For each physiological description A–E, select the most appropriate option from the following list of terms related to the autonomic nervous system.
1. Generalized sympathetic activity.
2. Generalized parasympathetic activity.
3. Cholinergic effect.
4. a alpha adrenergic effect.
5. B1 beta one effect.
6. B2 beta two effect
- Following a painful injury, a person’s heart rate abruptly falls from 100 to 50 beats per minute.
- In a period of excitement, a person’s heart rate rises to 120 beats per minute and the person is aware of the heart pounding in the chest.
- After a large meal, a person retires to bed, feeling pleasantly relaxed and warm. Heart rate is 60 per minute, digestion of the meal is proceeding.
- A student with asthma inhales a medication which acts by stimulating receptors on bronchial smooth muscle and is relieved to find that the chest tightness and wheeze associated with breathing have disappeared.
- During strenuous sporting activity a 20-year-old has a heart rate of 200 beats per minute, is highly alert, has moderately dilated pupils and is sweating profusely.
Medicine
A. Option 3 Cholinergic effect. Severe pain can lead to a burst of activity in cardiac vagal nerves; these parasympathetic nerves release acetylcholine at their terminals around the sinuatrial node to cause marked cardiac slowing.
B. Option 5 B1 effect. Tachycardia and increased force of cardiac contraction are specific cardiac sympathetic effects mediated through stimulation of B1 adrenoceptors in the sinuatrial node and the myocardium respectively.
C. Option 2 Generalized parasympathetic activity. Relaxation is associated with parasympathetic activity and antagonized by sympathetic activity; warmth is associated with relatively high skin blood flow as sympathetic nerves are ‘switched off’; a heart rate of 60, and digestive activity both require considerable parasympathetic activity to the heart (vagus nerves) and the gut.
D. Option 6 B2 effects. Stimulation of B2 receptors mediates relaxation of bronchial muscle; such medication is a common inhalational treatment for asthma.
E. Option 1 Generalized sympathetic activity. A heart rate of 200 is the maximal predicted for a 20-year-old, it is produced by removal of vagal tone and a maximal level of sympathetic tone to the heart; increased alertness, dilated pupils and sweating are all indications of sympathetic activity
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