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Thread: [Anatomy] CNS Control of Autonomic Function

  1. #1

    Default [Anatomy] CNS Control of Autonomic Function

    Several levels of CNS complexity are required to coordinate and regulate ANS function. Thus, despite the name "autonomic," the ANS is a regulated nervous system, not an independent one. Autonomic function is influenced by four CNS regions: cerebrum, hypothalamus, brainstem, and spinal cord.

    [Anatomy] CNS Control of Autonomic Function-screen-shot-2016-04-16-at-7-20-39-pm-png

    ANS activates are affected by conscious activities in the cerebral cortex and subconscious communications between association areas in the cortex with the centers of sympathetic and parasympathetic control in the hypothalamus. Additionally, sensory processing in the thalamus and emotional states controlled in the limbic system directly affect the hypothalamus.

    The hypothalamus is the integration and command center for autonomic functions. It contains nuclei that control visceral functions in both divisions of the ANS, and it communicates with other CNS regions, including the cerebral cortex, thalamus, brainstem, cerebellum, and spinal cord. The hypothalamus is the central brain structure involved in emotions and drives that act through the ANS. For example, the sympathetic nervous system fight-or-flight response originates in the sympathetic nucleus in this brain region.

    The brainstem nuclei in the midbrain, pons, and medulla oblongata mediate visceral reflexes. These reflex centers control accommodation of the lens, blood pressure changes, blood vessel diameter changes, digestive activities, heart rate changes, and pupil size. The centers for cardiac, digestive, and vasomotor functions are housed within the brainstem.
    Clinical Pharmacy Specialist - Infectious Diseases

  2. #2

    Default Reflex and central control of autonomic activity

    As is the case for alpha-motor neurons, the activity of autonomic nerves depends on reflexes and on descending excitatory and inhibitory inputs from several brain regions. For example, preganglionic sympathetic neurons in the IML receive excitatory input from the rostral ventrolateral medulla and the paraventricular nucleus of the hypothalamus and inhibitory input from medullary raphe neurons. In addition to these direct pathways to the IML, there are many brain regions that feed into these pathways to regulate autonomic nerve activity. These include the caudal ventrolateral medulla, nucleus of the tractus solitarius, and locus ceruleus. This is analogous to the control of somatomotor function by areas such as the basal ganglia and cerebellum.

    PS: Remember the five components of a reflex?

    The hypothalamus is often regarded as a major central autonomic control area. Indeed, many of the complex autonomic mechanisms that maintain homeostasis are integrated in the hypothalamus. The hypothalamus also functions with the limbic system as a unit that regulates emotional and instinctual behavior. It interconnects with nuclei in the midbrain, pons, and medulla to regulate autonomic activity.
    Clinical Pharmacy Specialist - Infectious Diseases

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