Essay on Study Guide

Submitted By dymondjbb
Words: 4599
Pages: 19

Saladin 5e Extended Outline

Chapter 5

Histology

I. The Study of Tissues (pp. 152–154) A. Histology is the study of tissues and how they are arranged into organs. (p. 152) B. A tissue is a group of similar cells and cell products that arise from the same region of the embryo and work together to perform a specific role. (p. 152) 1. The four primary tissues are epithelial, connective, nervous, and muscular tissue. (Table 5.1) 2. These tissues differ in the types and functions of their cells, the characteristics of the matrix around the cells, and the relative amount of space cells and matrix occupy. 3. The matrix is composed of fibrous proteins and a clear gel known as ground substance, tissue fluid, extracellular fluid, interstitial fluid, or tissue gel. C. Human development begins with a single cell, the fertilized egg, which divides to produce scores of identical, smaller cells. (p. 153) 1. The first tissues are organized into three strata called the primary germ layers: ectoderm, mesoderm, and endoderm. 2. The ectoderm is an outer layer that gives rise to the epidermis and nervous system. 3. The endoderm is an inner layer that gives rise to the mucous membranes of the digestive and respiratory tracts and to digestive glands. 4. The mesoderm is between the other two layers and eventually turns into a tissue called mesenchyme; this gives rise to muscle, bone, blood, and some other tissues. D. Tissue specimens are preserved in a fixative and cut into very thin slices called histological sections only one or two cells thick, and then stained to bring out detail. (pp. 153–154) 1. Sectioning reduces a three-dimensional structure to a two-dimensional slice. (Fig. 5.1) a. An object may look different when cut in different planes of section. b. A particular section may miss some structures. 2. A tissue cut in the long direction is a longitudinal section (l.s.); a cut perpendicular produces a cross section (c.s. or x.s.)or transverse section (t.s.); a cut at an angle is an oblique section. (Fig. 5.2) 3. Liquid tissues and soft tissues may be prepared as smears in which the tissue is rubbed or spread across the slide. 4. Membranes and webby tissues are sometimes laid out on a slide as a spread. (Fig. 5.14)
II. Epithelial Tissue (pp. 153–160) A. Epithelial tissue is a flat sheet of closely adhering cells, one or more cells thick, with the upper surface usually exposed to the environment or to an internal space. (p. 154–155) 1. Epithelium covers the body surface, lines body cavities, forms the external and internal linings of many organs, and constitutes most gland tissue. 2. Epithelium almost always lies on a layer of loose connective tissue and is dependent on this tissue’s blood supply for nutrients and waste removal. 3. The basement membrane anchors an epithelium to the underlying connective tissue. 4. Epithelia are classified into two broad categories: simple and stratified. a. In a simple epithelium, every cell touches the basement membrane. b. In a stratified epithelium, some cells rest on top of other cells and to not contact the basement membrane. (Fig. 5.3) B. Generally, a simple epithelium has only one layer of cells. (p. 155) (Table 5.2) (Figs. 5.4, 5.5, 5.6, 5.7) 1. Three types of simple epithelia are named for the shape of their cells: simple squamous (scaly), simple cuboidal, and simple columnar. 2. In the fourth type, pseudostratified columnar epithelium, shorter cells do not reach the free surface, but all cells reach the basement membrane. 3. Simple columnar and pseudostratified columnar epithelia often produce mucus, which is secreted by goblet cells. C. Stratified epithelium…