1. Digestive System

Question 1

Name the 7 main parts that make up the digestive system

Answer 1

Mouth, Pharynx, Oesophagus, Stomach, Small intestine, Large Intestine and Rectum

Question 2

Name the 4 accessory organs of the digestive system

Answer 2

Salivary Gland, Liver, Gall Bladder and Pancreas

Question 3

Why digest?

Answer 3

Fuel cells, break down large molecules to smaller ones which can then diffuse into cells and bloodstream for usage

Question 4

What are the 4 main phases of gastrointestinal system?

Answer 4

Motility, Secretion, Digestion and Absorption

Question 5

Which of the 4 phases are not controlled?

Answer 5

Absorption

Question 6

What can be secreted into the lumen?

Answer 6

Enzymes (for digestion), salt, water, Mucus, HCl, HCO3

Question 7

What is the inner-most layer of the lumen wall?

Answer 7

Mucosa

Question 8

What is the function of the mucosa?

Answer 8

Increase surface area due to folded membrane, protective surface, secretes enzymes, defence against bacteria.

Question 9

Name the three layers of the mucosa and their function

Answer 9

Mucous Membrane (protect surface, contains exocrine and endocrine gland cells), Lamina Propria (lyphoid tissue - important for defence) and Muscularis Mucosa (smooth muscle)

Question 10

What is the function of the submucosa?

Answer 10

Thick layer of connective tissue for distensibility and elasticity. Contains larger blood and lymph vessls and contains nerve network which stimulates contraction and hormonal release.

Question 11

Name the nerve network of the submucosa and muscularis externa

Answer 11

Submucosal plexus and myentric plexus

Question 12

Name the muscle that makes up the muscularis externa

Answer 12

Smooth muscle

Question 13

What affect do each layer in the muscularis externa have on the lumen when contracted?

Answer 13

Circular layer (contraction decreases diameter of lumen) and longitudinal layer (contraction shortens tube).

Question 14

What does contraction of muscularis externa result in?

Answer 14

Produces mixing and propulsive movement

Question 15

What is the function of the serosa?

Answer 15

Secrete serous fluid for lubrication - prevents friction

Question 16

What is the function of mesentry?

Answer 16

Holds lumen to body wall - fIxation in the body and allows movement for mixing.

Question 17

What does enteric innervation mean?

Answer 17

Within tract (involves myentric and submucosal plexus) and is interconnected (motor, secretory and sensory neurones)

Question 18

What does extrinsic innervation mean?

Answer 18

Brain innervation - further away.

Question 19

What effect does parasympathetic innervation have on the activity of the gut

Answer 19

Increases activity - rest and digest

Question 20

What is the function of villi?

Answer 20

Increases surface area due to folded epithelial layer (e.g. Small intestine: 300m2) - shedding (whole new lining every 5 days) - absorption via capillaries (except for fats (lacteal))

Question 21

What is secreted by the salivary gland and why?

Answer 21

Salt, water, mucus, amylase - lubraication and polysaccharide (starch) digestion

Question 22

Which part of the digstive system secretes lingual lipase?

Answer 22

Tongue for lipid digestion

Question 23

Why is mucus secreted by the oesophagus?

Answer 23

Lubrication - prevents friction

Question 24

Why is HCl secreted by the stomach?

Answer 24

Activates Pepsin to pepsinogen which digests proteins.

Question 25

What is the function of HCO3?

Answer 25

Bicarbonate neutralises chyme and adjusts pH after stomach.

Question 26

Where is bile salts stores?

Answer 26

Gall Bladder

Question 27

What is secreted by the liver?

Answer 27

Bile slats, HCO3 and waste

Question 28

Where is most of digestion taken place?

Answer 28

Small Intestine

Question 29

Where is water reabsorpted to prevent loss?

Answer 29

Large Intestine

Question 30

Is mucus secreted in the large Intestine?

Answer 30

Yes for lubrication

Question 31

What is the function of the rectum?

Answer 31

Defecation

Question 32

What makes up carboydrates?

Answer 32

Monosaccharides

Question 33

Fatty Acids and Glycerol form what?

Answer 33

Lipids (fats)

Question 34

Name a polysaccharide?

Answer 34

Glycogen, Cellulos, Amylopectin, amylose (strach)

Question 35

What does amylase do and where is it secreted?

Answer 35

Amylase breaks down strach in the mouth

Question 36

How is glucose transported into epithelial cells?

Answer 36

Via cotransport with Na+ ions

Question 37

How is fructose transported into epithelial cells?

Answer 37

Via protein channel straight into cell

Question 38

How does pepsinogen digest proteins?

Answer 38

Breaks bonds between amino acids

Question 39

What is the difference between endopeptidases and exopeptidases?

Answer 39

Endopeptidases break bonds between AAs, Exopeptidases act on the ends of chains

Question 40

What type of molecule is moved into epithelial cells via endocytosis

Answer 40

Small peptides

Question 41

How is amino acids transported into epithelial cells?

Answer 41

Via co-transport with Na+ ions

Question 42

Name the 3 lipases and what do they act on?

Answer 42

Lingual, gastric and pancreatic lipases and they act on lipids (fats)

Question 43

Where is most lipids digested?

Answer 43

Small intestine

Question 44

What is the problem with large lipid droplets?

Answer 44

Small surface area: volume ratio - not many enzymes can act on the lipids at once.

Question 45

What do bile salts do?

Answer 45

Increase SA:V ratio by creating several small droplets from one big one creating more sites for enzymes to act upon. They also prevent reaggregation of droplets together.

Question 46

What are micelles?

Answer 46

Small droplets which act as reservoir to store FAs and glycerol

Question 47

How are FAs and glycerol secreted out of epithelial cells and where to?

Answer 47

Exocytosis (vesicles) into lacteal.

Question 48

How is water absorbed?

Answer 48

Osmosis via channel transporters down osmotic graident.

Question 49

How are fat soluble vitamins absorbed?

Answer 49

Follow fat absorption

Question 50

How is vitamin B12 absorbed?

Answer 50

Bind to intrinsic factor.

Question 51

What does the control of the GI respond to?

Answer 51

Distension, osmolarity and acidity and concentration of molecules

Question 52

Name the 3 types of control systems

Answer 52

Neural, Hormonal and Local muscle response

Question 53

what does submucosal plexus control?

Answer 53

Exocrine and endocrine secretions

Question 54

What does the myenteric plexus control?

Answer 54

Control of peristaltic secretions

Question 55

What is the effect of thinking about food?

Answer 55

Causes changes in CNS and affect enteric NS so you start to produce hormones and saliva.

Question 56

Do short reflexes involves the brain?

Answer 56

No but long reflexes do

Question 57

What stimulates hormonal release?

Answer 57

Receptors in contact with the luminal contents detect extremes in distension, osmolarity and acidity etc...

Question 58

How is hormones secreted into blood?

Answer 58

Endocrine gland secretion

Question 59

What are the two families of hormones?

Answer 59

Gastrin and Secretin

Question 60

Name the 3 phases of GI control

Answer 60

Cephalic, Gastric and Intestinal.

Question 61

Which part of the body is the site of cephalic phase

Answer 61

Head

Question 62

Name the two phases of GI control which affected by hormonal control

Answer 62

Gastric and Intestinal

Question 63

Control of gastric phase happens in response to what?

Answer 63

Distension, Acidity and Peptides

Question 64

What influences cephalic phase?

Answer 64

Touch, sight, taste, thought

Question 65

What is mastication?

Answer 65

Chewing phase

Question 66

Is mastication voluntary?

Answer 66

Yes but eventually you swallow due to excess saliva

Question 67

Which parts of the mouth contain receptors that produce a reflex

Answer 67

Gums and Hard Palate

Question 68

Saliva in mouth is secreted in response to what?

Answer 68

Presence of food in mouth

Question 69

How is food prevented from entering the lungs

Answer 69

Glottis closes to prevent food going down trachea, aryno-oesophageal opens to allows food into oeophagus to stomach

Question 70

What is peristalsis?

Answer 70

Constriction and shortening of tube, which moves contents though intestinal tract, mixing an propelling food though.

Question 71

What is secondary peristalsis?

Answer 71

Oesophageal distension and it occurs when indigested food has been left behind after primary peristalsis.

Question 72

What causes mixing?

Answer 72

Reduction in lumen diameter moves some parts forward and other parts in reverse.

Question 73

Name the 3 parts of stomach

Answer 73

Fundus, Body and Antrum

Question 74

What is the function of stomach?

Answer 74

Acts as a store for food, mixing, breaks down big molecules into smaller ones, more manageable liquid (chyme)

Question 75

What does the pyloric sphincter do?

Answer 75

Prevents food coming back from small intestine.

Question 76

What prevents food re-entering oesophagus?

Answer 76

Oesphageal sphincter

Question 77

Name the 3 cells in stomach and what do they secrete?

Answer 77

Mucous (mucus), parietal (HCl) and chief (pepsinogen)

Question 78

What is receptive relaxation?

Answer 78

Take extra volume of food with little rise in stomach pressure stimulated by eating

Question 79

What is the function of the body in the stomach?

Answer 79

Storage

Question 80

Where does mixing take place in the stomach?

Answer 80

Antrum

Question 81

What controls emptying in the stomach?

Answer 81

Factors in the duodenum

Question 82

Why does excess fat slow emptying of stomach?

Answer 82

Fat digestion is slow and so to reduce build up of fats in small intestine and less waste emptying is reduced

Question 83

Name two factors that affect gastric emptying.

Answer 83

Amount of chyme, Fat, Acid, Hypertonicity and distension.

Question 84

Does intense pain inhibit motility?

Answer 84

Yes

Question 85

What membrane potential change causes contraction?

Answer 85

Parasympathetic depolarisation.

Question 86

What secretes gastric juice

Answer 86

Oxyntic mucosa and pyloric gland areas.

Question 87

What stimulates chief cells?

Answer 87

ACh, Gastrin

Question 88

What is the postprandial alkaline tide?

Answer 88

They secrete bicarbonate ions into blood causing temporary increase in pH - maintain plasma's electrical balance. Back optimal pH.

Question 89

Which of the 3 phases causes a decrease in HCl

Answer 89

Intestinal Phase

Question 90

How is pepsinogen converted to pepsin

Answer 90

Pepsinogen released by chief cells, mixes with HCl, causing pepsinogen activation to become pepsin (change conformation)

Question 91

What is secreted from pancreas?

Answer 91

HCO3 and enzymes

Question 92

Where does most digestion take place?

Answer 92

Small intestine

Question 93

What is secreted when pH lowers in the small intestine

Answer 93

Plasma secretin levels increases, and pancreas increases bicarb concentration and that neutralises acid in small intestine.

Question 94

What does CCK do?

Answer 94

Increased levels increases enzymes released by pancreas which increases rate of digestion of fats and proteins.

Question 95

What stimulates the release of HCO3 from epithelial cells of bile duct?

Answer 95

Secretin.

Question 96

What is the sphincter of Oddi

Answer 96

Smooth muscle which relaxes when we eat to allow bile and pacreatic juice to flow into small intestine.

Question 97

Does contraction of gall bladder release or inhibit the release of bile salts

Answer 97

Releases.

Question 98

Does peristalsis occur in the small intestine?

Answer 98

Yes

Question 99

What does Gastro-ileal reflex do?

Answer 99

Increases segmentation which stimulates colonic peristalsis and provides an urge to defecate.

Question 100

What is the migrating mobility complex?

Answer 100

Short peristaltic waves which pushes indigestible foods through the small intestine. (2hrs)

Question 101

What does motilin do?

Answer 101

Increase peristaltic mobility.

Question 102

What does relaxation of ileocecal sphincter result in?

Answer 102

Chyme moving into large intestine.

Question 103

What is intestinal segmentation?

Answer 103

Causes mass movement through large intestine

Question 104

Which part of the anus is voluntarily controlled?

Answer 104

External Anal sphincter.

Question 105

Describe renal distension.

Answer 105

Internal sphincter relaxes, external contracts, increased peristalsis in sigmoid colon and increases rectal pressure.