Identify and distinguish between cilia and microvilli both in light and electron micrographs based on the type of epithelium in the light microscope and based upon structure at the EM level. Distinguish the basement membrane with the light microscope and its components, the basal lamina and the reticular lamina, in electron micrographs.
Recognize the junctional complex and its components, the zonula occludens, the zonula adherens and the macula adherens in electron micrographs. Distinguish between multicellular and unicellular glands. Distinguish between serous and mucous secretory glandular cells. Slide 18 Uterine tube.
Simple squamous epithelium can be studied by looking at cells which line blood and lymph vessels. These flattened cells are called endothelial cells. The nuclei are frequently found protruding into the lumen of the vessel.
Observe the numerous large blood vessels present in the periphery of this section. Simple squamous epithelium is also the outer covering of the uterine tube which is termed the mesothelium. Slide 35 Kidney. Simple cuboidal epithelium is prominent in the cortex and medulla of the kidney.
Proximal convoluted tubules , distal convoluted tubules , and collecting ducts are examples of simple cuboidal epithelium. Slide 52 Duodenum. Locate a large fingerlike projection at the surface of the organ this is an intestinal villus. Observe that the projection has an internal component and a surface. The surface of each villus is covered with simple columnar epithelium.
The free surface of these cells has very tiny projections called microvilli , which are specialized for absorption absorptive cells. Numerous mucus-secreting cells, known as goblet cells because of their shape, are dispersed between the absorptive cells. In the lab or on Hippocrates, locate an electron micrograph of an intestinal absorptive cell and compare the details which you see in your light microscope with those seen on electron micrographs.
Slide 13 Trachea. Note the ciliated, pseudostratified columnar epithelium lining the tracheal lumen. This epithelium is commonly referred to as "respiratory epithelium". Compare cilia with the microvilli on Slide The different types of epithelial tissues are characterized by their cellular shapes and arrangements: squamous, cuboidal, or columnar epithelia. Single cell layers form simple epithelia, whereas stacked cells form stratified epithelia.
Very few capillaries penetrate these tissues. Glands are secretory tissues and organs that are derived from epithelial tissues. Exocrine glands release their products through ducts.
Endocrine glands secrete hormones directly into the interstitial fluid and blood stream. Glands are classified both according to the type of secretion and by their structure. Merocrine glands secrete products as they are synthesized.
Apocrine glands release secretions by pinching off the apical portion of the cell, whereas holocrine gland cells store their secretions until they rupture and release their contents. In this case, the cell becomes part of the secretion. In observing epithelial cells under a microscope, the cells are arranged in a single layer and look tall and narrow, and the nucleus is located close to the basal side of the cell.
The specimen is what type of epithelial tissue? Which of the following is the epithelial tissue that lines the interior of blood vessels? Which type of epithelial tissue specializes in moving particles across its surface and is found in airways and lining of the oviduct? The structure of a tissue usually is optimized for its function. Describe how the structure of the mucosa and its cells match its function of nutrient absorption. The mucosa of the intestine is highly folded, increasing the surface area for nutrient absorption.
A greater surface area for absorption allows more nutrients to be absorbed per unit time. In addition, the nutrient-absorbing cells of the mucosa have finger-like projections called microvilli that further increase the surface area for nutrient absorption.
Skip to content The Tissue Level of Organization. Learning Objectives By the end of this section, you will be able to: Explain the structure and function of epithelial tissue Distinguish between tight junctions, anchoring junctions, and gap junctions Distinguish between simple epithelia and stratified epithelia, as well as between squamous, cuboidal, and columnar epithelia Describe the structure and function of endocrine and exocrine glands and their respective secretions.
The Epithelial Cell Epithelial cells are typically characterized by the polarized distribution of organelles and membrane-bound proteins between their basal and apical surfaces. Cell to Cell Junctions Cells of epithelia are closely connected and are not separated by intracellular material.
Types of Cell Junctions. The three basic types of cell-to-cell junctions are tight junctions, gap junctions, and anchoring junctions. Classification of Epithelial Tissues Epithelial tissues are classified according to the shape of the cells and number of the cell layers formed Figure. Cells of Epithelial Tissue. Simple epithelial tissue is organized as a single layer of cells and stratified epithelial tissue is formed by several layers of cells.
Goblet Cell. Stratified Epithelium A stratified epithelium consists of several stacked layers of cells. Summary of Epithelial Tissue Cells. Glandular Epithelium A gland is a structure made up of one or more cells modified to synthesize and secrete chemical substances.
Endocrine Glands The secretions of endocrine glands are called hormones. Exocrine Glands Exocrine glands release their contents through a duct that leads to the epithelial surface. Glandular Structure Exocrine glands are classified as either unicellular or multicellular. Types of Exocrine Glands. Modes of Glandular Secretion. These glands secrete oils that lubricate and protect the skin.
They are holocrine glands and they are destroyed after releasing their contents. New glandular cells form to replace the cells that are lost.
Chapter Review In epithelial tissue, cells are closely packed with little or no extracellular matrix except for the basal lamina that separates the epithelium from underlying tissue. Interactive Link Questions Watch this video to find out more about the anatomy of epithelial tissues. The inside of the mouth, esophagus, vaginal canal, and anus.
Review Questions In observing epithelial cells under a microscope, the cells are arranged in a single layer and look tall and narrow, and the nucleus is located close to the basal side of the cell. Critical Thinking Questions The structure of a tissue usually is optimized for its function. Previous: Types of Tissues. Which type of epithelial cell makes up the outermost layer of skin? Possible Answers: Ciliated pseudostratified epithelial cells.
Correct answer: Stratified squamous epithelial cells. Explanation : Keratinized stratified squamous epithelium makes up the outer layer of skin. Example Question 4 : Epithelium And Endothelium.
Possible Answers: Transitional epithelium. Correct answer: Simple epithelium. Explanation : Since capillaries are the site of diffusion of substances oxygen and carbon dioxide, for example , they need to have extremely thin walls. Example Question 5 : Epithelium And Endothelium. Where would one expect to find simple columnar epithelium with microvilli? Possible Answers: Thyroid gland. Correct answer: Small intestine.
Explanation : Since we are looking for a single layer of cells, we must rule out any area of the body that is subject to lots of friction. Example Question 6 : Epithelium And Endothelium. Where would one expect to find stratified squamous epithelium? Possible Answers: Skin. Correct answer: All of these. Explanation : All of these areas of the body are subject to lots of friction. Copyright Notice. View Tutors. Jordan Certified Tutor.
University of Alabama at Birmingham, Bachelor of Sc Katie Certified Tutor. Matilda Certified Tutor. London Metropolitan University, Bachelors, Biochemistry. Since stratified epithelium consists of two or more layers, the basal cells divide and push towards the apex, and in the process flatten the apical cells.
Stratified epithelia can be columnar, cuboidal, or squamous type. However, it can also have the following specializations:. In keratinized epithelia, the most apical layers exterior of cells are dead and lose their nucleus and cytoplasm. They contain a tough, resistant protein called keratin. This specialization makes the epithelium waterproof, and it is abundant in mammalian skin. The lining of the esophagus is an example of a non-keratinized or moist stratified epithelium.
Transitional epithelia are found in tissues that stretch and it can appear to be stratified cuboidal when the tissue is not stretched, or stratified squamous when the organ is distended and the tissue stretches. It is sometimes called the urothelium since it is almost exclusively found in the bladder, ureters, and urethra.
Learning Objectives Classify epithelial tissue by cell shape and layers. Key Points There are three principal cell shapes associated with epithelial cells: squamous epithelium, cuboidal epithelium, and columnar epithelium. There are three ways of describing the layering of epithelium: simple, stratified, and pseudostratified. Pseudostratified epithelium possesses fine hair-like extensions called cilia and unicellular glands called goblet cells that secrete mucus. This epithelium is described as ciliated pseudostratified epithelium.
Stratified epithelium differs from simple epithelium in that it is multilayered.
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