Lab 7: Human Circulatory System Physiology Flashcards
What is the hearts rhythmical contraction sequence triggered by?
Action potentials from myocardial cells that are conducted in a coordinated fashion throughout the entire heart.
What is an excellent conductor of electricity and electrical activity?
Bodily fluids
Can electrical activity be easily recordable at the surface of the body?
yes!
Using electrodes placed on opposing sides of the heart, this electrical current can be measured as an electrical potential across the body surface and displaced over time as an
Electrocardigram (ECG)
P wave-
Atrial deplorization
QRS complex
atrial replorization and ventricular depolarization
T wave
Ventricular repolarization
Several aspects of the heart activity can be modified by what?
autonomic nervous system
electrical signals to initiate vertebrate heart contraction originates in what?
myocardial cells
How is excitation or inhibition of the heart accomplished?
by changes to the contraction rate and various other parameters associated with myocardial contraction. an obvious example of excitiation is excercise.
On an ECG a change in heart rate can be easily measured as a change in
P-P interval.
How is an increased heart rate accomplished by?
reducing the time between beats (T-P interval) and the overall time that a complete depolarization/repolarization cycle occurs ( P-T interval). the latter is accomplished by altering the conduction velocity of the electrical signals as they travel throughout the heart.
where does the blood go once it is ejected from the heart?
Arterial system
The arterial system functions as a what?
Pressure reservoir in that the amount of blood flow is directly related to the pressure difference along an artery.
What is the relation between heart function and centralized blood pressure?
Increased heart function will increase centralized blood pressure!
Vasconstriction
of the arteries will increase centralized blood pressure
Vasodilation
of the arteries will decrease centralized blood pressure
Autonomic nervous system effects on the arterial system can be used to alter…
the distribution of blood to various organs in the body depending on the metabolic needs of the animals. Ex.) blood flow to the gut decreases during exercise, while blood flow to the skeletal muscle increases dramatically.
Can the autonomic nervous system directly influence heart rate?
Yes
In fight or flight the sympathetic nervous system releases…
epinephrine from the adrenal glad which binds to receptors on the heart causing it to beat faster.
what does the parasympathetic release?
acetycholine from the vagus nerve binds to receptors on the heart causing it to beat slower.
baroreceptor reflex:
is one of the most important of these feedback loops. This reflex normally acts to ensure that central arterial blood pressure is maintained at a level appropriate for metabolic activities in the body, but that is no too high to cause rupture of arterial vessels or excess fluid leakage from the capillaries.
What activity uses the barrorector alot
Diving uses the baroreceptor reflex to coordinate heart activity arterial blood pressure and peripheral blood flow. Diving usually causes selective pheripheral vasoconstriction. However this selective vasconstriction that takes lace during diving has the potential to cause a significant increase in the blood pressure of the central arteries.
Diving bradycardia
where heart rate is substantially reduced to ensure that blood pressure in central arteries does not exceed safe levels.
