AP Lab Exam 2/3 (Written)

Four tissue classifications

Epithelial, connective, muscle (3 kinds: skeleton, smooth, cardiac), nervous

Epithelial tissue location

Lines body surfaces (inside and out), major tissue of glands (thyroid, etc.

Epithelial tissue characteristics

1. Polarity (apical (free) surface, basal surface, basement membrane)

2. Cellularity (lots of cells)

3. Specialized contacts (tight junctions, desmosomes)

4. Innervated

5. Avascular

6. High regenerative ability

Epithelial tissue functions

Protection, diffusion, excretion, secretion, absorption, filtration, sensory reception

Epithelial tissue classification criteria

1. Shape of cells at apical surface

2. # of layers

Endocrine gland

Secrete their products (hormones) into a body fluid (primarily blood)

Exocrine glands

“Duct” glands, secrete their products onto an external or internal body surface; Vary in shape, complexity, and method of secretion

Merocrine glands (exocrine gland)

Most numerous, secrete their products as the products are producted (Ex. Salivary glands)

Apocrine glands

Accumulate products at apex of cell which pinches off (Ex. mammary glands)

Holocrine glands

Accumulate products until they rupture (Ex. Sebaceous (oil) glands

Connective tissue location

Most widely distributed (found throughout the body)

Connective tissue characteristics

1. Common origin: arises from mesenchyme (embryonic tissue)

2. Degrees of vascularity: varies from richly vascularized (bone, areolar) to poorly vascularized (dense regular) to avascular (cartilage)

3. Comprised of a non-living and a living component

Connective tissue non-living component

Extracellular matrix

Connective tissue extracellular matrix

Comprised of the ground substance and fibers (secreted by the cells)

Connective tissue living component

Cells

Ground substance (connective tissue)

Nonliving, amorphous material, fills spaces and contains fibers. The consistency varies depending on the specific tissue

Collagen fiber (connective tissue)

Most abundant fiber type; composed of the protien collagen; arranged in bundles; provides great tensile strength; strongest fiber

Elastic fiber (connective tissue)

Comprised of the protein elastin; coiled structures; ability to stretch and recoil

Reticular fiber (connective tissue)

Comprised of the protein collagen; arranged in a delicate, branched network; weakest fiber

Cells of connective tissue

• Fibroblast → fibrocytes

• Chondroblast → chondrocyte

• Osteoblast → ostocyte

• Hemocytoblast (blood stem cell)

• mast cells

• macrophages

• leukytes (white blood cells)

Connective tissue functions

protection, binding, support, insulation, repairs tissue damage, energy storage, blood cell production, transport of materials, fills spaces

Simple squamous

• single layer of squamous cells

• Location: alveoli, lining of heart chambers, lining of blood vessels, kidney glomeruli, serosae (serious membranes)

• Function: diffusion, secretion, filtration

Stratified squamous

• multilayered, in which cells at apical layer are squamous

• Location: epidermis, lining of esophagus, lining of oral cavity, lining of vagina

• Function: protection (against abrasion)

Simple cuboidal

• Single layer of cuboidal cells

• Location: kidney tubules, ducts of glands, ovary surface

• Function: absorption, secretion

Simple columnar

• Single layer of columnar

• Location: lining of stomach, lining of small intestine, lining of large intestine, lining of gallbladder

• Function: absorption, secretion

Transitional

• Multilayered, in which cells at apical layer are dome shaped

• Location: lining of ureters, lining of bladder, lining of urethra

• Function: ability to distend

PSCCE (pseudostratified cilliated columnar epithelium)

• Single layer of columnar cells, in which the nuclei are not in alignment (thus gives the illusion of being stratified), cilia (tiny hairs) emanate from apical surface, also note goblet cells

• Location: lines trachea, lines most of the upper respiratory tract

• Function: movement of mucus via ciliary action, secretion

Areolar

• Gel-like matric, well-vascularized, all three fiber types present, cells include: fibroblasts, macrophages, mast cells, and leukocytes (white blood cells)

• Location: underlies lining epithelial, surrounds capillaries, surrounds organs

• Function: Conveys fluid, holds fluid, cushions organs, phagocytosis (because of macrophages and leukocytes), important in inflammation (because of mast cells)

Adipose

• Gel-like matrix, well-vascularized, many adipocytes (fat cells) - large cells containing fat with nucleus pushed to an edge of the cell

• Location: hypodermis, breasts, around heart, around kidneys, around eyeballs, in abdomen

• Function: protection, insulation, energy storage

Reticular

• Gel-like matrix, well-vascularized, contains reticular cells, contains reticular fibers

• Location: lymph nodes, spleen

• Function: body defense, provides an internal network that supports cells

Dense regular

• Dense with collagen fibers that run in the same direction, poorly vascularized, main cell type: fibroblasts

• Location: ligaments, tendons, aponeuroses (flat tendons)

• Function: Provides tensile strength in a single direction

Dense irregular

• Dense with collagen fibers thar run in different directions, well vascularized

• Location: dermis, submucosa of digestive tract, joint capsules

• Function: provides tensile strength in different directions

Elastic tissue

• Dense with elastic fibers, well-vascularized

• Location: wall of the aorta, wall of arteries, vocal cords

• Function: stretch and recoil

Hyaline cartilage

• Chondrocytes in lacunae, avascular, many collagen fibers, (but imperceptible), “glassy” appearance to matrix, most abundant cartilage type

• Location: tip of nose, articular cartilage, tracheal cartilages, epiphyseal plate, costal cartilages, embryonic skeleton

• Function: provides support, resiliency

Elastic cartilage

• Chondrocytes in lacunae, avascular, more elastic fibers than hyaline cartilage (also collagen fibers)

• Location: epiglottis, ear

• Function: structural support, flexibility

Fibrocartilage

• Alternating sequence of collagen fibers and chondrocytes in lacunae, avascular

• Location: intervertebral discs, menisci (knee), pubic symphysis

• Function: shock absorption (absorbs compressive shock)

Bone (compact)

• presence of osteons, osteocytes, trapped in lacunae, collagen fibers, mineralized (calcified), well-vascularized

• Location: bone

• Function: protection, structural support, movement, mineral storage, hematopoiesis, lipid storage

Blood

• Living cells (erythrocytes (red blood cells), leukocytes (white blood cells), and platelets) within non-living plasma

• Location: blood vessels, heart chambers

• Function: transport, body defense, blood clot formation

Skin

Epidermis (stratified squamous - keratinized) and dermis (connective tissue)

Hypodermis

Adipose and loose connective tissue (areolar), binds skin to underlying organs, not part of skin

Epidermis

Avascular, comprised of a keratinized stratified squamous epithelium

Keratinocytes

• Comprises most epidermal cells

• Produces keratin (fibrous protein that gives the epidermis its protective properties)

• Arise from the stratum basale where most of mitosis occurs

• As the cells age, they produce more keratin and deteriorating organelles are replaced with keratin

Stratum basale (with regards to keratinocytes)

Layer that receives nutrient and oxygen via diffusion from the dermal blood vessels. Layer grows and divides, pushing older cells farther away from the dermis and closer to the skin surface

How long does it take for a new epidermis to be formed

25-45 days

Melanocytes

• Specialized cells in the epidermis that produce melanin

• Located in the deeper epidermal layers and have branching processes (spider arms)

• Melanin is transported to the ends of these processes and then are taken up by keratinocytes

Melanin

Pigment that is responsible for skin color; Absorbs UV rays and thus helps protect the body from the damaging affects of UV rays. (Exposure to UV rays stimulates the production of more melanin)

Skin color

• Genetically determined; Due to melanin (people vary in the amount of melanin that they produce and kind of melanin); can be used to help determine someone’s health

Factors that affect skin coloration

Diet (carotene), physical factors

Cyanosis

Lack of oxygen

Jaundice

Accumulation of bilirubin

Langerhan cells

Macrophages that arise from the bone marrow and migrate to the epidermis. These cells function in body defense and help to activate the immune system

Merkel cells

• Present in small numbers at the epidermis (dermis junction)

• These cells are associated with sensory nerve endings (combination is called Merkel disc)

• Function as a sensory receptor for touch

Thick skin

• Soles of feet, palms of hands, fingertips

• Has 5 layers

Thin skin

• Has 4 layers (stratum lucidum is absent, other strata thinner)

• Have hair follicles

Stratum basale

• Deepest epidermal layer

• Single layer of cells firmly attached to the dermis (wavy boarder)

• Lots of mitotic division

• Keratinocytes, melanoxytes and Merkel cells are found here

Stratum spinosum

• Several rows of keratinocytes (referred to as prickle cells in this layer due to shape)(contain pre-keratin filaments)

• Melanin granules and Langerhans’ cells here

  • Langerhans’ cells are most abundant in this layer

Stratum granulosum

• 3-5 rows fo keratinocytes

• Cells flatten, organelles begin to disintegrate, accumulating keratohyaline granules (to form keratin) and lamellated granules (water-resistant glycolipid)

Stratum lucidum

• Only in thick skin areas

• Few layers of clear, dead cells

Stratum corneum

• 20-30 (3/4 of epidermis) rows of dead cells filled with keratin

Living cells in the epidermis

Stratum basale, stratum spinosum, stratum granulosum

Nonliving cells in the epidermis

Stratum lucidum, stratum corneum

Dermis

• Connective tissue that contains fiber, muscles, nerves, blood vessels, lymphatics, hair follicles, sebaceous glands, and sudoriferoud glands and elastic fibers

• Cells include fibroblasts, macrophages, white blood cells, and some mast cells

Fingerprints

Epidermal ridges, dermal papillae, and ridges

Papillary layer

• Top 20% of dermis

• Areolar connective tissue

• Dermal papillae: capillary loops, free nerve endings, Meissner’s corpuscles

Reticular layer

• Lower 80%

• Dense irregular connective tissue (collagen fibers provide strength and resiliency, helps skin to be kept hydrated; elastic fibers allow for stretch and recoil)

Hair follicles

• Everywhere except palms, soles, nipples, lips, and parts of genitalia

• Epidermal tissue that extends into the dermis (root)

• Cells at base associated with blood vessels undergo mitosis as the new cells push away the older cells, the older cells fill with keratin and die

• Hair extends beyond the skin surface as the shaft

• A hair is dead epidermal cells

Arrector pili muscle

• Attached to each hair follicle

• When contracted, hair stands upright

Sebaceous glands

• Holocrine glands associated with hair follicles

• Produce sebum (oil), which keeps skin soft and waterproof

• Absent from palms and soles

• Activated during puberty

Nails

• Protective covering on the distal ends of fingers and toes

• Is a nail plate that lies over the nail bed (derived from epithelial cells)

• Contains hard keratin

Sudoriferous glands

Sweat glands

Eccrine glands

• Coiled structures in the dermis that have a duct which carries its product (sweat - water, salt, antibodies, and wastes (urea, uric acid) to a pore (opening) on skin surface

• Responds to body temperature

• Numerous on palms, soles, forehead

• Exocrine glands, specifically merocrine glands

Apocrine glands

• Numerous in axillary and anogenital areas

• Duct empties into hair follicle

• Milky color due to additional components (fatty substance and proteins) in sweat

• Function at puberty, activated in pain and stress, activity increased during sexual foreplay

Ceruminous glands

Modifies apocrine glands in external ear canal, secrete cerumen (earwax)

Mammary glands

Special sweat glands that secrete milk

Functions of integumentary system

• Protection (protection against abrasion, invasion, dehydration, and UV radiation)

  • physical: skin continuity, keratin. water resistant glycolipids

  • chemical: Acid mantle (reduces bacterial replication), antibacterial agents, melanin

  • biological: Langerhans’ cells (Immunity - both specific and non-specific)

• Body temperature regulation: sweating and regulation and blood flow

• Sensory reception: reception of stimuli (temperature, touch, pressure, pain)

  • Meissner’s corpuscles

  • Pacinian corpuscles

• Excretion: water, salts, organic compounds (wastes)

• Metabolic functions (Ex. vitamin D synthesis (aids in absorption of Ca & P))

• Blood reservoir

Meissner’s corpuscle

Touch receptor in dermal papillae

Pacinian corpuscle

Receptors for deep pressure (located in deep dermis or hypodermis)

Skin cancer

1 in 5 americans

Basal cell carcinoma

• Keratinocytes of the stratum basale

• Lesions shiny, rounded nodules that form into ulcer with pearly, beaded edge

• Often on sun exposed areas of face

• Most common, least malignant

Squamous cell carcinoma

• Keratinocytes of stratum spinosum

• Lesion is reddened papule

• Most often on head (scalp, ears, bottom lip) and hands

• Grows quickly and will metastasize if not removed

• Chance of cure is good with early detection and treatment

Melanoma

• Cancer of the melanocytes, can occur wherever there is pigment

• Spreading brown/black patch

• Most dangerous (metastasizes quickly to lymph and blood vessels, resistant to chemo)

• 5% of skin cancers (incident is on the rise)

• If lesion is greater than 4mm thick, survival change is low

ABCD(E) Rule

• Asymmetry

• Border irregularity

• Color

• Diameter

• (Elevation)

Burns

• Tissue damage resulting from heat, electricity, radiation or chemicals

• Loss of body fluids (dehydration and electrolyte balance) leads to renal failure and circulatory failure

• Infection: burns are sterile for 24 hours, highly susceptible to infection afterwards

  • Ability of immune system to fight infection is reduced

1st degree burns

• Only epidermis damaged

• Symptoms: redness, pain, swelling

• Heal: 2-3 days

• Ex. Mild sunburn

2nd degree burn

• Epidermis and upper dermis damaged

• Symtoms: Blistering, redness, pain, swelling

• Heal: 3-4 weeks

3rd degree burns

• Epidermis and dermis completely damaged

• Cherry red, grey-white or blackened look

• No pain (no nerve endings)

Critical burns (3)

1. Over 25% of the body has 2nd degree burns

2. Over 10% of the body has 3rd degree burns

3. 3rd degree burns of face, hands, and feet

Rule of nines

Assessment technique for burns; 11 areas of the body accounting for 9% of body area, 1% for genitals

Athlete’s foot

Fungal infection (usually in skin of the toes and soles)

Boil

Bacterial infection (caused by bacteria entering hair follicle)

Herpes

Infectious conditions caused by Herpes simplex virus, recurring clusters if vesicles

Cutaneous membrane

• Dry membrane; the skin

• Organ system comprised of keratinized stratified squamous epithelium (epidermis) attached to a thick dense irregular connective tissue (dermis)

Mucous membranes (mucosae)

• Wet (moist) membranes

• Lines body cavities that open to the exterior (hollow organs and passageways of the digestive tract, and urinary tract)

• Comprised tissue called the lamina propria (in come mucosae, there is a third layer of smooth muscle)

Serous membranes

• Wet (moist) membranes

• Located in closed central body cavities

• Comprised of simple squamous epithelium (mesothelium) resting on a thin layer of areolar connective tissue

• produces serous fluid; the fluid provides lubrication for ease of movement

  • (heart - parietal and visceral layers of the serous pericardium)

  • (thoracic cavity) - parietal pleura and visceral pleura)

  • (abdominopelvic cavity - parietal peritoneum and visceral peritoneum)