chapter 15 digestive system and nutrition chapter assessment

Match the enzyme(s) with its (their) function(s): 1. peptidase 2. amylase 3. nuclease 4. lipase 5. pepsin 6. trypsin, chymotrypsin, carboxypeptidase 7. sucrase, maltase, lactase

1. Breaks down peptides into amino acids. 2. Breaks down starch into disaccharides. 3. Breaks down nucleic acids into nucleotides. 4. Breaks down fatty acids and glycerol. 5. Breaks down proteins into peptides 6. Begins protein digestion. 7. Break down disaccharides into monosaccharides.

Match the organ or gland with the enzyme(s) it secretes 1. salivary glands (serous cells) 2. stomach (chief cells) 3. pancreas (acing cells) 4. small intestine (mucosal cells)

1.Amylase. 2.Pepsin. 3. Trypsin. Chymotrypsin. Carboxypeptidase. 4.Peptidase. Sucrase, maltase, lactase.

List the major parts of the alimentary canal, then separatley list the accessory organs of the digestive system.

Alimentary canal: Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. accessory organs: Salivary glands, liver, gallbladder, and pancreas.

discus the absorption of amino acids, monosaccharides, glycerol, fast acids, electrolytes, and water from substance in the small and large intestine.

Amino acids are absorbed by the villi by means of active transport. The blood then carries them away. Monosaccharides are absorbed by the villi by diffusion, facilitated diffusion, or active transport. The blood then carries them away. Fatty acids and glycerol are absorbed by diffusion into the lacteals of the villi. They are then carried away by lymph. Diffusion and active transport into the villi absorb electrolytes. Water is absorbed by osmosis into the villi.

Functions of the digestive system include: a. Mechanical breakdown of foods. b. Chemical breakdown of foods. c. Breaking large pieces into smaller ones without altering their chemical composition. d. breaking food into simpler chemicals e. All of the above.

E.

Describe the structure of a tooth

Each tooth consists of two main portions called the crown and the root. The crown is the portion above the gum and is covered by glossy white enamel. Beneath the enamel is the bulk of the tooth, which is made up of dentin. Dentin surrounds the central cavity, which houses the blood vessels, nerves and connective tissue. The root is enclosed by cementum, which is surrounded by the periodontal ligament. The region where the crown and root meet is called the neck.

List the steps in swallowing:

First stage: Voluntary. Food is chewed and mixed with saliva. Tongue rolls mixture into bolus, and forces it into the oropharynx. Second Stage: Swallowing begins as food reaches the oropharynx. 1. The soft palate (and uvula) raises, preventing food from entering the nasal cavity. 2. They hyoid bone and larynx are elevated. The epiglottis closes off the top of the larynx. 3. Tongue is pressed against the soft palate, sealing off the oral cavity from the nasopharynx.. 4. Longitudinal muscles in the pharyngeal wall contract, pulling the pharynx upward toward the food. 5. Muscles in the laryngopharynx relax, opening the esophagus. 6. A peristaltic wave begins in the pharyngeal muscles and forces food into the esophagus.

Distinguish between mixing and propelling movements:

Mixing occurs when smooth muscles in small segments of the tube contract rhythmically. Ex: When the stomach is full, waves of muscular contractions mix food with digestive juices that the mucosa secretes. Propelling movements contract a ring of muscles in the wall of the tube. At the same time, the muscular wall just ahead of the ring relaxes. Pushes the tubular contents ahead of it.

Contrast the composition of the layers of the wall of the alimentary canal:

Mucosa: surface epithelium, underlying connective tissue, and a small amount of smooth muscle form this layer. in some regions the mucosa is folded with tiny projections that extend into the passage way, or lumen, or the digestive tube. Protects the tissues beneath it and carries on secretion and absorption. Submucosa: loose connective tissue, as well as glands blood vessels, lymphatic vessels, and nerves. Its vessels nourish surrounding tissues and carry away absorbed materials. Muscular Layer:two coats of smooth muscle tissue. the fibers of the inner coat encircle the tube. Provides movement of the tube, consists of two coats of smooth muscle tissue (circular fibers and longitudinal fibers). Serosa: visceral peritoneum of epithelium on the outside and connective tissue beneath. Protect underlying tissues and secrete serous fluid, which moistens and lubricates the tube's outer surface so that organs within the abdominal cavity slide freely against one another.

Distinguish between primary and secondary teeth:

Primary teeth (deciduous teeth), usually erupt through the gums (gingiva) at regular intervals between the ages of 6 months-4 years. Secondary teeth (permanent teeth) push the primary teeth out of their sockets. Erupt at six years-seventeen years.

Discuss the functions of the mouth and its parts:

The mouth receives food and begins digestion by mechanically breaking up solid particles into smaller pieces (mastication) and mixing them with saliva. The lips, cheeks, tongue, and palate surround the mouth, which includes a chamber between the palate and tongue (oral cavity) as well as a narrow space between the teeth, cheeks, and lips (vestibule).

Explain the stimulus for and response of the parasympathetic nervous system in digestion:

When a person tastes, smells, or even sees appetizing food, or when food enters the stomach, parasympathetic impulses on the vagus nerves stimulate the release of neurotransmitter acetylcholine (Ach). This Ach stimulates gastric glands to secrete abundant gastric juice, which is rich in hydrochloric acid and pepsinogen. These parasympathetic impulses stimulate certain stomach cells to release gastrin (peptide hormone), which increases the secretory activity of gastric glands.

List the steps in defecating

a person can usually initiate defecation reflex by holding a deep breath and contracting the abdominal wall muscles. this action increases internal abdominal pressure and forces the feces into the rectum. as the rectum fills, the wall distends, triggering the defection reflex that stimulates peristaltic waves in the descending colon. the internal anal sphincter relaxes. at the same time, other reflex involving the aural region of the spinal cord strengthen the peristaltic waves, lower the diaphragm close the glottis, and contract the abdominal wall muscles. these actions further increase internal abdominal pressure and squeeze the rectum. the external anal sphincter is signaled to relax and the feces are forced to the outside.

The teeth that are best adapted for grasping and tearing food are the: a. Incisors. b. Canines. c. Premolars. d. Molars.

b. canines

Explain how hormones control the secretions and/or release of secretions from the stomach, pancreas, and gallbladder

stomach: Gastrin - is in the stomach and stimulates the gastric glands to secrete pepsinogen (an inactive form of the enzyme pepsin) and hydrochloric acid. Secretion of gastrin is stimulated by food arriving in stomach. pancreas: Regulated by the endocrine and nervous systems. Ex: When parasympathetic impulses stimulate the pancreas to release digestive enzymes. gallbladder: The intestinal mucosa release the hormone cholecystokinin in response to proteins and fats in the small intestine.