Anatomy and Physiology of the Digestive System

Introduction

“Anatomy is scientific study of the structures of the body and their relationship with each other.”

“Physiology is scientific study of the functions of the body and how their work together as systems.”

Anatomy study helps in understanding the human body part structures, and the physiology study helps to know the functions of those parts that help the organism in its action performance.

The knowledge on the human physiology and anatomy forms the basis of all medicine. Without knowing how the body is made up, how it can go wrong and how it works, we cannot even picture the effective treatments. Most functions of the body are not voluntarily controlled, they occur deliberately to build, maintain and endure life. Learning physiology and anatomy means that we know the general basics of medicine where disease is abnormal structure (anatomy) or function (physiology) of the human’s body cells, tissues, muscles and organs, and if you understand the normal function and structure it is easy to realize the source of the problem.

This assignment will identify and describe functions of the main components of the digestive system; identify cell and tissue types; identify and describe the urinary system. The resources used to complete this assignment were tutor notes, “Creative Training learners manual”, Tucker L. “An introductory guide to Anatomy & Physiology”, free multimedia resources and OpenStax College “Anatomy & Physiology”.   

Part A

(i) Identify the parts of the digestive system on the diagram overleaf.

(ii) Explain the function of each part of the digestive system identified in the diagram above.

(iii) Outline the composition of Proteins, Fats and Carbohydrates, and explain how each of them are digested and absorbed by the body.

“The digestive system are system by which ingested food is acted upon by physical and chemical means to provide the body with absorbable nutrients and to excrete waste products; in animals the system includes the alimentary canal extending from the mouth to the anus, and the hormones and enzymes assisting in digestion.” http://www.dictionary.com/

Digestion is important for processing food into nutrients, which the body uses for energy, growth, and cell repair. The major functions of the digestive system are

• Ingestion
• Digestion
• Absorption
• Defecation.

The organs of the digestive system can be divided in to

• Gastrointestinal tract includes: mouth, oesophagus, stomach, small intestine and large intestine.
• Accessory organs includes: teeth, tongue, salivary glands, gallbladder, liver and pancreas

(i) Identify the parts of the digestive system on the diagram overleaf.

Smooth muscle- lining of the walls of gastrointestinal tract involuntary contracts and relaxes creating wave like contractions called peristalsis that helps to move food along gastrointestinal tract and helps to mix the substances. Segmentation contractions move Bolus (partialy digested food) in oesophagus. Every cell of the body needs nourishment, but most cells are immobile and their can’t travel to source of food. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and transports them to the cells through the body. The digestive system breaks down nutrients from food and drink into carbohydrates, protein, fats, and vitamins.

The functions of digestive system are:

• Ingestion- taking food in to gastrointestinal tract
• Propulsion- moves the substances along gastrointestinal tract (peristalsis & segmentation)
• Digestion is divided into:

1) Mechanical breakdown of food (chewing & segmentation)

2) Chemical breakdown of food by enzymes (very efficient catalysts for biochemical reactions) produced by glands and accessory organs of the digestive system

• Absorption- process when digested food substances pass through walls of some organs of the gastrointestinal tract into bloodstream.
• Elimination- food substances which cannot be digested and absorbed are excreted as faeces.

(ii) Explain the function of each part of the digestive system identified in the diagram above.

The gastrointestinal tract is the main system to breakdown and transforms food into microscopic substances that necessary to maintain body cells and tissues in different areas of the body.

1. The Mouth The first of the activities of the digestive system -ingestion starts when the food is taking into the alimentary canal trough to the mouth. There the food is chewed, teared and grinded by teeth.

The Teeth:There normally are 32 teeth in adult mouth and there are 4 types of teeth. Each type of the teeth has their own function in the breakdown the food.

• Incisors- 4 in each jaw, sharp, narrow-edged teeth used for cutting and biting
• Canines- 2 in each jaw, between incisors and premolars, sharp, pointed teeth used to tear food
• Premolars- 4 in each jaw, blunt, broad teeth with two sharp ridges used to chew food
• Molars- 6 in each jaw, there are similar but larger than premolars, each has a four sharp ridges used to crash and chew food.

The Tongue: Muscular organ with many taste buds and receptors. Responsible for the tastes: sweet, sour, bitter and salt. Tongue moves food from tooth to tooth forming starch with help of saliva.

The Salivary Glands: There are three pairs salivary gland: the parotid gland, submandibular and the sublingual gland. Liquid called saliva is secreted from glands; it contains water, mucus and the enzyme- salivary amylase. The function of saliva is to lubricate food with mucus for swallowing. It also acts to keep the mouth and teeth clean and kill bacteria, because saliva contains lysozyme and antibodies and it starts digestive process on carbohydrates adding saliva to starch. Both types of digestion- mechanical and chemical, starts in the oral cavity.

2. The Oesophagus

Oesophagus is hallowing muscular tube that leads from throat to the stomach. The epiglottis (a small flap that protects windpipe) prevents from choking. Food moves along oesophagus by peristalsis pushing the bolus forward to the stomach. The lining of the oesophagus secretes mucus to ease the passage of food.