Cardiovascular System Overview Flashcards
What are the functions of the cardiovascular system?
To transport nutrients, oxygen and waste products around the body
To transfer heat - generally from core to skin
Buffer body pH
Transport hormones
Assist in response to infection
Assist in urine formation
The pulmonary artery splits in two so that one artery travels to the left lung and the other to the right. T/F?
True
In most people, how many pulmonary veins are there?
Four
The valves of the heart open and close simultaneously in response to what kind of gradient?
Pressure gradient
What is the name of the ‘heart strings’ which help to orientate the heart valves?
Chordae tendinea
When listening to the heart with a stethoscope two heart sounds should be heard. What do these sounds represent?
The first is the AV valves closing, the second is the semilunar valves closing.
What are the two elements if the cardiac cycle called?
Systole - contraction
Diastole - realaxation
What is the end systolic volume?
The left over blood in the heart following a heart contraction as not all the blood volume is pumped out
What is the stroke volume of the heart?
The volume of blood ejected from the heart per beat
What are the names of the two nodes of the heart involved in contraction?
Sinoatrial node
Atrioventricular node
What does the P wave of an electrocardiogram show?
Atrial depolarisation
What does the QRS complex of an electrocardiogram show?
Ventricular depolarisation
What does the T part of an electrocardiagram show?
Ventricular repolarisation
Why is atrial repolarisation not seen on an ECG?
Because it is masked by the QRS complex
The delay through the AV node in the contraction of the heart is represented by what phase of an ECG?
The P R interval
The plateau phase of heart contraction is shown on am ECG as what phase?
The S T interval
In phase three of an action potential in the SA node, how does repolarisation occur?
By the outward movement of potassium
What occurs during phase four of an action potential in the SA node?
Calcium ions move inwards and potassium ions move outwards causing a very gradual depolarisation until a threshold is met and an action potential fired.
What is the main adrenoceptor that exists on nodal tissue in the heart?
Beta one receptors
The right vagus nerve terminates on the SA node and the left vagus nerve terminates on the AV node. T/F?
True
What effect will increased volume of blood in the heart have on the heart muscle?
The strength of heart muscle contractions will increase
The action potential for a Purkinji fibre is similar to that of a neuron. T/F?
True
Which node acts as the main pacemaker of the heart?
The SA node
Because of the SA node the heart does not require innervation to initiate an action potential. Why is it, then, that it does recieve innervation?
The nerves to the heart control are not necessary for contraction to occur but they control pace at which it contracts
Describe the events of mid to late diastole.
The atria and ventricle are both relaxed but atrial pressure is higher than ventricular pressure because the atria are filling with blood so the AV valves are open and blood flows from the atria into the ventricle. The semilunar valves are closed. Ventricular pressure slowly increases as it fills with blood. Towards the end of diastole the SA node discharges and the atria contract to force the remaining volume of blood into the ventricle
Describe the events of systole.
From the AV node the wave of depolarisation passes over the ventricular tissue and the ventricles contract. This increases ventricle pressure so that the AV valves close. Once the pressure in the ventricle increases enough the semilunar valves will open and blood is forced from the ventricles into the arteries. Blood is ejected rapidly at first, then more slowly towards the end of systole. As blood flows into the arteries, there pressure increases to a point where it is greater than ventricular pressure and the semilunar valves close.
Describe the events of early diastole.
The semilunar valves close because arterial pressure is increasing and ventricular pressure is decreasing as the ventricles relax. The AV valve also remains closed because ventricular pressure is still higher than atrial pressure. Once the ventricles have relaxed further atrial pressure will be greater than ventricular pressure so the AV valves open allowing blood to fill the heart again
What is the clinical relevance of diastolic pressure?
It is during diastole that the myocardium itself is supplied with oxygenated blood through the coronary arteries - this is different from all other tissues which receive blood during systole
Diseases or inherited conditions causing a fault in The electrical conduction system of the heart will result in what symptoms?
Lightheadedness
Palpitations
Syncope
Cardiac arrest
