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Anatomy lab. 7 nervous sys.
The nervous system controls and coordinates the body's activities. It has two main parts: 1. The central nervous system (CNS) consisting of the brain and spinal cord which acts as the control center. 2. The peripheral nervous system (PNS) consisting of nerves that connect the CNS to the rest of the body and allows communication. The nervous system receives sensory input, integrates the information, and causes motor responses via output from the CNS to muscles and glands. It works through neurons, which are specialized cells that transmit electrochemical signals, and neurotransmitters which allow communication between neurons.
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Anatomy lab. 7 nervous sys.
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- 2. Nervous System • Mastercontrolling and communicating system.
- 3. Basic Functions 1.1. SensoryinputSensory input – gather information 2.2. IntegrationIntegration – process and interpret sensory input 3.3. Motor outputMotor output – response by muscles and glands
- 5. Organization A.A. Central NervousSystem (CNS)Central Nervous System (CNS) ▫ Brain & spinal cord ▫ Integrative and control centers A.A. Peripheral Nervous System (PNS)Peripheral Nervous System (PNS) ▫ Nerves (spinal nerves, cranial nerves) ▫ Communication lines between CNS and rest of body ▫ Two Divisions:Two Divisions: 1.1. Sensory (afferent) DivisionSensory (afferent) Division: Sensory receptors CNS 2.2. Motor (efferent) DivisionMotor (efferent) Division: CNS effectors (muscles & glands)
- 6. Motor Division • Somaticnervous systemSomatic nervous system (voluntary) – control skeletal muscles • Autonomic nervous systemAutonomic nervous system (ANS) (involuntary) – regulate smooth muscles, cardiac, glands – Subdivisions: sympatheticsympathetic & parasympatheticparasympathetic
- 7. • The cerebrumis the largest part of the brain and controls voluntary actions, speech, senses, thought, and memory. • The surface of the cerebral cortex has grooves or infoldings (called sulci), the largest of which are termed fissures. Some fissures separate lobes. • Each convolution is delimited by two sulci and is also called a gyrus (gyri in plural)
- 9. The Forebrain: most anteriorand most prominent part of the mammalian brain Thalamus: Part of the Diencephalon Center of forebrain Relay Station for Sensory Information Hypothalamus: Part of Diencephalon Regulates homeostasis, sexual behavior, fighting, feeding Pituitary Gland Endocrine gland attached to the base of the hypothalamus
- 13. Cerebellum Location • Sits inthe posterior fossa • Straddles the brainstem • Forms the roof of the fourth ventricle Main Functions • Entirely motor and operated at an unconscious level • Maintains balance • Maintains posture and controls eye movement •Influences posture and muscle tone • Coordinates movement
- 16. cerebrospinal fluid (CSF) clear,colourless liquid that fills and surrounds the brain and the spinal cordand provides a mechanical barrier against shock. •Formed primarily in the ventricles of the brain •supports the brain and provides lubrication between surrounding bones and the brain and spinal cord..
- 18. Nervous TissueNervous Tissue 1.1.NeuronsNeurons (nerve cells) - transmit message Anatomy: ▫ Cell bodyCell body – contains nucleus; metabolic center ▫ DendriteDendrite – fiber that conveys messages toward cell body ▫ AxonAxon – conduct nerve impulses away from the cell body ▫ Axon terminalsAxon terminals – end of axon; contain neurotransmitters & release them ▫ Synaptic cleft/synapseSynaptic cleft/synapse – gap between neurons
- 20. Nervous TissueNervous Tissue 2.Supporting cells (NeurogliaNeuroglia) CNSCNS:: astrocytes, microglia, ependymal cells, oligodendrocytesastrocytes, microglia, ependymal cells, oligodendrocytes barrier between capillaries and neurons protect neurons immune/defense line brain and spinal cord cavities wrap nerve fibers produces myelin sheaths (covering) PNSPNS: Schwann cells, satellite cells: Schwann cells, satellite cells surround large neurons protect & cushion
- 22. • MyelinMyelin:: whitish,fatty material that covers nerve fibers to speed up nerve impulses • Schwann cellsSchwann cells:: surround axons and form myelin sheath • Myelin sheathMyelin sheath:: tight coil of wrapped membranes • Nodes of RanvierNodes of Ranvier: gaps between Schwann cells
- 23. • GangliaGanglia: collectionsof cell bodies • Bundles of nerve fibers = tractstracts (CNS) or nervesnerves (PNS) • White matterWhite matter: dense collections of myelinated fibers • Gray matterGray matter: unmyelinated fibers & cell bodies
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- 25. 1. Functional Classification:direction nerve impulse is traveling Sensory neurons Motor neurons Interneurons carry impulses from sensory receptors to CNS carry impulses from CNS to muscles & glands connect sensory & motor neurons Vision, hearing, equilibrium, taste, smell, pain, pressure, heat
- 26. 2. Structural Classification:# processes extending from cell body Multipolar Bipolar Unipolar 1 axon, several dendrites 1 axon, 1 dendrite 1 process Most common (99%) Rare Short with 2 branches (sensory, CNS) Eg. Motor neurons, interneurons Eg. retina, nose, ear Eg. PNS ganglia
- 27. Neuron ClassificationNeuron Classification Neuronclassification is based partly upon the shape of the perikaryon and partly on the number and orientation of cell processes.
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- 30. Neuron Function 1.1. IrritabilityIrritability:ability to respond to stimulus & convert to nerve impulse 2.2. ConductivityConductivity: transmit impulse to other neurons, muscles, or glands
- 31. Multiple Sclerosis (MS) •Autoimmune disease • Myelin sheaths destroyed reduced to hardened lesions (scleroses) • Blindness, muscle weakness, speech disturbance, urinary incontinence • Treatment: interferons, glatiramer (hold off attacks)
- 33. Nerve Conduction • Actionpotential reaches axon terminal vesicles release neurotransmittersneurotransmitters (NT)(NT) into synaptic cleftsynaptic cleft • NT diffuse across synapse bind to receptors of next neuron • Transmission of a nerve impulse = electrochemicalelectrochemical eventevent
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- 35. Neurotransmitters • ExcitatoryExcitatory: causedepolarization • InhibitoryInhibitory: reduce ability to cause action potential • Eg. acetylcholine, serotonin, endorphins
- 36. Neurotransmitters NeurotransmitterNeurotransmitter ActionAction Affectedby:Affected by: Acetylcholine muscle contraction botulism, curare (paralytic), nicotine Dopamine “feeling good” cocaine, amphetamines Serotonin sleep, appetite, nausea, mood, migraines Prozac, LSD, ecstasy Endorphins inhibit pain morphine, heroin, methadone GABA main inhibitory NT alcohol, Valium, barbiturates
- 38. Reflexes • Rapid, predictable,involuntary responses to stimuli 1.Somatic Reflexes: stimulate skeletal muscles – Eg. jerking away hand from hot object 1.Autonomic Reflexes: regulate smooth muscles, heart, glands – Eg. salivation, digestion, blood pressure, sweating
- 39. Reflex Arc (neuralpathway) Five elements: 1. Receptor – reacts to stimulus 2. Sensory neuron 3. CNS integration center 4. Motor neuron 5. Effector organ – muscle or gland
- 42. Patellar (Knee-jerk ) Reflex ReflexActivities Pupillary Reflex
- 43. • Stretch reflex •Tapping patellar ligament causes quadriceps to contract knee extends • Help maintain muscle tone, posture, & balance • Optic nerve brain stem muscles constrict pupil • Useful for checking brain stem function and drug use
- 44. Flexor (withdrawal) reflex: painfulstimulus withdrawal of threatened body part – Pin prick Plantar reflex: draw object down sole of foot curling of toes – Babinski’s sign: check to see if motor cortex or corticospinal tract is damaged
- 45. The Babinski reflexoccurs after the sole of the foot has been firmly stroked. The big toe then moves upward or toward the top surface of the foot. The other toes fan out
- 46. Voluntary Reactions • Moreneurons and synapses are involved longer response times Reflex = Involuntary Reaction Voluntary Reaction