Cardiovascular System Flashcards
Define the pulmonary circulation?
Blood flow between right ventricle & left atrium via the lungs.
What does the cardiovascular system consist of?
Heart, blood vessels (arteries,veins,capillaries), blood, medulla oblongata (control centre)
Define the systemic circulation?
Blood flow from left ventricle to right atrium via the body.
What is the purpose of the coronary arteries?
Oxygenated blood from aorta to the myocardium
What is the purpose of the cardiac veins?
Deoxygenated blood to the right atrium via the coronary sinus.
Name the 3 principle layers of the heart?
Endocardium, myocardium, pericardium
Whee would you find the endocardium?
Inner lining of heart chambers
Where would you find the myocardium?
Cardiac muscle. Thickest in the left ventricle
Where would you find the pericardium?
Covering layer of the heart that forms a sac.
What is the name of the inner lining of the pericardial sac?
Epicardium
What is the name of the valve located between the right atrium & right ventricle?
Tricuspid valve
What is the name of the valve located between the left atrium & left ventricle?
Bicuspid (mitral) valve
What is the name of the valve located at the entrance to the pulmonary trunk (pulmonary Artery)?
Pulmonary valve
What is the name of the valve located at the entrance to the aorta?
Aortic valve
What is the role of the heart?
Role of the heart is to receive blood from tissues and lungs and to pump blood around two circulations (pulmonary & systemic)
What is the purpose of the atria?
Receive blood returning from the body (right atrium) & lungs (left atrium)
What is the purpose of the right ventricle?
Pumps blood to the lungs
What is the purpose of the left ventricle?
Pumps blood to the systemic arteries
What is intrinsic rhythmicity?
Contraction & relaxation of myocardial cells.
Under what circumstances can intrinsic rhytmicity only happen?
Response to electrical changes in the cell.
Where is electrical activity spontaneously generated?
Sino-atrial node
Where is the sino-atrial node located?
Wall of the right atrium close to the entrance of the superior vena cava.
What does the sa node contain?
Pacemaker cells (show pacemaker activity)
How does the sa node work?
Fires impulses (action potentials) spontaneously & sets the rhythm of the heart.
Where are action potentials conducted?
Throughout the myocardium. First atria electrically excited then ventricles electrically excited.
What is the conduction system of the heart?
San- atria- avn (delayed)- ventricles
What fibres carry impulses around the ventricular myocardium?
Bundle of his, bundle branches & purkinje
In an ecg what does the p wave measure?
Atrial depolarisation ( electrical excitation)
In an ecg what does the qrs complex measure?
Ventricular depolarisation
In a ecg what does the t wave measure?
Repolarisation of ventricles ( return to non-excited state)
What are the 3 stages of the cardiac cycle?
Systole, myocardium repolarises, diastole
Define systole?
Blood is squeezed from the atria into ventricles & then ejected from the ventricles.
What follows electrical excitation?
Mechanical contraction (systole)
Define diastole?
Relaxation. Refills with blood.
Define myocardium repolarisation?
Returns to its resting electrical state
What valves close at the start of ventricular systole & open at the start of ventricular diastole?
Tricuspid & bicuspid (mitral) valves
What valves open at start of ventricular systole & close at start of ventricular diastole?
Aortic & pulmonary valves.
The heart sounds ‘lub’ & ‘dub’ correspond to what?
Closure of certain heart valves.
Define cardiac output?
Volume of blood ejected from the left ventricle in one minute.
What does cardiac output depend on?
Bpm & stroke volume
Define stroke volume?
Volume of blood ejected from by the left ventricle in one heartbeat.
What is the equation for cardiac output?
Cardiac output = heart rate x stroke volume
Define heart rate?
Number of times heart beats in one minute (bpm)
What is the normal range for heart rate?
60 - 80 bpm
Name the principle pulse points?
Temporal, carotid (neck), brachial (inside elbow), radial (wrist), femoral (groin), popliteal (back of knee). Dorsalis pedis (top of foot)
What can alter heart rate?
Exercise, stress, drugs, hormones, nervous system
What does the autonomic nervous system do?
Controls physiological processes we have no control over (conciousley) “automatic”
Hat effect does the parasympathetic nervous system have on the heart?
Slows heart rate ( important during rest)
What effect does the sympathetic nervous system have on the heart?
Accelerates heart rate during exercise or challenges of any kind.
What hormones can increase heart rate & stroke volume?
Adrenaline, noradrenaline, thyroxine
What is a normal maximum heart rate?
170 - 209 bpm
What is tachyardia?
Heart rate above 100 bpm at rest
What is bradycardia?
Heart rate below 50 bpm at rest.
Under what circumstance may you find someone with a slower resting heart rate?
Fitness
What influences stroke volume?
Venous return ( circulating blood volume), reduced venous return (e.g. Haorrhage) reduces sv & thus cardiac output
What is a typical stroke volume for a standard man?
70mls per heart beat
What determines stroke volume?
How strongly ventricles contract
What can change stroke volume?
Exercise, stress, drugs, nerves, hormones
What effect does sympathetic stimulation have on stroke volume?
Increases force of heart beat & increases stroke volume
What effect does parasympathetic stimulation have on stroke volume?
Tends to reduce stroke volume.
