Histology Objectives

Question 1

Histology

Answer 1

study of tissues

Question 2

Extracellular Matrix

Answer 2

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.

Question 3

Ground Substance

Answer 3

the protein/polysaccharide component “glue” of the extracellular matrix.

Question 4

Extracellular Fibers

Answer 4

component of the extracellular matrix (usually made of protein)

Question 5

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)

Answer 5

1. Type/Quantity of Intercellular Material: essentially none
2. Regenerative Capacity: high
3. Major Types: membranous and glandular epithelium
4. Origin: endoderm, mesoderm, and ectoderm
5. Function: secrets and covers surfaces

Question 6

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)

Answer 6

1. Type/Quantity of Intercellular Material: a small amount of c.t. proper
2. Regenerative Capacity: low
3. Major Types: smooth, cardiac, and skeletal muscle tissue
4. Origin: mesoderm
5. Function: contracts (can create electrical impulses)

Question 7

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)

Answer 7

1. Type/Quantity of Intercellular Material: abundant fibers and ground substance
2. Regenerative capacity: high
3. Major Types: c.t. proper, bone, blood, cartilage, adipose tissue, and Reticular connective tissue, Bone Marrow tissue, Primitive connective tissue
4. Origin: mesoderm
5. Function: joins (connects) other structures

Question 8

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)

Answer 8

1. Type/Quantity of Intercellular Matrix: essentially none
2. Regenerative Capacity: low
3. Major Types: not subdivided into types, but has two major cell types
4. Origin: ectoderm
5. Function: conducts impulses

Question 9

Gives the names of all 4 ways you can name a muscle cell

Answer 9

muscle cells, myofibers, muscle fibers, myocytes

Question 10

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)

Answer 10

1. under direct voluntary control of nervous system
2. alternating stacks of myofilaments in the myofibrils causes a differential cross-hatched or striated appearance
3. large cylindrically-shaped cells
4. several nuclei located near the peripheral aspects of the cytoplasm
5. located in the skeletal muscles

Question 11

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)

Answer 11

1. has inherent rhythmicity and thus is involuntary
2. striated
3. branched ( Y shaped) cells
4. centrally located nucleus
5. located in the contractile parts of the heart

Question 12

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)

Answer 12

1. it is involuntary, has inherent rhythmicity and is under the influence of the autonomic nervous system
2. there are no striations
3. fusiform shaped
4. single, centrally located nuclei
5. 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

Question 13

Membranous Epithelium

differentiate on the basis of blood supply, presence of basement membrane, and general location in body

Answer 13

1. avascular, aneural, and varies in thickness from one cell to several dozen cells thick
2. cells are separated by a basement membrane
3. covers the outer surfaces and the inner surfaces of the body

Question 14

Glandular Epithelium

differentiate on the basis of blood supply, presence of basement membrane, and general location in body

Answer 14

1. highly vascularized, innervated
2. lacks a basement membrane
3. located in glands

Question 15

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)

Answer 15

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

Question 16

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.

Answer 16

1. 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”
2. 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)

Question 17

Discuss the kinds and functions of modifications found in the surface cells of membranous epithelium.

Answer 17

1. Cilia- relatively long projections that the cells use to propel materials along the surface
2. Microvilli- specialized for absorption by increasing the surface area
3. 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)

Question 18

Endocrine/Exocrine

Define the following terms used to classify glandular epithelium

Answer 18

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)

Question 19

Simple/Compound

Define the following terms used to classify glandular epithelium

Answer 19

Simple: non-branching of ducts
Compound: branching of ducts

Question 20

Eccrine (merocrine)

Answer 20

watery secretion, no structural parts of the secretory cells become part of the secretion
ex) some sweat glands, salivary glands, liver, pancreas

Question 21

Apocrine

Answer 21

parts of secretory cells are lost into (become part of) the secretion
ex) mammary glands and some sweat glands (stinky sweat)

Question 22

Holocrine

Answer 22

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)

Question 23

Acinar

Answer 23

shape of their secretory units is spherical

Question 24

Tubular

Answer 24

shape of their secretory units is tubular

Question 25

Tubuloacinar

Answer 25

shape of their secretory units is both tubular and acinar

Question 26

Differentiate the development of endocrine vs. exocrine glands.

Answer 26

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

Question 27

List 3 components found in all connective tissues.

Answer 27

Fibroblasts secrete three kinds of extracellular products and well as the ground substance of the matrix: 1. Collagenous fibers (composed of protein called collagen) 2. Elastic fibers (composed of protein called elastin) 3. Reticular fibers (composed of protein called reticulin)

Question 28

Classify c.t. proper on the basis of density, arrangement, and fiber composition.

Answer 28

1. Fiber Density (loose/dense) - tightly packed vs. considerable space around them 2. Fiber Arrangement (regular/irregular) - oriented in a relatively parallel manner or not parallel to each other 3. 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

Question 29

Name the subtypes of cartilage and state the predominant fiber type present in each

Answer 29

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)

Question 30

Differentiate the two groups of cells found in nervous tissue.

Answer 30

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

Question 31

Axon

Answer 31

neuronal processes that carry impulses away from the cell bodies

Question 32

Dendrites

Answer 32

processes that conduct impulses toward the cell body.

Question 33

Connective Tissue Proper | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 33

1. fibroblasts, fibrocytes, and several others 2. collagenous, elastic, reticular 3. loose/dense, regular/irregular, and fiber type taxonomy (collagenous, elastic, reticular) 4. tendons, ligaments, facia, periosteum, endosteum, epimysium, plus a framework for most organs 5. present to some degree in all organs

Question 34

``` Bone Tissue (major cells present, fibers, major subtypes, locations in body, peculiar features) ```

Answer 34

1. osteoblasts, osteocytes, osteoclasts 2. collagenous 3. compact, spongy 4. within the named bones of the body 5. has hard matrix because of mineral deposits, has cells in lacunae

Question 35

Cartilage | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 35

1. chondroblasts, chondrocytes, chondroclasts 2. collagenous, elastic, reticular (resemble these) 3. fibrocartilage, elastic cartilage, hyaline cartilage 4. articular surfaces of bones, costal cartilages, intervertebral dics, pinna of ear, tracheal cartilages 5. has firm matrix, has cells in lacunae, no mineral

Question 36

Blood | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 36

1. RBC's and WBC's 2. potential fibers (fibrinogen) 4. within organs of cardiovascular system 5. the only liquid tissue

Question 37

``` Adipose Tissue (major cells present, fibers, major subtypes, locations in body, peculiar features) ```

Answer 37

1. adipose cells 2. collagenous 4. within subcutaneous tissue, medullary cavities of bones, peritoneum, pericardium 5. consists of many adipocytes within connective tissue proper

Question 38

Reticular Connective Tissue | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 38

1. reticular cells 2. reticular 4. lymph nodes, spleen, thymus, medullary cavities of bones 5. requires special stains to demonstrate

Question 39

Bone Marrow Tissue | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 39

1. hemocytoblasts and all of their derivatives 2. reticular 4. within medullary cavities of many bones 5. consists of reticular c.t. plus differentiating blood cells

Question 40

Primitive Connective Tissue (mesenchyme) | major cells present, fibers, major subtypes, locations in body, peculiar features

Answer 40

1. mesenchymal cells 2. very few present 4. nucleus pulposus of intervertebral discs, around vessels 5. can undergo rapid metaplasia for repair of damage

Question 41

Regenerative Capacity

Answer 41

significant in predicting the long term outcome of various types of injuries

Question 42

Scarring

Answer 42

results from the proliferation of c.t. proper after an injury