Control of Heart Rate Flashcards
What is heart rate?
Heart rate is the number of heartbeats per minute.
What factors affect heart rate?
Factors that affect heart rate include exercise, stress, adrenaline, and body position.
What is the role of the sinoatrial (SA) node?
The SA node acts as the natural pacemaker of the heart, initiating electrical impulses that trigger the heart to contract.
What is the role of the atrioventricular (AV) node?
The AV node delays the electrical impulse from the SA node to allow the atria to fully contract before the ventricles contract.
What is the pathway of electrical impulses in the heart?
The electrical impulse moves from the SA node → atria → AV node → bundle of His → Purkinje fibers → ventricles.
How does the sympathetic nervous system affect heart rate?
The sympathetic nervous system releases adrenaline, which increases heart rate by stimulating the SA node and other parts of the conduction system.
How does the parasympathetic nervous system affect heart rate?
The parasympathetic nervous system releases acetylcholine, which slows the heart rate by inhibiting the activity of the SA node.
What is the role of the medulla oblongata in controlling heart rate?
The medulla oblongata monitors blood pressure and blood gas levels, and adjusts heart rate via the sympathetic and parasympathetic nervous systems.
How does exercise affect heart rate?
Exercise increases heart rate to supply more oxygen and glucose to muscles, mediated by increased sympathetic nervous activity.
What is the role of baroreceptors in controlling heart rate?
Baroreceptors detect changes in blood pressure and send signals to the medulla oblongata to adjust heart rate accordingly.
What is the role of chemoreceptors in controlling heart rate?
Chemoreceptors detect changes in blood pH (due to CO₂ levels) and oxygen levels, influencing heart rate to maintain homeostasis.
How does the heart respond to low blood oxygen levels?
Low oxygen levels trigger chemoreceptors to send signals to the medulla oblongata, which increases heart rate to improve oxygen delivery.
How does the heart respond to high blood carbon dioxide levels?
High CO₂ levels trigger chemoreceptors to increase heart rate to remove excess CO₂ and maintain pH balance.
What is the difference between the sympathetic and parasympathetic nervous systems?
The sympathetic nervous system accelerates heart rate (fight or flight), while the parasympathetic system slows it down (rest and digest).
What is the role of adrenaline in controlling heart rate?
Adrenaline increases heart rate by stimulating the SA node and enhancing the conduction of electrical impulses in the heart.
What is the Frank-Starling law of the heart?
The Frank-Starling law states that the more the heart muscle is stretched (due to increased venous return), the stronger the contraction, leading to increased stroke volume.
What happens during ventricular systole?
During ventricular systole, the ventricles contract to pump blood into the arteries, causing an increase in blood pressure.
What happens during ventricular diastole?
During ventricular diastole, the ventricles relax and fill with blood from the atria, causing a decrease in blood pressure.
How does the autonomic nervous system regulate heart rate?
The autonomic nervous system adjusts heart rate by sending signals via the sympathetic and parasympathetic pathways based on inputs from baroreceptors and chemoreceptors.
