Histology
Study of Tissues
Unit 3 Synopsis
In this unit, you will learn the types of tissues and cells we will encounter during this class. We will utilize microscopes to have hands-on experience in tissue identification and proper utilization of laboratory equipment.
Microscope
General directions for microscope use
Familiarize yourself with microscope anatomy and the function of each part. You will be expected to set up and adjust the microscope for histological identification.
Review Video:
Textbook: 3.1: Introduction to the Microscope - Biology LibreTexts
Please note that although on the video, she started on the 100x power, you should always start with the lowest setting, get the coarse focus done then can move to the next power. This is the easiest way to get the clearest view.
We will practice this in class.
Cell Identification and Classification
Histological classifications
There are 4 major classifications of tissues: epithelial, connective, muscle, and nervous.
Epithelial Tissue:
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Anatomy: One or more layers of densely arranged cells, very little extracellular matrix. Form sheets or glands
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Physiology: Covers and protects the body surface, lines body cavities; movement of substances, including absorption, secretion, and excretion; glandular activity
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Examples: Skin, lining of respiratory, digestive, urinary, and reproductive tracts, glands of the body
Connective Tissue:
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Anatomy: sparsely arranged cells surrounded by a large proportion of extracellular matrix, often containing structural fibers
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Physiology: Supports body structures, transports substances throughout the body
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Examples: bones, articulations, tendons, ligaments, fat, blood
Muscle Tissue:
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Anatomy: long fiber-like cells, sometimes branched, capable of pulling loads, extracellular fibers sometimes hold muscle fiber together
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Physiology: produces body movements, produces movements of organs such as the stomach and heart, produces heat
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Examples: cardiac, skeletal muscle (biceps, quadriceps, gastrocnemius), smooth muscle (walls of hollow organs such as stomach
Nervous Tissue:
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Anatomy: Mixture of many cells, neurons, and neuroglia
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Physiology: Communication between body parts, integration and regulation of bodily functions
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Examples: brain, spinal cord, sensory organs
Classification of Epithelial Tissue
Cell Shape Classifications
Squamous - flat
Cubodial - cube
Columnar - column
Pseudostratified columnar- appears to be multiple layers, but is a single layer of columnar cells
Number of layers Classifications
Simple - one layer
Stratified - multiple layers
Pseudostratified - one layer that appears to be more than one
When identifying the classification, the cell shape is determined by the top layer
Specializations
Keratinization: keratin is a special, waterproofing protein that can be found on the epidermis
Cilia: Small, hairlike structures that allow for the movement of materials around a cell
Goblet cells: specialized simple columnar cells that produce mucus
Transitional epithelium (urothelium)