Gastric Secretion Flashcards Preview

Physiology and Neuroscience > Gastric Secretion > Flashcards

Flashcards in Gastric Secretion Deck (40):
1

What does mechanical digestion consist of?

Chewing (mouth)
Churning (stomach)
Segmentation (small intestine)

2

What is propulsion?

Swallowing (oropharynx)
Peristalsis (oesophagus, stomach, small intestine, large intestine)

3

What is the stomachs anatomy?

Mucosa
Submucosa- contains submuscosal plexus
Muscularis externa- contains myentric plexus
Serosa

4

Where does gastric secretion occur?

In the lumen

5

What is stomach mucosa composed of?

Simple columnar epithelium
Gastric pits

6

What do gastric pits lead to?

Gastric glands

7

What do gastric glands produce?

Gastric juice

8

What is Wheater's Functional Histology of stomach mucosa?

F- foveolae (gastric pits)
CC- chief cells
MM- muscularis mucosae
SM- submucosa

9

What do gastric glands in the fundus and body of the stomach produce?

Most of the gastric juice (oxyntic glands)

10

What does gastric juice aid in?

Stomach functions

11

What do gastric glands comprise?

Hydrochloric acid
Pepsinogen
Intrinsic factor
Mucus

12

What are some examples of gastric gland cells?

Parietal cells
Chief cells
Mucous cells

13

What do Parietal cells do?

Secrete intrinsic factor
Secrete HCl

14

Why is intrinsic factor needed in the body?

Needed for absorption of Vitamin B12

15

Why is HCL needed in the body?

Because it has a pH of roughly 1-3, it has the ability to:
Kill microbes
Denatures proteins
Activate enzymes

16

What do Chief cells do?

Secrete pepsinogen
Secrete gastric lipase

17

Why is pepsinogen needed in the body?

Converted to pepsin by HCL
Breaks certain peptide bonds

18

Why is gastric lipase needed in the body?

Splits short-chain triglycerides into fatty acids and monoglycerides

19

What to mucous cells do?

Secrete mucous
Superficial epithlia
Mucuous neck celss

20

What does mucous do in the body?

Forms a protective barrier
Has alkaline properties

21

What is gastropathy?

Damage to stomach mucosa

22

What can damage stomach mucosa?

Can by caused by drugs, infection, stress, alcohol, radiation therapy

23

What does damage to stomach mucosa cause?

Usually leads to ulceration

24

How is gastric secretion regulated?

Neural and hormonal mechanisms

25

What type of events regulate gastric secretion?

Stimulatory and inhibitory events

26

What are the 3 phases to regulate gastric secretion?

Cephalic (reflex) phase: few minutes prior to food entry
Gastric phase: 3–4 hours after food enters the stomach
Intestinal phase: brief stimulatory effect as partially digested food enters the duodenum, followed by inhibitory effects

27

What is the cephalic phase?

Smell, sight, thought, taste of food activates CNs
Facial, glossopharyngeal and vagus nerves are activated
Salivary and gastric glands are activated
Prepares mouth and stomach for food

28

What is the gastric phase?

Food distends the stomach and stimulates stretch receptors
Chemoreceptors in stomach detect increase in pH
peristalsis and gastric juice secretion
Chyme empties into duodenum
↓pH and ↓distension

29

What type of feedback loop is the gastric phase?

Negative

30

What is gastric secretion regulated by?

Gastrin

31

What is gastrin released by?

G cells of gastric glands

32

What is gastrin released in response to?

Released in response to food in stomach and parasympathetic stimulation

33

Where is gastrin released into?

Bloodstream

34

What does gastrin stimulate?

Stimulates gastric juice secretion and prevents acid reflux

35

What is gastrin inhibited by?

Inhibited when pH < 2.0 – negative feedback

36

Where does the intestinal phase begin?

Small intestine

37

What does the intestinal phase inhibit?

Exit of chyme from stomach
Inhibition of gastric motility
Contraction of pyloric sphincter

38

What does the intestinal phase inhibit?

Gastric secretions

39

What does the intestinal phase promote?

Digestion of food in SI
Neural enterogastric reflex

40

What is the hormonal element in the intestinal phase?

CCK and secretin