Question

1. Identify the organs of the alimentary canal from proximal to distal, and briefly state their function

2. Identify the accessory digestive organs and briefly state their function

Answer 1

Answer

The organs of the alimentary canal from proximal to distal are :

1) Mouth
Function : It is the site for food ingestion. In mouth the food is crushed and grided into small pieces by the teeth.
- Food is mixed with saliva and bolus is formed.

2) Pharynx
Function : It serves as the passage way for both air and the food.
- Oropharynx and laryngopharynx directs the food into esophagus.

3) Esophagus
Function : It is a long tube that runs down to abdominal cavity in order to transport the food into the stomach.

4) Stomach
Function : Stomach is the site for food storage.
- The chemical digestion of protein begins by an enzyme pepsinogen released in the stomach.
- Gastric acid converts pepsinogen into pepsin.

5) Small intestine
Function : It is the site for digestion and absorption of all the macronutrients (carbohydrates, proteins and lipids)
- Villi and microvilli present on the cells enchance the surface area for nutrient absorption.
- It also release enzymes such as maltase, lactase for digestion of disaccharides.

6) Large intestine
Function : It functions to reabsorb water and electrolytes from the undigested waste.
- Intestinal bacteria produces vitamin K.
- It produces feces

7) Rectum
Function : It serves as the site for storage for fecal matter.

8) Anal canal  
Function : The fecal matter passes through anal canal and is removed out of the body dring defecation reflex thorugh anal opening.

The accessory digestive organs are :

1) Salivary glands
Function : They produce saliva and release it into the mouth through salivary ducts.
- Salivary amylase present in saliva breaks down starch into maltose.

2) Liver
Function : It produces bile.
- Bile eulsifies large lipid molecules from food into small droplets to facilitate its chemical breakdown.

3) Gallbladder
Function : It serves as the site for bile concentration and storage.
- It releases bile into duodenum when stimulates by a hormone called cholecystokinin.

4) Pancreas
Function : Exocrine portion of pancreas release digestive enzymes and bicarbonate into the duodenum.
- Th enzymes such as procarboxypeptidase, tyrpsinogen are responsible for protein digestion.
- Enzyme pancreatic amylase digests carbohydrates.
- Enzyme pancreatic lipase digests small lipid droplets into monoglycerides and fatty acids.