Bio unit 3

• Neuron


  A nerve cell, the structural and functional unit of the nervous system

  Carries info from one location to another

  Can survive for over 100 years, does not undergo cell division after adolecence
• afferent neurons


  Information moving towards the brain/ spinal cord, moving away from specific organ/ area
• Efferent neurons


  Information moving way from the brain/ spinal cord, moving towards a specific organ/ area
• Three parts of the neuron

  Dendrite, cell body, axon
• Dendrite


  Site for receiving signals from other neurons

  Numbers can range from 1-1000's depending on function
• Cell body


  (Soma), has a large centrally located nucleus with large nucleolus

  Contains variety of cell structures (mitochondria, lysosomes, golgi,,,)
• Axon


  Long cylindrical extension of the cell body, ranging 1mm-1m

  Myelin sheath, Schwann cells, node of ranvier
• Myelin sheath

  Fatty layer covering axon, insulates neuron to prevent short circuiting of impulse to neighbouring neurons . Allows several neurons to exist side by side within a nerve (found in PNS)
• Schwann cells


  Insulating cells that together form the myelin sheath, also may allow regeneration of damaged neuron, if damage is not severe
• Node of ranvier


  The gap between each Schwann cell, a nerve impulse traveling along a myelinated neuron is able to jump from node to node, spreading up the impulse wave
• Classes of neurons

  Sensory, interneurons, motor
• Sensory neurons


  Pick up sensory info from the environment via sensory receptors (temperature and pressure receptors in the skin) and carry it to the CNS
• Interneurons


  (Association) carries info from one neuron to another, can receive info from sensory neuron or another interneuron

  Involved in reflexes (sends signals to brain from spinal cord, back through motor neuron before the brain can process the action)
• Motor neuron


  Carries info from CNS to another effector (a muscle fiber for contraction, or a gland for secretion)
• Nervous system

  Sends signals from every part of your body to your brain

  Uses electrochemical signals to communicate
• Two parts of nervous system

  central nervous system and peripheral nervous system
• Central Nervous system

  brain and spinal cord
• Peripheral nervous system


  Nerves coming off of brain and spinal cord

  12 cranial nerves

  31 spinal nerves
• two parts of the peripheral nervous system

  somatic nervous system and autonomic nervous system
• Autonomic nervous system


  Involuntary movements (digestion, breathing)
• somatic nervous system


  Involves skeletal muscles

  Responsible for voluntary movements and reflexes
• Two parts of autonomic nervous system

  sympathetic and parasympathetic
• Sympathetic nervous system

  Fight of flight

  Increases adrenaline for running

  Increases heart rate by expanding arteries

  Increasing breathing for blood
• parasympathetic nervous system

  Supports homeostasis

  Decreases adrenaline, heart rate, breathing by relaxing arteries

  Calms you down and brings you back to equilibrium
• Reflexes


  A part of the SNS that happens unconsciously (falling and catching yourself)

  The purpose being to protect yourself
• Reflex arc

  Stimuli > Sensory receptor > sensory neuron (Afferent) > spinal cord(interneuron) > brain(effector) > motor neuron (efferent) > response
• Left hemisphere


  Speech, logic, processing info, language
• Right hemisphere


  Visual perception, interpreting non-verbal info
• Middle part of the brain

  Fissure
• Worm like groves in brain

  Convolutions
• Two parts of the nervous system

  central nervous system and peripheral nervous system
• Two parts of peripheral nervous system

  autonomic and somatic
• Two parts of autonomic nervous system

  sympathetic and parasympathetic
• Six nervous systems

  Central, peripheral, autonomic, somatic, sympathetic, parasympathetic