CVS Flashcards
Where is the heart found?
Middle mediastinum
What is the heart surrounded by ?
Pericardium
Describe the pericardium?
Fibroserous fluid filled sac surrounding the musclular body of the heart and roots of the great vessels
Give the functions of the pericardium
Fixes the heart and limits rotation
prevents over filling due to inextensible fibrous layer
lubrication
protection from infection as it acts as a barrier from the lungs which are susceptible to injury
Describe the two layers of the pericardium
Fibrous layer - continuous with the central tendon of the diaphragm
Serous layer - outer parietal layer and internal visceral layer made up of mesothelium
What is the innervation of the pericardium? What are its spinal roots?
Phrenic nerve (C3-C5)
What clinical relevance does the fibrous pericardium have?
During accumulation of fluid - pericardial effusion within pericardial cavity leading to increased pressure and chambers are compressed reducing the CO.
What is the clinical relevance of the transverse pericardial sinus? Where is it found ?
Can be used to located and subsequently ligate arteries during coronary bypass grafting.
It is a passage through pericardial cavity located posteriorly to ascending aorta and pulmonary trunk, anteriorly to SVC and superior to LA
Where does the apex of the heart point?
Anterior inferior direction
What is the anterior border of the heart?
Right atrium
What is the posterior border of the heart ?
Left atrium
What is the inferior border of the heart?
Both ventricles
What is the right pulmonary border of the heart?
Right atrium
What is the left pulmonary border of the heart?
Left ventricle
What are sulci and what do they create?
Divisions in the heart which form grooves
Where is the coronary sinus and what travels in it ?
Transverse around the heart- wall dividing atria and ventricles
Contains vascualture
What does the anterior and posterior interventricular sulci divide?
Run vertically and separate ventricles
What is the formation of the pericardial sulci?
Passageways formed in way in which percardium folds around the great vessels.
What are the two pericardual sulci? Where are they found ?
Oblique pericardial sulci- posterior surface of the heart
Transverse pericardial sulci- superiorly found
What are the two things that may happen to a valve?
Stenosis and regurgitation
If changes occur to a valve what may be heard? Why?
Murmur due to tuberlent flow
What murmurs caused by valve changes are heard during systole?
Pulmonary and aortic valve stenosis
Mitral valve prolapse
Mitral/ tricuspid regurgitation
What murmurs caused by valve changes are heard during diastole?
Aortic/ pulmonary regurgitation
Mitral/ tricuspid stenosis
What forms the IVC?
Joining of the two common iliac veins
What forms the SVC?
Joining of the two brachiocephalic veins
What are the three branches of the aortic arch?
Brachiocephalic
Left common carotid
L subclavian
Describe an aortic dissection
Tear in the inner wall which restricts blood flow and causes shearing of the blood vessels layers from each other.
Describe an aortic aneurysm
Dilation of artery underlying weakness can lead to rupture and therefore huge haemorhaging causing death.
How are the mitral and tricupsid valves shut? What is heard when they shut?
Contraction of small muscles - papilary muscles attached to valves by chordae tendinae . The first heart sound S1 or lub.
Describe the aortic valve. What is its significance in terms of filling of the coronary arteries?
Fibrous ring where 3 cusps attach
Opening to the coronary vessels found above L and R cusps so when valve opened these are covered so filling occurs during diastole.
What happens to the heart sounds during inspiration?
Inspiration causes blood into the thorax increasing right ventricular pressure leading to the shutting of the aortic valve first
How can you tell between the heart sounds S1 and S2?
2nd heart sound higher pitch shorter duration and lower intensity
Describe the inner surface of the RA?
2 parts divided by the crista terminalis
Posterior - smooth walls from sinus venous
anterior -muscular wall and right auricle from primitive atria
Describe the inner surface of LA?
inflow portion smooth from pulmonary veins
outflow- pectinate muscle and L auricle from atria
Describe the atrial septa
Oval shaped depression called fossa ovalis from foramen ovale
Describe the inner surface of the RV?
Triangular shape
Anterior border - trabeculae carnae
Inferior inflow -papillary muscles and chordae tendinae
moderator band contains - right bundle branches
Describe the LV composition
Increased muscle as needs to generate higher pressure
papillary muscles contain trabeculae carnae
Describe the ventricular septa
Membranous and muscular parts
Give a general description of the layers of the heart muscle?
Endo–> myo–> epi cardium
Describe the endocardium
Inner most layer - lines cavities and valves of the heart
loose connective tissue and simple squamous epithelial tissue
regulates contractions and aids cardiac embyrological development
What are the two main types of endocarditis ?
Infective and non infective
What is the subendocardial layer?
joins endo and myocardium - loose fibrous connective tissue and contains the perkinji fibres so if damaged can lead to arrthymias
Describe the myocardium
Cardiac muscle - straitated muscle that contracts involuntarily.
What is the subepicardial layer?
Joins myo and epicardium
Describe the epicardium?
Outer most layer composed of CT, fat and simple squamous epithelia.
Where do the coronary arteries arise from?
Aortic coronary sinuses L and R
What does the L coronary artery branch into?
Left anterior descending and circumflex and left marginal artery
What does the R coronary artery branch into?
Right marginal artery and posterior interventricular artery
What areas of the heart does the R coronary artery supply?
RA, both nodes, posterior part of the interventicular septum
Where of the heart does the right marginal supply?
RV and apex
Where does the posterior interventricular artery supply?
Both ventricles and posterior 1/3 of IVS
Where does the L coronary artery supply?
LA, LV, IVS and AV bundles
Where does LAD supply?
RV, LV, anterior 2/3 of IVS
Where does the left marginal supply?
LV
Where does the circumflex supply?
LA LV
Where do the cardiac veins drain into ?
Coronart sinus on posterior aspect of the heart
Some drain directly into the RA
What are the tributaries to the coronary sinus and where do the come from?
Great cardiac vein - from apex follows anterior interventricular groove
Small cardiac vein - right side anterior
Middle cardiac vein - posterior surface
What valve is found between the RA and RV?
Tricuspid
What receptors innervate the cardiac vasculature to cause vasodilation?
B2 adrenoceptors
What allows the spread of AP in cardiomyocytes?
Intercolated discs
What sets the heart rate usually ? Why ?
SAN
Because it has the quickest rate of impulse generation
How are impulses generated in the SAN?
Funny current allows the threshold to be regularly reached
Why can electrical impulses not spread directly to ventricles ?
Insulation from cartilaginous rings of heart
How long and where is the action potiental delayed for?
At the AVN for 120ms.
What change produces S1?
closing of the AV valves
What change produces S2?
Closing of the outflow valves
What do s3 and s4 produce?
Gallop rhythm
What is the pressure in the RA?
0-8mmHg
What is the pressure in the RV during diastole?
0-8 mmHg
What is the pressure in the RV during systole?
15-30 mmHg
What is the pressure in the LA?
0-10 mmHg
What is the pressure in the LA during diastole?
1-10 mmHg
What is the pressure in the LA during systole?
100-140 mmHg
What is the pressure in the pulmonary artery during diastole?
4-12mmHg
What is the pressure in the pulmonary artery during systole?
15-30mmHg
What is the pressure in the aorta during diastole?
60-90mmHg
What is the pressure in the aorta during systole?
100-140 mmHg
Describe the pathway of vessels from the heart back to the heart
Large elastic arteries Medium arteries arterioles metarterioles capillary beds post capillary venules venules medium veins large veins heart
What is the function of the fluid between the visceral and parietal layers of the serous pericardium?
lubrication
Describe cardiac tamponade
Pericardial effusion- accumulation of blood or pus leading to insufficient filling and obstructive shock as decreased filling presents with Becks Triad
What is pericardiocentesis?
Drainage of fluid in cardiac tamponade.
Wide bore needle inserted L 4/5th intercostal space near sternum
Describe the changes that would be noticed on examination of a patient with pericarditis
Chest pain
ST elevation in ALL leads
Rustle on ausculation - serous layer can become roughened and fibrosed.
Where do you listen to the aortic valve?
2nd intercostal R sternal edge
Where do you listen to the pulmonary valve?
2nd intercostal L sternal edge
Where do you listen to the triscupid valve?
4th intercostal space L sternal edge
Where do you listen to the mitral valve?
5 th intercostal space midclavicular line L
Give the equation for cardiac output
CO=SV x HR
Give the equation for Blood pressure
BP= CO x TPR
so
BP= SVxHRxTPR
What is stenosis?
Narrowing when opening
What is regurgitation ? What is it also called?
Not closing
incompetence
What is atresia?
Valve not present or fused
What does the ANS and CNS regulate?
HR, BP, temp
When is sympathetic nervous system dominante?
Under stress
When is the parasympathetic nervous system dominante ?
Basal conditions
Describe the parasympathetic input of the heart?
Preganglia at CNX synapse with postganglia on epicardium or within walls of the SA or AV node
What parasympathetic receptors are present in the heart? What neurotransmitter is released?
Ach at M2 receptors
What is the effect of activation of the parasympathetic nervous system at the heart?
Decrease heart rate ( negative chronotropic response)
Describe the sympathetic input of the heart?
Post ganglia via paravertebral chain innervate the nodes and myocardium
What sympathetic receptors are present in the heart? What neurotransmitter is released?
Release nor adrenaline on the alpha 1 adrenoceptors
What is the effect of activation of the sympathetic nervous system at the heart?
Increase HR and force of contraction
Explain the mechanism behind the changes that occur on activation of the parasympathetic nervous system at the heart
Increased K+ conductance leading to decreased cAMP levels and decreasing the pacemaker potential
Explain the mechanism behind the changes that occur on activation of the sympathetic nervous system at the heart
Increased Na+ conductance leading to increased cAMP levels and increasing the pacemaker potential.
Activated PKA phosphorylates Ca channels leading to increased Ca entry and increased contraction force- CICR
What receptors are found in most arteries and veins? What is there action?
alpha 1 adrenoceptors - contract with circulating adrenaline
What is special about the coronary and skeletal muscle vasculature?
Have B2 adrenoceptors which cause dilation during increased stress due to increased adrenaline - over ride a1
How is change in condition detected and converted into a change in pressure?
Baroreceptors in the carotid sinus and aortic arch detect high pressure send increased AP due to increased sensitivity to stretched
Low pressure detected by atrial receptors
Define flow
Volume of fluid per unit of time passing a given point
Define velocity
Rate of movement of fluid particles along a tube
What is the equation for pressure?
Pressure = flow x resistance
What does poiselles law state?
Increase in resistance with R to the power four
What is Becks Triad?
Hypotension,raised JVP and distant muffles of examination
Where is blood flow fastest?
Total cross sectional area is at its least- capillary bed
How long is a cardiac action potential ? What does this relate to ?
280-300ms
Ventricular systole
Describe the conduction pathway of the heart?
SAN
Over atrial- atrial systole
AVN- delayed for 120
spreads down IV septum to apex and ventricles contract from apex upwards forcing blood out of the outflow valves
Describe the development of a CVA or TIA
Thrombus forms on wall of LA ( can occur in atrial fribrilation) can break off and pass into artery suppling the brain resulting in CVA or partial occlusion would lead to TIA
What is a consequence of aortic valve stenosis ?
Increased afterload leading to LV hypertrophy
Where in the system is pressure high? why ?
arteries to drive the blood through arterioles
Where in the system is pressure low? why ?
Venules and veins - low resistance and therefore low pressure needed to drive blood
What factors affect the systolic pressure?
Force of contraction, TPR and stretchiness of aorta
What factors affect the diastolic pressure?
Systolic and TPR
What is the pulse pressure?
Difference between systolic and diastolic pressure
How do you calculate an average pressure?
Diastolic + 1/3 pulse pressure
Describe reactive hyperaemia
loss of circulation increased metabolites released ( H+, K+, adenosine)- effect dependent on production and removal rate.
Poor perfusion - increased metabolites leads to arterial dilation which washes away increased metabolites .
What does an increased in TPR mean?
Decreased need for flow
What is central venous pressure ?
Pressure in great veins
What does central venous pressure depend on?
Return from the body, pumping of the heart , gravity and muscle pumping
Define heart failure
State in which heart cannot maintain adequate perfusion of the body to meet its needs despite adequate filling pressure
What are some causes of heart failure?
MI, aortic stenosis, mitral prolapse , hypertension or dilated cardiacmyopathy
Draw a SAN action potential and label the ion channel changes
CHECK IN NOTES
Draw a cardiac myocytes action potential and label the ion channel changes
CHECK IN NOTES
When would you get an upwards deflection on an ECG?
Depolarization towards +ve electrode
Repolarization away +ve electrode
When would you get a downwards deflection on an ECG?
Depolarization away +ve electrode
Repolarization towards +ve electrode
What is the amplitude of a wave on an ECG dependent on?
how much muscle
how directly towards the electrode excitation is moving
Describe the changes that bring about a P wave?
Deploarisation from SA to AV node causing atrial systole
Describe why we see a return to normal between the P wave and the Q wave ?
Delay of electrical activity by 120ms at the AVN
Describe the changes that bring about a Q wave?
Activity spreads down the bundle of his depolarising the septum
What brings about the R and S waves?
R- activity across ventricular walls
S- up side walls
What brings about a T wave?
repolarisation of the ventricle walls
Why do we not see repolarization in the atrias on an ECG?
Lost in QRS complex
In what plane do the chest leadds view the heart?
Horizontal
Where is V1 placed?
4th intercostal R
Where is V2 placed?
4th intercostal L
Where is V4 placed?
5th intercostal mid clavicular line
Where is V6 placed ?
5th intercostal mid axillary line
How do you calculate a regular heart rate on an ECG?
300/ number of large squares between sucessive beats
What is the cardiogenic region?
Region of mesoderm by the cranial end of the embyro which develops into the heart, BV and blood cells during gastrulation.
What effect does lateral folding have on the future heart?
Creates heart tube - endocardial tubes fuse at middle
What effect does cephalocaudial folding have on the future heart?
brings the tube into the thoracic region - head and tail tuck around the oropharyngeal membrane putting primative heart in thoracic cavity with pericardial cavity inferior but heart beginning to form within it.
What happens to the membrane that suspends the heart is the pericardial sac during embyronic development?
Degenerates
How does blood flow in the primtative heart tube?
Caudal to cranial
From caudal to cranial what are the layers of the primitative heart?
sinus venosus atrium ventricle bulbus cordis tuncus arteriosus aortic roots
Why does looping occur?
Continued elongation results in bending - doesnt fit in pericardial sac as this doesnt grow proportionally to heart
In what direction does the cephalic portion move?
Ventrally, caudally and right
In what direction does the caudal portion move?
Dorsally, cranially and left
What does the looping give?
Transverse pericardial sinus- arteries in front of veins
Puts primordium R ventricle closest to outflow tract
Puts primordium L ventricle - closest to inflow tract
Atrium dorsal to bulbus cordis ie inflow dorsal to outflow
