HISTOLOGY Lab Objectives: Students should be able to... 1. Visually identify each class of tissue and examples within each class 2. Indicate the location (in the human body and/or organ) and function of each example. 3. Identify parts associated with specific examples of particular tissues 4. Identify the various tissues and structures associated with the integumentary system I. Overview Tissue - groups of cells with similar structure and function Four principle human tissue types: Epithelium (covering) Connective (support) Muscle (movement) Nervous (control) II. Epithelium Epithelia are classified according to their shape and arrangement. Shape: squamal cuboidal, columnar Arrangement: simple (pseudostratified) or stratified Types of epithelium Simple squamal, simple cuboidal, simple columnar, pseudostratified columnar, stratified squamal, stratified cuboidal, stratified columnar, and transitional Know all types of epithelium and their description, function, and location Epithelium that will be observed in the lab: Simple squamal lungs Key terms to know: alveoli and alveolar space In this image you see round spaces made up of individual flattened cells (simple squamal epithelium) linked together. Each round space is called an alveolus.
Simple squamal kidneys Key terms to know: Bowmans (Glomerular) capsule, renal corpuscle, renal tubule (nephron) In this image you see a round structure that contains a mass of cells insides. Under the microscope you will see that surrounding this round structure is a single layer of flat cells. The single layer in this tissue is called the Bowman s capsule and the inner mass of cells are called the Glomerulus Simple cuboidal kidneys Key terms to know: renal tubule (nephron) In this image you see circles composed of one layer of cube-shaped cells (simple cuboidal epithelium). The circles are kidney (renal) tubules. Inside each circle is space and is referred to as the lumen. Simple columnar intestine (and/or observe this tissue in the gall bladder) Key terms to know: goblet cells and cilia In this image you see tissue lined with a single layer of column-shaped cells (simple columnar epithelium)
Pseudostratified -(ciliated columnar) lungs Key terms to know: goblet cells and cilia In this image you see (on the left hand side) column-shaped cells that are staggered to give you the impression that there is more than one layer of cells. However, there is only one layer! In addition, the cells should have long wispy cell extensions called cilia. Stratified squamal tongue Key terms to know: keratinized and non-keratinized In this image you see a rounded structure called a papilla. On the top of this papilla are many layers of flat cells (stratified squamal epithelium). Also notice that there are clusters of lighter cells on either side of the papilla. These clusters are called taste buds. Stratified squamal skin Key terms to know: keratinized and non-keratinized In this image you see many layers of flat cells (stratified squamal epithelium)
Transitional urinary bladder In this image you see many layers of cells but do not see only one type of cell shape. Rather, you can see some that are all three epithelial cells shapes and even some round or triangular looking cells! III. Connective Tissue Connective tissue is classified based upon the presence of a cell and the type of extra-cellular matrix (ground substance and fibers) Classes of connective tissue: loose, dense, cartilage, and other Loose: areolar, adipose, and reticular Dense: dense regular and dense irregular Cartilage: hyaline, elastic, and fibrocartilage Other: bone and blood Know all types of connective tissue and their description, function, and location Connective tissue that will be observed in lab: Areolar - gell-like matrix contains all three fiber (collagen, elastin, and reticular); cell type = fibroblast; widely distributed under epithelium; and forms lamina propria and wraps and cushions organs.
Adipose - matrix contains sparse amount of all three fibers; adipocytes have a flattened nucleus as a result of fat droplets contained inside of cell; used as fuel resource. Reticular - reticular fibers w/ reticular cells in loose ground substance; found in lymph nodes, bone marrow, and spleen; fibers form internal skeleton that supports other cell types Dense regular - fibroblasts with collagen fibers; forms ligaments (connecting bone to bone), tendons (connecting bone to muscle), and aponeurosis (connecting muscle to muscle).
Dense irregular irregularly arranged collagen fibers with fibroblast; found in the dermis of the skin and fibrous joint capsules; withstands tension and provides strength. Hyaline - chondroblasts produce matrix with few collagen fibers, chrondrocytes located within lacunae (spaces); found in ribs, nose, trachea, and the larynx; supports and reinforces. Elastic - chondroblasts produce matrix with elastic fibers; supports external ear; maintains shape and structure.
Fibrocartilage - matrix similar to hyaline but less firm and also contains more and thicker collagen fibers; component of intervertebral discs; gives tensile strength. (slides may not be available) Bone (osseous) - hard, calcified matrix containing many collagen fibers; osteocytes lie in lacunae; high vascularized; forms skeletal system; provides support and protection as well as blood production. Obvious haversian (central) canal with many lamellae and canaliculi present. Blood - Erythrocytes (RBCs), Leukocytes (WBCs) and cell fragments called Thrombocytes (Platelets); located in blood vessels; transports respiratory gases, wastes, nutrients, etc...
IV. Muscular Tissue Highly vascularized muscular tissue is comprised of elongated cells (called fibers) containing myofilaments (actin and myosin proteins). There three types of muscular tissue: skeletal, cardiac, and smooth Muscle tissue that will be observed in lab: Skeletal - long, cylindrical, multinucleate cells with striations (specific arrangement of actin and myosin); attached to skeleton and skin; under voluntary control; provides movement. Cardiac - branching, uninucleate, striated cells with junctions (intercalated discs); located in the walls of the heart; is under involuntary control; propels blood (circulation). Smooth - spindle-shaped, uninucleate cells without striations; found in the walls of hollow organs; under involuntary control; propels substances.
V. Nervous Tissue Nervous tissue (nervous system) conducts electrical impulses and has integrative functions. Nervous tissue is composed of neurons which are branching cells located in the brain, spinal cord, and nerves. Neurons transmit electrochemical signals from sensory receptors to effectors. Neuroglia are cells surrounding neurons and help to feed, support, and protect. Neurons are composed of dendrites, a cell body, and an axon. Nervous tissue that will be observed in lab: Nervous Tissue In this view you see a neuron with its cell extensions. What you cannot tell is whether or not the cells extensions are dendrites or an axon. VI. Use of the Integumentary System Skin is one component of the integumentary system Human skin is composed of many tissue types. Using slides provided, identify the various tissue types: stratifed squamous epithelium, dense irregular connective, adipose, and stratified cuboidal. In addition, please identify the two layers of the dermis (epidermis and dermis), the hypodermis (subcutaneous), and the following accessory structures associated with the skin: hair follicle and shaft, sebaceous gland, stratum corneum, stratum basale (if visible). Using the skin models provided, identify the following: epidermis, dermis, hypodermis, stratum corneum and basale, hair shaft and follcile, sebaceous and eccrine (sudoriferous) gland, Pacinian corpuscle, Meissner's corpuscle, dermal papillae, arrector pili, arteries and veins, and lymph vessels. Models used in lab: