Cardio-Respiratory Week Three Flashcards
Where do the coronary arteries arise?
Aortic sinus
What is the first branch of the right coronary artery?
Atrial branch. This gives of the sun-atrial branch
What branch right coronary artery goes around the front?
Right marginal branch
What branch of the right coronary artery goes around the back?
The posterior descending artery (interventricular)
What is the first branch of the left coronary artery?
Anterior interventricular artery (left anterior descending). This gives off the descending arteries.
What branch the left coronary artery goes around the back?
Circumflex artery. This gives of the left marginal branch
What are thebesian veins?
These are the veins that blood travels into from the sub-endocardium. These veins will then drain into the larger veins.
Where does the great cardiac vein originate and what artery does it follow?
The great cardiac vein (GCV) runs in the anterior interventricular groove and drains the anterior aspect of the heart where it is the venous complement of the left anterior descending artery.
Where does the small cardiac vein originate and what artery does it follow?
The small cardiac vein is a vein of the heart which accompanies the acute marginal artery from the RCA. It courses in the right posterior atrioventricular groove and drains into the coronary sinus close to it’s termination but may drain directly into the right atrium. It drains the right ventricle.
Where does the middle cardiac vein originate and what artery does it follow?
The middle cardiac vein or posterior interventricular vein is a vein of the heart which accompanies the posterior interventricular artery. It courses in the posterior interventricular groove and drains directly into the coronary sinus close to it’s termination. It drains the posterior wall of both ventricles and the posterior interventricular septum.
Where does the posterior vein of the left ventricle originate and what artery does it follow?
The posterior vein of the left ventricle is a vein of the heart which courses over the inferior wall of the left ventricle and drains into the coronary sinus to the left of where the middle cardiac vein drains into the sinus. It drains, not unsurprisingly, the inferior wall of the left ventricle.
Which set of veins drain directly into the right atrium?
anterior veins of the right ventricle
What are the venae cordis minimae?
A small group of veins that are within the walls of each chamber and drains directly into their respective chamber.
What is arteriosclerosis?
This is the thickening and hardening of the walls of the arteries
What is atherosclerosis?
This is the build-up of plaque in arteries which eventually causes hardening and narrowing of the arteries
How can the endothelium become damaged?
LDL, smoking, hypertension, irritants. These irritants cause the breakdown and allows LDL to enter the endothelium.
What does the endothelium release in response to irritants and what affect does this have?
The endothelium will resale ROS and MMPS. The macrophages will also release the same. This causes LDL oxidation.
How to foam cells develop?
These are formed by the macrophages. During the pathogenesis of atherosclerosis, macrophages will increase the expression of scavenger recepotrs in response to M-CSF. These will mediate LDL uptake and this forms foam cells.
What will foam cells release?
IGF-1: causes smooth muscle migration and proliferation
IL-1, IL-6 and TNF: inflammation and recruitment of more macrophages
Describe a fibrous cap, something that is present in atherosclerosis
This is formed by smooth muslce, proteoglycans and elastin. It overlies a fatty streak (dead foam cells). The smooth muslce Underneath will deposit calcium and this causes calcium crystals. Normally, the HDL will release the calcium but the accumulation of plaque messes with their ability. This results in calcium stiffening the walls.
What is the difference between fibrolipid plaques and fibrous plaques?
Fibrolipid plaques do not narrow the lumen as the muslce layer expands.
Fibrous plaques involves narrowing.
During, atherosclerosis, T cells will accumulate. They will release interferon-beta. What is the affect of this?
Inflammation
Describe the pain felt in angina pectoris
Pressure. Squeezing.
What is stable Angina?
This is the most common and pain will occur when the demand on the heart is increased, eg exercise. This will usually occurs with >70% stenosis. The pain will go away at rest.
What is unstable Angina?
There is pain present during rest and exercise. This is usually caused by a rupture of a plaque. This is an emergency and there is a high risk of MI.
What is Vasospastic Angina?
Ischaemia is a result of coronary artery vasospasm. There is constriction of smooth muscle and pain can occur at any time. Due to extreme contraction, all layers are affected and this causes transmural ischaemia.
What drugs can cause vasospasm of the heart and hence cause vasospastic angina?
Beta-adrenoreceptors
What is Prinzmetal’s angina another name for?
Vasospastic Angina
Give the mechanism of action of Organic nitrates
These mimic the actions of nitric oxide. They work directly on smooth muslce and cause dilation.
The nitrate groups on the drugs interact with enzymes and intracellular sulfhydryl groups to form NO. This stimulates the activation of guanylate cyclase and this forms cGMP. This causes dephosphoryalion of myosin light chains and this results in vasodilation.
What are the overall effects of organic nitrates?
There is vasodilation of large veins.
Increase cGMP inhibits calcium entry and hence causes dilation.
Organic nitrates give a higher dilation of veins than arteries, what is the significance of this?
Venous dilations predomination means that venous preload and pressure id decrease. This reduces ventricular wall stress and therefore oxygen demand by the heart decreases.
Systemic arterioles dilation will reduce afterload and this will also reduce ventricular wall stress.
What enzyme converts nitro-glycerine into NO?
Aldehyde dehydrogenase
What is the timing of nitro-glycerine?
It works within 2-5 minutes and wears off within 30 minutes.
Why is nitro-glycerine given sublingually?
If it is given orally, it will be heavily metabolised by the first-pass effect
How long should the nitro-glycerine free period last?
Over 8 hours
Give two examples of long-acting nitrates
Isosorbide dinitrate ( 4-6 hours ) and Isosorbide mononitrate ( 6-8 hours) . These are taken orally due to no first pass effect.
Why do organic nitrates cause a headache?
Dilation of cerebral arteries
What kind of drug is Verapamil?
Calcium-Channel blocker
What kind of drug is Diltiazem?
Calcium-Channel blocker
What kind of drug is Amlodipine?
Calcium-Channel blocker
What kind of drug is Nifedipine?
Calcium-Channel blocker
What are the two mechanisms is which calcium L-channel blockers work?
Open channel block: the pore in which calcium travels through is blocker
Allosteric modulation: drugs binds to the allosteric site and causes shape change which limits the opening
Give examples of Open calcium- channel blockers
Verapamil and Diltiazem
Give examples of allosteric modulation calcium blockers?
Amlodipine and nifedipine
Out of the following drugs, which is best form smooth muslce and which is best of cardiac muslce?
Smooth muslce: nifedipine, diltiazem, verapamil.
Cardiac muscle: verapamil, diltiazem, nifedipine
Give examples of non-selective beta blockers
Propranolol, nadolol, pindolol
Give examples of selective beta blockers
Atenolol, metaprolol, nebrulol
Describe the beta-one receptors in the heart
When these become activated, they form cAMP and this increase calcium, resulting in increased heart rate and contraction.
Describe the beta-two receptors blood vessels
There is increases smooth muslce relaxation.
What is the mechanism of action of Ranolazine?
This blocks inward sodium channels in cardiomyocytes. Increased sodium would lead to increase calcium through the sodium-calcium exchanger. By blocking the receptor, there is a prevention of calcium overload and hence reduced myocardial oxygen demand.
What is the mechanism of action of Ivabradine?
This blocks ‘If’ channels (funny channels). These are located in the SA node and are responsible for cardiac pacemaker activity and by blocking them, there is a reduction heart rate and a reduction in myocardial demand.
What is the mechanism of action of Nicorandil?
This activates potassium channels and causes vasodilation.
What enzyme do statins inhibit?
HMG CoA reductase
What is HMG CoA reductase responsible for? This is the enzyme that statins inhibit
HMG CoA reductase is involved in cholesterol synthesis. Activation of this enzyme causes activation of SREBP, a transcription factor that up-regulates the LDL receptor.
PCI is surgery used to treat heart conditions. What is it?
PCI is percutaneous coronary intervention. This is where a fine guide is placed across the coronary stenosis and a balloon is inflated. This dilates the stenosis. A coronary scent is placed for ‘scaffolding’.
What causes the pain in Angina?
A build up of metabolites (potassium, carbon dioxide, lactate, adenosine) which activate sensory nerves and causes the pain.
What is the difference between cAMP and cGMP.
These are both secondary messengers.
cAMP is synthesized from ATP by adenylyl cyclase and its synthesis is stimulated by G proteins.
cGMP is synthesized from GTP by guanylyl cyclase and its synthesis is active by nitric oxides.
On an ECG, what does a P wave represent?
Atrial depolarization
On an ECG, what does a P-R interval represent?
Delay through AV node
On an ECG, what does a QRS complex represent?
Ventricular depolarization
On an ECG, what does a T wave represent?
Ventricular repolarization
On an ECG, what does a ST segment represent?
The isoelectric period where both ventricle are depolarized.
On an ECG, what does a U wave represent?
Purkinje repolarization
On an ECG, what does a QT interval represent?
Time taken for both ventricular depolarization and repolarization to occur
Where are the six chest electrodes placed on the heart for an ECG?
V1: right 4th intercostal space
V2: left 4th intercostal space
V3: midway between V2 and V4
V4: midclavicular line in 5th intercostal space
V5: same level as V4 on left anterior axillary midline
V6: same level as V4/5 on left mid-axillary line
What plane and the chest and limb electrodes on?
Chest: transverse
Limb: coronal
How many seconds does one small square equal on an ecg?
0.04 seconds
What view of the heart does chest electrodes V1 and V2 give?
Septal
What view of the heart does chest electrodes V3 and V4 give?
Anterior
What view of the heart does chest electrodes V5 and V6 give?
Lateral
What is the normal axis of the heart?
+90 to -30
What is the axis for left an right heart deviation?
Left: -90 to -30
Right: +90 to +180