Chapter 12: Neural Tissue12-1 Describe the anatomical and functional divisions of the nervous system. P.375- Innervate: are distributed to1. Identify the two anatomical divisions of the nervous system. The twoanatomical divisions of the nervous system are the central nervous system(CNS), consisting of the brain and spinal cord, and the peripheral nervoussystem (PNS), consisting of all neural tissue outside the CNS. Bundles of axons(nerve fibers) in the PNS are called nerves. 2. Identify the two functional divisions of the peripheral nervous system,and cite their primary functions. The two functional divisions of theperipheral nervous system are the afferent division, which brings sensoryinformation to the CNS from receptors in peripheral tissues and organs, andthe efferent division, which carries motor commands from the CNS to muscles,glands, and adipose tissues (or fat adipocytes, a loose connective tissue) calledeffectors.3. Identify the two components of the efferent division of the PNS. The twocomponents of the efferent division of the PNS are the somatic nervoussystem (SNS), which controls skeletal muscle contractions, and the autonomicnervous system (ANS), which controls smooth muscle, cardiac muscle, adiposetissue, and glandular activity. 4. What would be the effect of damage to the afferent division of the PNS?Damage to the afferent division of the PNS, which is composed of nerves thatcarry sensory information to the brain and spinal cord, would interfere with aperson’s ability to experience a variety of sensory stimuli. P. 37612-2 Sketch and label the structure of a typical neuron, describe the functions of each component, and classify neurons on the basis of their structure and function. - Neurons are nerve cells specialized for intercellular communication p. 376- A synapse is a site of intercellular communication from one nerve cell and some other cell; if the other cell is not a neuron, the term neuromuscular or neuroglandular junction is often used. Telodendria end in snaptic terminals, which are also known as synaptic knobs, axon terminals, and synaptic boutons.Neurotransmitters released from the synaptic terminals of the presynaptic cell affect the postsynaptic cell, which may be a neuron or another type of cell. - •Synapses: neural communication site- •Pre synaptic cell: Which sends a message and includes the synaptic terminal- •Post synaptic cell: Receives message from presynaptic cell- •Synaptic cleft= A small gap that separates the presynatpic neuron fromthe postsynaptic neuron - •Synaptic knob = synaptic terminal- •Synaptic terminal = synaptic knob, at distal tip of each telodendrion of the neuron, that houses the synaptic vesicles. 1- •Synaptic vesicle: at end of axon is the synaptic terminal that contains membranous synaptic vesicles; travel in the fast stream in the axoplasmic transport- •Content of the synaptic vesicles? neurotransmitters- •Neurotransmitter for release is stored in presynaptic membrane. - •Motor unit: all the muscle fibers controlled by a single motor neuron, the size of which is an indication of how fine the control of movement can be. The muscle fibers of each motor unit are intermingled with those of other motor units.(p. 301)- Neuromuscular junction= where the motor neuron and the muscle fibermeet, communication between the nervous system and the skeletal muscle fiber occurs, also as a synapse between a neuron and a muscle cell - Neuro glandular junction: a neuron controls or regulates the activity of secretory (gland) cell p.377-Anaxonic neurons: are small and have no anatomical features that distinguishdendrites from axons. All the cell processes look alike. Anaxonic neurons arelocated in the brain and in special sense-organs. Their functions are poorlyunderstood. - Bipolar neurons: have two distinct processes—one dendrite that branchesextensively into dendritic branches at its distal tip, and one axon—with the cellbody between the two. Bipolar neurons are rare. They occur in special senseorgans, where they rely information about sights, smell, or hearing fromreceptor cells to other neurons. Bipolar neurons are small. The largest measureless than 30 µm from end to end. -Unipolar neuron: or pseudounipolar neuron, the dendrites and axon arecontinuous—basically, fused—and the cell body lies off to one side. In such aneuron, the initial segment lies where the dendrites converge. The rest of theprocess, which carries action potentials, is usually considered an axon. Mostsensory neurons of the peripheral nervous system are unipolar. There mayextend a meter or more, ending at synapses in the central nervous system. Thelongest carry sensations from the tips of the toes to the spinal cord. -Multipolar neurons: have two or more dendrites and a single axon. They arethe most common neurons in the CNS. All the motor neurons that controlskeletal muscles, for example, are multipolar neurons. The axons of multipolarneurons can be as long as those of unipolar neurons, and the longest carrymotor commands from the spinal cord to small muscles that move the toes. 5. Name the structural components of a typical neuron. Structuralcomponents of a typical neuron include a cell body or soma (which containsthe nucleus and perikaryon), dendrites, an axon, telodendria, Nissl bodies,neurofilament, intermediate neurotubules, neurofibrils, axoplasm,axolemma, initial segment, axon hillock, and collaterals. The perikaryon of amultipolar neuron contains organelles, including neurofilaments,neurotubules, and neurofibrils. The axon hillock connects the initialsegment of the axon to the cell body, or soma. The axoplasm contains2numerous organelles. Collaterals may branch from an axon, with telodendriabranching from the axon’s tip. 6. Classify neurons according to their structure. According to structure, neuronsare classified as anaxonic, bipolar, unipolar, and multipolar. (Figure 12-3).7. Classify neurons according to their function. According to function, neuronsare classified as sensory neurons, motor neurons, and interneurons. Sensoryneurons, which form the afferent division of the PNS, deliver informationreceived from interoceptors, exteroceptors, and proprioceptors to the CNS.Interoceptors