Bio 131 Chapters 4&5 Study Guide 1. Individual body cells are specialized. 2. What is a tissue? A group of cells similar in structure that perform common or related function 3. What is histology? Histology is a subsection of microscopic anatomy. It is the study of tissues. 4. What are the four basic tissue types? a. Epithelial Tissue b. Connective Tissue c. Muscle Tissue d. Nervous Tissue Epithelial Tissue 5. What is epithelial tissue (epithelium)? A sheet of cells that covers body surfaces of cavities 6. What are the two main forms of epithelium? a. Covering and lining epithelia i. Found on external and internal surfaces (ex. skin) b. Glandular epithelia i. Secretory tissue in glands (ex. salivary glands) 7. What are the main functions of epithelia? a. Protection, absorption, filtration, excretion, secretion, and sensory reception 8. What are the five distinguishing characteristics of epithelial tissue? a. Polarity b. Specialized contacts c. Supported by connective tissues d. Avascular, but innervated e. Regeneration 9. Tell me about polarity. a. Cells have polarity (a top and a bottom) b. Apical surface is the upper free side and is exposed to the surface or cavity i. Most apical surfaces are smooth, but some have specialized fingerlike projections called microvilli. c. Basal surface is the lower attached side and faces inwards toward body i. Attaches to the basal lamina, an adhesive sheet that holds basal surface of epithelial cells to underlying cells d. Both differ in structure and function. 10. Tell me about specialized contacts. a. Epithelial tissues need to fit closely together. i. Many form continuous sheets. b. Specialized contact points bind adjacent epithelial cells together. i. Lateral contacts include tight junctions and desmosomes. 11. Tell me about connective tissue support. a. All epithelial cells are supported by connective tissue. b. The reticular lamina is deep to the basal lamina and consists of a network of collagen fibers. c. The basement membrane is made up of the basal and reticular lamina. It reinforces the epithelial sheet and resist stretching and tearing. It also defines the epithelial boundary. * i. *Exceptions include cancerous cells which can invade boundaries resulting in metastasis. 12. Tell me about avascular, but innervated. a. No blood vessels are found in epithelial tissue. i. Must be nourished by diffusion from underlying connective tissues. b. Epithelia are supplied by nerve fibers. 13. Tell me about regeneration. a. Epithelial cells have high regenerative capacities. b. It is stimulated by a loss of apical-basal polarity and broken lateral contacts. c. Some cells are exposed to friction or hostile substances, resulting in damage. i. They must be replaced. ii. Replacement requires adequate nutrients and cell division. 14. All epithelial tissues have two names. a. The first name indicates the number of cell layers. i. Simple epithelia are a single layer thick. ii. Stratified epithelia are two or more layers thick and involved in protection (ex. skin). b. The second name indicates the shape of the cells. i. Squamous cells are flattened and scale-like. ii. Cuboidal cells are box-like, cubes. iii. Columnar cells are tall and column-like. c. In stratified epithelia, shape can vary in each layer, so the cell is named according to the shape in the apical layer. 15. Simple epithelia is involved in absorption, secretion, or filtration. 16. Tell me about simple squamous epithelium. a. Cells are flattened laterally and cytoplasm is sparse. b. They function where rapid diffusion is priority (ex. kidney, lungs) 17. Two special simple squamous epithelia are based on locations. a. Endothelium is the lining of lymphatic vessels, blood vessels, and the heart. b. Mesothelium is the serous membranes in the ventral body cavity. 18. Tell me about simple cuboidal epithelium. a. It is a single layer of cells. b. They are involved in secretion and absorption. c. They form the walls of the smallest ducts of glands and many kidney tubules. 19. Tell me about simple columnar epithelium. a. They are single layers of tall, closely packed cells. b. Some layers contain mucus-secreting goblet cells. c. They are involved in the absorption and secretion of mucus, enzymes, and other substances. i. Ciliated cells move mucus. d. Found in the digestive tract, gallbladder, ducts of certain glands, bronchi, and uterine tubes. 20. Tell me about pseudostratified columnar epithelium. a. Cells vary in height and appear to be multi-layered and stratified, but tissue is actually single layered simple epithelium i. Pseudo means false ii. Many cells are ciliated. b. They are involved in secretion, particularly of mucus, and also in movement of mucus by ciliary sweeping action. c. Located mostly in upper respiratory tracts, ducts of large glands, and tubules in testes. 21. Stratified epithelial tissues involve two or more layers of cells. a. New cells regenerate from below. i. Basal cells divide and migrate toward surface. 22. Tell me about stratified squamous epithelium. a. It is the most widespread of stratified epithelia. b. The free surface is squamous, with deeper cuboidal or columnar layers. c. Located in areas of high wear and tear (ex. skin). d. Keratinized cells found in skin; nonkeratinized cells are found in moist linings. 23. Tell me about stratified cuboidal epithelium. a. They are quite rare. b. They are found in some sweat and mammary glands. c. Typically only two cell layers thick. 24. Tell me about stratified columnar epithelium. a. They also have very limited distribution in the body. b. Small amounts found in pharynx, male urethra, and lining some glandular ducts. c. Usually occurs at transition areas between two other types of epithelia. d. Only the apical layer is columnar. 25. Tell me about transitional epithelium. a. Forms the lining of hollow urinary organs. i. Found in the bladder, ureters, and urethra. ii. Basal layer cells are cuboidal and columnar. iii. Ability of cells to change shape when stretched allows for increased flow of urine, and in the case of the bladder, more storage space. 26. Tell me about glands. a. A gland is one or more cells that make and secrete an aqueous fluid called a secretion. b. Glands are classified by the site of product release. i. Endocrine are internally secreting (ex. hormones). ii. Exocrine are externally secreting (ex. sweat) c. There are two types of relative numbers of cells forming the gland. i. Unicellular (ex. goblet cells) ii. Multicellular (ex. salivary) 27. Tell me about endocrine glands. a. They are ductless. i. Secretions are not released into a duct. They are released into surrounding interstitial fluid, which is picked up by the circulatory system. b. They secrete (by exocytosis) hormones, which are messenger chemicals that travel through lymph or blood to their specific target organs. c. Target organs respond in some characteristic way 28. Tell me about exocrine glands. a. Secretions are released onto body surfaces, such as skin, or into body cavities. b. They are more numerous than endocrine glands. c. They secrete products into ducts. d. Examples include mucous, sweat, oil, and salivary glands. e. They can be unicellular or multicellular. 29. Tell me about unicellular exocrine glands. a. The only important unicellular glands are mucous cells and goblet cells. b. They are found in the epithelial linings of intestinal and respiratory tracts. c. All produce mucin, a sugar-protein that can dissolve in water to form mucus, a slimy, protective, lubricating coating 30. Tell me about multicellular exocrine glands. a. Multicellular exocrine glands are composed of a duct and a secretory unit. b. They are usually surrounded by supportive connective tissue that supplies blood and nerve fibers to glands i. Connective tissue can form capsule around gland, and also extend into gland, dividing it into lobes. c. Classified by structure and mode of secretion. d. Tell me about the structure of multicellular exocrine glands. i. Simple exocrine glands have unbranched ducts. ii. Compound glands have branched ducts iii. In a tubular gland, secretory cells form a duct; however, in an alveolar gland, secretory cells form sacs. 1. Tubuloalveolar glands have both types. e. Modes of secretion by multicellular exocrine glands. i. Merocrine: most secrete products by exocytosis as secretions are produced (ex. sweat, pancreas) ii. Holocrine: accumulate products within, then rupture (ex. sebaceous oil glands) iii. Apocrine: accumulate products within, but only apex ruptures; whether this type exists in humans is controversial (ex. possibly in mammary cells) Connective Tissue 1. What is connective tissue? The most abundant and widely distributed of primary tissues 2. What are the major functions of connective tissue? a. Binding and support, protecting, insulating, storing reserve fuel, and transporting substances (blood) 3. What three characteristics make connective tissue different from other primary tissue? a. They all have common embryonic origin; all arise from mesenchyme tissue as their tissue of origin. b. They have varying degrees of vascularity (cartilage is avascular, bone is highly vascularized). c. Cells are suspended/embedded in extracellular matrix (ECM) (protein-sugar mesh) i. The matrix supports cells so they can bear weight, withstand tension, and endure abuse. 4. What are the three main elements of connective tissues? a. Ground substance: an unstructured gel-like material that fills space between cells i. It is a medium through which solutes diffuse between blood capillaries and cells. ii. Components of ground substance 1. Interstitial fluid 2. Cell adhesion proteins (“glue” for attachment) 3. Proteoglycans (sugar proteins), made up of protein core and large polysaccharides a. Example: chondroitin sulfate and hyaluronic acid 4. Water is also trapped in varying amounts, affecting viscosity of ground substance b. Fibers: three types of fibers that provide support i. Collagen is the strongest and most abundant type. It is tough and provides high tensile strength. ii. Elastic Fibers are networks of long, thin, elastin fibers that allow for stretch and recoil. iii. Reticular are short, fine, highly branched collagenous fibers (different chemistry and form from collagen fibers). Branching forms networks that offer more “give”. c. Cells: two types of cells, “blast” cells and “cyte” cells i. “Blast” cells are an immature form of cells that actively secretes ground substance and ECM fibers. 1. Fibroblasts are found in connective tissue proper 2. Chondroblasts are found in cartilage 3. Osteoblasts are found in bone 4. Hematopoietic stem cells are found in bone marrow ii. “Cyte” cells are mature, less active forms of “blast” cells that now become part of and help to maintain the health of the matrix. iii. iv. Fat cells (Adipocytes) store nutrients. White blood cells (Leukocytes) make tissues that respond to injury. There are different types such as neutrophils, eosinophils, and lymphocytes. v. Mast cells initiate local inflammatory responses against foreign microorganisms that they detect. vi. Macrophages are phagocytic cells that “eat” dead cells and microorganisms, as well as functioning in the immune system. d. The first two elements (ground substance and fibers) together make up the extracellular matrix. e. Composition and arrangement of these three elements vary considerably in different types of connective tissues. 5. What are the four main classes of connective tissues? i. Connective tissue proper ii. Cartilage iii. Bone iv. Blood Connective Tissue Proper 6. Tell me about connective tissue proper. a. Connective tissue proper consists of all connective tissues except bone, cartilage, and blood. b. There are two subclasses of connective tissue proper. i. Loose connective tissue ii. Dense connective tissue 7. Tell me about loose connective tissues. a. There are three types: Areolar, Adipose, and Reticular. 8. Tell me about areolar connective tissue. a. It is the most widely distributed connective tissue. b. It supports and binds other tissues. c. It is the universal packing material between other tissues. d. It contains fibroblasts that secrete loose arrangement of mostly collagen fibers e. Loose fibers allow for increased ground substance, which can act as a water reservoir by holding more interstitial fluid. f. Macrophages and fat cells are contained in spaces. 9. Tell me about adipose tissue. a. The first type is white fat. i. This is similar to areolar tissue, but has greater nutrient storage. ii. Cells are called adipocytes. iii. Scanty matrix. iv. It is richly vascularized. v. It functions in shock absorption, insulation, and energy storage. b. The second type is brown fat. i. Brown fat uses lipid fuels to heat bloodstream rather than to produce ATP, as does white fat. 10. Tell me about reticular connective tissue. a. It resembles areolar tissue, but fibers are thinner reticular fibers. b. Fibroblast cells are called reticular cells. i. They secrete reticular fibers made up of thin collagen. c. Reticular fibers form a mesh-like stroma that acts as a support for blood cells in lymph nodes, spleen, and bone marrow. 11. Tell me about dense connective tissue. a. There are three types: dense regular, dense irregular, and elastic. 12. Tell me about dense regular connective tissue. a. It has a very high tensile strength, meaning it can withstand high tension and stretching. b. Closely packed bundles of thick collagen fibers run parallel to the direction of the pull. i. The fibers appear as white structures. ii. The fibers are slightly wavy, so they stretch a little. c. Fibroblasts manufacture collagen fibers and ground substance. d. Dense regular connective tissue has very few cells and ground substance, it is mostly made of fibers. e. It is very poorly vascularized. i. Ex. tendons and ligaments 13. Tell me about dense irregular connective tissue. a. It has the same elements as dense regular, but bundles of collagen are thicker and irregularly arranged. b. Dense irregular forms sheets rather than bundles. c. It resists tensions from many directions. d. It can be found in dermis, fibrous joint capsules, and fibrous coverings of some organs. 14. Tell me about elastic connective tissue. a. Some ligaments are very elastic. i. Ex. ligaments connecting adjacent vertebrae must be very elastic. b. It is also found in the walls of many large arteries. i. Ex. arteries need to stretch when blood enters and recoil to push blood out Cartilage 15.