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A&P.Ch11.nervous
| Question | Answer |
|---|---|
| functions of nervous system (5) | sensory input; integration; homeostasis; mental activity; control of muscles & glands |
| sensory input | conscious: sight, smell, hearing taste, touch, etc. unconscious: blood pH, blood gases, blood pressure, etc. |
| integration | brain & spinal cord process information - may respond immediately, store as memory, or ignore |
| homeostasis | regulate & coordinate trillions of cells; heart rate must deliver blood; nervous system controls structures to maintain homeostasis |
| mental activity | brain includes consciousness, thinking memory & emotions |
| control of muscles & glands | skeletal muscles are consciously controlled; cardiac & smooth muscles contract autorhythmically; also controlls secretions of glands, sweat glands, salivary, digestive, etc. |
| Central nervous system (CNS) | consists of brain & spinal cord |
| where are the brain & spinal cord continuous? | at foramen magnum |
| Peripheral nervous system (PNS) | external to central nervous system (CNS); consists of sensory receptors, nerves, ganglia and plexuses |
| sensory receptors | are 1.) endings of nerve cells or 2.) separate, specialized cells that detect terperature, pain, touch pressure light, sound, odors & other stimuli |
| nerve | a bundle of exons & their shetaths the connect the CNS to sensory receptors, muscles, & glands |
| Cranial nerves | twelve pairs originate from the brain |
| spinal nerves | originate from the spinal cord |
| Ganglion | a collection of neuron cell bodies located outside the Central nervous system |
| Plexus | extensive network of axons & also neuron cell bodies, located outside the CNS |
| Peripheral Nervous system has ___ divisions | 1.) the sensory or afferent division and 2.) the motor or efferent division |
| sensory or afferent division of PNS | transmits electric signals FROM sensory receptors TO CNS |
| motor or efferent division | transmits action potential s FROM CNS to effector organs, such as muscles & glands |
| Motor Division of CNS or PNS? is further dividied into ____ divisions | two divisions: 1) somatic nervous system and 2) autonomic nervous system (ANS) |
| Somatic nervous system transmits action potentials | from the CNS to skeletal muscles |
| afferent | L. "to bring to" -inflowing; conducting toward a center; denoting certain arteries, veins, lymphatics and nerves |
| efferent | L. efferens, to bring out - conducting ouward from an organ or part; e.g., efferent connections of a group of nerve cells, or excretory duct of an organ |
| synapse | junction of a nerve cell with another cell (can be muscle cell or other cells, smooth muscle cells, gland cells |
| Autonomic Nervous System (ANS) is subdivided into | sympathetic & parasympathetic divisions |
| sympathetic | active during physical activies |
| parasympathetic division | regulates resting or vegetative functions, such as digesting food or emptying the urinary bladder |
| Enteric nervous system | consists of plexuses within the wall of the digestive tract |
| where are cell bodies of sensory neurons? | in ganglia near the spinal cord OR near the origin of certain cranial nerves |
| synapse | junction of a nerve cell with another cell |
| the Autonomic nervous system (ANS) transmits | action potentials from the CNS to (3) smooth muscle, cardiac muscle and certain glands |
| Does the ANS handle subconscious control? | Yes |
| What is another word for the type of control the ANS has? | involuntary |
| enteric (def.) | relating to the intestine G. enterikos from enterika "bowels" |
| what does sensory divison of the PNS do? | detects stimuli and transmit information on the form of action potentials to the CNS |
| what are the components of the nervous system? | neurons and nonneural cells |
| what are the nonneural cells? | neuroglia or glial cells (nerve glue) hold brain together |
| what type of cell makes up more than 1/2 the brain's weight? | neuroglia cells |
| neurons | receive stimulia dn transmit action potentials to other neurons or effector organs |
| another name for neuron | nerve cells |
| neuron | the morphologic and functional unit of the nervous system |
| what are parts of neuron (3) | 1.cell body 2. dendrites 3. axon |
| axon | also called nerve fibers |
| axon | refers to "axis" straight alignment & uniform diameter of most axons |
| axon (def.) | the singles pppprocess of a nerve cell that under normal conditions conducts nervous impulses away from the cell body and its remaining processes (the dendrites) |
| where does the axon occur? | in most neurons, a single axon arises from a cone-shaped area of the neuron cell body called the axon hillock |
| do axons occur just one to a neuron? | no-it can branch to form collateral axons or side branches |
| what is the plasma membrane of the axon called? | axolemma (the axon husk) |
| what is at the end of the axon? | presynaptic terminals |
| what is another name for presynaptic terminals? | terminal boutons |
| what is in the presynaptic terminals? | many small vesicles containing neurotransmitters |
| neurotransmitters | any specific chemical agent released by a persynaptic cell on excitation that crosses the synaptic cleft and stimulates or inhibits the postsynaptic cell |
| where are action potentials generated? | at TRIGGER ZONE |
| where is trigger zone? | axon hillock and the part of the axon nearest to the cell body |
| do axons have transport mechenisms? | Yes, indeed they do--movement of cell materials, waste & germs can be transported. Ex. rabies can enter axon endings of damaged skin & are transported to the CNS |
| dendrites | short, highly branched cytoplasmic extensions that are tapered from their bases at the neuron cell body to their tips |
| what are dendrites? | the input part of the neuron; when stimulated, they generate small electric currents that are conducted to the neuron cell body |
| dendrites | branching processes of a neuron that receives stimuli and conducts potentials toward the cell body |
| types of neurons | neurons are classified according to function or structure |
| function classification of neurons | based on DIRECTION in which action potentials are conducted - afferent conduct TOWARD CNS while efferent conduct AWAY from CNS |
| structural classification of neurons | based on number of processes (multipoloar, bipolar, or unipolar) |
| neuroglia | "nerve glue" - there are two kinds - CNS (4 kinds) and PNS (2 kinds) |
| neuroglia of the CNS | astrocytes, ependymal cells; microglia; oligodendrocytes |
| astrocytes | astrocyte processes form fett that cover the surfaces of neurons and blood vessels; they provide structural support and form the blood-brain barrier |
| astrocyte role in the blood-brain barrier | astrocytes release chemical that mpromote the formation of tight junctions between the endothelial cells of capillaries; only certain substances can pass from blood into the nervous tissue of the brain & spinal cord |
| what is purpose of blood-brain barrier? | protects neurons from toxic substances in the blood;allows exchange of nutrients and waste products between neurons & blood; and keeps blood fluctuations from affecting the functions of the brain |
| ependymal cells | line the ventricles (cavities) of the brain & central canal of the spinal cord; secrete & circulate cerebrospinal fluid |
| choroid plexuses | specialized ependymal cells and blood vessels are in certain regions of the vesicles; secrete cerebrospinal fluid |
| what is on free surface of ependymal cells? | cilia - to circulate cerebrospinal fluid |
| microglia | specialized macrophages in the CNS that become momblie and phagocytic in response to inflammation--they phagocytize necrotic tissue; microorganisma, & foreign substances |
| how can a pathologist identify damaged areas in CNS during an autopsy? | large numbers of microglia migrate to areas damaged by infection, trauma, or stroke |
| oligodendrocytes | have cytoplasmic extensions that surround axons and form myelin sheaths |
| oligo dendrocytes | Gr. oligo - prefix meaning "few" a little; too little; too few |
| neuroglia of the PNS | Schwann cells (or neurolemmocytes) and satellite cells (within ganglia) |
| schwann cells or neurolemmocytes | wraps around an axon, forming a myelin sheat |
| what is difference between schwann cells & oligodendrocytes? | schwann cells wrap around just ONE CELL, whereas oligodendrocytes have feet which wrap around several |
| schwann cells | cells of ectodermal (neural crest)origin that compose a continuous envelope around each nerve fiber of peripheral nerves |
| satellite cell | surround neuron cell bodies in ganglia; provide support and nutrients to the neuron cell bodies |
| myelinated axons | extensions form (either from oligodendrocytes or schwann cells) which wrap around a segment of the axon; have small breaks |
| nodes of ranvier | interruptions in the myelin sheath |
| what are internodes? | the areas of the axon covered by myelin |
| unmyelinated axons | one schwann cell surrounds several axons |
Created by:
walterina4327