Autonomic System

Key Term Definition
Parasympathetic Division •Preganglionicneurons in –brain stem–S2-S4–Cranial nerves III, VII, IX, X
•Preganglionicneurons synapse on terminal ganglia located near target organ.
•Preganglionicfibers –long and myelinated.
•Postganglionic fibers –short and unmyelinated.
AUTONOMIC NEUROTRANSMITTERS •Transmission is primarily cholinergic, but also adrenergic and peptidergic.
•All preganglionicfibers release ACh(i.e. parasymp. & sympathetic).
•Parasympathetic postganglionic fibers release also release ACh
•Sympathetic postganglionic fibers releas
SYMPATHETIC DIVISION •Prega neurons in T1 -L2 in the lat horns.
•Prega neurons send fibers out the ventral root to the symp trunk.•Postgan fibers leave symp trunk and pass through spinal nerve again before going to target organ
•preg:short/unmyelinated
•postg:long/myelinat
Divisions of the Autonomic Nervous System •Sympathetic division–Prepares the body for action
•Parasympathetic division–Settles the body down
•Enteric division–Control of function of digestive organs
Characteristics of ANS •two-neuron pathway
•Sensory signals from viscera and skin send signals to autonomic neurons in brain and spinal cord.•A prega cell body within the CNS
•Prega synapse w/ postg in the PNS
•The postg terminates on the effector organ
Differences between Somatic Motors System and ANS •Somatic motor neurons project directly to skeletal muscles (monosynaptic)
•Autonomic pathway is dysynaptic. Preganglionicneurons project to postganglionic neurons, which project to the target organs.
Hypothalamic Functions •Neuroendocrine:Hypothalamic pituitary portal system: Releasing and inhibiting hormones that target pituitary
•Regulatory
•Limbic: Hypothalamus is critical for making the connections between the expression of affect and the motor response
Hormones of the Hypothalamus •Provided to the anterior pituitary
–TRH, GnRH, GHRH, CRH, somatostatin–Dopamine
•Providedto the posterior pituitary
–ADH, oxytocin
Zones of the Hypothalamus •Medial:VMH (satiety/agression control), Dorsomedial n.(feeding behavior/insulin control) •Lateral: LHA (appetite stimulation) •Paraventricular: Paraven&supraopn.(oxytocin/AHD), Preopticn(reprod& autonomic functions), anthyp(Parasymp),suprachi(circ r)
Hypothalamus Characteristics and Functions -Phylogenetically old
-Influences nearly all bodily functions
-Mechanisms
-neuronal (ANS)
-hormonally (via pituitary stimulation)