Flashcards in CVS case study questions Deck (11):
What causes the peak of depolarisation at the start?
Influx of Na+
- T tubule membrane depolarised
What ion is most important for standing membrane potential?
What happens to force of contraction when there is sympathetic stimulation of the heart? and why?
- due to increases in CO and HR.
- The activity causes faster depolarisation of the SAN causing a faster HR.
- This is caused by the noradrenaline binding to beta 1 adrenergic receptors causing cAMP increase, activating PKA.
- This then phosphorylates the L-type channels and the SR releases channels.
- Ergo, this leads to an increased (ca) binding to troponin C, and therefore more cross bridges form.
What occurs in exercise to lead to an increase in CO?
Activity of skeletal muscles, leading to increased venous tone, pressure and return.
- This increases the EDV, preload and the SV.
- This increases CO, causing increased sympathetic activity and adrenaline, and increased venoconstriction and HR.
Why does venous return lead to increased CO?
Increased venous return, more blood to atria, increased EDV, increase preload, increased SV (due to Starling's law) causing increased CO.
State 2 "western" lifestyle factors that contribute to atherosclerosis
Smoking and Obesity
Name 2 of the 3 cells involved in atherosclerosis
- Vascular smooth muscle cells
- Vascular endothelial cells
Name 2 non-modifiable risk factors for atherosclerosis
Describe 3 ways in which changes in arterial wall in atherosclerosis can lead to clinical problems
- Embolism: occlusion of a small vessel at a distant site
Name 2 ways in which vascular smooth muscle cells contribute to the stability of the plaque
- Increases collagen synthesis, forming a fibrous cap, increased matrix deposition.
- Increased thickness of the smooth muscle around the plaque to prevent rupture.