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Chapter 12: Efferent Division and Autonomic Control

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Terms in this set (20)

  • What are the main components of the nervous system?
    Central Nervous System (CNS) and Peripheral Nervous System (PNS). CNS includes brain and spinal cord; PNS includes sensory (afferent) and motor (efferent) neurons.
  • What is the difference between sensory and motor neurons?
    Sensory neurons carry signals from organs to CNS; motor neurons carry signals from CNS to muscles and glands.
  • What are the two main divisions of the autonomic nervous system?
    Sympathetic division (fight or flight) and parasympathetic division (rest and digest).
  • What is the general pathway of autonomic efferent neurons?
    A preganglionic neuron from CNS synapses in an autonomic ganglion with multiple postganglionic neurons that innervate target tissues.
  • How do the parasympathetic and sympathetic divisions differ in pre- and postganglionic neuron length?
    Parasympathetic: long preganglionic, short postganglionic neurons. Sympathetic: short preganglionic, long postganglionic neurons.
  • What neurotransmitter and receptor are found at the pre- to postganglionic synapse in both autonomic divisions?
    Acetylcholine (ACh) acting on nicotinic cholinergic receptors.
  • What neurotransmitters and receptors are found at the neuroeffector junction in the parasympathetic division?
    ACh acting on muscarinic cholinergic receptors.
  • What neurotransmitters and receptors are found at the neuroeffector junction in the sympathetic division?
    Mostly norepinephrine (NE) and epinephrine (E) acting on alpha and beta adrenergic receptors. Sweat glands use ACh with muscarinic receptors.
  • What is the role of the adrenal medulla in the sympathetic nervous system?
    Acts as a modified ganglion; chromaffin cells release epinephrine into the blood as a neurohormone.
  • What is a varicosity in the autonomic nervous system?
    Swollen regions along postganglionic axons that release neurotransmitter over a wide area of target tissue.
  • What are the main receptor subtypes for sympathetic adrenergic receptors?
    Alpha receptors: α1 (smooth muscle contraction), α2 (inhibits insulin, contracts GI sphincters). Beta receptors: β1 (heart), β2 (bronchioles, blood vessels), β3 (adipose tissue).
  • What is the function of the somatic motor division?
    Controls voluntary skeletal muscle movement via a single somatic motor neuron to muscle fibers.
  • What neurotransmitter and receptor are involved at the neuromuscular junction?
    Acetylcholine (ACh) acting on nicotinic cholinergic receptors.
  • Describe the sequence of events at the neuromuscular junction during muscle activation.
    Action potential arrives, voltage-gated Ca2+ channels open, ACh is released, binds nAChR, causing EPSP, and ACh is degraded by acetylcholinesterase.
  • What is the role of the hypothalamus in autonomic control?
    Integrates sensory input and initiates autonomic, endocrine, and behavioral responses to maintain homeostasis.
  • What are some autonomic control centers in the brainstem?
    Medulla and pons regulate blood pressure, breathing, and bladder control.
  • What is meant by 'homeostasis is a dynamic balance between autonomic branches'?
    Parasympathetic and sympathetic systems have antagonistic effects to maintain internal stability.
  • What is the reflex pathway sequence?
    Stimulus → Sensor → Input signal → Integrating center → Output signal → Target → Response.
  • How do alpha-1 adrenergic receptors affect blood vessels?
    Cause smooth muscle contraction leading to vasoconstriction.
  • How do beta-2 adrenergic receptors affect bronchioles?
    Cause smooth muscle relaxation leading to bronchodilation.