PNS and ANS Flashcards
Afferent
Sensory
Efferent
Motor neurons (to CNS)
Somatic
Skin, muscle, and joints (away from CNS)
Visceral
Lung, GI, Glands
Afferent neuron cell bodies are located
outside of the spinal cord
Efferent cell bodies are located
in the ventral horn
Nociceptors respond to
Chemicals. Also known as chemoreceptors.
Inflammatory reflex
inhibits cytokine synthesis through cholinergic anti-inflammatory pathway. Negative feedback. Ex. heart attack sends proinflammatory cytokines to brain. Brain sends ACh to slow down HR and prevent further damage
Mechanoreceptors respond to
Pressure and Stretch.
Hering-Breurer Reflex (inflation reflex)
Stretch receptors in pleurae and airways stimulated by lung inflation. Inhibitory signals to medullary respiratory centers end inhalation and allow expiration
Proprioceptors respond to
Changes in muscle length or tension.
Golgi tendon organ senses
muscle tension and force
Muscle spindles sense
Muscle length and changes in length (stretch)
Motor unit
motor neuron and the skeletal muscle fibers it innervates
Upper motor neurons originate and travel where
originate in the cerebral cortex and travel down to the brain stem or spinal cord
Lower motor neurons begin and travel where
Begin in the spinal cord and go not to innervate muscles and glands throughout the body
What is released by all somatic motor neurons at their synapses and always excites muscle contraction
ACh. EPSP is created. End plate potential
Myasthenia gravis
Autoimmune disorder that causes weakness in skeletal muscle due to antibodies binding to nAChRs. Most affected are eyes, face, and swallowing.
Treatment for myasthenia gravis
Use an AChE inhibitor such as neostigmine or pyridostigmine to block the break down of ACh. Side effects include increased salivation and slow HR, sometimes low BP
Sympathetic stimulation does what
1.) Increase HR and contractility
2.) constricts blood vessels
3.) Bronchodilation of lungs
4.) decreased gut motility and secretions, increased sphincter contraction
Parasympathetic stimulation does what
1.) Lowers HR and contractility
2.) No effect on blood vessels?
3.) Bronchoconstriction
4.) Increased gut motility and secretions, sphincter relaxation
Efferent nerves typically originate from the
medulla
autonomic control of respiratory drive and cardiovascular function originates in the
medulla
Sympathetic preganglionic neurons stimulate the adrenal medulla to release what
Epinephrine and norepinephrine (4:1 ratio)
Somatic nervous system receptor at the motor end plate
N1 receptor (nicotinic acetylcholine receptor)
ANS parasympathetic stimulation goes to what receptor in the ganglion
N2 receptor and then muscarinic receptor via acetylcholine
ANS sympathetic stimulation goes to what receptor in the ganglion
N2 receptor and then alpha and beta adrenergic receptors via Norepinephrine
ANS sympathetic stimulation goes to what receptor in the adrenal medulla
N2 and chromatin cell to produce epinephrine release
Sympathetic pathway
Short preganglionic neuron and longer ADRENERGIC postganglionic neuron
Parasympathetic pathway
Longer preganglionic neuron and shorter CHOLINERGIC postganglionic neuron
N1 receptor location
Skeletal muscle
N2 receptor location
postganglionic neurons
M1 receptor location
CNS, salivary glands, and parietal cells. Increase IP3 and DAG. Excitatory (increase contraction of smooth muscle)
M2 receptor location
Heart. Decrease cAMP and is inhibitory
Effects of ACh on different receptors
1.) Nicotinic receptors N1, N2 - depolarization (excitatory)
2.) Muscarinic receptors M2 - slows heart hyper polarization (Inhibitory) and M3 smooth muscle contraction depolarization (closes K+ channels (excitation)
M3 receptor location
Smooth muscle and exocrine glands. Increase IP3 and DAG
Alpha 1 receptors do what
Postsynaptic. Located on smooth muscle throughout the body and increases intracellular calcium concentrations. Causes blood vessel constriction, inhibits insulin release, and relaxes intestines. Leads to increased IP3 and DAG. NE>EPI
Alpha 2 receptors do what
Presynaptic. Decrease NE release through negative feedback. Inhibits CGCC. EPI>NE
Beta 1
Epi>NE (increases HR and contractility) Heart
Beta 2
EPI»NE (bronchodilation and some vasodilation) Lung
