Gastrointestinal Tract - Stomach

Question 1

Where is the stomach located?

2

Answer 1

Inferior to the diaphragm

Upper left quadrant of the abdominal cavity

Question 2

List the four main functions of the stomach.

Answer 2

Stores ingested food

Mechanical breakdown

Secretes enzymes and acids

Secretes intrinsic factor (IF)

Question 3

What does the stomach store?

Answer 3

Ingested food

Question 4

What does the stomach secrete?

3

Answer 4

Enzymes

Acids

Intrinsic factor

Question 5

Why does the stomach secrete enzymes and acid?

Answer 5

To break chemical bonds of ingested food

Question 6

What happens if not enough intrinsic factor is secreted?

Answer 6

Not enough IF leads to pernicious anaemia

Question 7

Describe the structure of the stomach. (5)

Answer 7

Greater curvature

Lesser curvature

Oblique angle

Folds -> rugae ->pits -> glands

Receptors

Question 8

What are the names for the two types of curvature in the stomach?

Answer 8

Greater and lesser curvature

Question 9

What angle is the stomach at?

Answer 9

An oblique angle

Question 10

Why is the angle of the stomach important?

Answer 10

This means the stomach is always higher than the pyloric sphincter and the body of the stomach

Question 11

What is the name given to the area where the oesophagus meets the stomach?

Answer 11

The pyloric sphincter

Question 12

Why does the oesophagus need to be above the pyloric sphincter?

Answer 12

To prevent reflux

Question 13

What puts you at risk of reflux?

Answer 13

Being obese -> large amounts of fat around the stomach leads to an increased pull of gravity on the stomach leading to a more horizontal stomach -> causing reflux

Question 14

How much liquid can the stomach hold when not stretched?

Answer 14

One litre

Question 15

How much liquid can the stomach hold when it is stretched?

Answer 15

Four litres

Question 16

What do the folds of the stomach create?

Answer 16

Rugae

Question 17

What are rugae?

Answer 17

Folds of the stomach

Question 18

What do rugae form?

Answer 18

Pits

Question 19

What forms pits in the stomach?

Answer 19

Rugae

Question 20

What do pits in the stomach form?

Answer 20

Glands

Question 21

What forms glands in the stomach?

Answer 21

Pits

Question 22

How do the glands in the stomach work?

Answer 22

They secrete their products out between rugae

Question 23

What receptors are found in the stomach?

3

Answer 23

Mechanoreceptors

Osmoreceptors

Chemoreceptors

Question 24

Give an example of a mechanoreceptor.

Answer 24

Stretch receptors

Question 25

How do osmoreceptors work?

Answer 25

They determine osmolarity of surrounding concentrations -> determine what response is needed to digest a substance with a high concentration of protein

Question 26

How do chemoreceptors work in the stomach?

Answer 26

They determine how acidic a substance is and organise a suitable response to digest the substance

Question 27

What is the overall function of the receptors in the stomach?

Answer 27

The detect what is in the stomach and what is happening in the stomach

Question 28

Describe the epithelia of the mucosa of the stomach.

Answer 28

Simple columnar epithelium

Question 29

What is different about the muscularis externa in the stomach compared to anywhere else in the GIT?

Answer 29

There is a third type of muscle

Question 30

What are the three types of muscle fibres in the stomach?

Answer 30

Oblique fibres Circular fibres Longitudinal fibres

Question 31

What is the function of the oblique fibres in the stomach?

Answer 31

This allows the stomach to ring itself out like a cloth

Question 32

Name the five cell types found in the pits/glands of the stomach.

Answer 32

Neck cells Parietal cells Chief cells P/D1 cells G cells

Question 33

What is secreted by the neck cells?

Answer 33

Mucous

Question 34

How long does it take for the neck cells to turnover?

Answer 34

They have a high turnover rate of 5 days

Question 35

What will increase the turnover rate of neck cells?

Answer 35

Alcohol

Question 36

What will happen to the neck cells if one drinks too much alcohol? (2)

Answer 36

Turnover rate is too high Forms gastric ulcers as cells below the chief cells come in contact with the acid of the stomach and become damaged

Question 37

What do parietal cells secrete?

Answer 37

They secrete Hydrochloric acid (HCL)

Question 38

What is HCL used for? | 5

Answer 38

Denature proteins Break down cell walls Break down connective tissues Protection -kill microorganisms Activate pepsin

Question 39

What does HCL do to proteins?

Answer 39

Denatures them

Question 40

What does HCL break down? | 2

Answer 40

Connective tissue Cell walls

Question 41

What does HCL protect us from?

Answer 41

Microorganisms

Question 42

What does HCL activate?

Answer 42

Pepsin

Question 43

What is found in chyme? | 5

Answer 43

``` Intrinsic factor Mucus Pepsinogen HCL Hormones ```

Question 44

What is the role of intrinsic factor in chyme?

Answer 44

Enters the Small intestine where it absorbs vitamin 12

Question 45

How does deficiency of intrinsic factor result in pernicious anaemia?

Answer 45

This is because intrinsic factor is needed to absorb vitamin 12 in the small intestine which is needed to form red blood cells

Question 46

What do the chief cells secrete?

Answer 46

Pepsinogen

Question 47

How are chief cells involved in the break down of proteins?

Answer 47

Chief cells secrete pepsinogen which is an inactive form of pepsin (an enzyme which breaks down proteins into smaller parts)

Question 48

What activates pepsin in the stomach?

Answer 48

HCL

Question 49

Where are P/D1 cells found?

Answer 49

The fundus of the stomach

Question 50

What is the fundus of the stomach?

Answer 50

The highest part of the stomach -> its higher than the pyloric sphincter

Question 51

What is secreted by the P/D1 cells?

Answer 51

A hormone called ghrelin

Question 52

What is ghrelin?

Answer 52

An enterogasterone ->hormone in the GIT

Question 53

What is the role of ghrelin?

Answer 53

It stimulates the hunger sensation

Question 54

How does ghrelin stimulate hunger? | 3

Answer 54

P/D1 cells enter your bloodstream where they reach the hypothalamus and bind to it They then secrete ghrelin This tells you to eat

Question 55

What hormone is the opposite of ghrelin?

Answer 55

Lectin

Question 56

What does lectin do?

Answer 56

It tells you when your full

Question 57

What is secreted by G cells?

Answer 57

Gastrin

Question 58

What is gastrin?

Answer 58

An enterogasterone

Question 59

What do G cells do? | 2

Answer 59

They detects undigested material such as proteins and secrete gastrin accordingly If food is about to enter the small intestine but it has not been fully digested these G cells will increase their gastric secretions to ensure chyme is the right consistency

Question 60

What is the formation of gastric juice often called?

Answer 60

The Alkaline Tide

Question 61

What is the pH of gastric juice?

Answer 61

1.5

Question 62

What is the first step in the Alkaline Tide?

Answer 62

H+ produced in parietal cell by reduction of CO2 +H2O

Question 63

What cells produces H+?

Answer 63

Parietal cells

Question 64

How do parietal cells produce H+

Answer 64

By reducing CO2 and H2O

Question 65

What happens to the H+ produced by the parietal cells?

Answer 65

They are transported into the gastric glands

Question 66

What is the third step of the Alkaline Tide?

Answer 66

The HCO-3 diffuses into interstitial fluid via counter transport with Cl-

Question 67

How does the HCO-3 diffuse into the interstitial fluid?

Answer 67

Via counter transport with Cl-

Question 68

What is the fourth step in the Alkaline Tide?

Answer 68

HCO-3 diffuses into circulation which raises pH (alkaline tide)

Question 69

What is the fifth/final stage in Alkaline Tide?

Answer 69

Cl- diffuses into gastric gland via Cl- channels