Digestive System

Question 1

Digestive system

Answer 1

The body needs a constant supply of energy to perform its tasks and maintain life. The digestive system converts food eaten into fuel for the body’s energy demands.

A human digestive system will process about 50 tons of food in a lifetime. Digestion is a mechanical (chewing and swallowing) and chemical (breaking down with enzymes, acids, and secretions) process.

Question 2

Function: Food processing and storage

Answer 2

breaks down food into smaller particles (mechanical digestion), converts food into substances that can be absorbed (chemical digestion), moves food materials through the gastrointestinal tract, and stores nutrients until needed.

Question 3

Function: Manufacture

Answer 3

manufactures enzymes, hydrochloric acid, intrinsic factor, mucus, and other materials to assist in digestion. Manufactures regulatory hormones in stomach and vitamin K and some B-complex vitamins in the large intestine.

Question 4

Function: Absorption

Answer 4

provides absorption of nutrients, mainly from small intestine, into capillaries.

Question 5

Function: Reabsorption and Elimination

Answer 5

Reabsorbs water for reuse by the body, reabsorbs minerals and vitamins, forms feces from remaining waste products, and produces defecation.

Question 6

Structures of the Digestive system

Answer 6

(Mouth)
-Salivary Glands
-Teeth
-Tongue
-Pharynx
      -Epiglottis
(Esophagus)
-Peristalsis

Question 7

Mouth

Answer 7

also known as the oral cavity which takes in food and where digestion begins (cephalic phase). Ingestion (“to take in”) is the primary function of the mouth by receiving food and to begin digestion of starch/carbohydrates via saliva.

Question 8

Salivary Glands

Answer 8

three pairs of salivary glands pour 1 to 1.5 L of saliva into the mouth. Two types of saliva exist, one is watery and thing to facilitate swallowing by wetting the food. The other type is thicker containing mucin which lubricates and causes food to stick together to form a bolus (ball or lump) of food. Ptyalin which is present in saliva breaks down starch into smaller sugar molecules.

Question 9

Teeth

Answer 9

set in the maxilla and mandible. Their chief function is to break down food into smaller particles via chewing (mastication). Incisors are the front teeth which cut and tear food. Canines are pointed side teeth which hold, pierce, and tear food. Molars crush and grind food.

Question 10

Tongue

Answer 10

tough skeletal muscle, covered with a smooth mucus membrane. The tongue assists with speech, senses temperature and texture of food, mixes food with saliva, and moves food into position to be chewed. Swallowing (deglutition) assists with moving the bolus to the esophagus.

Question 11

Pharynx

Answer 11

passageway approximately 5 in (12.7 cm) long used for food and air. The epiglottis prevents aspiration of food due to the larynx and pharynx being close to each other. The epiglottis is a flap which covers the larynx and trachea during swallowing.

Question 12

Smooth muscles

Answer 12

pass food through the entire GI tube by waves of contractions, called peristalsis. Peristalsis is an alternating muscular relaxing and contraction, without which digestion cannot occur.

Question 13

Esophagus

Answer 13

approximately 10 in (25.4 cm) in length and 2 cm in diameter and follows the curvature of the vertebrae. The role of the esophagus is to serve only as a passageway and extends from the pharynx down the neck and thorax through an opening in the diaphragm to the stomach. Food passes through in 5 to 10 seconds. The cardiac sphincter lies between the esophagus and stomach. The cardiac sphincter prevents food from backing up into the esophagus.

Question 14

Peristalsis

Answer 14

the involuntary constriction and relaxation of the muscles of the intestine or another canal, creating wave-like movements that push the contents of the canal forward.

Question 15

Structures of the Digestive system part 2

Answer 15

Stomach
Small intestine
    -Duodenum
     -Jejunum
     -Ileum
Large intestine "aka colon"
      -Ascending
       -Transverse
       -Descending

Question 16

Stomach

Answer 16

located in the upper left side of the abdominal cavity. The stomach functions as a reservoir and a “food blender” The gastric (peptic) phase of digestion begins in the stomach. Stomach is a C-shaped muscular, collapsible pouch which is capable of expanding. The stomach volume is approximately 1/5 cup when empty and more than 8 cups after a meal. The pyloric sphincter controls the opening between the lower stomach and duodenal portion of the small intestine. Foods in the stomach mix with mucus and gastric acid, pepsin, and other digestive enzymes. Chyme is produced from the food after exposure to the digestive juices which has a semi-liquid, milky form. Peristalsis moves the chyme to the pyloric sphincter. Reverse peristalsis and contraction of the abdominal muscles and diaphragm forces food back through the esophagus and mouth in a process called vomiting (emesis).

Question 17

Small intestine

Answer 17

intestinal phase of digestion begins with the small intestine. The small intestine is the longest portion of the digestive tract which is approximately 20 ft. (6.1 m) long. Most digestive processes occur in the small intestine. Enzymes are secreted from the intestinal glands and act as catalysts that promotes and speeds up chemical reactions to break down carbohydrates, proteins, and fats into materials cells can use. The small intestine is divided into three portions:

Question 18

Duodenum (Small Instenstine)

Answer 18

first portion of the small intestine (about 10-12 inches in length). Here bile from the gallbladder and pancreatic juice from the pancreas aid in the digestion of fats.

Question 19

Jejunum (Small Intenstine)

Answer 19

(about 8 ft. long). The word jejunum derives from (fasting intestine) because it is almost always empty.

Question 20

Ileum (Small Intenstine)

Answer 20

(about 11 ft. long). The word ileum means “flank or groin”. The ileocecal valve connects the ileum to the large intestine.

Question 21

Large intestine

Answer 21

wider and shorter than the small intestine (approximately 2.5 inches in diameter) and only 5 ft (1.5 m) long. Water reabsorption is the large intestines main function. Absorption of vitamins and minerals and formation and defecation of feces also occurs here. The large intestine is made up of the cecum, colon, rectum, and anus. The anus serves as the sphincter leading to outside the body where waste products are secreted. The colon is divided into the ascending, transverse, and descending colon. Undigested material are eliminated from the large intestine after water reabsorption.

Question 22

Metabolism

Answer 22

defined as “biotransformation” and are broken down into two categories.

Question 23

Catabolism (Metabolism)

Answer 23

(destruction) is breaking down of larger molecules into smaller ones.

Question 24

Anabolism (Metabolism)

Answer 24

(construction) is synthesis (combining) of smaller substances into new organized substances to be used by body cells. (Smaller molecules combine to form larger molecules).