Nervous System pt. 1

• The nervous system

  The ultimate control center of the body overseeing all communication among the organ systems
• Functions of the nervous system

  1. Sensory input

  2. Integration

  3. Motor output

  
• Nervous tissue


  • Densely packed with neurons (nerve cells) and neuroglia (glial cells)

  
• Neurons


  Excitable cells that respond to stimuli by conducting impulses to transmit signals
• Neuroglia


  Supportive cells that provide nutrition, insulation, and help with signal transmission
• Neuron structure

  • Soma (cell body)
  • Processes (dendrites and axon)
  • Axon terminals

  
• Myelin sheath


  • Covers long axons to protect and electrically insulate them, increasing the speed of nerve impulse transmission
• Nodes of Ranvier


  • Unmyelinated gaps in the myelin sheath that aid in increasing the velocity of nerve signal conduction
• Neuron classification by structure

  • Multipolar
  • Bipolar
  • Unipolar

  
• Neuron classification by function


  • Sensory (afferent) neurons
  • Motor (efferent) neurons
  • Interneurons (association neurons)

  
• Nervous System


  The system that coordinates the body's voluntary and involuntary responses to internal and external stimuli

  
• Main divisions of the Nervous System

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)

  
• Central Nervous System (CNS)


  • Brain and spinal cord
  • Integration and control center
• Peripheral Nervous System (PNS)

  • Spinal and cranial nerves
  • Communication system between the CNS and the rest of the body

  
• Parts of the CNS

  • Brain
  • Spinal cord

  
• Brain


  • Protected by the skull and surrounded by layers of tissue (meninges) and cerebrospinal fluid that cushion the brain from injury
  • Ventricles = Hollow fluid-filled cavities within brain that contain the choroid plexus which makes cerebrospinal fluid

  
• Main parts of the brain

  • Cerebrum
  • Cerebellum
  • Brainstem

  
• Cerebrum


  • The largest part of the brain
  • Made of left and right hemispheres
  • Also divided into 4 lobes
  • Functions in learning, speech, emotion, reasoning, vision, hearing, and fine movements
  • Surface is the cerebral cortex and is arranged in folds to increase surface area
• Cerebellum


  • Maintains posture and balance
  • Coordinates timing and patterns for smooth and agile subconscious movements
• Brainstem


  • Base of the cerebrum and anterior to the cerebellum
  • Includes the medulla oblongata, midbrain, and pons
  • Relays info between rest of the brain and the spinal cord
  • Coordinates a lot of automatic functions like respiration, circulation, body temperature, sleep, digestion, and swallowing

  
• Divisions of the Peripheral Nervous System (PNS)

  • Sensory (Afferent) Division
  • Motor (Efferent) Division

  
• Sensory (Afferent) Division


  • Receives sensory stimuli to send back to CNS/brain
  • Somatic sensory fibers carry info from the skin, skeletal muscles, and joints
  • Visceral sensory fibers carry info from the visceral organs
• Motor (Efferent) Division


  • Sends out information from the brain to effector organs like muscles (so they will contract) and glands (so they will secrete)
• Parts of the Motor (Efferent) Division

  • Somatic Nervous System
  • Autonomic Nervous System
• Somatic Nervous System


  • Conduct impulses from CNS to skeletal muscles
  • Controls voluntary movements

  
• Autonomic Nervous System


  • Conduct impulses from CNS to smooth muscles, cardiac muscles, and glands
  • Controls involuntary movements of the heart, lungs, stomach, etc. (where cardiac and smooth muscles are)

  
• Parts of the Autonomic Nervous System

  • Sympathetic
  • Parasympathetic

  
• Integration


  The process of receiving and processing information from the senses, and coordinating the body's responses
• Spinal cord


  A long, thin bundle of nerves that runs from the brain down the back; serves as a conduit for messages between the brain and the rest of the body
• Brain


  The control center for the nervous system and the body as a whole; responsible for processing sensory information, thinking, and decision-making
• Central Nervous System (CNS)


  The part of the nervous system that consists of the brain and spinal cord; responsible for integration and control of the body's functions
• Nervous System


  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Peripheral Nervous System (PNS)

  • Sensory (Afferent) Division
  • Motor (Efferent) Division
  • Somatic Nervous System
  • Autonomic Nervous System
• Autonomic Nervous System


  • Sympathetic
  • Parasympathetic
• Autonomic Nervous System


  The "involuntary" division
• One stress signal


  Responses in multiple effector organs at once
• Autonomic Nervous System


  Focuses on what your body needs to do RIGHT NOW
• Motor (Efferent) Division


  • Preganglionic cells are shorter than postganglionic
  • Uses neurotransmitter NE and hormones for stimulation and inhibition
  • Is antagonistic to the sympathetic division, but they can work cooperatively
• Sensory (Afferent) Division


  Sensory nerve receptors take in stimuli from our physical environments and send them to the brain to interpret and respond to
• Types of sensory receptors

  • Mechanoreceptors: mechanical force, like vibration, pressure, stretch, and touch
  • Thermoreceptors: change in temperature
  • Photoreceptors: light
  • Chemoreceptors: chemicals
  • Nociceptors: pain