Practice questions Flashcards
Provide a one sentence definition of afterload
Blood pressure in aorta + pulmonary artery which ventricles must overcome to eject blood
Describe how activation of B1 adrenergic receptors increases contractile strength of myocardial cells
B1 receptors linked to G proteins which activate adenylate cyclase –> converts ATP into cAMP which activates Protein Kinase A. PKA then phosphorylates and opens L – type calcium channels which increase calcium influx. An increase in intracellular calcium concentrations and increased calcium/troponin C binding increasing contractile force of the sarcomeres.
Explain why localized increase in tissue fluid protein concentration may result in a localised tissue oedema
The direction and rate of fluid movement across capillaries is determined by the relative strengths of hydrostatic and oncotic pressures. Oncotic pressure, which promotes fluid absorption into capillaries, is generated by a higher protein concentration of plasma compared to the surrounding
tissue fluid. A localised increase in tissue fluid protein concentration will diminish the osmotic gradient, reduce oncotic pressure, and decrease the rate of fluid absorption. Fluid can then accumulate in the tissue causing oedema and swelling.
