cardiovascular system Flashcards
What is the transthoracic plane?
horizontal plane at junction of manubrium to the sternum
what is the level of the heart?
T2-5 thoracic level and ribs
what is the mediastinum?
area between pleura/ both lungs and above the diaphragm
what are the subdivisions of the mediastinum?
superior
anterior
middle
posterior
superior mediastinum
above transthoracic plane - angle of louis
anterior mediastinum
anterior to pericardium
middle mediastinum
pericardium and its contents
posterior mediastinum
posterior to pericardium
what are the contents of the superior mediastinum?
arch of aorta and its 3 divisions
superior vena cava
vagus nerve - right branch runs posterior to superior vena cava
left vagus splits to create left recurrent laryngeal nerve which loops under the aortic arch
thymus
what are the major branches of the aortic arch?
- brachiocephalic artery
- Left subclavian artery
- Left common carotid artery
what are the borders of the superior mediastinum?
thoracic inlet
manubrium
vertebral bodies of T1-4
pleura of the lungs
What are the contents of the anterior mediastinum?
thymus - usually in children as shrinks with age
What are the borders of the anterior mediastinum?
body of sternum
pericardium
pleura of lungs
diaphragm
what are the contents of the middle mediastinum?
pericardium heart tracheal bifurcation - left and right main bronchi ascending aorta pulmonary trunks superior vena cava cardiac plexus phrenic nerves - L&R
what is the cardiac plexus?
collection of sympathetic (T1-4) and parasympathetic nerves (vagus) that innervate the heart
what are the contents of the posterior mediastinum?
thoracic aorta - crosses diaphragm at T12
oesophagus
thoracic duct
sympathetic trunks
what are borders of the posterior mediastinum?
transthoracic plane pericardium vertebral bodies of T5[12 pleura of lungs diaphragm
what are the borders of the middle mediastinum?
transthoracic plane
pericardium
pleura of the lungs
diaphragm
what are the layers of arterial wall?
tunica intima
tunica media
tunica adventitia
tunica intima
endothelial cells with a thin subendothelium of connective tissue and discontinuous elastic laminae
tunica media
elastic membranes and smooth muscle cells
tunica adventitia
thin layer containing lymphatics, nerves and blood supply for the artery itself
what are the layers of the heart?
pericardium
epicardium - connective areolar tissue
myocardium - cardiomyocytes and connective tissue
endocardium - thin layer of connective tissue and endothelium
what are the layers of the pericardium?
2 layers:
1. outer, fibrous, tough sac = fibrous pericardium
2. inner serous sac which splits into 2 more layers:
- parietal pericardium
- visceral pericardium/ epicardium
cavity contains pericardial fluid for lubrication
what does the pericardium allow?
heart has room to move in the pericardium but effusion or bleeding into this space will constrict the heart as the fluid is trapped resulting in a cardiac tamponade.
Epicardium
outermost layer of heart wall
forms visceral layer of pericardium
composed of connective tissue and fat, the connective tissue secretes the lubricating fluid into the pericardial cavity
external surface is lined by simple squamous epithelial cells
subpericardial layer separates the epicardium from myocardium
myocardium
made of cardiac muscle
endocardium
innermost layer of heart wall
lines the cavities and valves
similar to endothelial lining of blood vessels
loose connective tissue and simple squamous epithelium
subendocardial layer
subendocardial layer
joins the endocardium and myocardium
contains loose fibrous tissue, vessels and nerves of heart
purkinje fibres are located here
what does infective endocarditis do and what causes it?
affects valves
causes heart murmurs
caused by alpha haemolytic strep from dental work
fibrous cartilage of the heart
dense collagen framework
forms 4 rings around openings of heart valves
what does the fibrous cartilage of the heart do?
structural foundation of heart valves - keeps them open and prevents overstretching
anchors the myocardium
electrical insulator between atria and ventricles
right atrium
receives blood from superior and inferior vena cava
and opening of coronary sinus
75% of cardiac venous return
25% empties into atria and ventricles via transmural and endomural systems
tricuspid valve into ventricle
fossa ovalis in interatrial septum
right ventricle
ejects blood to lungs through pulmonary valve and pulmonary trunks
left atrium
receives blood from 4 pulmonary veins
mitral valve into left ventricle - bicuspid
left ventricle
pumps blood to systemic circulation through aortic valve
how is the left side of the heart different from the right?
3 x more muscular than right
can generate 4-6 x the pressure of right side
right side of the heart
weaker/ less muscular and generates less pressure than the left side.
valve structure
made of mainly collagen layers with elastin and proteoglycan
allow for one way flow of blood
how do the mitral and tricuspid valves work?
supported by chordae tendineae which are supported by papillary muscles which contract to put tension on chordae tendineae resisting pressure from blood trying to get back into atria
how do the aortic and pulmonary/ semilunar valves work?
3 cusps
open by blood from ventricles pushing them out and collapsing them
close when blood in aorta/ pulmonary trunks tries to return to ventricles as it will fill the cusps first, opening them up and clasping them shut.
what are all the coronary arteries?
right coronary left coronary right marginal left anterior descending left marginal posterior interventricular circumflex
what part of the heart does the right coronary supply?
right atrium
SAN
AVN
posterior part of interventricular septum
what part of the heart does the right marginal supply?
right ventricle
apex
what part of the heart does the posterior interventricular supply?
right and left ventricles
posterior 1/3 of interventricular septum
what part of the heart does the left coronary supply?
left atrium and ventricle
interventricular septum
AV bundles
what part of the heart does the left anterior descending supply?
right and left ventricle
anterior 2/3 of interventricular septum
what part of the heart does the left marginal supply?
left ventricle
what part of the heart does the circumflex artery supply?
left atrium and left ventricle
morphology of skeletal muscle
long and cylindrical
morphology of cardiac muscle
branched
morphology of smooth muscle
spindle
nuclei of skeletal muscle
many located peripherally
nuclei of cardiac muscle
1 or 2 located centrally
nuclei of smooth muscle
1 located centrally
T tubules of skeletal muscle
yes, form triad with sarcoplasmic reticulum
T tubules of cardiac muscle
yes, form dyad with sarcoplasmic reticulum
T tubules of smooth muscle
no, have caveolae - lipid invaginations
regulation of cross-bridge formation in skeletal muscle
troponin
regulation of cross-bridge formation in cardiac muscle
troponin
regulation of cross-bridge formation in smooth muscle
calmodulin activated by Ca2+ which activates myosin light chain kinase
control of contraction of skeletal muscle
motor neurones
control of contraction of cardiac muscle
autonomic nerves
control of contraction of smooth muscle
autonomic nerves
hormones
what pressure does the left side of the heart generate?
arterial pressure systemically = 120mmHg
systemic mean capillary pressure = 17mmHg
what pressure does the right side of the heart generate?
systemic arterial pressure = 25mmHg
systemic mean capillary pressure = 7mmHg
