Norepinephrine (i) is released by sympathetic fibres (ii) is released by parasympathetic fibers (iii) increases the heart rate (iv) decreases blood pressure. Which of the above statements are correct?
- (i) and (iii)
- (ii) and (iii)
- (ii) and (iv)
- (i) and (iv)
Answer
(1) (i) and (iii)
Solution
(i) Correct: norepinephrine (noradrenaline) is the neurotransmitter released by sympathetic nerve fibres.
(ii) Incorrect: parasympathetic fibres release acetylcholine.
(iii) Correct: as per NCERT, adrenaline and noradrenaline increase the heart beat and the strength of heart contraction.
(iv) Incorrect: by increasing the heart rate and constricting blood vessels, norepinephrine raises (not lowers) blood pressure.
∴ Statements (i) and (iii) are correct.
Answer: (1)