Heart Flashcards
Which arteries deliver blood to the myocardium?
Coronary arteries
What delivers oxygen poor blood to the coronary sinus from the heart?
Cardiac veins
Why does the heart need no external nerves to beat?
The heart is made up of cardiomyocytes. Waves of excitation are sent from the SAN which allow the heart to beat. No external nerves are needed for the heart to beat. But vagus nerve and sympathetic cardiac nerves control the SAN.
How does the parasympathetic nervous system affect heart rate?
Decreases heart rate.
Parents want you to slow down while driving
Which nerve controls the parasympathetic heart rate ?
Vagus nerve
How does the sympathetic nervous system affect heart rate?
Increases heart rate
What nerve controls the sympathetic nervous system ?
Sympathetic cardiac nerves
What nerve controls the sympathetic nervous system ?
Sympathetic cardiac nerves
How many beats per minute is normal heart rate ?
60-100 beats per minute
What is Tachycardia?
Heart rate over 100 beats per minute. Tach = too fast
Bradycardia
Heart rate under 60 beats per minute
What is the function of the atrioventricular node?
Adds a brief delay between contraction of the atria and ventricles.
Describe the cardiac conduction system ?
SA node
Atrioventricular node
Bundle of his
Left and Right bundles
Purkinje fibers = coordinate ventricular contraction
Where are the purkinje fibers found?
Walls of the ventricles
Another name for systole?
Ventricular contraction
Another name for diastole?
Ventricular relaxation
At what point is the pressure in the arteries the lowest?
ventricular relaxation. When blood is coming out of the atria into the ventricles.
At what point is the pressure in the arteries the lowest?
ventricular relaxation. When blood is coming out of the atria into the ventricles.
What causes the lub and dub sounds of the heart?
Closing of the atrioventricular or semilunar valves
What causes the ‘lub’ sound
Atrioventricular valve closing
What causes the ‘dub’ sound
Semilunar valve closing
Systole occurs between which sounds?
lub and dub
Diastole occurs between which sounds ?
dub and lub
What connects cardiomyocytes togther?
Intercalated discs
What are intercalated discs made up of ?
Desmosomes and Gap Junctions
Describe desmosomes?
small proteins that adhere cardiomyocytes together.
they look like stitches
Describe gap junctions?
protein tunnels that connect the cytoplasm of cardiomyocytes.
This allows the movement of ions between cardiomyocytes and allows action potantials to be sent between cells?
What is cardiac syncytium ?
The cardiac syncytium is a network of cardiomyocytes connected by intercalated discs that enable the rapid transmission of electrical impulses through the network, enabling the syncytium to act in a coordinated contraction of the myocardium
What to electrodes attached to the chest measure?
Depolarization
What does P wave represent ?
Atria depolarization
What does Q wave represent?
Depolarization through the interventricular septum
What does the R wave represent?
Depolarization through the ventricles
What does S wave represent ?
Completion of ventricular depolarisation
What does QRS complex represent?
Broad view of ventricular depolarisation.
What does T wave represent?
Ventricular repolarisation
Why cant you see atrial repolarization wave on a ECG?
There is no visible atrial repolarization wave because it’s hidden by the dominant QRS complex.
What is the stroke volume?
Volume of blood pumped from the heart with each beat. Typically refers to the volume of blood ejected from the left ventricle.
What equation do you use to work out the stroke volume ?
EDV - ESV = SV
(End - diastolic volume) - (End - systolic volume) = Stroke Volume
EDV - is the volume of blood after diastole
ESV - after systole a little blood is left in each ventricle which is called the ESV.
What does EDV - ESV = SV mean ?
Amount of blood before ventricular circulation - Amount if blood after ventricular circulation = blood pumped out at ventricular circulation
What does cardiac output tell us ?
Cardiac output: The volume of blood pumped by the heart in one minute
What is the equation for cardiac output ?
CO = HR x SV
Cardiac Output = Heart rate x stroke volume
Why is knowing the cardiac output important ?
Too high or low cardiac output can indicate heart problems.
What does TPR stand for and what does it mean ?
Total Peripheral Resistance and it means the total resistance blood faces while flowing through vasculature ( veins / arteries / capillaries).
What does vasoconstriction do to TPR?
Increases TPR
What does vasodilation do to TPR?
Decreases TPR
What does SBP stand for and what does it mean ?
Systolic blood pressure (SBP): Highest pressure in your arteries
What does DBP stand for and what does it mean ?
Diastolic blood pressure (DBP) : Lowest pressure in your arteries
How is blood pressure often written ?
120/80 mm Hg
The number at the top is systolic blood pressure
The number at the bottom is your diastolic blood pressure
mm Hg means millimeters of mercury
What does Map stand for and what is its equation ?
Mean Arterial Pressure
MAP is a better indicator of blood pressure than SBP or DBP.
MAP = CO x TPR
What are the two equations for finding out MAP ?
MAP = CO x TPR
MAP = (SV x HR) x TPR
What is the name of the technique used to measure blood pressure using a blood pressure cuff?
Auscultation
What is another name for blood pressure cuff?
Sphygmomanometer
What are the 3 tissue layer of a vein or an artery?
tunica intima
tunica media
tunica externa
Describe tunica intima layer of a vessel?
Tunica intima is made up of a single layer of endothelial cells ( simple squamous epithelium) which line the lumen of the vessel.
It reduces the amount of friction the blood experiences when flowing through the vessel.
Describe the tunica media layer of a vessel ?
Tunica media can change the size of a blood vessel, so how much blood can go through a vessel. So tunica media can cause vasodilation or vasoconstriction of the blood vessel.
Tunica media is made up of smooth muscle cells and elastic fibers.
Describe the tunica externa layer of a vessel?
The tunica externa layer is the outer layer of a blood vessel. Its made up of:
- connective tissue
- collagen
- elastin
- nerve fibers ( the tunica externa has nerves which communicate with the tunica media and stimulate vasodilation or vasoconstriction ).
What makes tunica media layer of a blood vessel highly elastic ?
Thick tunica media
High amounts of elastin