Heart Activity Flashcards
Describe the path for deoxygenated blood.
- > Right atrium - via the superior vena cava (upper body), inferior vena cava (lower body), coronary sinus (heart muscles)
- > Right ventricle
- > To the lungs - Pulmonary artery for oxygenation and removal of carbon dioxide by gaseous exchange
Describe the path for oxygenated blood.
- > From lung to left atrium - 4 pulmonary veins
- > Left ventricle
- > To the body - aorta, blood to organs and muscles for the supply of nutrients and oxygen and removal of metabolic waste
What is innervation?
The arrangement or distribution of nerves to an organ or body part
What is the atrioventricular node responsible for?
It is in the wall between the right atrium and ventricle. Electrical discharge passes via the atrioventricular bundle to the ventricles. Begins the QRS in EKG (depolarisation of the right and left ventricles of the heart.
Explain the process of innervation in both the sympathetic and parasympathetic nervous systems.
Parasympathetic: acetylcholine as transmitter. Vagal inhibition of the SA node, normally reduces HR to approx. 70BPM
Sympathetic: norepinephrine as transmitter. HR output increased vis increase in the rate of SA node discharge, increase excitability of cardiac tissue
How is heart rate measures and calculated?
ECG leads attached to the manubrium (sternum), left third rib, and right shoulder.
It is measured by the formula:
60,000/IBI (in ms)
What is Respiratory Sinus Arrhythmia (RSA)?
The natural arrhythmia that occurs through the influence of breathing on the flow of sympathetic and vagal impulses. RSA is heart rate variability in synchrony with respiration. The R-R interval is shortened during inspiration and prolonged during expiration.
Explain Lacey’s Intake-Rejection Hypothesis with relation to heart rate,
HR and BP influence cortical activity, therefore affect sensitivity to stimuli
- Cardiac deceleration facilitates stimulus intake
- Cardiac acceleration facilitates stimulus rejection
How is the observed response to a stimulus calculated?
Observed response = ECR1 + ECR2
ECR1 - the brief deceleration, marker of involuntary transient detection, primary (reflex) bradycardia, obligatory
ECR2 - the acceleration, reflects cognitive processing, never seen alone obtain by subtraction
What does the coronary sinus do?
The coronary sinus is located at the back of the atrium and it empties blood from the heart veins into the right atrium.
What is the sinoatrial node responsible for?
It is located at the rear wall of the atrium. It is the pacemaker it is responsible for regular electrical discharge which begins the firing pattern of the whole heart. This is seen in the P wave, beginning contraction and pushing blood to ventricles.
What is the process of QRS waves?
P - begin contraction and pushing blood to ventricles
QRS - depolarisation of ventricles
T - repolarisation of ventricles
