Module 2 (LEC): Histology | Integumentary System Flashcards
Epithelial Tissue
- sheets of closely packed cells
- protection, exchange, secretion
Connective Tissue
- sparse cells in extracellular matrix
- building and support of other tissues
- bones (muscle attachment) & blood (transport)
Muscle Tissue
- moves when cells contract
Nervous Tissue
- cells comprising the nervous system in brain, spinal cord, and peripheral nerves
What are the steps for preparation of a specimen?
- obtain sample w/proper orientation
- fix/preserve specimen
- embed in support medium
- sectioning
- staining
- examination
Orientation
- improper orientation = damaged tissue
- embedded with least resistance to knife
Fix/Preserve
deactivate enzymes to prevent degradation
Embedding
prevent physical changes
Paraffin Wax Embedding
wax fills the tissue, supporting cellular components
Freezing
rapidly frozen in liquid nitrogen to harden the tissue
Sectioning
slicing of specimen with microtome
Methyl Blue
stains collagen blue
Hematoxylin and Eosin (H&E)
differentiation of nucleic acids in nucleus from proteins in cytoplasm
Hematoxylin
stains nuclei purple
Eosin
stains basic structures pink (proteins, membrane)
Van Gieson
stains connective tissue fibers (collagen, muscle, and elastic fibers)
Trichrome
- stain cellular components using three different dyes
- helpful for highlighting red blood cells within vessels
Silver Nitrate
- Golgi Method: stain whole tissue black (neurons)
Light/Optical Microscope
- beams of wavelengths through lens to magnify image
- magnification: 2,000x
- chromatic dyes to highlight tissue/cell components
Electron
- particle beams through magnetic lens to produce 2D and 3D images
- magnification: 2,000,000x
- stains by increasing electron absorption, electron dense heavy metals
Squamous
flat and plate like
Cuboidal
cube-like w/ similar height, width, and depth
Columnar
column shaped, height 2-3x width
Exocrine Glands
- glandular and duct portion
- secrete non-hormone products into ducts, carry to other organs or outside the body
What are the three types of Exocrine Glands?
merocrine, apocrine, holocrine
Endocrine Glands
- only glandular portion, LACK ducts
- product hormones secreted directly into the bloodstream
What are the glandular and duct portions of glands lined with?
glandular: secretory glandular epithelium
duct: simple cuboidal or columnar epithelial cells
Merocrine
- secrete vesicles containing cell products
- sweat and salivary glands
Apocrine
- product accumulates on apical surface of secreting cell and is cleaved
- mammary glands
Holocrine
- secrete by shedding whole cells
- sebaceous glands
Fibroblasts
produce collagen and ground substance
Adipocytes
store lipids to provide energy
Chondroblasts
secrete components of ECM of cartilage
Osteoblasts
secrete components of ECM of bone
Myofibroblasts
contractile cells of smooth muscle, also secrete ECM
Mast Cells
store and secrete histamine and heparin, involved in inflammation
What are the two types of white blood cells?
Macrophages and Plasma Cells
Macrophages
destroy bacterial and cellular debris via exocytosis
Plasma Cells
secrete antibodies in defense of pathogens
What are the two components of extracellular matrix?
fibers and ground substance
What are the three types of loose connective tissue?
areolar, adipose, and reticular
What are the three types of dense connective tissue?
dense regular, dense irregular, and elastic
Areolar Tissue
- contains collagen, elastic, and reticular fibers
- found in subcutaneous tissue
Adipose Tissue
- consists of adipocytes that store fat/lipids as triglycerides
- found in subcutaneous tissue
Reticular Tissue
- consists of reticular fibers (very fine but strong when branched)
- found in spleen and lymph nodes
Dense Regular Connective Tissue
- uniformly arranged collagen
- tendons and ligaments
Dense Irregular Connective Tissue
- irregular arrangement of tightly packed collagen
- found in dermis, heart, and periosteum (surrounding bone)
Elastic Connective Tissue
- elastic fibers and fibroblasts
- found in lungs and elastic arteries
Cartilage
- dense network of collagen or elastic fibers
- ECM formed by chondroblasts
Bone
- move, support, and protect organs
- store calcium and phosphorous and house red and yellow bone marrow
- formed by osteoblasts which mature into osteocytes
Liquid Connective Tissue
- blood: RBC, WBC, and platelets
Skeletal Muscle Tissue
- long, thin, cylindrical cells with striated fibers and peripheral nuclei
- attached to bones via tendons
- voluntary movement, posture, heat production
Cardiac Muscle Tissue
- branched striated fibers connect via discs with 1-2 central nuclei
- muscular component of heart
- contraction of heart muscle for pumping blood
Smooth Muscle Tissue
- spindle shaped, NOT striated, with 1 central nucleus
- blood vessels, lung airways, walls of GI and GU tracts
- constriction of vessels, airways, and tracts
Neurons
- respond to stimulus by converting into an action signal (electrochemical signal)
- axon: long, singular projection
- dendrites: numerous short branches
Neuroglia
- provide support, nourishment, and protection to neurons
- small cell body with nucleus and cytoplasmic processes
Gliosis
production of glial cells in the CNS in response to injury resulting in scar formation within nervous tissue
What are the two categories of membranes?
Epithelial and Synovial
Epithelial Membranes
- consist of epithelium overlying connective tissue
What are the three types of Epithelial Membranes?
mucous, serous, and cutaneous
Mucous Membranes
line body cavities or tracts open to external environment
Serous Membranes
cover visceral organs and line body cavities
Cutaneous Membranes
skin or epidermis, overlying the dermis
Synovial Membranes
- line the cavities of mobile joints
- composed of synoviocytes which create synovial fluid for lubrication of cartilages associated with joints
What does the Integumentary System include?
skin, hair, nails, sweat glands
The Integumentary System accounts for what percentage of our body weight?
15%
What are some of the functions of the skin?
protection, thermoregulation, excretion, absorption, vitamin D synthesis, cutaneous sensation
Epidermis
- epithelial tissue [no blood vessels]
- outermost layer of skin
- contains 4 main cell types: keratinocytes, melanocytes, Langerhans cells, Merkel cells
- 3 pigments that contribute to skin color: hemoglobin, melanin, carotene
Dermis
- dense connective tissue
- deep to epidermis
- collagen and elastic fibers
- papillary & reticular layer
Hypodermis
- connective tissue (adipose)
- NOT considered skin layer
- contains loose areolar tissue, fat, sensory receptors, and blood vessels
- connects skin to bone and muscle
Keratin
forms barrier against pathogens and protects deeper tissues against heat abrasion
Sweat
secreted onto the skin (via sweat glands) to inhibit a microbial growth
Defensins
antimicrobial proteins that help prevent colonization of pathogens
Glycolipids
regulates water content (alongside sebum/oily secretions)
Melanin
absorbs UV radiation to prevent damage
Langerhans Cells
signaling cells to alert the body of pathogens, important immunological component
Keratinocytes
produce keratin and lamellar granules, most common cell, gives skin protective properties
Melanocytes
produce melanin granules
Merkel Cells
tactile cells associated with sensory nerve endings for touch reception
Normal Flora
healthy microbial populations preventing overgrowth of pathogens
What are the layers of the epidermis?
stratum corneum
stratum lucidum
stratum granulosum
stratum spinosum
stratum basale
Stratum Corneum
- most superficial layer
- 20-30 layers of dead keratinocytes void of organelles
Stratum Lucidum
- only found in hairless skin (fingertips, palms, soles of feet)
- several layers of dead keratinocytes
Stratum Granulosum
- 3-5 layers of mature keratinocytes that produce keratin and lamellar granules
Stratum Spinosum
- contains 8-10 layers of keratinocytes joined via desmosomal connections
- also contains Langerhans cells
Stratum Basale
- deepest layer
- single layer of cuboidal cells superficial to basal membrane
Sebaceous Glands
secrete sebum (oily substance) to soften the skin
Sweat Glands
secrete salt and water to regulate body temperature
Merocrine Sweat Glands
found all over skin and highly concentrated in palms of hands and soles of feet
Apocrine Sweat Glands
large sweat glands located in the axilla and anogenital regions
Ceruminous Glands
secrete cerumen (ear wax) to protect and lubricate the external ear
Hair
composed of dead, keratinized epithelial cells and associated with arrector pili muscles
What are the five parts of the nail?
plate, bed, lunule, matrix, hyponychium
Plate
translucent, visible portion of nail
Bed
connective tissue deep to nail plate
Lunule
half-moon shared area at proximal portion of nail
Matrix
site of active nail growth
Hyponychium
thickened free edge of the nail
Epidermal Wound Healing
- stratum basale detaches from plasma membrane and basal epithelial cells cover the wound
- epidermal growth factor is released to promote basal stem cell division to replace
- contact inhibition prevents continued migration of epithelial cells
Deep Wound Healing occurs when
both epidermis and dermis have been injured
Inflammatory Phase
- formation of blood clot (hemostasis)
- histamine released for vasodilation(widening of blood vessels) to promote WBC to enter tissue
Proliferation and Migratory Phase
- epithelial cells migrate across deep surface of the scab to cover the wound
- fibroblasts enter and secrete granulation tissue
Maturation and Remodeling
- organization of collagen fibers and blood vessels returned to normal
Fibrosis
formation of scar tissue (collagen fibers) secreted by fibroblasts
Keloid
result of excess production of collagen in the formation of a scar
