Muscle tissue, Nervous tissue (lab 6)

Nervous and Muscular Tissues—Excitable Tissues

-Excitability—a characteristic of all living cells Developed to highest degree in nervous and muscular tissues -Membrane potential—electrical charge difference (voltage) that occurs across the plasma membranes is the basis for their excitation -Respond quickly to outside stimulus by means of changes in membrane potential -Nerves: changes result in rapid transmission of signals to other cells Muscles: changes result in contraction, shortening of the cell

skeletal muscles

-Exerts mechanical force, generates a lot heat. -Long, threadlike cells called muscle fibers -Most attach to bone -Exceptions: in tongue, upper esophagus, facial muscles, some sphincter muscles (ringlike or cufflike muscles that open and close body passages) -Contains multiple nuclei adjacent to plasma membrane -Striations—alternating dark and light bands Voluntary—conscious control over skeletal muscles

cardiac muscle

-Limited to the heart -Myocytes or cardiocytes are shorter, branched, and notched at ends -Contain one centrally located nucleus surrounded by light-staining glycogen -Intercalated discs join cardiocytes end to end -Provide electrical and mechanical connection Striated and involuntary (not under conscious control)

muscle tissue characteristics

-Muscular tissue—elongated cells that are specialized to contract in response to stimulation -Primary job is to exert physical force on other tissues and organs -Creates movements involved in body and limb movement, digestion, waste elimination, breathing, speech, and blood circulation Important source of body heat -Three types of muscle: skeletal, cardiac, and smooth (exerts mechanical force) generates a lot heat Controlled by nervous system and have rich blood and nerve supply

neurons

A nerve cell; an electrically excitable cell specialized for producing and transmitting action potentials and secreting chemicals that stimulate adjacent cells.

axon

A process of a neuron that transmits action potentials; also called a nerve fiber. There is only one axon to a neuron, and it is usually much longer and much less branched than the dendrites.

neuroglia (glial)

All cells of nervous tissue except neurons; cells that perform various supportive and protective roles for the neurons.

Smooth muscle

Lacks striations and is involuntary Relatively short, fusiform cells (thick in middle, tapered at ends) One centrally located nucleus Visceral muscle—forms layers of digestive, respiratory, and urinary tract: propels contents through an organ, regulates diameter of blood vessels

dendrite

Process of a neuron that receives information from other cells or from environmental stimuli and conducts signals to the soma. Dendrites are usually shorter, more branched, and more numerous than the axon and are incapable of producing action potentials

Muscle tissue types

Smooth, Cardiac and Skeletal

neurosoma (soma)

cell body, that houses the nucleus and most other organelles.

Neuron parts

neurosoma (cell body) dendrites axon (nerve fiber)

Nervous tissue

tissue composed of neurons and neuroglia. Characteristics are neurons are excitable conduction of signals by traveling electrical signals Neuroglial (glial)