unit 5

Question 1

what is digestion?

Answer 1

chemical and mechanical breakdown of food and absorption of nutrients

Question 2

digestive system, what does it do?

Answer 2

responsible for process of digestion

Question 3

what does mechanical digestion do?

Answer 3

breaks down large pieces of food into smaller ones without changing chemical composition

Question 4

what does chemical digestion do?

Answer 4

breaks down large nutrient molecules into smaller chemicals by breaking chemical bonds

Question 5

the digestive system consists of…

Answer 5

1. the alimentary canal (digestive or GI tract), which leads from mouth to anus
2. several accessory organs whose secretions help the processes of digestion

Question 6

what is the alimentary canal?

Answer 6

a muscular tube that passes through thoracic and abdominopelvic cavities, food passageway between the mouth and anus, approx. 8 meters long

Question 7

the structure of the wall of the alimentary canal consists of the same 4 layers throughout its length, these layers are

Answer 7

1. mucosa (inner layer of wall, mucous membrane surrounding lumen of tube, consists of epithelium, protects tissues of canal, secretion and absorption)
2. submucosa (lies under mucosa), consists of loose connective tissue, nourishes surrounding layers
3. muscularis (2 layers of smooth muscle propelling food through canal)
4. outer serous layer (or visceral peritoneum, protects tissues and secretes serous fluid to reduce friction between organs

Question 8

motor functions of the alimentary canal are of 2 types, which?

Answer 8

1. Mixing movements: occur when smooth muscles contract rhythmically in small sections of tube, segregation in small intestine aids mixing by alternately contracting and relaxing smooth muscle in each area)
2. Propelling movements: include wavelike motion called peristalsis, ring of contraction in portion of tube occurs while relaxation occurs ahead of ring, allowing for a mass of food to be propelled to next segment of tube

Question 9

the mouth is…?

Answer 9

the first portion of the alimentary canal, receives food and begins mechanical digestion BY MASTICATION AKA CHEWING, surrounded by lips, cheeks, tongue, palate.

oral cavity= chamber between palate and tongue

vestibule = narrow space between teeth, cheeks, and lips

Question 10

cheeks…

Answer 10

form the lateral walls of the mouth and are involved in chewing and expression

Question 11

lips are…

Answer 11

highly mobile structures that surround the mouth opening and contain sensory receptors to detect temp and texture of food