GIT

Question 1

What is long reflex?

Answer 1

Occurs when there is an outside presence of food. I.e. food is seen or smelt which begins the digestive process through salivation

Question 2

What is the short reflex?

Answer 2

Occurs when there is food or substance present IN the GIT tract

Question 3

What are the four functions of the oral cavity?

Answer 3

• ingestion and sensory analysis
• mastication
• lubrication
• limited digestion

Question 4

What are the functions of saliva?

Answer 4

• chemical ad mechanical digestion beginning in the mouth
• exocrine secretion
• under autonomic control

Question 5

Describe what salivary secretion does?

Answer 5

• softens and lubricates food
• chemical digestion: salivary amylase and some lipase
• saliva has a protective function

Question 6

What is the protective function of saliva?

Answer 6

It is the first defense we have against bacteria

Question 7

What is another name for swallowing?

Answer 7

deglutition

Question 8

What is deglutition?

Answer 8

the swallowing reflex

1. Tongue pushes bolus against soft palate and back of mouth, triggering swallowing reflex
2. Breathing is inhibited as the bolus passes the closed airway
3. Food moves down into the eosophagus, propelled by peristaltic waves and aided by gravity

Question 9

What are the three functions of the stomach?

Answer 9

• storage
• digestion: lipids and proteins
• defense against swallowed pathogens

Question 10

How does digestive activity begin in the stomach?

Answer 10

the long vagal reflex of the cephalic phase

Question 11

What are the three exocrine cells in the stomach?

Answer 11

• mucus cells
• parietal cells
• chief cells

Question 12

What are the endocrine/paracrine cells of the stomach?

Answer 12

• enterochramaffin-like (ECL) cells
• D cells
• G cells

Question 13

What are the two most imprtant cells for stomach digestion?

Answer 13

parietal and chiief cells

Question 14

Explain the steps of HCL secretions

Answer 14

Parietal cells pump H+ (from carbonic acid breakdown) into stomach lumen via H+/K+/ATPase (proton pumps)

• H+ requires active transport
• K+ can diffuse across the membrane

Question 15

What are the two roles of HCl in the stomach?

Answer 15

• activates pepsinogen (zymogen) - converts it into active pepsin
• contributes to nonspecific disease resistance by destroying most ingested pathogens

Question 16

What can be some negative side effects of HCl in the stomach?

Answer 16

Damage to the mucosa lining, breaking down protective measures resulting in erosion of the stomach wall, inflammation and peptic ulcer

Question 17

What are the two types of control of gastric secretion?

Answer 17

neural and hormonal control

Question 18

Explain neural control of the regulation of gastric secretion

Answer 18

• Acetylcholine (ACh) - released by intrinsic nerve plexuses within the stomach, under the control of short local reflexes and vagal stimulation

Question 19

Explain hormonal control of the regulation of gastic secretiion

Answer 19

• Enterochromaffin-like (ECL) cells: secrete histamine among the perietal and chief cells (oxyntic mucosa)
• G cells - secrete gastrin into the bloodstream
• D cells - secrete somatostatin in response to acid

Question 20

What is segmentation?

Answer 20

Back and forth muscle movement of the SI which helps to mix and move food

Question 21

What are the three main functions of the liver?

Answer 21

1. Metabolic functions
2. Bile production
3. Blood circulation and filtration

Question 22

What are the 6 metabolic functions of the liver?

Answer 22

• carbohydrate metabolism
• lipid metabolism
• synthesis of proteins/enzymes and hormones
• drug metabolism/Xenobiotic detoxification
• RBC recycling and waste product removal
• storage of vitamin (A, D, K) and mineral (iron, copper)

Question 23

What are the functions of bile?

Answer 23

• lipid digestion and absorption, absorption of cholesterol and fat soluble vitamins: A, D, E and K
• Major route for cholesterol synthesis and degradation

Question 24

What is the function of Bile Salts

Answer 24

emulsify large fat particles into tiny particles that can be attached by lipases

Question 25

What are the endocrine functions of the pancreas?

Answer 25

secretes insulin and glucagon

Question 26

What are the exocrine functions of the pancreas?

Answer 26

secretes digestive enzymes and bicarbonate. | - digestive enzymes are secreted as zymogens activated in the the small intestine

Question 27

hat does the pancreatic dict do?

Answer 27

delivers digestive enzymes and buffers to duodenum. | - common bile duct and pancreatic duct penetrate duodenal wall

Question 28

What are the exocrine cells of the pancreas?

Answer 28

``` Acini: clusters of secretory cells called acinar cells - contain zymogen granules with digestive enzymes Ductal cells (epithelial cells): produce alkaline secretion and transport all secretions ```

Question 29

What are the endocrine cells of the pancreas?

Answer 29

Endocrine cells of pancreatic (langerhans) islets: secrete insulin and glucagon into bloodstrream

Question 30

Explain the integration of gastric and intestinal phases for the pancreas

Answer 30

1. Chyme activates ENS 2. Secretin blocks acid secretion and motility. Also, increase release of bicarbonate 3. CCK blocks acid secretion and motility. Also, increase secretion from pancreas. 4. Endocrine cells - blocks acid secretion and motility

Question 31

Explain digestion of molecules in the SI

Answer 31

- carbohydrates absorbed as monosaccharides - proteins absorbed as short peptides - lipid digestion depends on bile salts and lipases absorbed by lacteal ducts - nucleic acids are digested into nitrogenous bases and monosaccharides

Question 32

How does the small intestine absorb vitamins and minerals?

Answer 32

- fat-soluble vitamins absorbed by fats - water-soluble vitamins are absorbed by mediated transport: vitamin B12 is absorbed when complexed to intrinsic factor and absorbed in the ileum - mineral absorption usually occurs by active transport: iron and calcium absorption is actively regulated; sodium is absorbed by enterocytes and colocytes

Question 33

Explain the breakdown of carbohydrates

Answer 33

Starch, glycogen -> disaccharides -> monosaccharides

Question 34

What are the two eznymes which move glucose from the lumen on the SI into the body?

Answer 34

GLUT5 and GLUT2

Question 35

What kind of transport is required for digestion and absorption of carbohydrates?

Answer 35

ACTIVE | Therefore, requires ATP

Question 36

Where does digestion and absorption of proteins take place?

Answer 36

The stomach | - ACTIVE TRANSPORT

Question 37

Where does digestion and absorption of fat take place?

Answer 37

Small intestine | - PASSIVE TRANSPORT

Question 38

Where do we absorb most of our vitamins and minerals?

Answer 38

the large intestine

Question 39

What are the functions of minerals in the body?

Answer 39

1. cell growth and repair 2. metabolism 3. nerve and muscle function

Question 40

What are the two most common mineral deficiencies in Australia?

Answer 40

- calcium: leading to osteoporosis | - Iron: leading to anaemia

Question 41

How does fibre get absorbed through the GIT tract?

Answer 41

resistant to digestion and absorption in the SI and undergo complete or partial fermentation in the LI. Acidic environment in stomach can break down fibre in stomach

Question 42

What are factors that stimulate hunger?

Answer 42

- thoughts, sights, smells and sounds of food - appealing tastes - contraction of empty stomach - release of ghrelin - low levels of nutrients in intestines - low levels of circulating nutrients

Question 43

What are factors that cause satiety?

Answer 43

- food in stomach causing stretching and pressure - intestinal distension and presence of food in the intestines signals brain directly and triggers release of satiety hormones - high blood levels of nutrients

Question 44

What is MR?

Answer 44

metabolic rate | - the rate at which energy is spent in the body in a given period of time

Question 45

What is BMR

Answer 45

Basal Metabolic Rate - measured under ideal conditions: - physical and mental rest, no food within 12h - comfortable room temperature

Question 46

Immune functions: M cells

Answer 46

M cells sample the gut contents of the gut - immune cells secrete cytokines: attract additional immune cells, cytokines trigger inflammatory response, increase in Cl-, fluid, and mucus secretion

Question 47

Why do we vomit?

Answer 47

It's a protective reflex