Functions of alimentary tract

Question 1

What are digestive functions of stomach?

Answer 1

accommodation + storage
mechanical + enzymatic breakdown
slow delivery of chyme to duodenum

Question 2

What are 9 functions/mechanisms of alimentary tract?

Answer 2

1. storage 2. paracrine secretions 3. exocrine secretions 4. endocrine secretions 5. absorption 6. Motility/transport 7. excretion/ transport 8. Defence 9. Metabolism

Question 3

What are 2 structures involved in storage?

Answer 3

Stomach

Colon/rectum

Question 4

What is chyme?

Answer 4

a thick semifluid mass of partially digested food and digestive secretions that is formed in the stomach and intestine during digestion

Question 5

How many litres of gastric juice does stomach store per 24hrs?

Answer 5

stomach stores 2-3 litres of gastric juice/24 hr

Question 6

What does gastric juice consist of?

Answer 6

mucus, pepsinogen, intrinsic factor, lipase

Question 7

What is function of gastric juice?

Answer 7

it helps in digestion + absorption of food

Question 8

What cells secrete mucus?

Answer 8

goblet cells + mucus neck cells

Question 9

What is role of mucus in stomach?

Answer 9

acts as lubricant by acting as barrier that protects stomach + colon especially from gastric acid (prevent trauma)

Question 10

What is role of lipase in stomach?

Answer 10

it converts TGs into FA + glycerol

Question 11

What cells secrete pepsin?

Answer 11

chief cells secrete pepsin

Question 12

What cells secrete pepsinogen?

Answer 12

peptic cells

Question 13

What factor allows pepsinogen to be converted/activated to pepsin?

Answer 13

the action of HCl

Question 14

What cells secrete HCl?

Answer 14

parietal cells

Question 15

What is function of HCl in stomach?

Answer 15

important in defence

Question 16

What cells secrete intrinsic factor?

Answer 16

parietal cells

Question 17

What is function of intrinsic factor in stomach?

Answer 17

important for Vit B12 absorption

Question 18

What are paracrine secretions?

Answer 18

often called local hormones -> secreted from cells in mucosa but unlike hormones, chemicals acts locally on adjacent cells via interstitial fluid

Question 19

Give example of paracrine secretions? What does it do?

Answer 19

Somatostatin inhibits gastrin release in stomach somatostatin is inhibitory + acts in paracrine fashion to block G cells

Question 20

What is one of key mediators in acid secretion?

Answer 20

Gastrin

Question 21

Too much acid secretion leads to …… to kick in

Answer 21

Somatostatin

Question 22

What type of cells release somatostatin?

Answer 22

D cells

Question 23

What type of cells release gastrin?

Answer 23

G cells

Question 24

Give examples of exocrine glands?

Answer 24

salivary glands, gastric glands, pancreas and liver

Question 25

What does salivary gland secrete?

Answer 25

mucus (lubrication fro mastication + speech), lipase

Question 26

What does gastric glands secrete?

Answer 26

HCl, pepsin, mucus

Question 27

What does pancreas secrete?

Answer 27

bicarbonate ions (-> secretion is under influence of secretin), enzymes (e.g. amylase, lipase, carboxypeptidase)

Question 28

What does liver secrete? what is importance of these secretions?

Answer 28

bile salts, bile acids | important in emulsification of fat

Question 29

What are endocrine secretions?

Answer 29

secretions called 'hormones' synthesised by ductless glands enter bloodstream, travel to target tissue where they bind to specific receptors to elicit their effects

Question 30

Give examples of endocrine secretions?

Answer 30

Gastrin, Secretin, CCK, insulin

Question 31

Where is gastrin released from ?

Answer 31

in stomach (G cells in antrum)

Question 32

Where is secretin released from?

Answer 32

duodenal mucosa

Question 33

Where is CCK released from?

Answer 33

duodenal mucosa

Question 34

Where is insulin released from?

Answer 34

pancreas (B cells)

Question 35

What are 2 structures involved in absorption?

Answer 35

small intestine + colon

Question 36

What is meaning of gut motility?

Answer 36

term given to the stretching and contractions of the muscles in GI tract.

Question 37

Movement of muscular wall (motility) allows:

Answer 37

movement from 1 region to another (law of gut); mass evacuation mechanical degradation e.g. gastric antrum mixing lumen contents ( can be both peristalsis + segmentation) e.g. in small intestine) transport of nutrients, water, urea + electrolytes digestion + absorption

Question 38

How are drugs and some products of normal metabolism leave the body (excretion)?

Answer 38

saliva, bile, salts, vomit

Question 39

How does indigestible food residues e.g. tomato skin leave body?

Answer 39

leave body in faeces

Question 40

What is gut epithelium?

Answer 40

gut epithelium is interface between contaminated outside world. it is exposed to external environment so it is unsterile

Question 41

the intestine is.....

Answer 41

largest mucosal surface in body

Question 42

What are some defence mechanisms that help to protect the gut?

Answer 42

``` sight, smell + taste vomit reflex acid in stomach (HCl) Mucus secretion natural bacteria flora aggregation of lymphoid tissues (e.g. peyers patches) able to respond to food borne antigens ```

Question 43

What is major metabolic organ in abdominal cavity?What is it involved in?

Answer 43

Liver | involved in carbohydrate, nitrogen + lipoprotein metabolism as well as production of bile, excretion of bilirubin