Digestion And Absorption

Front 1

What are the names of the 3 phases of digestion and absorption?

Back 1

1. Cephalic

2. Gastric

3. Intestinal

Hint 1

1. C

2. G

3. I

Front 2

What controls the Cephalic Phase? What is its primary function?

Back 2

1. By resources via the ANS

2. Stimulates saliva formation

Front 3

What initiates the cephalic phase? Relays info to?

Back 3

1. Sensory receptors pick up the sight, smell and taste of food.

2. Salivatory nuclei in medulla

Hint 3

1. Stimulation of...

2. Nuclei.

Front 4

The Salivatory nuclei sends the signal for...

Back 4

Parasympathetic Efferent Response; Vagal Stimulation for Acetylcholine Secretion.

Hint 4

PER, ACh

Front 5

What does the Parasympathetic stimulation lead to?

Back 5

1. Secretion of ACh & VIP by nerve endings which stimulates the Antrum's G-Cells.

2. Increased blood flow (Kallikrien & Bradykinin)

Hint 5

1. Neurotransmitters

2. Vasodilation

Front 6

What initiates Gastric Secretion? What kind of reflexes occur?

Back 6

1. Distention of the stomach

2. Vago-vagal & local reflexes

Hint 6

1. Distention: State of being stretched normal normal dimensions.

2. Controls the contraction of the gastrointestinal muscle layers in response to distension of the tract by food.

Front 7

What is the function of the Vago-vagal reflex?

Back 7

It allows for the accommodation of large amounts of food in the gastrointestinal tracts.

Front 8

What does ACh from the cephalic phase do? This leads to...

Back 8

1. Causes Gastrin secretion from G-cells (stomach).

2. HCL Gastric Secretion from Parietal Cells

Hint 8

1. Secretion from pyloric Antrum

2. HCL

Front 9

What regulates Gastric Secretion?

Back 9

1. Secretion of Secretin, CCK, GIP (Gastrin Inhibitory Peptide) by duodenum (intestinal phase)

2. Secretion of ACh by nerve endings

Hint 9

1. Inhibit G-Cells & Parietal Cells; secretions by S-cells, I-cells and K-cells

2. Stimulates Gastric Secretion

Front 10

What is the cause of Secretin, CCK and GIP being secreted in the Intestinal Phase?

Back 10

Protein Digestion products in the duodenum trigger the secretion.

Hint 10

Protein related

Front 11

What 3 factors allow enzyme-rich secretions by Acinar cells?

Back 11

1. ACh secretion

2. VIP (Vasoactive Intestinal Peptide) secretion with ACh & Gastrin

3. CCK secretion by I-cells in Intestinal Phase

Hint 11

1. Cephalic phase's Parasympathetic Vagal activity.

2. By G-cells in Antrum in the Gastric Phase.

3. I for Intestinal

Front 12

Low pH in the duodenum causes the secretion of...

What is the action of this hormone?

Back 12

1. Secretion of Secretin by S-cells.

2. Secretion of Bicarbonate-rich fluid by duct cells

Hint 12

1. Secretin

2. Alkaline to counter acidity

Front 13

What agents does the Pancreas secrete? Where are they stored?

Back 13

1. Proteolytic

2. Amylolytic

3. Lipolytic

4. Zymogen granules

Hint 13

Enzymes

Note: they are secreted in an inactive form: zymogen (e.g. Trypsinogen)

Front 14

What are the functions of Trypsin?

Back 14

1. Cleaves peptide bonds

2. Activates other enzymes

Hint 14

1. Protease

2. Activator

3. Along with Chymotrypsin

Zymogen: Trypsinogen activated by: Enteropeptidase

Front 15

What is Pancreatitis? What are the mild and severe case symptoms?

Back 15

1. Inflammatory disease with high incidence rate among alcoholics.

2. Interstitial oedema

3. Acinar cell Necrosis

4. Acini destruction (leads to Steatorrhoea)

Hint 15

1. General definition

2. Mild

3. Severe

4. Chronic

Front 16

What causes cystic fibrosis?

Back 16

1. Duct cells & other epithelial cells have atypical AMP-activated Cl- channels.

2. Loss of channel function reduces bicarbonate & water secretion.

3. The protein-rich secretion thickens leading to duct blockage.

Hint 16

1. Lots of a channel function

2. HCO3 & H2O

3. Primary secretion thickens

Front 17

Where are the key sites of nutrition absorption?

Back 17

1. Duodenum

2. Jejunum

3. Ileum

Hint 17

Small intestines

Front 18

Where are lipids primarily absorbed? Via?

Back 18

1. Jejunum

2. Diffusion, transporters and solvent drag

Hint 18

1. Across a leaky epithelium

2. Osmotic forces are important

Front 19

What is the function of Bile? Where does Bile Acid absorption occur?

Back 19

1. Emulsifies lipids into droplets for more Surface Area for Pancreatic Lipase Action.

2. Mostly in Ileum but also Duodenum, Jejunum and Ascending Colon

Hint 19

Small intestine with a part of three large intestine as well.

Front 20

Where is Cobolamin absorbed?

Back 20

Ileum

Hint 20

Part of the small intestine.

Front 21

How are carbohydrates digested?

Back 21

Firstly by Salivary Amylase, then by Pancreatic Amylase.

Hint 21

Involves the cephalic phase and exocrine function of the Pancreas.

Both are secreted in active form.

Front 22

How does alpha-amylase carry out its function?

Back 22

Endoenzyme action on linear 1,4 linkages between glucose residues.

Hint 22

Alpha glucose only!

Front 23

Most monosaccharides are absorbed...

Via...

Back 23

1. In the first 20% of the Small Intestine.

2. Enterocytes' Oligosaccharidases

Hint 23

1. SI; Microvilli (Brush border)

2. oligosaccharidases have catalytic domains facing the lumen. I.e. Lactase, Maltase (glucoamylase), Sucrase (sucrase-isomaltase)

Front 24

Glucose & Galactose can...

Back 24

Compete to bind and be transported by apical SGLT-1.

Hint 24

SGLT-1: Sodium-Glucose Linked Transporter

Front 25

What is the function of GLUT-2?

Location?

Back 25

1. When glucose in the lumen is high, GLUT-2 is inserted into the apical membrane to further facilitate transport.

2. Apical membrane of Enterocytes.

Hint 25

Remember that GLUT-2 has a low affinity for Glucose

Front 26

What normally transports Fructose?

Back 26

Apical GLUT-5

Hint 26

Glucose Transporter also found on enterocyte

Front 27

How are proteins digested in the Stomach? In the Pancreas?

Back 27

1. Gastric enzymes (Pepsin)

2. Pancreatic Enzymes (Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B)

Hint 27

Both are secreted in inactive forms.

Pepsin: an endopeptidase from Pepsinogen.

Front 28

What do Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B give rise to?

Back 28

1. Procarboxylase A&B give rise to exopeptidase enzymes

2. The rest do endopeptidase enzymes

Hint 28

Endo our Exo?

Front 29

How are proteins digested?

Back 29

Firstly by Gastric enzymes (Pepsin), then by Pancreatic Enzymes (Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B)

Hint 29

Both are secreted in inactive forms.

Pepsin: an endopeptidase from Pepsinogen.

Front 30

What do Trypsinogen, Chymotrypsinogen, proelastase & Procarboxylase A&B give rise to?

Back 30

1. Procarboxylase A&B give rise to exopeptidase enzymes

2. The rest do endopeptidase enzymes

Hint 30

Endo our Exo?

Front 31

Define Endopeptidase and Exopeptidase.

Back 31

1. Enzymes which break peptide bonds other than the terminal ones in a peptide chain.

2. Enzymes which break terminal peptide bonds in a peptide chain.

Hint 31

Breakage of terminal peptide bonds.

Front 32

What is the location and function of Peptidases?

Where does the digested protein go?

Back 32

1. Exist on the brush-border

2. Hydrolysis of oligopeptides into amino acids

3. Intestinal capillaries

Hint 32

Brush border consists of microvilli composed of Enterocytes

Front 33

What are Enterocytes? Function?

Back 33

1. Simple columnar epithelial cells

2. Degrade lysosomes

3. Uptake of proteins, carbohydrates, lipids, water and ion in the intestines.

4. Uptake of Vitamin B12 Cobolamin.

Hint 33

1. Epithelial cell; forms microvilli on villi of intestines

2. Degradation

3. Uptake of everything

4. Uptake of a vitamin

Front 34

What is the location and function of M-cells (Microfold Cells)?

Back 34

1. Line Peyer's Patches and BALT

2. Package proteins into vesicles and transport organisms & particles from gut lumen to immune cells.

Hint 34

1. Peyer & Bronchus Associated Lymph Tissue

2. Packaging & transportation

Front 35

94% of Bile salts that enter the intestines...

Back 35

Are reabsorbed.

Front 36

What is the location and function of M-cells (Microfold Cells)?

Back 36

1. Line Peyer's Patches (lymphoid nodule of ileum) and BALT

2. Package proteins into vesicles and transport organisms & particles from gut lumen to immune cells.

Hint 36

1. Peyer's Patches are unique to ileum. BALT: Bronchus Associated Lymph Tissue

2. Packaging & transportation

Front 37

94% of Bile salts that enter the intestines...

Back 37

Are reabsorbed.

Front 38

What are the 3 functions of the Gall Bladder?

Back 38

1. Acts as a Bile Reservoir

2. Concentrates Bile

3. Emptying mainly by CCK

Hint 38

1. Storage

2. Concentration

3. Empties

Front 39

What is the major factor of Bile regulation?

Back 39

1. Return of Bile salts is the major factor.

2. Cholesterol Gall stones

Hint 39

1. Secretin enhances Bicarbonate-rich watery fluid by duct cells.

2. Excess cholesterol causes crystal formation; acts as Ca2+ & PO4 salts' nuclei

Front 40

Lipids are digested by...

MOA? Limitation?

Back 40

1. By Salivary, Gastric and Pancreatic Lipase.

2. Splits bonds linking FA to 1st & 3rd Carbons of glycerol.

3. Limited action without colipase.

Hint 40

1. Mouth, stomach & Pancreas

2. Triacylglycerol

3. Colipase

Front 41

Name and describe the MOA of 2 Pancreatic Lipases.

Back 41

1. Pancreatic Phospholipase A: breaks down Lecithin

2. Pancreatic Cholesterol Esterase: breaks 2-ester linkages of TAG

Hint 41

1. Lecithin a.k.a phosphatidyl Choline, needs Ca2+ and bile salts

2. TAG ester bond

Front 42

Lipids pass across brush border...

If they are big /small...

Back 42

1. And are re-esterified in Enterocytes' smooth ER.

1. Big lipids are secreted as fat droplets across bilateral membrane and enter lacteals via exocytosis

2. Small lipids enter intestinal capillaries.

Hint 42

1. Small intestine has villi with micro villi (brush border) which is made up of Enterocytes.

2. Lacteals (lymphatic capillaries)

3. Intestinal capillaries

Front 43

How are Vitamins Digested?

Back 43

1. Fat-soluble Vitamins (ADEK) USE the same pathway as fat absorption.

2. Water-soluble use diffusion/carrier mediated transport.

Hint 43

1. Fat:lipid

2. e.g. B1 (thiamin) & C (ascorbic acid) use Na+-dependant carriers

Front 44

Vitamin B12 (Cobolamin) is released from food...

Back 44

Via Pepsin Action

Hint 44

Enzyme

Front 45

Cobolamin then binds to...

It is then released from degraded H_ and binds to...

Back 45

1. Haptocorrin at low pH

2. Intrinsic Factor

Hint 45

1. Found in saliva; condition protects it from Gastric Juices.

2. IF is secreted by parietal cells

Front 46

Vitamin B12 (Cobolamin) is released from food...

Back 46

Via Pepsin Action

Hint 46

Enzyme

Front 47

Cobolamin then binds to...

It is then released from degraded H_ and binds to...

Back 47

1. Haptocorrin at low pH

2. Intrinsic Factor

Hint 47

1. Found in saliva; condition protects it from Gastric Juices.

2. IF is secreted by parietal cells

Front 48

The Cobolamin-IF complex is absorbed...

Enterocyte processing binds Cobolamin to...

Back 48

1. By the Ileum

2. Transcobalamin II

Hint 48

1. Absorption is Ca2+ dependant.