As you step into a new baking shop, you smell the freshly baked bread and pastries which
ensues in saliva production. What phase is initiated? evacuation gastric intestinal cephalic
Deep sea diving is a very exciting but dangerous exercise, which gas can cause death when it is
not released properly? O_2 N_2 CO_2 H_2O
Solution
1. The cephalic phase of gastric secretion occurs even before food enters the stomach, especially
while it is being eaten. It results from the sight, smell, thought, or taste of food, and the greater
the appetite, the more intense is the stimulation. The cephalic phase leads to the formation of
saliva by the smell of food. So, the correct answer is option d.
2. Oxygen is toxic at sufficient partial pressure. Scuba divers use a soft suit and breathe an air
mixture at ambient pressure, which increases with depth, so that pure oxygen is toxic at depths
below 10 metres. Natural air contains enough oxygen to become toxic at a depth below about 50
metres. Nitrogen is not toxic, but at pressure causes nitrogen narcosis or decompression sickness
so that extended use at depth below about 30 metres is not recommended. Helium is neither toxic
nor narcotic, but expensive, so deep divers use a more complex breathing gasor use a hard suit
and breathe air at surface pressure. The answer is option a (oxygen).
ensues in saliva production. What phase is initiated? evacuation gastric intestinal cephalic
Deep sea diving is a very exciting but dangerous exercise, which gas can cause death when it is
not released properly? O_2 N_2 CO_2 H_2O
Solution
1. The cephalic phase of gastric secretion occurs even before food enters the stomach, especially
while it is being eaten. It results from the sight, smell, thought, or taste of food, and the greater
the appetite, the more intense is the stimulation. The cephalic phase leads to the formation of
saliva by the smell of food. So, the correct answer is option d.
2. Oxygen is toxic at sufficient partial pressure. Scuba divers use a soft suit and breathe an air
mixture at ambient pressure, which increases with depth, so that pure oxygen is toxic at depths
below 10 metres. Natural air contains enough oxygen to become toxic at a depth below about 50
metres. Nitrogen is not toxic, but at pressure causes nitrogen narcosis or decompression sickness
so that extended use at depth below about 30 metres is not recommended. Helium is neither toxic
nor narcotic, but expensive, so deep divers use a more complex breathing gasor use a hard suit
and breathe air at surface pressure. The answer is option a (oxygen).
