CH3&4 Nervous System

• Autonomic System is always...

  excitation or inhibition
• What is the structure of spinal nerves in the peripheral nervous system?


  They pass between vertebrae and divide into a dorsal (sensory/afferent) and ventral (motor/efferent) root.
• Pairs of Cranial nerves in the Peripheral NS


  12 pairs of cranial nerves (controlling facial & sensory muscles). May be sensory, motor, or mixed.
• Which organs are primarily affected by the Sympathetic Nervous System?

  Heart, blood vessels, sweat glands, adrenal medulla
• What is the neurotransmitter associated with the parasympathetic nervous system?

  Acetylcholine
• What are the two types of motor neurons in the Autonomic Nervous System?


  1. Myelinated Preganglionic in CNS, 2. Unmyelinated postganglionic in Ganglia targeting visceral effectors like cardiac and smooth muscle
• What the autonomic nervous system targets


  Involuntary glands and muscle
• Somatic NS is always...

  Excitation
• When is the parasympathetic nervous system most dominant?

  When the body is at rest
• What the Somatic NS Contains


  Contains one motor neuron for voluntary movement

  
  

  contains myelinated axon = saltatory conduction occurs
• What function does the parasympathetic nervous system primarily serve?

  Conserving energy and maintaining body functions
• Where does the Autonomic Nervous System operate via cells?


  Medulla oblongata (respiratory centre, homeostatic gas concentrations) and Hypothalamus (adrenaline and non-adrenaline release)
• What physiological responses are triggered by the Sympathetic Nervous System in threatening situations?

  Increase in heart rate, vasodilation, sweating, release of adrenaline/non-adrenaline
• What is the primary neurotransmitter of the Sympathetic Nervous System?


  Non-adrenaline
• parasympathetic nervous system


  maintains body functions by conserving heat, most dominant when the body is at rest
• How many pairs of spinal nerves are in the peripheral nervous system?

  31 pairs of spinal nerves
• sympathetic nervous system


  reduces responses that prepare the body for fight or flight activity with the help of adrenaline/non adrenaline release from the adrenal medulla
• What are the two sets of nerve fibers in the Autonomic Nervous System?


  1. Sympathetic, 2. Parasympathetic
• What is a bipolar neuron?

  A neuron with two processes, one axon and one dendrite arising from opposite sides of the cell body.
• Where are bipolar neurons commonly found?

  They are commonly found in sensory neurons passing through the dorsal root.
• Example of a bipolar neuron

  sensory neuron - retina of the eye
• ganglia/ganglion


  a group of nerve cell bodies outside the brain and spinal cord
• Purpose of Myelin sheath


  acts as an insulator so heat doesn't pass through, protecting axon damage and speeds up nerve impulse.
• Axon/Neuron Diagram

  
• dendrite


  an extension of the nerve body that carries nerve impulses to the cell body
• Characteristics of Neurons (3)

  1. don't live for a long time

  2. don't divide

  3. Transmit nerve impulses
• Secondary Functions of a Neuron (3)

  1. contraction

  2. secretion

  3. constriction
• What is a multipolar neuron?


  A nerve cell with one axon and many dendrites.
• Where does a multipolar neuron pass through?


  The ventral root.
• What neurotransmitter does a multipolar neuron release in synaptic transmission?

  Acetylcholine.
• myelin sheath


  a white, fatty sheath that surrounds some nerve fibres
• meninges


  three protective membranes that surround the brain and spinal cord
• spinal reflex arc


  the pathway travelled by a nerve impulse from receptor to effector in a spinal reflex
• innate reflex


  a response to a stimulus that is acquired genetically, present at birth for protectional purposes
• reflex


  a rapid, automatic response to a stimulus to maintain homeostasis
• receptor


  a structure that detects a stimulus
• osmoreceptor


  a receptor sensitive to osmotic pressure of body fluids
• electrochemical change


  the change in electrical voltage brought about by change I the concentration of ions inside and outside the cell membrane
• depolarised


  describes the membrane of a nerve cell where there is no difference in electrical charge between the inside and outside nerve cell membrane
• nerve impulse


  the electrochemical change that travels along the nerve axon