Cardiovascular and respiratory systems Flashcards
Describe the concept of brain stem “centers” for respiratory and cardiovascular control
CV: pressor and depressor centers with efferent output via sympathetic and parasympathetic nerves to heart and resistance vessels.
Explain the organization of key reflexes: the baroreceptor reflex and respiratory chemoreflex
- The heart beat originates at the SA node but cardiovascular function and blood pressure regulation depend on an autonomic control system that modulates sympathetic and parasympathetic activity to heart and resistance vessels based on feedback from the baroreceptors that detect changes in blood pressure. We monitor and regulate the blood pressure.
- Respiration originates within medullary neurons that drive motor output via the phrenic nerve to diaphragm and other respiratory muscles. The level of ventilation is determined by a control system the modulates respiratory motor activity based on feedback from chemoreceptors in the carotid body and in the brain. We monitor and regulate the PaCO2.
Describe how fear can influence autonomic nervous system functions
Amygdala fear response results in sympathetic activity and strengthening of the smooth muscles of the vasculature
Compare and contrast physiological processes involved in respiratory and cardiovascular control
- The basic brainstem neuron groups involved in these two control systems are located close together but are not identical. The NTS receives afferent input from carotid body and carotid sinus. The source of sympathetic control is the RVLM. The region of the nucleus ambiguous contains many respiratory neurons a subset of which may be the respiratory pacemakers.
Explain the role of reflex feedback circuits versus inputs from higher CNS centers and the influences of physiological states
Neuronal activities from parts of the CNS rostral to the brainstem can impinge upon these brainstem cardiorespiratory control sites and cause mischief. Seizures represent an abnormal form of neuronal activity, which can cause death presumably via cardiorespiratory effects (SUDEP). Profound emotional experiences can also cause death. Sleep is associated with cardiorespiratory events of surprising malevolence.
What are the similarities between cardiovascular and respiratory systems?
- brainstem vital for fxn
- afferent information incorporated into reflex feedback
- Brainstem sites involved overlap but use different neurons
- Higher CNS can have significant impact on brainstem systems
What are differences between the cardiovascular and respiratory control system?
- heart beat initiated at SA node but modulated by brainstem. Brainstem also regulates vascular resistance
- Breathing initiated at brainstem
Pressor center is located in the:
Rostral ventrolateral medulla (RVLM): catecholamine cells projecting
Depressor Center is located in the:
Caudal VentroLateral Medulla (CVLM):
Nucleus of the solitary tract
carries neurons from the carotid sinus
At what level would you find the RVLM?
medulla. CVLM depressor are more caudal
what are the major brainstem neurons for cardiovascular control?
- NTS
- nucleus ambiguus
RVLM
CVLM
Important rostral sites in cardiovascular control
Amygdala (emotional response on cardiovascular centers–causing arrhythmias)
LHA
paraventricular nucleus
Insular cortex
What is the mechanism by which amygdala causes sudden death?
excessive sympathetic stimulation (ventricular fibrillation) or excessive parasympathetic stimulation
Increased sympathetic activity is related to hypertension. What is the theory behind this?
Intermittent stress increases sympathetic activity and vascular resistance. This causes hypertrophy of vascular smooth muscle and permanently increased resistance and blood pressure.
