CHAPTER 4 - HISTOLOGY: THE STUDY OF TISSUES
I. HISTOLOGY - study of tissues
A. 4 TYPES
GENERAL - multiple modifications
1. EPITHELIAL
2. CONNECTIVE
SPECIALIZED - 1 function/EXCITABLE
3. MUSCLE
4. NERVOUS
B. CLASSIFICATION
1. FORM/SHAPE - EPITHELIAL & CONNECTIVE
2. EXTRACELLULAR MATERIAL - CONNECTIVE
3. FUNCTION - MUSCLE & NERVOUS
C. BIOPSY - tissue sample for diagnosis
II. EPITHELIAL - lines all FREE SURFACES (Tab. 4.1, p. 113)
- highly CELLULAR - very little extracellular material
- BASEMENT MEMBRANE
- NON-VASCULAR - diffusion
A. CLASSIFICATION (p 111,114-117; Tab. 4.5, p. 118-119)
1. # LAYERS
a. SIMPLE - 1 layer
b. STRATIFIED - 2 or more layers
c. PSEUDOSTRATIFIED - "false-layered"
2. SHAPE
a. SQUAMOUS - “scale”, flat
- diffusion, filtration, protection
b. CUBOIDAL - boxes
- absorption, secretion
c. COLUMNAR - tall, may be ciliated/microvilli
- absorption, secretion
d. TRANSITIONAL - cuboidalèsquamous
- stretching, bladder
3. STRATIFIED SQUAMOUS
a. KERATINIZED - SKIN - protection/êH2O loss
- dead & enucleated @ free surface
- DESQUAMATION - loss of outer cells
b. MOIST -mouth, esophagus, anus, vagina
- alive & nucleated @ free surface
- eases/prevents friction
4. ENDOTHELIUM - SIMP. SQU. EPITH. lining blood vessels
5. MESOTHELIUM - " " " lining body cavities
6. Combine #layers & shape = name of epithelium
B. CELL CONNECTIONS (Fig. 4.2, p. 119)
1. BIND
a. DESMOSOMES/HEMIDESMOSOMES - "spot welds"
b. ZONULA ADHERENS - "sewn" near free surface
2. SEAL - ZONULA OCCLUDENS
a. TIGHT JUNCTION = Z. ADHERENS + Z. OCCLUDENS
3. COMMUNICATION - GAP JUNCTION - channels
C. GLANDS - (Figs. 4.3, p. 120)
- secrete
- EPITHELIAL tissue - mostly
- ENDOCRINE - ductless, later
- EXOCRINE - with ducts, now
1. EXOCRINE - maintain contact w/EPITH. from which derived
a. UNICELLULAR - goblet/mucous cells
- gut & resp. epith.
*KNOW b. MULTICELLULAR (p. 120)
SIMPLE COMPOUND
TUBULAR TUBULAR
BRANCHED ACINAR
COILED
ACINAR
c. PRODUCTS (Fig. 4.4, p. 121)
i. MEROCRINE - product released, no cells lost
- SWEAT glands open to skin
- thermoregulation
ii. APOCRINE - portion of cell lost w/product
- SWEAT glands open to base of
hair or skin, BODY ODOR
- mammary glands
iii. HOLOCRINE - whole cells lost w/product
- SEBACEOUS glands - oils
III. CONNECTIVE TISSUE - C.T. (Tab. 4.6, p. 124; Tab. 4.7, p. 125-126; 128-132)
- cells separated by NON-LIVING EXTRACELLULAR MATRIX
- VASCULARIZED except CARTILAGE
A. LIVING, FIBROBLASTS - form C.T;. aka stem, mast, mesenchyme
1. -BLASTS - immature, deposit new matrix material, repair
2. -CYTES - mature cells, maintain matrix
3. -CLASTS - dissolve/remove matrix
B. NON-LIVING, EXTRACELLULAR MATRIX (Fig. 4.5, p. 123)
1. PROTEIN FIBERS - 2 kinds
a. COLLAGEN - strong, abundant; RETICULAR - thin coll.
b. ELASTIN - flexible
2. GROUND SUBSTANCE = MATRIX - 2 non-proteins
a. HYALURONIC ACID - slippery fluid, lubricant
b. PROTEOGLYCANS - resilient, hold lots of H2O
C. FUNCTION - LIPSTTIC
LUBRICATION, IMMUNITY, PROTECTION, SUPPORT, TRANSPORT
THERMOREGULATION, INSULATION, CONNECT
D. CLASSIFICATION - see lab notes
1. FIBROUS
a. LOOSE or DENSE
b. REGULAR or IRREGULAR
c. COLLAGEN or ELASTIN
d. SPECIAL
i. ADIPOSE
ii. RETICULAR
iii. BONE MARROW - later
2. FIBROUS + GROUND SUBSTANCE
a. BONE - later
b. CARTILAGE
i. HYALINE - tough, support, thin collagen, TRACHEA
ii. ELASTIC - rigid & elastic, coll + elas., EARS
iii. FIBROCART. - cushion, thick coll., between BONES
iv. STRUCTURE: (Fig. 6.1, p. 173)
3. FLUID/MATRIX - BLOOD & LYMPH – later
IV. MEMBRANES - EPITH + C.T. it rests on (Fig. 4.7, p. 138)
TYPE EPITHELIUM BASEMENT MEMB. C.T.
A. MUCOUS - opens GUT - SIMP. COLUMN THICK THICK,
to surface RESP. - P.C.C.E. LOOSE IRR.
- MUCUS MOUTH/ESOPH. -moist = LAM. PROP
B. SEROUS - no SIMPLE SQ. THIN THIN,
opening to surface (MESOTHELIUM) LOOSE IRR.
- SEROUS FLUID - LUBRICANT
C. SYNOVIAL - joint NONE NONE MODIFIED
cavities, “freely movable” w/ADIPOSE
- SYNOVIAL FLUID - LUBRICANT
D. SKIN-CUTANEOUS STRAT. KER. THICK DENSE,
SQUAMOUS EPITH. IRREG. C.T.
V. INFLAMMATION - response to tissue damage (Fig. 4.8, p. 139)
A. RESPONSE - MEDIATORS - induce inflammation
1. PROSTAGLANDINS & HISTAMINES
B. SIGNS - 5
1. REDNESS/ERYTHEMA - é vasodilation
2. HEAT - é activity at site
3. SWELLING/EDEMA - é capillary permeability, H2O & proteins in
4. PAIN - a. PHYSICAL - pressure on nerves
b. CHEMICAL - mediators cause itch/burn
5. ê FUNCTION
C. PURPOSE
1. PROTECTION
2. é fluids è dilute toxins, wash site clean
3. é NEUTROPHILS èfight infection
4. CLOT - wall off & localize damage
VI. TISSUE REPAIR (Fig. 4.9, p. 141)
- REGENERATION - new cells same as old, no function loss
- REPLACEMENT - scar tissue, may be function loss
A. CLASSIFICATION OF CELLS
1. LABILE
a. divide constantly, regenerate easily
b. skin, mucous membranes, blood & lymph
2. STABLE
a. can regenerate when damaged
b. C.T., glands, liver, pancreas, endocrine glands,
smooth muscle
3. PERMANENT
a. limited ability to replicate/regenerate
b. nervous & muscle (skeletal & cardiac)
B. PRIMARY UNION - small, scab
1. CLOT - stops blood flow
2. SCAB - prevents infection
3. Regrowth of epidermis
4. Fibroblast - GRANULATION TISSUE - repairs damage
C. SECONDARY UNION - big
1. C.T. grows in first, WOUND CONTRACTION, pulls together edges
2. Epithelium regrowth later
3. SCAR - persistence of granulation tissue
4. SUTURE - reduces scars in secondary union
V. AGING
ê DIVISION, REPAIR, MAINTENANCE, REPLACEMENT, FUNCTION