The slides in this section are designed to provide a basic histology review related to topics introduced in the PhysioEx lab simulations and in your anatomy and physiology textbook. From the PhysioEx main menu, select Histology Tutorial. The opening screen should appear after a few seconds. The Sort by menu is located at the top left. Click on the white drop-down menu and select “Histology Review” from the list. You will note that the slides in the histology module are grouped in the following folders: Skeletal muscle slides Nervous tissue slides Endocrine tissue slides Cardiovascular tissue slides Respiratory tissue slides Digestive tissue slides Renal tissue slides Select the group of slides you wish to view, and then refer to the relevant worksheet in this section for a step-by-step tutorial. For example, if you would like to review the skeletal muscle slides, click on the Skeletal muscle slides folder, and then turn to the next page of this lab manual for the worksheet entitled Skeletal Muscle Tissue Review to begin your review. You will have the option of viewing slides with or without labels by clicking the On/Off buttons at the bottom left of the viewer. Since the slides in this module have been selected for their relevance to topics covered in the PhysioEx lab simulation, it is recommended that you complete the worksheets along with a related PhysioEx lab. For example, you might complete the Skeletal Muscle Tissue worksheet right before or after your instructor assigns you Exercise 2, the PhysioEx lab simulation on Skeletal Muscle Physiology. For additional histology review, turn to page 121.
Skeletal Muscle Tissue Review
From the PhysioEx main menu, select Histology Review Supplement. When the screen comes up, click Select an Image Group. From Group Listing, click Skeletal muscle slides. To view slides without labels, click the Labels Off button at the bottom right of the monitor. Click slide 1. Skeletal muscle is composed of extremely large, cylindrical multinucleated cells called myofibers. The nuclei of the skeletal muscle cell (myonuclei) are located peripherally just subjacent to the muscle cell plasmalemma (sarcolemma). The interior of the cell is literally filled with an assembly of contractile proteins (myofilaments) arranged in a specific overlapping pattern oriented parallel to the long axis of the cell. Click slides 2, 3. Sarcomeres are the functional units of skeletal muscle. The organization of contractile proteins into a regular end-to-end repeating pattern of sarcomeres along the length of each cell accounts for the striated, or striped, appearance of skeletal muscle in longitudinal section. Click slide 4. The smooth endoplasmic reticulum (sarcoplasmic reticulum), modified into an extensive network of membranous channels that store, release, and take up the calcium necessary for contraction, also functions to further organize the myofilaments inside the cell into cylindrical bundles called myofibrils. The stippled appearance of the cytoplasm in cells cut in cross section represents the internal organization of myofilaments bundled into myofibrils by the membranous sarcoplasmic reticulum. What is the functional unit of contraction in skeletal muscle?
Click slide 5. The neural stimulus for contraction arises from the axon of a motor neuron whose axon terminal comes into close apposition to the muscle cell sarcolemma. Would you characterize skeletal muscle as voluntary or involuntary?
Name the site of close juxtaposition of an axon terminal with the muscle cell plasmalemma.
Skeletal muscle also has an extensive connective tissue component that, in addition to conducting blood vessels and nerves, becomes continuous with the connective tissue of its tendon. The tendon in turn is directly continuous with the connective tissue covering (the periosteum) of the adjacent bone. This connective tissue continuity from muscle to tendon to bone is the basis for...