lesson 8 - monitoring the circulatory system Flashcards
What are the two nodes of the heart
- The sinoatrial node (SA) - aka the pacemaker.
- The atrioventricular node (AV)
What does the sinoatrial node do?
The SA node stimulates the muscle cells to contract and relax rhythmically. It also generates an electrical signal that spreads over the atria so they contract at the same time
What does the atrioventricular node do?
The signal from the SA node goes to the AV node, then to the bundle of His, then to the purkinje fibres which cause the contraction of the ventricles
What sound does the heart make?
The sounds “lub” and “dub” are made by the closing of valves.
How is the “lub” sound made
It’s from the closing of atrioventricular valves (tricuspid and bicuspid)
How is the “dub” sound made
It’s from the closing of the semilunar valves (aortic and pulmonary)
What are the atrioventricular valves
Tricuspid and bicuspid valves
What are the semilunar valves
Aortic and pulmonary valves
How many spikes are in the electrocardiogram and what are they?
There are 3 spikes: The P wave, the QRS complex, and the T wave
When does the P wave spike?
When the sinoatrial node fires and the atrias contract
When does the QRS complex spike?
It begins when the atrioventricular node stimulates the ventricles to contract and the atrioventricular valves close, producing the first heart sound “lub”
When does the T wave spike?
It occurs when the ventricles relax again, and the semilunar valves close to produce the second heart sound “dub.” The relaxation of the ventricles is followed by the next firing of the sinoatrial node for the next heartbeat
What is systolic pressure?
Maximum pressure in arteries when the ventricles contract to push blood forward
What is blood pressure?
Pressure that blood exerts on blood vessel walls
What is diastolic pressure?
Lowest pressure in arteries when the ventricles fill with blood
How is blood pressure measured?
Using a sphygmomanometer (sfig-mom-an-om-eter), a blood pressure cuff which is placed on an artery on the arm
How is blood pressure recorded?
mmHg (millimeters of mercury) as systolic of diastolic pressure.
What is the average blood pressure?
The average blood pressure is 120/80
What factors affect blood pressure?
Genetics, physical activity, stress, body temperature, diet, and medication
What is hypertension and what risks does it include?
Hypertension is a continous high blood pressure which causes damage to the arteries. It allows a higher risk of heart attack, stroke, and kidney failure
What is cardiac output?
The volume of blood pumped by the heart measured in mL/min
What does cardiac output indicate?
It indicates the total level of muscle work, how easily the heart fills with blood, and distensibility (stretchiness) of the ventricles
What is stroke volume?
The amount of blood pumped out of the heart with each heartbeat
How do you calculate cardiac output?
Heart rate x stroke volume = cardiac output
What is the average stroke volume?
(70bpm)(70mL)=4900mL/min
What is cardiovascular fitness?
The capacity of the heart, lungs, and blood vessels to deliver oxygen to working muscle tissues so they can maintain prolonged physical work.
