Nervous tissue study_questions
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The document contains questions and answers about the nervous system. It defines key terms like the three parts of the nervous system, structures of neurons, classifications of neurons, types of neuroglial cells, and processes like graded potentials, action potentials, and synaptic transmission. It describes the roles of ion channels and neurotransmitters in generating electrical signals in neurons and transmitting them across chemical synapses between neurons.
Nervous tissue study_questions
- 1. Nervous Tissue Study Questions 1. What are the three major functions and two major parts of the nervous system? The three major functions are sensory, integrative, and motor. The two major parts are the CNS, brain and the spinal cord and the PNS, everything but the brain and spinal cord 2. Considering the structure of a myelinated neuron define the following terms and list functions as appropriate: a. cell body: contains the cytoplasm and nucleus b. RER (Nissl bodies): rough endoplasmic reticulum. makes grey matter grey c. dendrite: nerve fibers or processes that extend from the cell body that conduct electrical signals toward the cell body d. axon: nerve fiber or process that extends from the cell body that conducts impulses away from the cell body e. axon hillock: cone shape. hillock meaning little hill. connector piece f. axon terminal: the split ends of the axon g. trigger zone: where action potential starts. where the electrical current begins
- 2. h. cell membrane : surrounds the entire neuron including dendrites, cell body, axon and synaptic ends. i. synaptic end bulb: dilated ends of axon terminals with vesicles that contain neurotransmitters j. neurotransmitter: a chemical substance that is released at the end of a nerve fiber by the arrival of a nerve impulse and, by diffusing across the synapse or junction, causes the transfer of the impulse to another nerve fiber, a muscle fiber, or some other structure k. myelin: whitish fatty sheath around most axons, cell membrane of axon insulates and increases speed of conduction l. node of Ranvier: gaps in the myelin sheath m. neurolema: outer nucleated cytoplasmic layer of Schwann cell that encloses myelin sheath 3. List and define three functional classifications of neurons. Sensory (afferent) neurons- carry sensory information from sensory receptors in different parts of the body into the CNS Interneurons- integrative function, mainly located in CNS between sensory and motor neurons. form the majority of neurons in the body Motor (efferent) neurons- carry motor information from the CNS to the effector 4. List and define three structural classifications of neurons. Where are they typically located?
- 3. Multipolar neuron- several dendrites and one axon extending from the cell body (most neurons in the CNS) Bipolar- one dendrite and one axon extending from the cell body. location eye, ear, and nose. Unipolar- one process extending from the cell body. location extends from fingers, toes (skin), to the dorsal root ganglion. 5. Describe the structure, function, and location of the following neuroglial cells: a. astrocytes location; CNS Structure; star shape function; support, help maintain proper chemical environment, and help maintain and regulate the blood brain barrier of the brain capillaries. b. oligodendrocytes location; CNS structure: a few branch cell function: produce myelin around axon c. microglia location: CNS Function: phagocytosis, remove debris, damaged tissue and microbes Structure:
- 4. d. ependymal location: CNS; lines the central canal of the spinal cord and the blood vessels in the brain called ventricles (choroid plexus) function: forms and secretes cerebral spinal fluid, from blood plasma structure: balloon like e. satellite cells Function: support, protect and nourish neuron cells. location: PNS; surrounds neuron cell bodies in ganglia. side of spinal cord, dorsal root ganglion Structure: surrounds a neuron body f. Schwann cells location: PNS function: CAN produce myelin around axon. grabs and holds onto a axon structure: long links with gaps between them 6. How can an axon in the PNS repair itself? must be an axon that is myelinated. the neuron cell body has to be intact. Some schwann cells be functional (neurolemma) to form a regeneration tube. Scar tissue doesn't grow too rapidly (can block the process) 7. Describe and define graded potentials-Both hyperpolarizing and depolarizing. hyperpolarizing graded potential- the chemical stimulus causes ions to flow through channels in the cell membrane so that the inside of the cell membrane becomes polarized, more negative than the resting potential.
- 5. Depolarizing- a mechanical stimulus causes ions to flow through channels in the cell membrane, so that the inside of the cell membrane becomes depolarized, less negative (more positive) than the resting potential. 8. Define and describe the neuron resting membrane potential and the three different gated ion channels resting membrane is -70 multivolts (mv): positive charges accumulate close to the outside surface of neuron in ECF. Negative charges are close to the inside surface in ICF of neuron cell membrane. The three different gated ion channels are Voltage, ligand (chemical), and mechanical. 9. Define and describe an action potential using the terms depolarization, repolarization, Na+ channel, K+ channel. an action potential has two main phases: depolarization- NA+ rushes in. and repolarization- K+ flows out (resetting phase). 10. Explain the difference between continuous and saltatory conduction. continuous conduction occurs in unmyelinated axons, slow, and goes step-by-step. Saltatory conduction- occurs in myelinated axons, passes from one node of Ranvier to the next. fast. 11. Describe the structure and function of a chemical synapse in detail. a chemical synapse- a junction between neurons: the first neuron changes an electrical current to a chemical signal that will drift to the 2nd neuron, the 2nd neuron will change the chemical signal back to a electrical signal 12. Describe and define an EPSP and an IPSP in detail.
- 6. EPSP (excitatory post synaptic potential)- caused by an excitatory neurotransmitter which depolarizes the postsynaptic neuron, making the inside more positive and generation of a nerve impulse more likely. IPSP (inhibitory postsynaptic potential)- caused by an inhibitory neurotransmitter which hyperpolarizes the postsynaptic neuron, making the inside more negative and generation of a nerve impulse more difficult.
- 7. EPSP (excitatory post synaptic potential)- caused by an excitatory neurotransmitter which depolarizes the postsynaptic neuron, making the inside more positive and generation of a nerve impulse more likely. IPSP (inhibitory postsynaptic potential)- caused by an inhibitory neurotransmitter which hyperpolarizes the postsynaptic neuron, making the inside more negative and generation of a nerve impulse more difficult.