ANS, Hypothalamus and Limbic System Flashcards
Autonomic Nervous System
Influenced by hypothalamus
ANS Functions
Maintains homeostasis
Regulates activity of internal organs and vasculature
Mechanoreceptors
Respond to pressure and stretch
Chemoreceptors
Sensitive to chemical concentrations in blood, medulla and hypothalamus
Stomach, taste bud and olfactory bulbs are examples
Nociceptors
Respond to stretch and ischemia
Thermoreceptors
Respond to small changes in temperature of circulating blood
Information from visceral receptors into CNS via….
Spinal cord via dorsal roots
Brainstem via CN VII, IX and X
Central Regulation
Visceral information enters brainstem and converges in solitary nucleus
From solitary nucleus, relayed to control areas in pons and medulla
Relayed to modulatory areas in hypothalamus, thalamus and limbic system
Location of Solitary Nucleus
Medulla
Central Regulation (Medulla)
Regulates heart rate, respiration, vasoconstriction and vasodilation
Central Regulation (Pons)
Regulates respiration
Central Regulation (Hypothalmus, Thalamus, and Limbic System)
Modulate brainstem autonomic control
Influences cardiorespiratory, metabolic, water reabsorption and digestive activity by acting on pituitary and control centers
Information is projected to limbic system
Who sends information directly to hypothalamus?
Olfactory
Small part of visual
Limbic System Components
Hypothalmus Nuclei of Thalamus Limbic cortex Hippocampus - memory center Amygdala - fear
Limbic System Functions
Emotion and memory functions
Influences motor and autonomic output via emotion
Sympathetic System
“Fight or Flight”
Cell bodies of preganglionic located in lateral horn (T1-L2)
Sympathetic System Function
Maintain optimal blood supply to organs
Regulate body temperature and metabolic rate
Regulates activity of viscera
Parasympathetic System
“Rest and Digest”
Preganglionic cell bodies in brainstem and sacral spinal cord (S2-S4)
Parasympathetic System Function
Energy conservation and storage
Decreases cardiac activity
Facilitates digestion
Regulates activity of viscera
Sympathetic Characteristics
Lot of input coming in
Two neuron system
Ganglia located closer to spinal cord
One neuron connection with adrenal gland
Parasympathetic Characteristics
Not a lot of input coming in, but vagus is important
Two neuron system
Neurotransmitters Released by ANS
Acetylcholine
Norepinephrine
Peripheral Nerve Injury (Clinical Correlation)
Loss of vascular control
Temperature regulation
Sweating
Spinal Region Injury (Clinical Correlation)
Completer S2-4 lesion or cauda equina produces flaccid bladder
Above sacral cord, hypertonic/hyperreflexive bladder
Lesion above T6 - autonomic dysreflexia
Brainstem Injury (Clinical Correlation)
Interfere with descending control of HR, BP and respiration
Affects cranial nerve nuclei
Cerebral Injury (Clinical Correlation)
Disrupts homeostasis with metabolic and behavioral dysfunctions
