Lab Seven Flashcards
What does the cardiac cycle in humans and other vertebrates involve?
The sequential contraction of the atria and the ventricles.
What is the heart’s rhythmical contraction sequence triggered by?
Action potentials from myocardial cells that are conducted in a coordinated fashion throughout the entire heart.
What are excellent conductors of electricity?
Bodily fluids.
Where can electrical activity easily be recorded?
The electrical activity in the interior portion of the body can be easily recorded at the body surface.
What is an Electrocardiogram (ECG)?
The electrical current measured as an electrical potential across the body surface, displayed over time.
What does the P wave represent?
Atrial depolarization.
What does the QRS complex represent?
Atrial repolarization and ventricular depolarization.
What does the T wave represent?
Ventricular repolatization.
When does atrial repolarization occur?
It occurs during ventricular depolarization.
Where can a change in heart rate easily be measured?
In the P-P interval.
How is an increased heart rate accomplished?
Measured in beats per minute, it’s accomplished by reducing the time between beats (T-P interval) and the overall time that a complete depolarization/repolarization cycle occurs (P-T interval).
What does the arterial system function as?
A pressure reservoir, in that the amount of blood flow is directly related to the pressure difference along an artery.
When is the highest level of pressure?
Immediately after the ventricles contract, known as systolic blood pressure.
When is the lowest level of pressure?
Just prior to the next contraction of the ventricles, known as the diastolic blood pressure.
What is blood pressure often represented as?
Systolic/diastolic, 120 mmHg/80 mmHg.
What can control the degree of contraction of the smooth muscles found in the walls of the arteries?
Signals from the autonomic nervous system, which will have a direct impact on blood pressure.
What does Vasoconstriction do?
Vasoconstriction of the arteries will increase centralized blood pressure.
What does Vasodilation do?
Vasodilation of the arteries will decrease centralized blood pressure.
Autonomic nervous system effects on the arterial system can be used to:
Regulate blood pressure and alter the distribution of blood to various organs in the body, depending on the metabolic needs of the body. Can also influence heart rate.
What is the Fight or Flight response?
A sympathetic nervous system response that releases epinephrine from the adrenal glands, which binds to receptors on the heart - causing it to beat faster.
What is the Rest and Digest response?
A parasympathetic nervous system response that releases acetylcholine from the vagus nerve, binding to receptors on the heart - causing it to beat slower.
What can peripheral feedback loops within the autonomic nervous system do?
Coordinated heart activity, arterial blood pressure, and overall blood flow.
What is the Baroreceptor Reflex?
One of the most important peripheral feedback loops, acts to ensure central arterial blood pressure is maintained at a level appropriate for metabolic activities in the blood, but that it is not too high to cause rupturing of the arterial vessels or excess fluid leakage from the capillaries.
What does diving cause?
Selective peripheral vasoconstriction and a sharply reduced blood flow to limbs, gut, and the skin - driving blood to the organs that need oxygen the most.
