The Digestive System - LO6

Question 1

what is digestion?

Answer 1

breakdown of large molecules through chemical and mechanical processes

Question 2

what is the digestive system?

Answer 2

a series of hollow organs joined in a long twisting tube from mouth to anus - aids food turning into energy and nourishing cells

Question 3

what are the functions of the mouth in digestion?

Answer 3

mechanical - teeth and tongue
chemical - saliva containing enzymes like amylase

Question 4

what are the components of saliva?

Answer 4

• 90% water
• enzymes (amylase)
• mineral ions
• mucus
• lysozymes

Question 5

what does the oesophagus play in digestion?

Answer 5

facilitates mechanical and muscular digestion, transporting food from mouth to stomach through peristalsis

Question 6

describe the digestion process in the stomach

Answer 6

churning and mixing food with gastric juice and HCL, aided by contractions, leading to the partial breakdown of proteins

Question 7

what is the function of the small intestine?

Answer 7

primary site of chemical digestion and absorption of nutrients, aided by villi and microvilli

Question 8

name enzymes present in the villi and their functions

Answer 8

• maltase ( breaks down maltose to glucose)
• trypsin (breaks down peptides to amino acid)
• lipase (breaks down fats into fatty acids and glycerol)

Question 9

what is the role of CCK in digestion?

Answer 9

a hormone - released by small intestine to stimulate contraction of gall bladder and release of pancreatic juices

Question 10

what are the main cell types of gastric glands and their functions?

Answer 10

• zymogenic ( peptic/chief cells) - secrete pepsinogen
• parietal cells - secrete HCL and mucus
• enteroendocrine cells- secrete gastrin

Question 11

what are the components of villi in the small intestine?

Answer 11

• capillary network
• lacteal
• intestinal glands

Question 12

what is bile and what are its functions?

Answer 12

bile is produced by hepatocytes and aids in emulsifying fats and digestion by lipase production

Question 13

what are the functions of the liver?

Answer 13

• synthesises bile salts
• proteins
• converts excess glucose to glycogen
• synthesises urea
• breaks down Hb
• stores fats

Question 14

describe the phases of gastric secretion

Answer 14

• cephalic phase
• gastric phase
• intestinal phase

Question 15

what is phase 1 of gastric secretion?

Answer 15

cephalic phase
- initiated by sensory stimuli like sight, smell, taste, or thought of food
- leads to increased gastric secretions and motility

Question 16

what is phase 2 of gastric secretion?

Answer 16

gastric phase
- initiated by distension of stomach stretch receptors and chemoreceptors detecting increased pH due to food
- leads to secretion of gastrin and gastric juices
- promotes peristalsis

Question 17

what is phase 3 of gastric secretion?

Answer 17

intestinal phase
- initiated by chyme entering duodenum
- leads to release of hormones (GIP, secretin, CCK) which inhibits gastric secretion and emptying
- prevents overload of duodenum

Question 18

what is gastric emptying?

Answer 18

process regulated by neural reflexes and hormones to control movement of food from stomach to intestine

Question 19

what is the neural reflex involved in gastric emptying?

Answer 19

enterogastric reflex - inhibits parasympathetic stimulation and simulating sympathetic impulses to regulate gastric emptying.

Question 20

what stimulates gastric emptying?

Answer 20

nerve impulses in response to distension of stomach and release of gastric gastrin - promotes food movement into intestine

Question 21

what inhibits gastric emptying?

Answer 21

factors like distension of duodenum and presence of acidic chyme, triggering enterogastric reflex and release of GIP and CCK - inhibits gastric emptying

Question 22

how do parasympathetic impulses affect digestion?

Answer 22

• they increase motility of small intestine
• stimulate secretion of pancreatic enzymes
• increase bile production

Question 23

how do sympathetic impulses affect digestion?

Answer 23

decreases intestinal motility