CHP5 Histology

E brain foot ie muscle tissue muscle muscle tissue

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Unformatted text preview: & minimizing small blood loss, secreting growth factors to promote vessel growth & maintenance maintenance Excitable tissues= nervous & muscle nervous muscle • Differences in electrical charge (voltage) across plasma Differences membrane results in excitation of cell (= membrane potential) potential • Action potential in nerves transmit signals & muscle contract Nervous Tissue Nervous Nervous tissue= neurons, neuroglia (glial cells) that protect neurons that & assist neurons assist • Brain, spinal cord, nerves, ganglia • Soma (cell body)= nucleus & organelles, integrates signals (input) from dentrites (input) • Dendrites= branching processes on soma that receive branching signals from other cells & transmit to soma signals • Axon= single, long nerve fiber that sends output message single, (AP) to other cells • Axon lengths vary, some > meter Axon (i.e., brain-foot) (i.e., Muscle tissue Muscle Muscle tissue= elongated cells specialized to contract to exert elongated physical force on tissues/organs physical 3 types= skeletal, cardiac, smooth Skeletal- llong, cylindrical, unbranched cells (muscle fiber); ong, multiple nuclei found along plasma membrane multiple • ‘Striated’ due to overlapping thick-thin filaments (myosin, Striated’ actin) actin) • ‘Voluntary’ control over muscle cells • Skeletal muscles, tongue, esophagus, voluntary sphincters of Skeletal lips, eyelids, urethra, anus lips, Muscle tissue (cont.) Muscle Cardiac- heart (& slightly into vessels); striated w/ shorter, heart branched cells (= myocytes) branched • 1 nucleus, surrounded by glycogen • Intercalated discs join cells together & have electrical & mechanical connections mechanical Cardiac tissue is involuntary Cardiac involuntary Smooth- llacks striations, short overlapping fusiform cells, 1 Smooth acks nucleus • Most visceral muscle= layers of tissue in walls of digestive, Most respiratory, urinary tracts, bld vessels, uterus, etc. respiratory, • Also in iris, in skin @ hair follicles; sphincters of Also urethra/anus urethra/anus • Involuntary; some smooth muscle forms adjacent layers of some circular/longitudinal tissue (i.e., esophagus, small intestine) circular/longitudinal • Peristalsis Intercellular junctions Intercellular Intercellular junctions= anchor cells to each other, help resist anchor stress, communicate w/ each other stress, • 3 types of junctions- tight, desmosomes, & gap types tight desmosomes gap (communicating) (communicating) Junctions Junctions Tight= completely encircles an epithelial cell near apex & joins completely it tightly w/ adjacent cells it • Proteins in membranes form ‘zipper’ of complementary Proteins grooves & ridges to seal intercellular space grooves • Prevents digestive juices from seeping btw cells & breaking Prevents down cells in stomach & intestines; keeps intestinal bacteria out of tissues; keeps movement of digested nutrients thru & not btw cells not Desmosomes= a ‘‘snap’ or ‘patch’ that holds cells together in snap’ order to resist mechanical stress order • Common in epidermis, cardiac muscle, cervix • Gap btw adjacent cells houses fine mesh of glycoprotein Gap filaments that terminate in a thickened plaque on the cell surface surface • Intermediate filaments form in cytoskeleton & penetrate plaque to Intermediate form a ‘J’ form Junctions (cont.) Junctions De...
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