Structure and function of the heart

Question 1

three layers of the heart

Answer 1

epicardium
myocardium - cardiomyoctyes and connective tissue
Endocardium - endothelium and thin layer

Question 2

what is there pericardium made of

Answer 2

parietal and visceral epicardium

Question 3

what is pericarditis

Answer 3

infllamtion of the pericardium can be caused b infections, cancer trauma or autoimmune response

Constrictive pericarditis (CP) is a potentially curable cause of diastolic heart failure. The scarred, and non-compliant pericardium causes restraint to early diastolic ventricular filling, resulting in the equalisation of intracardiac diastolic filling pressures, producing the so-called “single diastolic chamber

Question 4

what is the most common cause of pericarditis

Answer 4

viral infection

Viral infection is the most common cause of acute pericarditis and accounts for 1-10% of cases. The disease is usually a short self-limited disease that lasts 1-3 weeks and can occur as seasonal epidemics, especially coxsackievirus B and influenza.

Question 5

how many pulmonary arteries

Answer 5

2

Question 6

how many pulmonary veins

Answer 6

4 - sup and info on each side

Question 7

what is an auricle of the heart

Answer 7

entrance into a space of the heart

Question 8

auricle of right atrium enters deoxygenated blood and through right ventricle through atrioventricular valve ( tricuspid) with contract these goes into what

Answer 8

pulmonary artery

Auricle of left atrium - pulmonary veins back into left atria into left ventricle through atrioventricular valve ( mitral ) - blood through aorta

Question 9

when dilated the right ventricle looks like a semi oval and left ventricle looks like a circle - how does this change when contraction occurs

Answer 9

right - crescent shaped and thinner
left- very small circle

results in 4-6 times more pressure resulting of a ratio of left to right of 3:1

Question 10

what stops the signal passing to ventricles from atria

Answer 10

non conductivity tissue
AV node picks up central and sends signal down bundle of his left and right and goes to purkinje fibres and goes into ventricle tissue at the bottom.

Cardiomyocytes make up the atria (the chambers in which blood enters the heart) and the ventricles (the chambers where blood is collected and pumped out of the heart). … Cardiac pacemaker cells carry the impulses that are responsible for the beating of the heart.

Question 11

contraction of cardiomyocytes

Answer 11

AP runs down sarcolemma - membrane of cardiomyocyte and have t tubules - AP generated via autoarrtyic cells and this PA propogates along sarcolemma into t tubule - on membrane are calcium channels - these are L type calcium channels ( voltage gated) so opens these channels - so in extracellular fluid and space will be calcium ions that go in through them so increase in cytosol - also L type calcium channels closely related with sarcoplasmic reticulum in the cell - and this has a mich greater amount of calcium - big store of calcium - another type of receptors called RYR - ryanodine receptors - calcium binds to these and causes calcium that is stored in SR to come into cytosol - so contributes about 80% increase in calcium in cytosol - calcium binding - called calcium induced calcium release - really important in getting intracellular calcium levels high - this is due to action and myosin filaments - calcium bind to troponin that is intercellular to causes muscles to contract

Question 12

what are intercalated discs

Answer 12

Intercalated disks represent the undulating double membranes where two cells are tightly bound together by desmosomes and connected by gap junctions, allowing electrical impulse conduction from cell to cell.
sharing of cytosol
in disease there are other signals transmitted through these gap junction such as apoptosis - so causes a wave of cell death - myocardial infarction
Mexican wave from cell to cell via sodium channel sand voltage gate channels

Question 13

what percentage of blood goes passively into ventricles from atria

Answer 13

80%

Question 14

what does PACE stand for

Answer 14

Preload
afterload
contractiltiy
eart rate

Question 15

Preload, also known as the left ventricular end-diastolic pressure (LVEDP)

Answer 15

amount of ventricular stretch as the end of diastole - loading for next squeeze.

Question 16

stroke volume =

Answer 16

EDV - ESV
end diastolic volume - end systolic volume

ESV is the volume of blood after contraction that is left over

Question 17

Increases in EDV leads to increase in myocardial performance/contractility
This is due to

Answer 17

physical factors - more optimum myofilament overlapping - decreased lattice spacing - decreased distance between myofilaments - increased probability of interaction between contractile components causing cross bridging

Activating factors - increase in calcium sensitivity - multiple mechanisms - increased ca release
- Increased ca sensitivity

Question 18

when does preload/EDV increase

Answer 18

with venous return which therefore increases contractility therefore stroke volume thus cardiac output

Question 19

what is after load

Answer 19

Afterload, also known as the systemic vascular resistance (SVR), is the amount of resistance the heart must overcome to open the aortic valve and push the blood volume out into the systemic circulation

stroke volume - ESV

Afterload is simply put - pressure in which heart has to pump against , higher the pressure in systemic/ pulmonary circulation - more force/work required by the heart
Need some sort of gradient - smaller less flow ,

Question 20

what are the 3 main factors affecting ESV

Answer 20

preloads / EDV - EDV increase contractility les blood at end of contraction
Blood pressure regulation
Pressure volume loop - increased ESV

Question 21

An increase in afterload alters the slope ( correlation between pressure and volume - less opportunity for muscle to shorten so decreased SV ( if no compensatory response )

true or false

Answer 21

true

Question 22

does a fall in contractility affect SV

Answer 22

yes as weak ventricle reduces systolic contraction

a fall in compliance like fibrosis also reduced stroke volume

Question 23

the sympathetic nervous system causing drive to ventricular muscle fibres - what hormone and receptor do this on the cardiac muscle cells

Answer 23

NA and Beta1 receptors

Hormoanl control too with circulating adrenaline and noradrenaline

Question 24

what is ejection fraction

Answer 24

Ejection fraction (EF) is a measurement, expressed as a percentage, of how much blood the left ventricle pumps out with each contraction.

An ejection fraction of 60 percent means that 60 percent of the total amount of blood in the left ventricle is pushed out with each heartbeat.

Question 25

as well as ejection fraction the other way you can quantify contractility is by the ratio of SV to end diastolic volume - percentage as shown what is the formula

Answer 25

EF=SV/EDV over 75% could indicate hypertrophic cardiomyopathy 40-55 abnormal but maybe insignificant below 40 is HF

Question 26

what is positive chronotropic factors (including A & NA)

Answer 26

increase HR

Question 27

negative chronotropic factors (including Ach)

Answer 27

decrease HR

Question 28

what is the Bowditch effect

Answer 28

staircase phenomenon referring to idea that increase in HR increase the force of contraction generated my the myocardial cells with each heartbeat despite accounting for all other influences

Question 29

The Bainbridge reflex, also called the atrial reflex

Answer 29

is an increase in heart rate due to an increase in central venous pressure. Increased blood volume is detected by stretch receptors (Cardiac Receptors) located in both sides of atria at the venoatrial junctions Adjusts heart rate in response to venous return Stretch receptors in right atrium trigger increase in heart rate through increased sympathetic activity

Question 30

sympathetic activity increase permeability of membrane to sodium so this increases spontaneous depolarisation and reduces the to intimate depolarisation Parasympathetic decrease permeability to membrane of sodium but increase potassium and therefore decreases spontaneous depolarisation and increase time to iniaet depolarisation so decrease HR true or false

Answer 30

true

Question 31

Frank is also on bisoprolol, a selective β1-antagonist. Which of the following is INCORRECT with regard to explaining its affect on reducing CO. Reduced HR Reduced cardiac contractility Reduced renin release Reduced arterial tone

Answer 31

reduced arterial tone β1 blockade leads to: Reduced contractility – via a reduction in [CAMP]i Reduced HR – Reduced Ca+2 entry via CAMP-dependent PKactivity–L-type channel activity Reduced Renin secretion via selective β1 inhibition at JG cells

Question 32

what are cardiac enzymes and when are they released

Answer 32

Cardiac enzymes also known as cardiac biomarkers - include myoglobin , troponin and creatine kinase. These are released into circulation when myocardial necrosis( myocardial cell death or irreversible myocardial injury leading to leakage of intracellular components of damaged cardiomyocytes into the myocardial extracellular space) occurs as seen in a myocardial infarction.

Question 33

myoglobin is released into circulation with nay damage to muscle tissues including myocardial necrosis. why would the measurement of this cardiac enzyme not be used? but what is the benefit

Answer 33

it is non specific for MIs as skeletal muscles contain this it is detectable after 30mins of injury unlike troponin and CK which can take 3-4 Horus early marker and ions specific to the heart

Question 34

Troponin I and T are normal proteins important in contractile apparatus of cardiac myocytes. Proteins are released into circulation 3-4 hours after MI but how long do they remain detectable for

Answer 34

10 days however difficult to detect re-infarction levels of this are proportionate to the severity of the heart attack

Question 35

what type of creatine phosphkinase muscle enzymes are specific to myocardial cells

Answer 35

MB type specific to myocardial cells, whereas MM and BB specific to skeletal muscle and brain tissue. creatine kinase Starts after 3,4 and remains elevated for that long. Detection reinfarction in window of 4-10 dyas Specific isoenzymes for cardimyocytes Levels remain elevated fro 3-4 days post heart attack - best enzyme to look for repat infarction

Question 36

what is the best cardiac enzyme to use to look for repeat infarction

Answer 36

creatine kinase

Question 37

can Cardiac enzymes differentiate between angina and NSTEMI

Answer 37

NSTEMIS have increased troponin compared to unstable angina Best early biomarker is myoglobin Creatine kinase - likely to detect reinfarction

Question 38

off the ascending aorta what is the correct order of when arteries branch off

Answer 38

coronary arteries left and right brachiocephalic trunk which goes into right subclavian and right common carotid then left common carotid and then left subclavian after

Question 39

what is the cardiothoracic ratio - only reliable on PA film

Answer 39

cardio-thoracic ratio horizontal width of the heart divided by the widest internal diameter of the thorax

Question 40

AP vs PA film On chest X Ray have side markers - either AP or PA indicating whether they toot it front to back or back to front which heart looks bigger on what film

Answer 40

on an AP film only reliable on PA overall projection of the heart is a much more accurate reflection of its true size - if AP then you cant - obviously if got normally heart size on AP film - if slightly enlarged whether that is truly enlarged or due to projection - calling patients with cardiomegaly but when infact it is just the projection of the xray

Question 41

what does left ventricular failure lead to

Answer 41

Left ventricular failure leads to pulmonary oedema - because left ventricle is no longer working as efficient - blood back up in pulmonary circulation - fluid leaks into alveoli spaces from capillaries leading to pulmonary edema

Question 42

what does right ventricular failure lead to

Answer 42

Right ventricular failure leads to peripheral edema and raised JVP - right side doesn't work as efficiently - blood backs up in body so get peripheral such as in ankles and raised JVP Right ventricular failure often a consequence of left ventricular failure - termed congestive cardiac failure - degree of pulmonary and peripheral edema and raised JVP in same patient.

Question 43

what is the gold standard test for detecting clinically significant atherosclerotic coronary artery disease

Answer 43

formal coronary angiography Femoral artery puncture and catheter passed up through the iliac arteries and aorta into the coronary arteries Contrast injected and vessels imaged using x-rays - puncture common femoral artery using large needle then introduce catheter over a wire and go round arotic arch to arotic root then to preferential due left or right then squirt dye into vessels, whilst taking series of rapid fire xrays, to give you impression of what vessel looks like

Question 44

anginal pain is characterised by what

Answer 44

constricting discomfort in the front of the chest, or in the neck, shoulders, jaw or arms precipitated by physical exertion relieved by rest or GTN within about 5 minutes. CT for angina if hospitalised and confirmed