Factors Modifying Basic Heart Rate Flashcards
What factors modify the basic heart rate?
The autonomic nervous system, hormones, ions, and physical factors like age, gender, exercise, and body temperature can modify heart rate.
How do neural controls (ANS) affect heart rate?
During stress or physical activity, the sympathetic division of the autonomic nervous system speeds up the heart rate. The parasympathetic division (via the vagus nerve) slows the heart during non-crisis times.
What hormones and ions affect heart rate?
Epinephrine and thyroxine increase heart rate and contractility.
Calcium imbalances can depress or excessively contract the heart.
Potassium and sodium imbalances also modify heart activity, with low potassium causing weak heartbeats.
How do physical factors like age and temperature influence heart rate?
Age: Resting heart rate is highest in the fetus and decreases with age.
Gender: Females tend to have faster heart rates than males.
Heat: Increases heart rate by boosting metabolic rate.
Cold: Decreases heart rate.
Exercise: Increases heart rate and stroke volume via nervous system stimulation.
What is congestive heart failure (CHF), and what causes it?
Congestive heart failure (CHF) occurs when the heart’s pumping efficiency is reduced, often due to coronary atherosclerosis, hypertensive heart disease, or myocardial infarctions.
How is congestive heart failure treated?
Digitalis is prescribed to enhance contractility and increase stroke volume, which improves cardiac output.
What happens if the left side of the heart fails?
Left-sided heart failure causes pulmonary congestion and pulmonary edema as blood backs up into the lungs, leading to fluid leakage into lung tissue.
What happens if the right side of the heart fails?
Right-sided heart failure causes peripheral congestion, leading to swelling in the feet, ankles, and fingers as blood backs up in the systemic circulation.
What is the result of one side of the heart failing?
Failure of one side of the heart strains the opposite side, and eventually, the entire heart fails.
The vagus nerve
is the tenth cranial nerve (Cranial Nerve X) and is a key part of the parasympathetic nervous system. It is the longest cranial nerve, running from the brainstem through the neck, chest, and abdomen. The vagus nerve has a variety of functions:
Slows the heart rate: It helps lower heart rate by sending signals to the heart, which slows down the pacemaker activity in the sinoatrial (SA) node.
Regulates digestion: It stimulates muscles in the digestive tract, helping food move through the system and supporting processes like enzyme release.
Controls speech: The vagus nerve also influences the muscles used for speech and swallowing by controlling certain laryngeal and pharyngeal muscles.
Lowers blood pressure: By slowing the heart rate and promoting relaxation in the blood vessels, it helps reduce blood pressure.
Affects respiratory function: It helps regulate breathing patterns.
In short, the vagus nerve is essential for controlling several involuntary body functions, particularly those associated with rest-and-digest activities, balancing the body’s responses to stress and relaxation.
