Circulatory System Flashcards
Label the sternum and thoracic skeleton
Sternum: Manubrium Body Manubriosternal joint Xiphoid process
Thoracic Skeleton: Clavicle Scapula Sternum True ribs (1-7) False ribs (8-10) Floating ribs (11, 12) Costal cartilages Thoracic vertebrae Diaphragm
The chest cavity is divided into…
Median partition - mediastinum
Lateral pleura & lungs
The mediastinum extends to…
Root of neck above
Diaphragm below
Sternum anteriorly
Vertebral column Posteriorly
What are the subdivisions of the mediastinum?
Superior, inferior, anterior, middle and posterior
What is the pericardium?
Pericardium is a fibro-serous sac that encloses the heart and the roots of the great vessels
The heart lies within the pericardium in the mediastinum
Functions to;
restrict excessive movements of the heart as a whole
serve as a lubricated container in which the different parts of the heart can contract
What is fibrous pericardium?
Strong, fibrous layer
Firmly attached below to the central tendon of the diaphragm
Fuses with outer coats of great blood vessels that pass through it
Attached in front to sternum by sternopericardial ligaments
What is serious pericardium?
Two layers Parietal lines the fibrous pericardium Visceral closely covers heart (epicardium) Space between called pericardial cavity Contains pericardial fluid; lubricant
Why is LV thicker than RV?
Greater force required to pump blood through the body than to the lungs, so muscular wall of left ventricle is thicker than the right
What separates the four heart chambers?
Inter-atrial, interventricular and atrioventricular septa separate the four chambers of the heart
Label the heart structure
SVC- superior vena cava
IVC- inferior vena cava
What are the features of the right atrium?
Forms right border of heart
Receives blood through the SVC, IVC and coronary sinus
Coronary sinus returns blood from the walls of the heart itself
Label the right atrium
Crisla terminalis Musculi pectinati Fossa ovale Atroventricular orifice Right auricle
What are the features of the right ventricle?
Blood entering from right atrium moves in a horizontal and anterior direction
Outflow tract: pulmonary trunk
Pulmonary trunk closed by pulmonary valve–3 semilunar cusps
Label the right ventricle
Chordae tendinae
Tricuspid valve
Trabeculae carnae (including papillary muscles)
What are the features of the left atrium?
Forms most of base of heart
Blood enters X4 pulmonary veins
Anterior half is continuous with left auricle–No equivalent to the crista terminalis
Depression on interatrial septum is the valve of the foramen ovale
Blood moves into left ventricle via atrioventricular orifice–Guarded by the mitral valve
Label the left atrium
Left auricle
4 pulmonary veins
Foramen ovale
Mitral valve
What are the features of the left ventricle? Label the structure
Blood flows into the aortic vestibule
Guarded by the aortic valve
Similar in structure to pulmonary valve
As blood recoils after ventricular contraction, and fills the aortic sinuses formed by the cusps, it is forced into coronary arteries
What is the cardiac silhouette?
Cardiac silhouette refers to the outline of the heart as seen on frontal and lateral chest radiographs
The size and shape of the cardiac silhouette provide useful clues for underlying disease
From the frontal projection, the cardiac silhouette can be divided into right and left borders:
the right border is formed by the right atrium
the superior vena cava entering superiorly and the inferior vena cava often seen at its lower margin
the left border is formed by the left ventricle and left atrial appendage/auricle
the pulmonary artery, aortopulmonary window and aortic notch extend superiorly
Describe the pulmonary trunk
Arises slightly anterior to aortic orifice
Ascends posteriorly and to the left, lying anterior and to left of ascending aorta
Divides into left and right
Left: inferior to aortic arch
Right: posterior to ascending aorta and SVC
What are the features of the aorta?
Ascending within pericardial sac
Enters superior mediastinum = arch
Arch lies behind manubrium sterni, in front of trachea
Arches upwards and backwards
Becomes continuous with descending aorta
Aortic arch branches:
Brachiocephalic trunk (divides into right subclavian and right common carotid
Left common carotid
Left subclavian
What are the two parts of the vena cava?
Superior Vena Cava
Inferior half within pericardial sac
Inferior Vena Cava
Passes through diaphragm at T8 and enters fibrous pericardium
What are auscultation points and what can you hear from them?
Cardiac auscultation enables heart sounds to be listened to using a stethoscope for cardiac assessment
Normal heart sounds (lub-dub) are produced by the closure of the valves during a contraction
Valve sounds travel through the surrounding structures of the thoracic wall
Placement of the stethoscope differs from the position of the valve being examined (downstream from flow of blood)
Palpation of the ribs is used to determine which level a stethoscope needs to be placed
What is it called if a heart sound differs due to turbulent blood flow?
Heart murmur
What are the 4 auscultation points?
Aortic valve: medial end of the 2nd right intercostal space
Pulmonary valve: medial end of the 2nd left intercostal space
Tricuspid valve: 4th intercostal space at the lower left sternal border
Mitral valve: 5th left intercostal space at the mid-clavicular line
What are the three layers of the heart?
–Endocardium: inner most layer. Lines Cavities and heart valves
–Myocardium: composed of cardiac muscle and responsible for contraction of the heart
–Epicardium: outermost layer of the heart, formed by the visceral layer of the serous pericardium. It is composed of connective tissue and fat
Describe the endocardium
Structurally, the endocardium is comprised of loose connective tissue and simple squamous epithelial tissue
Similar in its composition to the tunica intima which lines the inside of blood vessels
Deep to the endocardium is the subendocardial tissue, which contains loose vascularized connective tissue
Subendocardial tissue also contains nerves as well as Purkinje fibres
In areas where the myocardium is thin (i.e. atria) the endocardium is relatively thicker
In addition to lining the inside of the heart, the endocardium also regulates contractions and aids cardiac embryological development