Question

 

1. List and describe the four stages of food processing.

2. Starting at the nasal cavity, list the major structures oxygen passes through to enter the

    alveoli of the lungs.

4. State the components of gastric juice and explain how it is secreted in order to protect
     the stomach layer.

6. Explain Boyle’s law in relation to the process of inhalation and expiration.

Answer 1

1.Answer- Four stages of food processing in our body are-

i) Ingestion- the process of intake of food.

ii) Digestion- the process of breakdown of complex food substances into simple absorbable forms.

iii) Absorption- the process by which simple absorbable compounds formed after digestion are get absorbed by alimentary canal.

iv) Egestion- is the process of removal of undigested food or waste material out of body.

2.Answer- Passage of air upto alveoli of lungs is as follows-

external nostrils - nasal cavity - nasal chamber - internal nares - pharynx (common passage for both food and air) - larynx (also known as voice box) - trachea (also called wind pipe) - bronchi (two side branches of trachea) - bronchioles (further branches of bronchi) - bronchioles divide and redivide to form narrower bronchioles which finally opens into alveoli of lungs.

4. Answer- The innermost wall layer of stomach i.e., mucosa contains gastric glands. Gastric glands have three major kinds of cells and there secretions are which as follows-

i) Mucus neck cells secretes - mucus

ii) Peptic or chief cells secretes - proezyme pepsinogen

iii) Parietal or oxyntic cells secretes - HCl & intrinsic gastric factor

During gastric juice secretion first of all mucus is released which cover somach wall and protects stomach wall from harmful effect of acid secretion.

6.Answer- Boyal's law- According to this law when temperature is constant for a gas than increase in its volume decreases its pressure and vice-versa.

Boyal's law in relation to inhalation- During inhalation thoracic cavity and our lungs expands as a result of which the volume of lungs increases which leads to decrease in pressure of air inside lungs. The decrease in pressure inside lungs as compared to ouside air leads to entry of air from outside to inside the lungs.

Boyl's law in relation to exhalation- During exhalation process the volume of thoracic cavity decreases which squeezes our lungs & thus leads to decrease in their volume which increases pressure inside lungs than outside air and thus air rushes out of lungs.