Lab #1: Histology

Question 1

Compound Light Microscope

Answer 1

Have two sets of magnifying lenses. Oculars and objectives.

Question 2

Ocular Lenses

Answer 2

Or eyepieces. Brings the image into focus for the eye. 10x magnification.

Question 3

Micrometer

Answer 3

Measuring skill in ocular lenses use to measure the height of the cells.

Question 4

Objective Lenses

Answer 4

Ranges from 4x to 100x magnification. You change magnification rotating the Rotating Nosepiece.

Initially you should always view slide in 4x objective first, and progressively move higher up when you focus the image.

Question 5

Stage

Answer 5

Platform on which the slide is placed.

Always secure the slide with the stage clip.

Question 6

Coaxial Stage Control

Answer 6

Allows movement of the slide in the x and y plane.

Question 7

Light Source

Answer 7

Illuminates the specimen. A dial on side of the scope controls the light intensity.

Question 8

Diaphragm

Answer 8

Alters the light or contrast, controled by a thin lever beneath stage.

Question 9

Coarse Focus

Answer 9

Controls height of the stage.

Question 10

Fine Focus

Answer 10

Optimize or fine-tune the focus, especially when viewing through higher power objectives.

Question 11

Interpupillary Distance

Answer 11

Distance between the oculars. Can be adjusted.

Question 12

Parfocal

Answer 12

When you switch the objective lenses, the image should stay relatively in focus. But if you alter the coarse control, the focus will be lost.

Question 13

Epithelia

Answer 13

Form the surface layer of the body, line body cavities, hollow organs and structures, and constitute most gland tissue. Any substance that enters or leaves the body must cross an epithelium.

Question 14

Epithelia Structure

Answer 14

All consist on one or more layers of tightly packed cells, and little or no extracellular matrix between cells. Distinguishing features of an epithelium include a free apical surface and a fixed basal surface.

Specialized intracellular junctions join adjacent cells, and a thin basement membrane separates the basal surface from underlying connective tissue layers. Although epithelia lack blood vessels, many sensory nerve endings are present. Epithelia have a high regenerative capacity that allows them to maintain their function.

Question 15

Epithelia Function

Answer 15

To resist dehydration and injury from physical, chemical, and biological agents; to selectively regulate materials entering and leaving the body; to secrete products produced by epithelial glands; and to monitor the environment through specialized sensory nerve endings and specialized epithelial cells.

Question 16

Simple Epithelium

Answer 16

Epithelium composed of one layer of cells.

Question 17

Stratified Epithelium

Answer 17

Epithelium composed of two or more layers of cells.

Question 18

Squamous Epithelium

Answer 18

Epithelium where the apical cells are flat and thin.

Question 19

Cuboidal Epithelium

Answer 19

Epithelium where the apical cells have a somewhat square shape.

Question 20

Columnar Epithelium

Answer 20

Epithelium where the apical cells have a rectangular shape.

Question 21

Transitional Epithelium

Answer 21

Found in the urinary tract, is a stratified epithelium that gives the impression of “transitioning” from cuboidal when the epithelium is relaxed to squamous when it is stretched.

Question 22

Pseudostratified Epithelium

Answer 22

Found in the trachea for example. It’s a simple epithelium in which all cells contact the basal lamina but only some reach the apical surface. Cells are of varying heights and their nuclei are at different positions in the epithelium, giving the impression of stratification.

Question 23

Ciliated or Nonciliated

Answer 23

Some epithelial classes have specializations of the free surface of apical cells. Simple columnar epithelial cells in some organs have cilia, which are small, fignerlike, motile projections. Thus, simple columnar epithelium is subclassified as ciliated or nonciliated.

Question 24

Microvilli

Answer 24

In parts of the digestive and urinary tracts, epithelial cells involved in absorption have a dense collection of short cytoplasmic processes called microvilli on their free surface.

Microvilli are nonmotile and serve to increase surface area. Because the microvilli appear fuzzy in the light microscope, cells with numerous microvilli are said to have a brush border.

Question 25

Keratinized or Nonkeratinized

Answer 25

A stratified epithelium has either dead or living cells as the surface layer. The dead cells contain the protein keratin. Therefore, stratified squamous epithelium is subclassified as keratinized or nonkeratinized.

Question 26

Connective Tissue Functions

Answer 26

Its primary functions include structural support, binding structures together, fat storage, exchange of nutrients and metabolic waste, and defense and protection.

Question 27

Connective Tissue Components

Answer 27

Share three basic components: cells, protein fibers, and ground substance. Together, the protein fibers and ground substance form the extracellular matrix. The proportions of these components, in addition to different cells and protein fibers, help define the various categories of connective tissue.

Question 28

Connective Tissue Proper

Answer 28

Contains two subcategories: loose connective tissue and dense connective tissue.

Question 29

Loose Connective Tissue

Answer 29

Has abundant ground substance with scattered cells and loosely arranged protein fibers.

Can be subdivided into areolar, adipose, and reticular connective tissue.

Question 30

Dense Connective Tissue

Answer 30

Has abundant tightly packed fibers but relatively few cells and little ground substance.

Can be subdivided into: dense regular, dense irregular, and elastic connective tissue.

Question 31

Areolar Connective Tissue

Answer 31

Found in the subcutaneous layer and around organs. It has a gel-like ground substance, numerous blood vessels, and scattered cells known as fibroblasts.

Question 32

Adipose Connective Tissue

Answer 32

Found in subcutaneous tissue and around some organs. It is composed of closely-packed adipocytes (or fat cells).

Question 33

Reticular Connective Tissue

Answer 33

Forms the stroma (a connective tissue framework) of lymph nodes, the spleen, the thymus, and bone marrow. It’s composed of a network of branched collagen fibers, known as reticular fibers, with scattered fibroblasts and leukocytes (or white blood cells) embedded in a gel-like ground substance.

Question 34

Dense Regular Connective Tissue

Answer 34

Forms tendons and most ligaments. It’s composed of densely packed, parallel collagen fibers with fibroblasts between the layers. Little ground substance.

Question 35

Dense Irregular Connective Tissue

Answer 35

Found in the dermis, periostrum, and perichondrium, and the capsule of organs. This tissue is composed predominantly of randomly arranged collagen fibers with fibroblasts interspersed. There’s more ground substance than found in dense regular connective tissue.

Question 36

Elastic Connective Tissue

Answer 36

Found in walls of elastic arteries, the trachea and bronchi, and the vocal cords. This type of tissue is composed predominantly of branching elastic fibers, with fibroblasts in some spaces between the fibers.

Elastic fibers, formed by the protein elastin, stretch under tension and then return to their original shape when tension is released.

Question 37

Supporting Connective Tissue

Answer 37

Can be subdivided into cartilage and bone.

Question 38

Catilage

Answer 38

Has a semisolid extracellular matrix that allows flexibility.

Three types include hyaline, elastic, and fibrocartilage.

Question 39

Bone

Answer 39

Has the solid matrix which is more regid and provides greater support.

Two types, compact and spongy.

Question 40

Hyaline Cartilage

Answer 40

Most common type. Found on the articular surfaces of synovial joints; it also forms the cartilage of the larynx, trachea, and nose.

Chondrocytes (or mature catilage cells) are found within small spaces called lacunae that are scattered irregularly in the extracellular matrix. Collagen fibrils are present within the matrix but not visible in the light microscope. A perichondrium, a dense irregular connective tissue sheath, overlies most cartilage.

Question 41

Elastic Cartilage

Answer 41

Found in the external ear and in the epiglottis. It contains abundant elastic fibers, which form a web-like mesh around lacunae that contain chondrocytes. Like hyaline cartilage, elastic cartilage usually has perichondrium.

Question 42

Fibrocartilage

Answer 42

Found in intervertebral discs, the public symphysis, and the menisci of the knee joint. It contains nymerous irregular bundles of collagen fibers.

The sparse ground substance contains chondrocytes within lacunae that are frequently arranged in parallel rows. Unlike hyaline and elastic cartilage, fibrocartilage doesn’t have a perichondrium.

Question 43

Compact Bone

Answer 43

Usually forms the hard, outer shell of bones. Concentric rings of bone called lamellae form cylindrical structures, known as osteons. Each osteon has a central canal that connects to a network of tiny branching passageways called canaliculi.

The central canal and canaliculi contain blood vessels. Osteocytes or mature bone cells occupy lacunae, small spaces between neighboring lamellae.

Question 44

Spongy Bone

Answer 44

Also known as cancellous bone. Usually forms inside of bones. It does not contain osteons. Slender bony plates, called trabeculae, form a bony network.

The spaces between trabeculae contain bone marrow and blood vessels. Osteocytes are scattered throughout the trabeculae. The combination of compact and spongy bone allows bones to be both strong and lightweight.

Question 45

Fluid Connective Tissue

Answer 45

Represented by blood.

Question 46

Blood

Answer 46

The formed elements of blood specifically, its cells and cell fragments include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets. The watery ground substance of blood contains dissolved protein fibers.

Question 47

Muscle Tissue Function

Answer 47

Primary function is to produce movement of the skeleton or other tissues of the body. This results in body or organ movement, maintenance of posture, communication (such as facial expression and vocalization), control of body openings, and heat production.

Question 48

Muscle Tissue Types

Answer 48

Skeletal, cardiac, and smooth.

Question 49

Skeletal Muscle

Answer 49

Under voluntary control and is usually attached to bones via tendons or other connective tissues.

Question 50

Cardiac Muscle

Answer 50

Found only in walls of heart and is under involuntary control. Cardiac muscle fibers are short, branched cells with one or two centrally located nuclei and numerous mitochondria. These fibers exhibit striations and banding patterns similar to those seen in skeletal muscle fibers.

Question 51

Intercalated Discs

Answer 51

Cell junctions that are unique to cardiac muscle. Two specializations within these junctions link cardiac muscle fibers both electrically and mechanically.

Question 52

Smooth Muscle

Answer 52

Located in the wall of blood vessels, ducts, and organs and is under involuntary control.

They’re elongated, with tapered ends (fusiform-shaped), and contain a single, centrally-located nucleus. The myofilaments are not arranged in any specific pattern and, therefore, do not produce visible striations of form sacromeres.

Question 53

Epidermis

Answer 53

Outermost layer of the skin. Composed of kerantinized stratified squamous epithelial tissue.

Question 54

Dermis

Answer 54

Below the epidermis. Composed of dense irregular connective tissue.

Question 55

Hypothermis

Answer 55

Or subcutaenous tissue. Composed primarily of loose connective tissue such as adipose and areolar tissues.