Understand Human Digestive System

Running Head: Biology Nutrition and Digestion 1
Understand Human digestive system
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Biology Nutrition and Digestion 2
3.0 Understand Human digestive system
3.1 Anatomy of digestive tract
Ingestion is the introduction of food in the mouth and fauces helps in its opening. Salivary
glands (paratoids, sublingual and submandibular) produces salivary amylase which breakdown
starch into smaller carbohydrates. Uvula helps block the nasal cavity during swallowing of food
and tongue helps to roll food into a bolus. Muscles found in the esophagus walls helps in
peristalsis mechanisms which push the bolus into the stomach. It is then digested by various
enzymes such as amylase which breaks starch further to small carbohydrates and pepsinogen
digest proteins into amino acids.
In the small intestines the presence of villi, mucosal folds and microvilli help in food absorption
where nutrients from the intestinal lining are absorbed into the bloodstream. Assimilation also
takes place where nutrients absorbed reach their target cells for utilization.
Egestion which is the discharge of undigested matter from the digestive tract takes place via the
anus (Kong and Singh, 2010).
3.2 Origin and functions of digestive secretions
Digestive system produces various secretions that help in food digestion and protect the
alimentary canal. These substances are either provided by cells or glands along the alimentary
canal. Type of flows varies with the kind of food to be digested. Salivary glands secrete salivary
amylase produced in the mouth acts on the starch and also have an antibacterial function. In the
stomach, gastric cells produce mucus which protects the stomach walls and tissues from acidity.
It also acts as a food lubricant. The gastric cells also produce pepsinogen which helps in protein
digestion. The pancreas produces enzyme amylase for carbohydrates breakdown and pancreatic
lipase for lipids and phospholipids digestion. Also produces trypsin enzyme which is inactive to