College of Osteopathic Medicine - Student Notes - PDF

College of Osteopathic Medicine Session Name: SF 02: Cell and Tissue Types Instructor: Dr. Marcos Garza Course: Scientific Foundations Learning Objectives Explain how Cell Theory and Stem Cell Theory apply to human physiology. Understand how the core concept of levels of organization applies...

College of Osteopathic Medicine Session Name: SF 02: Cell and Tissue Types Instructor: Dr. Marcos Garza Course: Scientific Foundations Learning Objectives Explain how Cell Theory and Stem Cell Theory apply to human physiology. Understand how the core concept of levels of organization applies to physiology. Analyze the structure-function relationship of tissues and organs based on their cellular and matrix compositions. Explain the physiological principle of physical properties of matter as it relates to cells and tissues. From Cell Theory to Stem Cells Cell Theory: Cells come from other cells, inheriting the same genetic material as their predecessors. Stem cells have 2 defining characteristics: Self-renewal: Stem cells make identical copies of themselves. Differentiation: Some of these stem cells suffer changes (mostly epigenetic) that lead them to have a more specialized behavior. Embryonal Stem Cells are the only true Totipotent Stem Cells. As they differentiate, more specialized (pluripotent) stem cells are made, such as mesenchymal, and hematopoietic stem cells. Embryological Origin of Cell Types The first major level of differentiation leads to the formation of 3 germinal layers: Ectoderm Mesoderm Endoderm Trans-differentiation across germinal layer doesn’t seem to happen naturally but is an area of active research. https://ecampusontario.pressbooks.pub/structureandfunction ofhumanbodymohawkedition/chapter/4-1-types-of-tissues/ Gartner Textbook of Histology (5 ed.). Fig. 6.1 Gartner Textbook of Histology (5 ed.). Fig. 6.1 Stevens & Lowes Human Histology. Fig. 1.3  Extracellular Tissue Cells Main Functions Matrix Epithelial Aggregated Small amount Lining of surface or polyhedral cells body cavities; glandular secretion Connective Several types of Abundant amount Support and fixed and protection of wandering cells tissues/organs Muscle Elongated Moderate amount Strong contraction; contractile cells body movements Nervous Elongated cells Very small amount Transmission of with extremely fine nerve impulses processes Junqueira's Basic Histology: Text and Atlas (17 Ed.). Tab 4.1 Levels of Organization The term “tissue” is often used for both simple (histological: epithelium, smooth muscle, dense connective, etc.) and compound (lung tissue, intestinal wall tissue, etc.). Organs are anatomically distinct groups of tissues that perform a specific function. In organs, simple tissue functions come together to provide richer, more complex functions. Stevens & Lowes Human Histology. Fig. 1.4 Organ Function Derives from Organization Consider the intestine’s tissues: Ciliated columnar epithelium for separation of food compartment and absorption. Connective tissue for shape, structure, and space. Smooth muscle tissue for motility of food. Vascular tissues (complex) for transport of nutrients. These tissues also convey physical characteristics: Epithelium is moderately impermeable to water and solutes. Connective tissue is soft (compliant). Muscle tissue is stronger and holds its shape (elastic). Some Physical Properties of Tissues (and Organs) Strength: Maximum stress that tissue can withstand before fail (tearing). Application: Tension before skin, muscles, or ligaments tear. Toughness: Ability to absorb energy and prevent fracture. Application: Force and angle of impact on bone fractures. Elasticity: Ability and force to return to its original shape. Application: Compression of blood by elastic arteries in arterial system leading to systolic and diastolic blood pressure. Compliance: Ease with which a tissue is deformed (changes shape or volume). Closely related to elasticity and often thought as its opposite (real opposite is called elastance, or stiffness). Application: ease with which lungs or bladder change volume. Consider Tissue Integration Take the duodenum, what tissues are found there? What are some of the functions of those tissues? How do those functions integrate to give the organ its functions?  Brief review of epithelial, connective, and muscle tissue functions and characteristics can be found in Blackboard.