Tag: evs - i

The oesophagus leads into the stomach. The stomach is a muscular sac. The stomach is the most important site of protein digestion. Stomach wall has peptic cells, chief cells secrete pepsinogen and oxyntic and parietal cells secrete hydrochloric acid. The pepsinogen is activated to pepsin on exposure to hydrochloric acid. The pepsin is a chief proteolytic enzyme of the alimentary canal. Another important enzyme of the stomach is lysozyme which is antibacterial. Thus, the correct answer is option C.

The pylorus is a narrow cone shaped constriction present at the end of the stomach and the beginning of the small intestine. It contains two region antrum which connects the parts of the stomach and pyloric canal which connects the stomach and small intestine.  Thus, the correct answer is option B.

The gastric mucosa is present is in the inner wall of the stomach which secretes 1.2 to 1.5 litres of gastric juice per day. Gastric juice is a mixture of HCl, mucous and digestive enzymes which makes food particles soluble, initiates protein digestion and converts the gastric contents to a semiliquid mass called chyme, thus preparing it for further digestion in the small intestine. This juice is highly acidic because of its hydrochloric acid content, and it is rich in enzymes. 

Indigestion is inability to properly digest food resulting in abdominal distension due to gas or flatus. It is caused by overeating, spicy food, anxiety and disturbed secretions of digestive tract.

Anatomical dead space refers to the volume of the respiratory tract where gas exchange does not occur, such as the trachea and bronchi.

Gas exchange in the alveoli occurs via simple diffusion, where gases move from an area of higher partial pressure to an area of lower partial pressure across the respiratory membrane.

• The lowest part of pharynx is the laryngopharynx. It has two apertures, the anterior slit is 'glottis', through which it opens into the larynx and the posterior slit is 'gullet', which leads to the oesophagus.
• Thus, larynx opens into the pharynx by glottis. The glottis bear a leaf-like a cartilaginous flap, called the 'epiglottis'. Epiglottis cover the glottis during swallowing, to prevent the entry of food into it.
  Hence, the correct answer is B.

The palate is the roof the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but, in most other tetrapods, the oral and nasal cavities are not truly separate. The palate is divided into two parts, the anterior bony hard palate, and the posterior fleshy soft palate (or velum). The diaphragm, located below the lungs, is the major muscle of respiration. It is a large, dome-shaped muscle that contracts rhythmically and continuously, and most of the time, involuntarily. The trachea, colloquially called windpipe, is a tube that connects the pharynx and larynx to the lungs, allowing the passage of air. Thus, option B is correct.

Respiratory membrane must be semi- permeable in nature to allow the passage of small molecules and ions. It should also support the process of diffusion. Only large molecules are transported using channels or porins. In root, the ascent of sap takes place through simple diffusion. If cell membrane was not semi permeable then it could have never happen. If it was permeable or impermeable then it is difficult for cell to survive. Thus, option C is correct.

Air enters the body through the nose and mouth. After the nose and mouth air goes through the pharynx or throat. After the pharynx, air goes into the larynx or voice box.