Ch 9: Autonomic Nervous System

• Sympathetic: fight or flight

  Parasympathetic: rest and digest
• Autonomic Nervous System:

  • no conscious control
  • motor/effect neurons
  • effect cardiac muscle, smooth muscle, and glands
  • release mainly Ach and NE
• Somatic Nervous System:

  • Effectors: skeletal muscle
  • Ganglia?: No
  • # of Neurons: 1
  • Denervate: Flaccid Paralysis
  • NTs: Ach
• Autonomic Nervous System:

  • Effectors: cardiac, smooth, glands
  • Ganglia?: Yes
  • # of Neurons: 2
  • Denervate: keeps muscle tone and function, more sensitive
  • NTs: Ach and Ne
• Sympathetic Division Anatomy:

  • originate in the spinal cord.
  • pre-gang synapse runs parallel to the spinal cord "chain"
  • mass activation
• Mass Activation: allows the sympathetic division to act as a single unit.

  • Divergence: one pre-gang neuron synapses on several post-gang neurons.
  • Convergence: multiple pre-gang neurons synapses on one post-gang neuron.
• Collateral Ganglia:

  • come from below the diaphragm
  • innervate organs of the digestive, reproductive, and urinary systems
• Adrenal Glands: on top of kidneys.

  • Outer layer: Cortex -> secrete steroid hormones
  • Inner Layer: Medulla -> secretes mostly E and NE
• Oculomotor (3): changes the shape of your lens.

  • Symptoms: diplopia, ptosis, paresis
• Facial (7): innervates the pharynx, palate, tongue, and lacrimal glands.
• Glossopharyngeal (9): parotid glands, tongue, palate, and pharynx.

  • Symptoms: difficulty swallowing, no gag reflex, issues with taste.
• Vagus (10): effects heart, lungs, stomach, pancreas, etc.

  • provides more of the parasympathetic innervation.
• Nerves from the Sacral Region: innervate the lower part of the intestines, reproductive organs, and urinary system.

  • pelvic nerves help in this.
• Sympathetic Function:

  • prepares body for fight/flight
  • increases heart rate, increases blood glucose, sends blood to skeletal muscle
  • Adrenal Medulla releases E + NE
• Parasympathetic Function:

  • release Ach from post-gang neurons
  • decreases heart rate, increases digestive activities, and dilates visceral blood vessels.
• Ach is released by all pre-gang neurons in both the parasympathetic and sympathetic systems.

  • can stimulate or inhibit based on receptors.
• Varicosities:

  • axons of post-gang -> enlargements -> release NTs
  • sym + para innervate the same tissue with different NTs
• A1: vascular smooth muscle of internal organs.

  • generate EPSP, causes smooth muscle to contract.
  • pale, queasy, and dry mouth due to no blood flow.
• A2: located on terminal buttons of symp. post-gang neurons.

  • release NE
  • keeps the fight/flight in check
  • receptors found primarily in the brain
  • lower blood pressure
• B1: found in the heart.

  • causes the heart to beat more forcefully
• B2: nonvascular smooth muscle of bronchioles and digestive organs.

  • generate IPSP, smooth muscle relaxes and bronchodilation.
  • inhibits the action of the stomach, small and large intestines.
• A1 Agonists: Phenylephrine & Pseudophedrine.

  • cause contraction of blood vessels.
  • nasal decongestants.
• A2 Antagonists: Yohimbine

  • block A2 receptors
  • raise blood pressure
  • help with male sexual function
• B1 Antagonist: Metaprolol and Atenolol.

  • decrease cardiac output
  • aka. beta blockers
• B2 Agonist: Terbutaline and Albuterol.

  • relieves symptoms of asthma
  • can also bind to B1 and creating high blood pressure
• Muscarinic Antagonists: Atropine

  • muscle relaxation in the bladder, respiratory passages, and intestines
• Nicotinic Receptors in autonomic ganglia. Ionotropic. EPSP. Blocked with Curarae.
• Muscarinic Receptors: found in visceral organs.

  • Eventually open with K+, Na+, Ca+ channels
  • Metabotropic
  • blocked with Atropine
• Nonadrenergic Noncholenergic Fibers:

  • NTs: ATP, VIP, nitric oxide
  • erection of the penis, innervating blood vessels, muscle relaxation
• Complementary Effects:

  • occasionally both divisions produce similar effects on the same target
  • Ex: salivary gland secretion
• Cooperative Effects:

  • both divisions produce different effects that are working together to promote a single action.
  • Ex: erection and ejaculation
• Organs only Innervated by the Sympathetic Division:

  • adrenal medulla
  • cutaneous effectors
  • most blood vessels that go to skeletal muscle
• Medulla Oblongata: cardiovascular, pulmonary, urinary, reproductive organs.
• Hypothalamus: body temperature, hunger, and thirst.

  • Major regulatory center of the ANS.
• Limbic System: emotional states with blushing, paleness, and fainting.
• Cerebellum: motion sickness nausea, sweating, and cardiovascular changes.
• Frontal and Temporal Lobes: aspects of emotion and personality. "Greater self"
• Aging:

  • associated with increased levels of sympathetic activity
  • increased risk of hypertension and cardiovascular diseases
  • stress activates the sympathetic division