1.1 The Cardiovascular System Flashcards
Bradycardia (definition)
A decrease in resting heart rate to below 60 beats per minute.
Heart Rate`(definition)
The number of times the heart beats per minute.
Stroke Volume (definition)
The volume of blood pumped out by the left heart ventricle in each contraction.
Cardiac Output (definition)
The volume of blood pumped out by the heart ventricles per minute.
Cardiac Output (calculation)
Cardiac Output = Stroke Volume x Heart Rate.
Ejection Fraction (definition)
The percentage of blood pumped out of the left ventricle each beat.
Cardiac Hypertrophy (definition)
The thickening of the muscular wall of the heart so it becomes larger and stronger; can also lead to developing a larger ventricular cavity.
Max Heart Rate (calculation)
220 - age (bpm)
Resting Heart Rate (definition)
The average number of heart beats per minute at rest.
What is the average resting heart rate?
72 beats per minute
Starling’s Law (definition)
The greater the venous return, the greater the strength of contraction in the heart.
Venous Return (definition)
The return of blood to the right side of the heart via the vena cava.
The heart muscle is myogenic, state what this means:
Myogenic - The capacity of the heart to generate its own impulses.
What do Chemoreceptors detect?
changes in Carbon Dioxide levels.
What do Baroreceptors detect?
Changes in the blood pressure (baro = pressure)
Suggest why the atria are smaller than the ventricles:
The atria only have to push blood down into the ventricles, whereas the ventricles have to push blood out of the heart and therefore have stronger muscle tissue surrounding it.
Which side of the heart is larger, and suggest why it is:
The left side is larger as it contains more muscular tissue in order to pump blood all around the body as apposed to the lungs (which are in close proximity to the heart).
What is the function of the Vena Cava?
Transporting de-oxygenated blood to the right atrium of the heart.
What is the function of the pulmonary vein?
Delivering oxygenated blood to the left atrium.
Wht is the function of the pulmonary artery?
Leaves the right ventricle with de-oxygenated blood to take to the lungs.
What is the function of the aorta?
Leaves the left ventricle with oxygenated blood for the body.
There are four main valves in the heart, what are their function?
Ensures blood flow is unidirectional, it does this by opening to allow blood to pass through and closes to prevent backflow.
What valve is located between the right atrium and right ventricle?
Tricuspid valve.
What valve is located between the left atrium and left ventricle?
Bicuspid valve.
Where are the semi-lunar valves?
They are found between the right and left ventricles (and the pulmonary artery and aorta).
Where does the electrical signal start in the cardiac conduction system?
In the sinoatrial node (SA node).
Where is the Sinoatrial node found?
In the wall of the right atrium.
Which component of the cardiac conduction system is commonly referred to as “the pacemaker”?
The SA node.
Describe the consequences of an electrical impulse being sent out of the SA node:
The impulse spreads through the atrial walls, causing them to contract and forcing blood into the ventricles.
What does the abbreviation AV node mean?
Atrioventricular node.
What is the function of the AV node?
The node relays the impulse (created by the AV node) between the upper and lower sections of the heart.
Approximately how long does the AV node delay the impulse, and what is the purpose of this delay?
0.1 seconds, it is to allow for full contraction of the atria before ventricular systole begins.
Where is the bundle of his located?
In the interventricular septum, (between the left and right ventricles).
State the function of the bundle of his:
It transmits the electrical impulses from the AV node to the ventricles in order to stimulate ventricular systole.
As an electrical impulse goes down the bundle of his, it splits into two branches before reaching a group of smaller bundles, what is the name of these muscles?
Purkinje fibres.
What is the function of purkinje fibres?
To conduct impulses in the walls of the ventricles in order to stimulate contractions.
What is the scientific name for contraction?
Systole.
What is the mnemonic used to summarise the cardiac conduction system?
S AN A trial systole A VN B undle of his P urkinje fibres V entricuar systole.
What is the sympathetic (nervous) system?
A part of the autonomic nervous system that speeds up heart rate.
What is the parasympathetic (nervous) system?
A part of the autonomic nervous system that slows down heart rate (to resting levels).
Which body parts make up the Central Nervous System?
The spinal cord and the brain.
What is the peripheral nervous system?
Nerve cells which transmit information to and from the CNS.
Both the Central and Peripheral nervous systems are controlled by the same part of the brain, what is the name of this?
Medulla Oblongarta.
What are the 3 types of “detectors” that feedback to the medulla oblongarta.
Chemoreceptor
Baroreceptor
Proprioceptors
What do chemoreceptors detect?
Changes in Carbon Dioxide levels.
Where are chemoreceptors found?
Carotid arteries.
Aortic arch.
Why is the chemoreceptor important during exercise?
Due to increased rate of respiration, CO2 levels increase. The chemoreceptors detect this and stimulate the sympathetic nervous system to increase heart rate and get rid of CO2.
What do baroreceptors detect?
Changes in blood pressure.
How do baroreceptors detect changes in blood pressure?
They have nerve endings that respond to the stretching of the arterial walls caused by pressure.
Blood pressure naturally increases during exercise, how do baroreceptors deal with this without setting off a false alarm to the medulla oblongarta.
They set a point for natural blood pressure level during exercise when it begins so that changes are relative to activity levels.
What do proprioceptors detect?
They detect and increase in muscle movement.
When proprioceptors detect increased muscle movement at the start of exercise, what happens?
The receptors send an impulse through the sympathetic nervous system to the SAN to increase heart rate.
What effect does the hormone adrenaline have on thee SA node?
It increases both the speed and force of impulses, increasing cardiac output as the heart rate increases. Resulting in more oxygen being supplied to the working muscles.
What is the stroke volume?
The volume of blood being pumped out by the heart ventricles in each cardiac contraction.
What is venous return?
The volume of blood returning to the heart through the veins.
What is the relationship between venous return and stroke volume?
If venous return increases, so will stroke volume as more blood enters the heart meaning more blood leaves the heart.
What is the diastole phase?
The phase in which the heart muscle relaxes to fill with blood.
What is ejection fraction?
The percentage of blood pumped out by the left ventricle per beat.
What is myocardium? (H)
The muscle tissue of the heart.
What is the average stroke volume at rest? (H)
70 ml
Explain the equation:
Q = SV x HR
Q = Cardiac Output SV = Stroke Volume HR = Heart Rate
Cardiac Output = Stroke Volume x Heart Rate.
What is Starling’s Law?
Increased venous return, Greater diastolic filling, Cardiac muscle stretches, More contraction force, Increased ejection fraction.
Maximum heart rate calculation:
220 - age (bpm)
Explain how an individual can undergo cardiac hypertrophy:
Regular aerobic training leads to the development of cardiac muscle, this is hypertrophy.