region in the skin
Up and down (nipple shape) barrier between the dermis and epidermis - it is not a straight barrier
Rule of nines
Used to estimate the amount of body that is burned - different proportions for adults and children Each area of the body is given a specific percentage Uses percentages to give an idea of the degree or percentage of damage
Skin grafts
Used with third degrees Split skin Artificial skin
The dermis carries the vascularization for the epidermis and the
dermis
