Histology Flashcards
Anatomy: Basics of Histology
What’s the study of tissues?
Histology
What are tissues?
Groups of similar cells & extracellular products that carry functions
How do you classify epithelial tissue?
Number (amount) AND Shape
Define: Intercellular Junctions
close connections in membrane of lateral surfaces(side)
What are the Intercellular Junctions?
Tight Junction (Zonula Occludens), Adhering Junctions (Zonula Adherens), Desmosomes (Macula Adherens), Gap Junction
Define: Zonula Occludens
Tight Junction: Closely associated areas of two cells whose membranes join together forming a virtually impermeable barrier.
EX: digestive tract
Define: Zonula Adherens
Adhering Junctions: cell junction where cytoplasmic face is linked to the actin cytoskeleton. They can appear as bands encircling the cell (zonula adherens) or as spots of attachment to the extracellular matrix (adhesion plaques).
Define: Macula Adherens
Desmosomes: (Greek: desmos=band, soma, body) buttons between cell stress points
EX: most epithelial tissues
Define: Basal layer
Basement structure: Extracellular layer in between Epithelial basal surface and connective tissue.
Define: Avascular
no blood vessels. obtain nutrients from apical surface or by diffusion across basal
What are the 3 layers of cells distinguished by number?
simple- 1 layer
stratified- +1layer
pseudostratified- false layers
Name Cell Classifications
Squamous, Cubidol, Columnar, Transitional
Define: Endothelium
Tissue that forms a single layer of cells lining various organs and cavities of the body. It is formed from the embryonic mesoderm.
EX: blood vessels, heart, and lymphatic vessels.
Define: Mesothelium
The epithelium that lines the pleurae, peritoneum, and pericardium (primary germ layer Mesoderm)
What are Glands?
individual/multicellular organs predominantly from epithelial tissue that secrete chemical substances
Squamous Cells
“scaly” and flat
Cubidol Cells
“cube” with round nucleus in the center
Colmunar Cells
“column”; nucleus basal
Transitional Cells
morph; change due to expanding epithelial
EX: empty bladder (polyhedral cell)
What does endocrine secrete?
Hormones
Merocrine (Eccrine) Glands
(Greek: meros=share)
package secretion in secretory vesicles, release through exocytosis
eccrine glands: sweat glands not connected to hair follicles
EX: Lacrimine (tears) gland, salivary, sweat
Which gland accumulates and then disintegrates?
How does it secrete it’s chemicals?
Holocrine Glands
secretory accumulates>cell dies>breask off>cell division at base
EX: sebaceous (oil) gland
Which gland’s secretion accumulates on applicable part of cytoplasm?
Apocrine Glands
(Greek: appo=off)
EX: axial
Anatomic Classification: Simple Gland
single, unbranched duct
Anatomic Classification: Compound Gland
branched ducts
Anatomic Classification: Acinar
expanded sacs
Anatomic Classification: Tubular
uniform diameter
Anatomic Classification: Tubuloacinar
Combination of acinar and tubular
What’s the purpose of Connective Tissue?
Support, Bind, Protect
What are the Connective Tissue characteristics?
cells, ground substance (matrix), protein fibers
What connective tissue is only present in the umbilical cord?
Mucous connective Tissue: (Warton’s connective jelly)
Define: stroma
internal part of organs. abundant. structural connective tissue
physically support organs & resist external forces
Define: Collagen Fibers
Unbranched extracellular,
strong, flexible, resistant to stretching, coarse, wavy bundles
25% body protein
EX: Tendons & ligaments
Define: Elastic Fibers
thinner than collagen fibers.
stretch and rejoin, wavy, branch
EX: lung tissue. blood vessels
Reticular Fibers
(rete=network)
thinner than collagen & elastic.
coated w/ glycoprotein.
Ex) Stroma
Describe Loose Connective Tissue.
What are the three types?
- most common type in vertebrates.
- holds organs in place, attaches epithelial tissue to other underlying tissues, surrounds blood vessels & nerves.
1. Areolar
2. Adipose
3. Reticular
Areolar Connective Tissue
- contain all cell types of connective tissue
- distort w/out damage
- everywhere: surrounds nerves, blood vessels, & individual muscle cells.
- subcutaneous layer to the skin
- fibroblast cells
Describe Adipose Connective Tissue
- Adipocytes: (white fat) loose, primarily of cells
- padding, cushions shocks, storage
Ex) FAT
Describe: Reticular Connective Tissue
reticular fibers, fibroblasts, leukocytes
forms stoma of lymphatic organs
EX: Immune system
Describe Dense Connective Tissue.
What are the 3 types?
- protein fibers, less ground substance than loose tissue.
1. Dense Regular
2. Dense Irregular
3. Elastic
Define: Fibroblasts
fibroblasts are widely dispersed in dense CT; irregular branching cells that secrete strong fibrous proteins and proteoglycans as an extracellular matrix.
Describe: Dense Regular Connective Tissue
-fibers packed tightly parallel
-single direction stress
-few blood vessels=long healing process
EX) tendons & ligaments.
Describe: Dense Irregular Connective Tissue
-bundles of collagen fibers, span all directions
-support stress from multiple directions
EX) deep portion of dermis
Describe: Elastic Connective Tissue
-branching elastic fibers & fibroblasts than loose
morph
EX: vocal cords
Describe: Hyaline Cartilage
-a translucent bluish-white type of cartilage
-most abundant & weakest
EX: joints, the respiratory tract, and the immature skeleton.
Define: Fibrocartilage
- contains fibrous bundles of collagen
- strongest, EX: intervertebral discs, pubic symphysis
Define: Elastic Cartilage
- (yellow cartilage) elastic fiber networks & collagen fibers.
- The principal protein is elastin.EX: epiglottis, external ear, Eustachian tube
What CT does Chondrocyte Cells represent?
Cartilage
What cartilage (CT) does Osteocyte (lacunae) represent?
Bone
Define: Cartilage
-firm, whitish, flexible connective tissue found in various forms
-more in infant skeleton, replaced by bone during growth.
-Lacunae hold osteocyties within extracellular matrix
perichondrium surrounds.
-outer fibrous dense CT & inner cellular layer
What are the 3 types of Cartilage?
- Hyaline
- Fibrocartilage
- Elastic
What’s the amount of organic/inorganic components in bones?
-⅓ organic components
collagen fibers & protein-carbohydrates=flexibility & tensile Strength-⅔ inorganic components
calcium salts, calcium phosphate=compressional strength
Store calcium & phosperous
What do bones store?
calcium & phosperous
Define Compact (cortial) Bone
- hard outer layer of bones, minimal gaps/spaces.
- Its porosity is 5–30%. 80% of the total bone mass
- smooth, white, and solid bone appearance
Describe Compact Bone Structure
Osteons/ Haversian System
- Lamellae: rings encircle central canal (vascular)
- Osteocytes: Bone cells
- Canaliculi: passageways in matrix
Define Trabecular (cancellous or spongy) Bone
-INTERIOR. Spaces. strong & lightweight
-highly vascular, contains red bone marrow where haematopoiesis, the production of blood cells, occurs.
EX) Ends of long bones, proximal to joints, within the interior of vertebrae.
What type of connective tissue is “fluid”?
Blood
What are Erythrocytes?
Red Blood Cells (RBC)
What are leukocytes? What are their purpose?
- White Blood Cells (WBC)
- Immune system
What are Placates?
What are their purpose?
What are they composed of?
- Plasma
- blood clotting
- dissolved protein fibers+watery ground substance
What do Goblet Cells do?
secrete mucus
Where can mucus membranes be found?
-internal to external environment
EX: respiratory, digestive, reproductive, urinar
Describe: Cutaneous Membrane
- SKIN (Epidermis)
- keratinized stratified squamous epithelium
Describe: Synovial Membrane
-“Free-moving’
-thin, well-vascularized, areolar, fibrous,
-secretes synovial fluid (lubricant)
EX) synovial joints, lines the joint capsule
Describe Serous Membrane (serosa)
-reduces friction from muscle movement
-Serous fluid (transudate): thin, watery, from blood plasma
-parietal of body cavity & visceral of organs
EX) Mesothelium: simple squamous epithelium
Describe: Skeletal Muscle Tissue
-voluntary striated muscle made up of elongated, multinucleated, transversely striated muscle fibers, having principally attachments to bones.
Define: Periphery
nucleus at side of cell
What’s myocardium?
thick middle layer of heart walls
Describe Cardiac Muscle Tissue
striated & involuntary (No NS stimulation)
Define: Intercalated Discs
-connections, strong gap junctions between cells. nerve impulse
EX) heart
Describe: Visceral Muscle Tissue
- Visceral= Smooth
- No cross striations.
- contracts slower than skeletal muscle but the contraction can be sustained over a longer period of time.
- EX) arteries, digestive tract, stomach, urinary bladder, blood vessels, heart
What are glial cells?
supporting cells; protect framework for neurons
What’s the Maturing Epithelium process called?
Metaplasia
What’s the process when tissue cells increase their number?
Hypertrophy
What’s the process of increased tissue size through mitosis?
Hyperplasia
What is the process called when a tumor(exceeding growth) forms?
Neoplasia
What is it called when tissue shrinks?
Atrophy
