Flashcards in Blood Pressure and Heart Rate (4) Deck (19):
What is systole?
Maximum pressure when heart pumps, occurs after contraction of ventricle
What is diastole?
The bottom level of pressure, occurs after contraction of atria
How do you measure heart rate (beats/time seconds)?
Systolic Pressure- Diastolic Pressure
How do you measure flow in terms of Darcy's Law?
Flow (volume/time)= Pressure 1- Pressure 2/ Resistance
Resistance- mmHg time/volume
What is another term for flow?
Cardiac Output (CO)
What is the equation to calculate Cardiac Output?
CO (volume/time)= (Arterial Pressure- Venous Pressure)/ Resistance
How do you calculate Arterial blood pressure?
Arterial blood pressure= CO x TPR (total peripheral resistance)
Arterial blood pressure= heart rate x stroke volume x TPR
What are the pacemakers in the parasympathetic nerve system?
Sino atrial (SA) node- iniates contraction
Atrioventricular (AV) node- drives system is SA node fails
What is Bradycardia?
Slowing down of heart rate
What is tachycardia?
Speeding up of heart rate
Where does each electrical signal in the heart begin?
What does an Electrocardiogram record?
Strength and timing of electrical signals as they pass through the heart
From the SA node where does the electrical signal move to?
Through the left and right atria
Causes atria to contract, helps move blood into lower chambers of the heart
What is the electrical signals recorded as that pass through the atria?
What does the electrical signal between the atria and ventricle pass through?
Atrioventricular node (AV)
What is the pathway of a electrical signal in the heart?
SA node-> Atria-> AV node (P wave)-> Ventricle-> Bundle of His->Contraction of heart (QRS wave)
What are the phases of action potential in heart cells?
1. Early repolarization- brings the potential down to a plateau level over 2 to 3 milliseconds
2. Plateau- accounts for most of the action potential duration
3. Repolarization- brings the potential back to resting level
4. Period between action potential- stable except in cells that have the property of autorhythmicity
What do baroreceptors do?
Pressure-sensitive neurones that monitor stretch in the aorta (prevent build up of pressure)