CARDIOVASCULAR 1 Flashcards
what do chest radiographs usually show?
size of cardiovascular structures & lung parenchyma- PA and lateral views are used
how does the system circulate blood?
via a pump (heart) & conductive system (blood vessels)
what are the 2 parts of the system?
pulmonary & systemic circulation
what is the main function of the pulmonary system?
transport blood through the lungs under low pressure- right sid eof heart doesn’t have a large muscle mass
why is the pulmonary system low pressure?
low resistance in pulmonary vessels- right ventrice has small muscle mass due to not having developed high pressures
what is the main function of systemic circulation?
transport blood through tissues under high pressure system due to high resistance in systemic vessels- left ventricle has large muscle mass due to high pressures
where is the heart located?
1/3 to right midline + 2/3 to left
how much does the cardiac silhouette occupy?
less than 50% of transverse diameter of the chest- if more, it could mean that there is a disease
how is the heart rotated?
entire heart is rotated to the left- right side of the heart in anterior
what forms the right border in an AP view?
right atrium
what forms the left border in an AP view?
left ventricle
what forms the superior border in AP view?
right & left atria
what forms the inferior border in AP view?
right ventricle- rests on central tendon of diaphragm
where is the base of the heart?
superior surface
where is the apex of the heart?
inferior surface
what is length of normal adult heart from base to apex?
12.5cm
what is heart located in & suspended by?
in mediastinum, suspended by pericardial sac
what does the mediastinum contain?
great vessels fibres, oesophagus & trachea
where does the aorta leave?
left ventricle
what is the aorta divided into?
ascending, aortic arch, descending
what does the aortic arch curves over?
curves posterior over left lung
where is the descending aorta?
slightly anterior & to left of vertebral column- called thoracic while in thorax, called abdominal while in aorta
what are the branches of the aortic arch?
brachiocephalic, left common carotid, left subclavian
what does the brachiocephalic trunk divide into?
right common carotid & right subclavian (vertebral artery arises from subclavian)
where does the pulmonary trunk leave?
right ventricle
what attaches pulmonary trunk to aortic arch?
ligamentum arteriosum
what does the SVC enter?
right atrium
what forms the SVC?
junction of brachiocephalic veins
what is the role of SVC & where is it located?
carries blood from thorax, head & neck- located posterior to ascending aorta
where does the IVC enter?
right atrium
what forms the IVC & where is it located?
formed by junction of iliac veins + ascends to right of abdominal aorta
where does the IVC pass through in diaphragm?
caval hiatus
what is the pericardium made of?
epicardium & parietal pericardium
what is the epicardium attached to?
attached to surface of heart
what is the partietal pericardium attached to?
inner surface of pericardial sac
what seperates the epicardium from pericardium?
pericardial cavity- filled with 15-50ml of pericardial fluid
what is the pericardial sac made of?
fibrous tissues
what does contraction of atrium do?
“tops up” the ventricle
what are the atria seperated by?
interarterial septum
what are extension of atria known as?
auricle
what are the valves of the ventricles?
atrioventricular valve & semilunar valves
what is the atrioventricular valve made of?
leaflets attached to papillary mucles by chordae tendinae
how many leaflets does right valve have?
three leaflets- tricupsid valve
how many leaflets does left valve have?
2 leaflets- bicupsid (mitral) valve
what is the function of semilunar valves?
seperate ventricle from great vessels- three crescent shaped cusps
what seperates right ventricle & pulmonary artery?
pulmonary valve
what seperates left ventricle & aorta?
aortic valve
what is the role of the valves?
act as seals- ensure blood flow is unidirectional- that backflow does not occur
what are valves attached to?
walls of chambers
what acts as anchors on the valves?
chordae tendinae & papillary muscles limit amount of movement
what makes the valves open & close?
pressure gradients
what happens if valves fail?
chambers of heart will not empty properly, chamber will contain excessive amount of blood, murmurs may be produced by regurgitation of blood through the failing valve
what is the heart made of?
myocardium
how does the heart function?
in a cycle of relaxation (diastole) followed by contraction (systole)
what supplies myocardium?
coronary circulation
where do left & right coronary arteries originate from?
at base of ascending aorta
what does coronary sulci mark the seperation of?
seperates atria & ventricles
what does interventricular sulcus seperate?
between the ventricles
what does the left coronary artery supply?
left ventricle, left atrium & interventricular septum
what does the left coronary artery divide into?
left interventricular (anterior descending) + circumflex
what does the left coronary artery travel in?
anterior interventricular sulcus to apex of heart
what does the circumflex travel in?
coronary sulcus and joins the right coronary artery
what does the right coronary artery supply?
right atrium, parts of both ventricles, parts of the conducting system
what does the right coronary artery divide into?
right interventricular
where does the coronary sinus collect blood from?
from myocardial veins & returns to right atrium
how is the cardiac muscle similar to skeletal muscle?
contracts when depolarised & force of contraction depends on resting length of muscle
how is the cardiac muscle different to skeletal muscle?
not under voluntary control & once one cell depolarised, all cells will- functions as a syncytium
what acts as the pacemaker?
whichever part depolarises firtst- usually sinoatrial (SA) node (in base of heart, above atrium)
what does the stretch of the muscle depend on?
the filling of the ventricles
what does the P wave represent in the ECG?
atrial contraction
what does the QRS complex mean in ECG?
ventricular contraction (and atrial relaxation)
what does the T wave mean in ECG?
ventricular relaxation
what can ECG signal be used for?
as reference for image collection & trigger imaging- identifies if valves are working properly
what happens during systole?
AV valves closed & semilunar valves open (pulmonary or aortic)
what happens during diastole?
AV valves open & semilunar valves closed- ventricle is not contracted
what is prospective gating?
image acquired at specific point in ECG cycle
what is retrospective gating?
imaging performed continuously with ECG signal stored
what is the stroke volume?
volume of blood pumped by the contracting ventricle on each beat
what is the cardiac output?
amount of blood pumped each minute (into either the systemic or pulmonary circulation)
what is heart rate regulated by?
sympathetic/parasympathetic balance- Q=HR x SV
what is the ejection fraction?
measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction as it does not empty each time it contracts- stroke volume divided by end distolic volume- proportion of end diastolic volme which is pumped out of heart is ejection fraction e.g. 50% is optimal
what is the ventricular volume at the end of filling phase known as?
end diastolic volume
how is ejection fraction calculated?
by echocardiography
what is the structure of blood vessels?
tunica intima, tunica media, tunica external
what is the tunica intima?
endothelial layer (regulate blood pressure) & underlying CT
what is the tunica media?
concentric layers of smooth muscle
what is the tunica externa?
connective tissue sheath
what type of pressure do arteries receive blood?
under high blood pressure from heart- arterial pressure is a function of vessel diameter
what are the walls of arteries made of?
have elastic walls- expand to accommodate surge of blood ejected from heart- pressure rise is limited because they expand
what is the main role of arterioles?
to control the distribution of blood flow around the body by changing diameter of blood vessels, the resistance to blood flow changes- also controls blood pressure
