PCB 3703C 3. Tissues notes.docx - ● Tissues: Collection of...

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Tissues:Collection of structurally similar cells with related function. The entire body iscomposed of only 4 major types of tissues.1. Muscle:Contractile tissue of the body and is derived from the mesodermallayer of embryonic germ cells. It’s classified as skeletal, cardiac, or smoothmuscle, and its function is to produce force and cause motion, either locomotionor movement within internal organs. Full of mitochondria because of ATP andactive transport.Skeletal muscle:Type of striated muscle, usually attached to the skeleton.Skeletal muscles are used to create movement, by applying force to bonesand joints; via contraction.Long, striated cells with multiple nuclei, contracts for voluntarymovementsSmooth muscle:Found within the walls or organs and structure such as theesophagus, stomach, intestine, bronch, uterus, urethra, bladder, and bloodvessels, and unlike skeletal muscle, smooth muscle is not under consciouscontrol.Long, spindle-shaped cells, each with a single nucleus, propulsionof substances along internal passageways.Cardiac muscle:Is also an “involuntary muscle” but is a specialized kindof muscle found only within the heart.Branching, striated cells fused as plasma membrane, pumping ofblood in the circulatory system.Smooth and cardiac muscle is controlled by the autonomic nervoussystem.2. Nervous:Nervous Tissueis specialized to react to stimuli and to conduct impulsesto various organs in the body which bring about a response to the stimulus.Nerve Tissue (as in the brain, spinal cord and peripheral nerves thatbranch throughout the body) are all made up of specialized nerve cellscalledneurons (covered by the fatty myelin sheath).Neurons areeasily stimulatedandtransmit impulses very rapidly.A nerve is made up of many neurons bound together by connectivetissue. A sheath of dense connective tissue, theepineuriumsurrounds the nerve.This sheath penetrates the nerve to form theperineuriumwhichsurrounds bundles of nerve fibers, blood vessels of various sizescan be seen in the epineurium.Theendoneurium,which consists of a thin layer of looseconnective tissue, surrounds the individual nerve fibers.
3. EpithelialEpithelial tissue and glandsEpitheliaare sheets of cells that cover body surfaces and cavities.Their functions are to protect the body (such as skin) or sensoryreception such as the olfactory epithelial cells, absorption, such asthe internal covering cells of the intestine, ion transport andfiltration, like the cells covering various tubules in the kidney.Glands are also covered internally by epithelial cells whichfunction in secretion of their products.Functions1.Protection:Epithelial cells from the skin protect underlyingtissue from mechanical injury, harmful chemicals, invadingbacteria and form excessive loss of water.

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Term
Spring
Professor
MORGAN
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