Introductory Lecture Flashcards
Coronary Arteries
Three layers of the arterial wall.
• Three layers:
- Intima (subendothelial layer)
- Media (middle layer) with smooth muscle cells.
- Adventitia (outer layer) with connective tissue and nerves.
What affect do NO have on arteries?
Causes vasodilation
Stages of atherosclerosis:
Causes of Chest Pain:
Explain myocardial referred pain.
Myocardial ischaemia (the loss of blood flow to a part of the heart muscle tissue) is possibly the best known example of referred pain; the sensation can occur in the upper chest as a restricted feeling, or as an ache in the left shoulder, arm or even hand.
History taking of Chest pain:
Angina ECG presentation and summary:
Describe the JVP waveform.
- watch a video on this.
- a wave: atrial contraction
- c wave: corresponds to right ventricular contraction causing the tricuspid valve to bulge towards the right atrium during RV isovolumetric contraction.
- x descent: closed tricuspid, ventricular systole, atrial relaxation
- v wave: maximal atrial filling
- y descent: emptying of atrium
How do the sympathetic and parasympathetic nervous systems control heart rate? What are the mechanisms?
Sympathetic–adrenaline/noradrenaline
Increase the phase 4 slope
By increasing Na+ influx
So the threshold is reached faster -↑HR
Parasympathetic –vagal stimulation –acetylcholine
Increase K+efflux
Lowers Phase 4 slope
- Prolongs time to reach threshold -↓HR
What happens to the JVP waveform in atrial fibrillation?
Absent waves.
What is orthopnoea?
Shortness of breath which occurs when lying flat.
What is the Anrep effect?
The Anrep effect is an autoregulation method in which myocardial contractility increases with afterload.
What is active hyperaemia?
Active hyperemia is the increase in organ blood flow (hyperemia) that is associated with increased metabolic activity of an organ or tissue. An example of active hyperemia is the increase in blood flow that accompanies muscle contraction, which is also called exercise or functional hyperemia in skeletal muscle.
Why might bradycardia follow an RCA occlusion?
- The RCA supplies the SA nodal artery in 60% of cases and the AV node in 90% of patients
- Without adequate oxygen, ATP levels are diminished
- This depresses the Phase 4 slope
- Increased time to threshold potential = bradycardia
How do diuretics affect preload?
Decrease preload.
How do diuretics affect cardiac output? Why?
Reduce cardiac output.
Diuretics decrease blood volume and venous pressure. This decreases cardiac filling (preload) and, by the Frank-Starling mechanism, decreases ventricular stroke volume and cardiac output
Aortic dissection
Aortic dissection (AD) occurs when an injury to the innermost layer of the aorta allows blood to flow between the layers of the aortic wall, forcing the layers apart. In most cases, this is associated with a sudden onset of severe chest or back pain, often described as “tearing” in character.
Angiotensin II constricts which arteriole?
Efferent arteriole
What are the different kinds of embolism?
Thromboem
Thrombus or embolus affecting where may cause bowel ischaemia?
Mesenteric circulation
