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The Importance of the Nervous System

The Importance of the Nervous System. SBI 4U January 14 th , 2013. Nervous System & Homeostasis. Human brain – control centre of the body If brain is damaged, other parts of your body effected as well

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The Importance of the Nervous System

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  1. The Importance of the Nervous System SBI 4U January 14th, 2013

  2. Nervous System & Homeostasis Human brain – control centre of the body If brain is damaged, other parts of your body effected as well Nervous system, body’s interface with external environment and the control system that manages the internal environment Physical, cognitive or physiological changes

  3. Neural Signalling Neuron: specialized nerve cell, functioning unit of nervous system Neural signalling: communication by neurons – process by which an animal responds appropriately to stimuli – reception, transmission, integration and response

  4. Neural Signalling Reception: detection Transmission: movement of a message Integration: sorting and interpretation, determining appropriate response Response: output or action

  5. Neural Signalling 3 functional classes of neurons: Afferent neurons: transmit stimuli to; Interneurons: integration info to formulate response; Efferent neurons: carry response signals to effectors

  6. Neural Signalling Efferent neurons that carry signals to skeletal muscles are called motor neurons Stimulus  afferent neurons  interneurons  efferent neurons  effectors  action

  7. Neuron Structure Vary in shape & size Enlarged cell body and 2 extensions Cell body (nucleus and most organelles)  synthesizes most proteins, carbsand lipids Dendrites receive signals and transmit toward cell body Axons conduct signals away from cell body to another neuron or effector Axon hillock Neuronal circuits

  8. Neuron Structure

  9. Neuron Support System Glial cells: structural support and metabolism of nerve cells Schwann cells, form layers of membrane called myelin sheaths around axons, gaps between Schwann cells, called nodes of Ranvier, expose axon membrane to extracellular fluids  speeds up the rate of electrical impulses Division and brain tumors

  10. Organization of Nervous System CNS and PNS CNS: coordinating centre  brain and spinal cord PNS: communicates with CNS. Subsystem PNS: afferent system (receives input through receptors) and the efferent system (carries signals to muscles and glands)

  11. Organization of Nervous System Efferent System divided into somatic system (communicates with skeletal muscles) and autonomic system (communicates with smooth muscles and glands) Somatic system: voluntary (some exceptions) Autonomic system: involuntary, digestion, secretion by sweat glands, circulation of the blood, etc;

  12. Organization of the Nervous System Autonomic System  sympathetic and parasympathetic divisions Sympathetic: dominates during stress, danger, excitement or physical activity Parasympathetic: dominates during quiet, low-stress situations, such as relaxation

  13. Reflex Arc Neural circuit  5 components: receptor, the afferent neuron, the interneuron, the efferent neuron, and the effector Reflex arc: travels through spinal cord, but does not require coordination from brain Ex: when your finger touches a very hot object

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