CH4 Flashcards
Histology
Study of tissues
Pathology
Study of cells and tissues
- Pathologist - specializes in this study and performs autopsies and makes diagnoses
Biopsy
sample of living tissue removed to be examined under microscope
Tissue
cells that usually derive from same embryonic tissue become specialized for a particular function
4 major types of tissues
- Epithelial tissue
- Connective tissue
- Muscle
- Nervous
Epithelial Tissue
covers body surface, lines hallow organs, body cavities and ducts; and forms glands
Connective tissue
binds together to protect/support the body and it’s organs
- Stores energy (fat) and provides immunity
Muscle
contracts to generate movement and forces
Nervous
initiates and transmits action potential (nerve impulses), helps coordinate body activities between different body regions
Cell junction
Contact points between adjacent cell plasma membranes to adhere, communicate, and maintain tissue integrity
Gap junction
Passageway for chemicals to move between cells
- Connexins form the transmembrane protein channels
- Found in: Eyes, GI tract, uterus, heart
Tight junctions
- prevents movement of material between cells by forming fluid tight seals
- Common on epithelial cells
- Found in: Stomach, bladder, intestines
Desmosomes
links epithelial cells to surrounding structures
- Made of plaques & transmembrane glycoproteins that extends across gaps and links cytoskeletons together
Hemidesmosomes
connects cells to basement membrane
Adherens junctions
made of plaque and anchor cells together. “Adhesion Belt” Encircles the cell
- Resists separation during contraction (ex: as food moves through digestive system -intestines)
Connective tissue is…
- Less cells, loose
- Highly vascular (except tendons and cartilage)
- Has nerve supply except cartilage
Epithelial tissue is…
- Tightly packed with many cells, arranged in sheets with many cell junctions
- No extracellular matrix - no surrounding framework holding cells together
- High mitotic rate (quick cell replacement)
- Avascular with nerve supply (no blood supply; nutrients diffuse from underlying connective tissue)
- Apical surface (top of epithelial cell that faces external environment or lumen of organ) and Basal surface (bottom of epithelial cell, touches basement membrane
- Function: protection, absorption, or secretion
Basement membrane
in epithelial tissue, a thin layer of fibrous material that anchors the epithelial tissue to the underlying connective tissue
Types of epithelial tissue
- Simple squamous
- Simple cuboidal
- Simple columnar
- Stratified squamous
- Stratified cuboidal
- Stratified columnar
- Pseudostratified columnar
- Transitional
Simple squamous
single layer of cells attached to basement membrane
- Diffuses, excretes, and absorbs and Found in alveoli of lungs and kidneys
Simple Cuboidal
single layer, cube shaped cells resting on basement membrane
- Found in Kidney, thyroid, glands and responisble for excreting and absorption
Simple columnar
single layer, elongated nuclei, flattened cells in direct contact with basement membrane
- Locations: GI tract (stomach, intestines)
- Functions: secretions and absorption
Stratified squamous
2+ layers of cells, protects underlying tissues. Deeper layers are cuboidal shape,superficial are squamous
- Basal cells replicate and shift from deep to superficial
- Keratinized - found in surface that needs more protection (tough protein)
- Non-keratinized - found in wet parts of body
- Functions: protection from abrasion and desiccation (drying out)
- Locations: Skin (keratinized), esophagus (non-keratin)
Stratified cuboidal
2+ layers
* Found in sweat glands, mammary glands
* Functions: secretion
Stratified columnar
2+ layers, top cells are columnar
Locations: pharynx, epiglottis, salivary glands
Pseudostratified columnar
Appears stratified but all cells are touching the basement membrane making one layer. Has cilia
- Locations: respiratory tracts
- Functions: secretion and transport of mucus
Transitional
apical (top layer) cells change shape from cuboidal to squamous when stretched. Can tolerate stretch and recoil
- Locations: Bladder and ureters
Exocrine
(Exits) glands with ducts to a body surface
Goblet cells - mucus, Sweat glands, Sebaceous glands, Secretory glands in GI tracts
Endocrine
lack ducts, secretes hormones through glands
Thyroid, Pituitary, Adrenal, Gonads
how many cells?
Structural classification of epithelial glands
Unicellular - goblet
Multicellular - many cells (sweat glands, oil glands, salivary glands)
Functional classification of epithelial glands
Merocrine - most common, secretes via vesicle
- Salivary and sweat glands
Apocrine - secrete by pinching off apical surface of glands
- Mammary, axillary and pubic glands
Holocrine - whole cell ruptures to become secretory product
- Sebaceous gland
Connective tissue cells
7
Fibroblasts
Plasma cells
Mast cells
Adipocytes
Leukocytes
Macrophages
Mesenchymal
Fibroblasts
secretes FIBers and matrix, produces matrix
Plasma Cells
develop antibody producing B cells (lymphocytes)
Mast cells
abundant along blood vessels, cause inflammation
Adipocytes
fat cells, store energy
Leukocytes
WBC, immune defense
Macrophages
phagocytic, eats foreign cells and cleans up waste
Mesenchymal
stem cells
-blast
produce matrix
-cyte
maintain matrix
-clast
destroy matrix
Connective tissue fibers
Fibers, elastic, reticular
Fibers
collagen: tough protein; ligaments, tendons, bone, cartilage
- Most abundant
Elastic
densely-packed fibers with stretching and recoil capacity; skin, blood vessels, lungs
Reticular
anchors cells in place
* Has collagen and glycoprotein; supports walls of blood vessels and filtering organs (liver, lymph nodes, spleen)
* Location: liver, spleen, and lymph nodes
* Provides supportive framework for soft organs
Embryonic connective tissue
M&M
- Mesenchyme - loose, embryonic tissue that develops into mature CT
- Mucous - inside umbilical cord of fetus, Wharton’s jelly
What tissues are mature CT
(loose) Areolar, adipose, reticular, dense regular/irregular, and elastic
Loose CT
loosely-packed fibers
Areolar
Location: upper dermis, surrounds vessels, between glands, nerves, skin, muscle
Function: supports and nourishes
Adipose
composed of cells with lipids
Location: hypodermis, around kidneys, mammary glands
Function: cushion, insulation, energy storage
Dense regular
- contains more collagen fibers, densely packed into parallel bundles.
- Gives tensile strength to tendons and ligaments.
- Avascular
Dense irregular
interwoven collagenous fibers (mesh-like)
Location: lower dermis and submucosa layer of GI tract
Specialized
1) Fluid CT
- Lymph
- Blood - contains erythrocytes (RBCs), leukocytes (WBCs), thrombocytes (platelets)
Cells circulate in extracellular liquid matrix called plasma
2) Supportive CT
3) Cartilage, bone
Cartilage
supportive CT made of collagenous fibers, flexible, occurs in areas that need support. Mature cartilage is avascular
3 types of cartilage
Hyline, elastic, fibrocartilage
Hyaline
most common, glassy matrix. Found in nose and covering the articulating surfaces where 2 bones meet
Elastic
stretch and recoil due to abundance of chondrocytes. Found in external ear, epiglottis, eustachian tube
Muscle tissue types
Skeletal, cardiac, smooth
Skeletal muscle
multinucleated, striated, voluntary. Attached to bones
Cardiac muscle
one nucleus, striated, involuntary, connected by intercalated discs. Heart wall
Smooth muscle
one nucleus, non-striated (smooth appearance), tapered, involuntary. Blood vessels and GI tract, hollow organs
Nervous tissue
Made up of two cells: neurons and neuroglia
- Transmits and receives impulses through dendrites and axons
Tissue repair
1) Fibrosis - scar formation
2) Epithelial - replaced by stem cells
3) Connective - bone continues to replace itself. Cartilage less renewal (depends on blood supply)
4) Muscular - limited repair, depends on blood supply to muscle
5) Nervous
- Peripheral nervous system (PNS) performs limited repair
- Central nervous system (CNS) - can’t be repaired (brain, spinal cord)
Aging and disorders
- Younger bodies have better blood supply, nutrition, and metabolism. Aging slows tissue repair
- Disorders of epithelial tissue are associated with affected organ (ex; skin cancer,, lung cancer)
- Disorders of connective tissue - more autoimmune (ex lupus, rheumatoid arthritis)
+ Lupus - immune system fights itself
+ RA - autoimmune and inflammatory diseases
