Regulation of Heart Rate by Autonomic Nervous System

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Heart Regulation by Chemoreceptors:

chemoreceptors under autonomic control

Heart Regulation by Baroreceptors:

baroreceptors under autonomic control

Regulation of Heart Rate by Autonomic Nervous System

• Cardiac Output = Stroke Volume X Heart Rate.

• Heart Rate is varied to produce change in CO and BP.

• CO rises during exercise.

• HR is best regulated by the autonomic NS and hormones from the adrenal medullae (epinephrine and norepinephrine).

• Sensory receptors > cardiovascular center in medulla oblongata > increase or decrease in frequency of nerve impulses in both sympathetic and parasympathetic branches of ANS.

• Sensory receptors: proprioceptors, chemoreceptors, and baroreceptors.

• Sympathetic neurons go from medulla oblongata > spinal cord (thoracic region) > SA (cardiac accelerator), AV, portions of myocardium.

This is how HR increases (Sympathetic Stimulation):

• Impulses from cardiac accelerator > norepinephrine released & binds to beta-1 on cardiac muscle > rate of depolarization increases > HR increases.

• Impulses from cardiac accelerator > norepinephrine released & enhances Ca2+ entry through the voltage-gated slow Ca2+ channels, increasing contractility.

This is how HR decreases (Parasympathetic Stimulation):

• Impulses > stimulate r. & l. vagus (CN X) n. to release ACh > heart (SA, AV, atrial myocardium) > HR decreases.

Additional Reading:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures

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1. Video of Neurology Examination in a Clinical Setting

Medical Images

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1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

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