Which of the following is a FALSE statement about sympathetic activity to the SA

Question

Which of the following is a FALSE statement about sympathetic activity to the SA node? A) Norepinephrine binds to beta] adrenergic receptors. 9. B) cAMP levels in the pacemaker cells increases. C) Funny channel opening is enhanced. D) The rate of spontaneous depolarization is increased. E) Potassium channel closing is enhanced. - 10. The effects of epinephrine on vascular resistance are dependent upon which of the following? A) concentration of local metabolites B) direction of change in mean arterial pressure C) specific baroreceptor activated (low or high pressure) D) relative distribution of alpha and beta receptors E) relative distribution of nicotinic and muscarinic receptors 11. Given the following information, calculate the net filtration pressure: capillary hydrostatic pressure- 30 mm Hg; interstitial fluid hydrostatc pressure capillary oncotic pressure -2 Hg. A) 40 mm Hg, favoring filtration B)-40 mm Hg, favoring reabsorption C) 10 mm Hg, favoring filtration D)-10 mm Hg, favoring reabsorption E) 0 mm Hg, no net force 5 mm Hg

Explanation / Answer

Ans. 9.

The choice is (E).

Potassium channel closing is enhanced is a false statement about sympathetic activity to SA node.

Ans.10.

The choice is (D).

The effects of epinephrine on vascular resistance are dependent upon relative distribution of alpha and beta receptors.

Vascular smooth muscles have alpha 1 and beta 2 receptors. Alpha 1 receptors are relatively more than Beta 2 receptors. Activation by epinephrine results in vasoconstriction and increase in peripheral resistance which causes increase in arterial blood pressure.

Ans.11.

The choice is (C).

The Net filtration pressure(NFP) = The difference between the net hydrostatic pressure (the difference between the blood and interstitial hydrostatic pressure) and the net colloid oncotic pressure (the difference between the blood and interstitial fluid oncotic pressure)

NFP= (30-5) - (25-10)

= 25 - 15

= 10 mm Hg.

Hence, the choice is 10 mm Hg, favouring filtration

The blood will move out(filter out) from capillaries to interstitial tissues because of high pressure in capillaries(10 mm Hg).

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