Histology Objectives Flashcards
Histology
study of tissues
Extracellular Matrix
material outside of and between cells. in many tissues it includes various types of proteinaceous fibers (extracellular fibers) as well as amorphous protein/polysaccharide material called ground substance.
Ground Substance
the protein/polysaccharide component “glue” of the extracellular matrix.
Extracellular Fibers
component of the extracellular matrix (usually made of protein)
Epithelial Tissue
(Compare the 4 basic tissues in regard to regenerative capacity, major subtypes, germ layer, type and quantity of intercellular material, and major functions)
- Type/Quantity of Intercellular Material: essentially none
- Regenerative Capacity: high
- Major Types: membranous and glandular epithelium
- Origin: endoderm, mesoderm, and ectoderm
- Function: secrets and covers surfaces
Muscle Tissue
(Compare the 4 basic tissues in regard to regenerative capacity, major subtypes, germ layer, type and quantity of intercellular material, and major functions)
- Type/Quantity of Intercellular Material: a small amount of c.t. proper
- Regenerative Capacity: low
- Major Types: smooth, cardiac, and skeletal muscle tissue
- Origin: mesoderm
- Function: contracts (can create electrical impulses)
Connective Tissue
(Compare the 4 basic tissues in regard to regenerative capacity, major subtypes, germ layer, type and quantity of intercellular material, and major functions)
- Type/Quantity of Intercellular Material: abundant fibers and ground substance
- Regenerative capacity: high
- Major Types: c.t. proper, bone, blood, cartilage, adipose tissue, and Reticular connective tissue, Bone Marrow tissue, Primitive connective tissue
- Origin: mesoderm
- Function: joins (connects) other structures
Nervous Tissue
(Compare the 4 basic tissues in regard to regenerative capacity, major subtypes, germ layer, type and quantity of intercellular material, and major functions)
- Type/Quantity of Intercellular Matrix: essentially none
- Regenerative Capacity: low
- Major Types: not subdivided into types, but has two major cell types
- Origin: ectoderm
- Function: conducts impulses
Gives the names of all 4 ways you can name a muscle cell
muscle cells, myofibers, muscle fibers, myocytes
Skeletal Muscle Tissue
(differentiate the 3 types of muscle tissue in regard to: voluntary/involuntary, presence/absence of striations, cell shape, number and position of nuclei, and location in body)
- under direct voluntary control of nervous system
- alternating stacks of myofilaments in the myofibrils causes a differential cross-hatched or striated appearance
- large cylindrically-shaped cells
- several nuclei located near the peripheral aspects of the cytoplasm
- located in the skeletal muscles
Cardiac Muscle Tissue
(differentiate the 3 types of muscle tissue in regard to: voluntary/involuntary, presence/absence of striations, cell shape, number and position of nuclei, and location in body)
- has inherent rhythmicity and thus is involuntary
- striated
- branched ( Y shaped) cells
- centrally located nucleus
- located in the contractile parts of the heart
Smooth Muscle Tissue
(differentiate the 3 types of muscle tissue in regard to: voluntary/involuntary, presence/absence of striations, cell shape, number and position of nuclei, and location in body)
- it is involuntary, has inherent rhythmicity and is under the influence of the autonomic nervous system
- there are no striations
- fusiform shaped
- single, centrally located nuclei
- located within the blood vessels, in the walls of visceral organs, at the base of hair follicles, and within the iris and ciliary body of the eye
Membranous Epithelium
differentiate on the basis of blood supply, presence of basement membrane, and general location in body
- avascular, aneural, and varies in thickness from one cell to several dozen cells thick
- cells are separated by a basement membrane
- covers the outer surfaces and the inner surfaces of the body
Glandular Epithelium
differentiate on the basis of blood supply, presence of basement membrane, and general location in body
- highly vascularized, innervated
- lacks a basement membrane
- located in glands
Classify membranous epithelium into 6 categories on the basis of its thickness (one cell/more than one cell) and the shape of the surface cells (squamous, cuboidal, columnar)
One cell thick 1. simple squamous epithelium 2. simple cuboidal epithelium 3. simple columnar epithelium More than one cell thick 4. stratified squamous epithelium 5. stratified cuboidal epithelium 6. stratified columnar epithelium
Name and state the location of two types of membranous epithelium that do not fit the usual classification scheme. Indicate what is meant by “respiratory” epithelium.
- Pseudostratified columnar epithelium: appears to be more than one cell thick because some cells are short and do not reach the surface (THEY ARE IN CONTACT WITH THE BASEMENT MEMBRANE SO ONLY ONE CELL LAYER THICK)
- located in the air conducting passageways of the respiratory system and is sometimes called “respiratory epithelium” - Transitional Epithelium: lines the urinary bladder, ureters, and part of the urethra
- appears to be composed of several layers of cuboidal cells but IN CONTACT WITH THE BASEMENT MEMBRANE SO ONLY ONE CELL THICK)
Discuss the kinds and functions of modifications found in the surface cells of membranous epithelium.
- Cilia- relatively long projections that the cells use to propel materials along the surface
- Microvilli- specialized for absorption by increasing the surface area
- Keratin- dense protein manufactured by the stratified squamous epithelium of the skin; it remains within the cells but imparts physical strength and resistance to desiccation (drying)
Endocrine/Exocrine
Define the following terms used to classify glandular epithelium
Endocrine Glands: glands that lose all connections to the surface and secrete their products directly into the bloodstream; their secretory products are called hormones
Exocrine Glands: glands that maintain a surface or lumen connection by being physically located at the surface (goblet cells) or by having a duct that reaches a body surface (or lumen)
Simple/Compound
Define the following terms used to classify glandular epithelium
Simple: non-branching of ducts
Compound: branching of ducts
Eccrine (merocrine)
watery secretion, no structural parts of the secretory cells become part of the secretion
ex) some sweat glands, salivary glands, liver, pancreas
Apocrine
parts of secretory cells are lost into (become part of) the secretion
ex) mammary glands and some sweat glands (stinky sweat)
Holocrine
entire cells of the gland are lost into (become part of) the secretion
ex) sebaceous glands of skin, ceruminous glands of external acoustic meatus (wax and oil)
Acinar
shape of their secretory units is spherical
Tubular
shape of their secretory units is tubular
Tubuloacinar
shape of their secretory units is both tubular and acinar
Differentiate the development of endocrine vs. exocrine glands.
All glandular epithelium develops from membranous (surface) epithelium. Membranous epithelium that becomes glandular may remain on the surface, maintain a surface contact in the form of a duct, or may lose a surface contact all together. If it maintains surface contact = exocrine glands. If it loses surface contact = endocrine glands
List 3 components found in all connective tissues.
Fibroblasts secrete three kinds of extracellular products and well as the ground substance of the matrix:
- Collagenous fibers (composed of protein called collagen)
- Elastic fibers (composed of protein called elastin)
- Reticular fibers (composed of protein called reticulin)
Classify c.t. proper on the basis of density, arrangement, and fiber composition.
- Fiber Density (loose/dense) - tightly packed vs. considerable space around them
- Fiber Arrangement (regular/irregular) - oriented in a relatively parallel manner or not parallel to each other
- Fiber type present (collagenous fiber, elastic fibers, and reticular fibers) - if they don’t have anything listed at all it’s assumed they have all 3
Name the subtypes of cartilage and state the predominant fiber type present in each
Fibrocartilage: dense collagenous fibers in the matrix impart strength and resistance to tearing and compression
-forms outer parts of intervertebral discs (between vertebrae)
Elastic cartilage: has significant numbers of elastic fibers in the matrix which impart flexibility
-found in the external ear and parts of larynx
Hyaline cartilage: has delicate collagenous (“reticular”) fibers within its matrix
-found on the articular surfaces of bones (think of fried chicken and the shiny part on the joint, made so your bones don’t rub together)
Differentiate the two groups of cells found in nervous tissue.
Neurons: so specialized they can’t divide; contain a central portion called cell body
-conducts impulses
Neuroglia: they DO NOT conduct electrical impulses but perform a number of other functions
Axon
neuronal processes that carry impulses away from the cell bodies
Dendrites
processes that conduct impulses toward the cell body.
Connective Tissue Proper
major cells present, fibers, major subtypes, locations in body, peculiar features
- fibroblasts, fibrocytes, and several others
- collagenous, elastic, reticular
- loose/dense, regular/irregular, and fiber type taxonomy (collagenous, elastic, reticular)
- tendons, ligaments, facia, periosteum, endosteum, epimysium, plus a framework for most organs
- present to some degree in all organs
Bone Tissue (major cells present, fibers, major subtypes, locations in body, peculiar features)
- osteoblasts, osteocytes, osteoclasts
- collagenous
- compact, spongy
- within the named bones of the body
- has hard matrix because of mineral deposits, has cells in lacunae
Cartilage
major cells present, fibers, major subtypes, locations in body, peculiar features
- chondroblasts, chondrocytes, chondroclasts
- collagenous, elastic, reticular (resemble these)
- fibrocartilage, elastic cartilage, hyaline cartilage
- articular surfaces of bones, costal cartilages, intervertebral dics, pinna of ear, tracheal cartilages
- has firm matrix, has cells in lacunae, no mineral
Blood
major cells present, fibers, major subtypes, locations in body, peculiar features
- RBC’s and WBC’s
- potential fibers (fibrinogen)
- within organs of cardiovascular system
- the only liquid tissue
Adipose Tissue (major cells present, fibers, major subtypes, locations in body, peculiar features)
- adipose cells
- collagenous
- within subcutaneous tissue, medullary cavities of bones, peritoneum, pericardium
- consists of many adipocytes within connective tissue proper
Reticular Connective Tissue
major cells present, fibers, major subtypes, locations in body, peculiar features
- reticular cells
- reticular
- lymph nodes, spleen, thymus, medullary cavities of bones
- requires special stains to demonstrate
Bone Marrow Tissue
major cells present, fibers, major subtypes, locations in body, peculiar features
- hemocytoblasts and all of their derivatives
- reticular
- within medullary cavities of many bones
- consists of reticular c.t. plus differentiating blood cells
Primitive Connective Tissue (mesenchyme)
major cells present, fibers, major subtypes, locations in body, peculiar features
- mesenchymal cells
- very few present
- nucleus pulposus of intervertebral discs, around vessels
- can undergo rapid metaplasia for repair of damage
Regenerative Capacity
significant in predicting the long term outcome of various types of injuries
Scarring
results from the proliferation of c.t. proper after an injury
