Bs Digestive Systems

Front 1

1. Catabolic reaction?
2. Anabolic rxn?

Back 1

1. Breakdown of molecules to supply energy.
2. Synthesis of macromolecules.

Front 2

Enzymatic hydrolysis accomplishes what?

Back 2

accomplishes digestive breakdown.

Front 3

What is vitamin?

Back 3

Not a substrate, but serve a catalytic role as enzyme cofactor or prosthetic groups.

Front 4

1 triglyceride + 2 H2O --------> 2 fatty acids + 1 monoglyceride. What enzyme causes this?

Back 4

pancreatic lipase

Front 5

polysaccharide + n H2O --------> disaccharide. What enzyme causes this reaction?

Back 5

pancreatic amylase & ptyalin (from saliva)

Front 6

Disaccharides --------> monosaccharide. What enzyme causes this reaction?

Back 6

disaccharidases (sucrase, lactase, maltase)

Front 7

polypeptide + n H2O ----->di/tripeptides. What enzyme causes this reaction?

Back 7

gastric acidity/pepsin & pancreatic proteases.

Front 8

di/tripeptides ------> amino acids. What enzyme causes this reaction?

Back 8

peptidases.

Front 9

3 characteristics of Gastrointestinal (GI) lumen.

Back 9

1. Inside the gut; continuous with the space outside body.
2. Usable components of food are extracted.
3. Wastes are excreted as feces.

Front 10

What is GI epithelium?

Back 10

Innermost lining of lumen, attached to a basement membrane. Top (apical) surface faces into lumen.

Front 11

What is tight junction of GI epithelium?

Back 11

Side barrier of epithelium cells that separates body fluids from extracellular environment.

Front 12

What is basolateral surface?

Back 12

Surface opposite the lumen (sides and bottom of an epithelial cell).

Front 13

2 layers of smooth muscle lining the gut.

Back 13

Longitudinal layer (outer) & circular layer (inner)

Front 14

5 characters that determine GI motility (rhythmic contraction)

Back 14

1. Exhibits automaticity
2. Functional syncytium
3. Enteric nervous system
4. increased/decreased hormonal input
5. Parasympathetic nervous system (sphincters relax, allowing passage of food thru gut)

Front 15

What is automaticity

Back 15

Muscles contract periodically w/o external stimulation, thus creating a spontaneous depolarization.

Front 16

Functional syncytium

Back 16

one cell has action potential and contracts; the impulse spreads to neighboring cells.

Front 17

2 purposes of GI motility.

Back 17

1. Mixing food by disordered contractions of GI smooth muscle.
2. Movement of food down the gut by peristalsis, an orderly form of contraction.

Front 18

1. Secretion
2. Excretion

Back 18

1. Relases of useful substance by cells
2. Disposal of waste product

Front 19

GI secretion is
1. stimulated by
2. inhibited by

Back 19

1. food in the gut & parasympathetic nervous system
2. sympathetic stimulation

Front 20

Exocrine glands

Back 20

organized into sacs called acini that secrete products (digestive ENZYMES)into ducts, which empty into GI lumen.

Front 21

Endocrine glands

Back 21

ductless glands; secretions (HORMONES) picked up by capillaries and enter bloodstream.

Front 22

GI Exocrine system consists of

Back 22

liver, gallbladder, pancreas, and epithelial cells in gut wall

Front 23

3 functions of epithelial cells of GI exocrine system.

Back 23

1. gastric enzymes from stomach wall.
2. goblet cells secreting mucus and protects/lubricates the entire gut.
3. secretion of water to dissolve food.

Front 24

GI Endocrine organs

Back 24

pancreas and gut wall cells. Secretions picked up by nearby capillaries.

Front 25

3 functions of mouth

Back 25

1. fragmentation of food by masticulation (chewing).
2. lubrication by saliva.
3. food ---> bolus

Front 26

saliva contains

Back 26

1. salivary amylase that hydrolyzes starch to dissacharide.
2. lysozyme that attacks bact cell wall.
**No digestion of proteins/fats in mouth!**

Front 27

upper & lower esophageal sphincters are

Back 27

2 muscular rings that regulate food flow (peristalsis)
*lower sphincter: prevents reflux of chyme into esophagus.

Front 28

3 functions of stomach

Back 28

1. partial digestion of food
2. regulated release of food into small intestine.
3. destruction of microorgs.

Front 29

3 roles of acidity of stomach

Back 29

1. destruction of microorgs
2.acid-catalyzed hydrolysis of dietary proteins
3. pepsinogen ---> pepsin.
** pH~2, secretion of HCl by parietal cells.

Front 30

Pepsin

Back 30

Secreted by stomach that catalyzes proteolysis (protein breakdown).
Pepsinogen (inactive) ---> pepsin (active) by gastric acidity, not by an enzyme.

Front 31

What is zymogen and how is it activated?

Back 31

It's an inactive precursor and activated by proteolytic activation: cleavage of the protein at a specific site
ex: pepsinogen & trypsinogen

Front 32

What is zymogen and how is it activated?

Back 32

It's an inactive precursor and activated by proteolytic activation: cleavage of the protein at a specific site
ex: pepsinogen & trypsinogen

Front 33

Chyme

Back 33

a broken-down food mixed w/ gastric secretions

Front 34

1. What is pyloric sphincter
2. What causes opening inhibition?

Back 34

1. Prevents food into duodenum.
2. Excessive acidity in duodenum inhibits further stomach empying by contracting, which is done by nerves and hormones.

Front 35

What inhibits the opening of pyloric sphincter?

Back 35

Excessive acidity in duodenum inhibits further stomach empying by contracting, which is done by nerves and hormones.

Front 36

What is the name of the hormone secreted by epithelial cells in duodenum?

Back 36

cholecystokinin.

Front 37

1. What is gastrin?
2. It's function?

Back 37

1. Hormone secreted by G cells (stomach wall ep. cells).
2. Stimulates acid & pepsin secretion and gastric motility.

Front 38

How is gastrin secretion stimulated?

Back 38

Stimulated by
1. food in stomach
2. parasympathetic stimulation.

Front 39

What is histamine?
What does blocking of histamine to a G cell receptor do?

Back 39

1. Cofactor of acid stimulation by gastrin.
2. Less gastric acidity.

Front 40

What does anti-histamine do?

Back 40

More gastric acidity.

Front 41

What is zymogen and how is it activated?

Back 41

It's an inactive precursor and activated by proteolytic activation: cleavage of the protein at a specific site
ex: pepsinogen & trypsinogen

Front 42

Chyme

Back 42

a broken-down food mixed w/ gastric secretions

Front 43

What is pyloric sphincter and what causes opening inhibition?

Back 43

Prevents food into duodenum.

Front 44

What inhibits the opening of pyloric sphincter?

Back 44

Excessive acidity in duodenum inhibits further stomach empying by contracting, which is done by nerves and hormones.

Front 45

What is the name of the hormone secreted by epithelial cells in duodenum?

Back 45

cholecystokinin.

Front 46

1. What is gastrin?
2. It's function?

Back 46

1. Hormone secreted by G cells (stomach wall ep. cells).
2. Stimulates acid & pepsin secretion and gastric motility.

Front 47

How is gastrin secretion stimulated?

Back 47

Stimulated by
1. food in stomach
2. parasympathetic stimulation.

Front 48

1. What is histamine?
2. What does blocking of histamine to a G cell receptor do?

Back 48

1. Cofactor of acid stimulation by gastrin.
2. Less gastric acidity.

Front 49

What does anti-histamine do?

Back 49

More gastric acidity.

Front 50

3 parts that make up small intestine (SI)

Back 50

duodenum, jejunum, ileum.
(Digestion completed at jejunum.)

Front 51

3 explanations why SI has large surface area.

Back 51

1. length (10 ft)
2. villi - multicellular projections in the wall.
3. microvilli - microscopic foldings of SI ep. cell membranes.

Front 52

Brush border

Back 52

Lumenal surface of small intestine.

Front 53

3 structures of villi and their description

Back 53

1. capilaries - absorb dietary monosaccharides and amino acids (a.a.)
2. small lymphatic structure called lacteals, which absorb dietary fats.
3. Peyer's patches - a part of immune system; collections of lymphocytes at the villi.

Front 54

Where do absorbed monosaccharides and a.a. go from villi?

Back 54

capillaries --> veins --> hepatic portal veins (liver). Basically, blood from gut to liver.

Front 55

Where to absorbed fats go from villi?

Back 55

lacteals --> large lymphatic vessels --> thoracic duct --> bloodstream.

Front 56

What 2 ducts empty into duodenum?

Back 56

1. Pancreatic duct, which delivers exocrine secretions.
2. Bile duct, which delivers bile.

Front 57

1. What is bile?
2. Where's it stored?

Back 57

1. Contains bile acids made from liver cholesterol, which is absorbed & recycled.
2. It's stored in gallbladder

Front 58

2 functions of bile

Back 58

1. Vehicle for the disposal (excretion) of waste products by liver
2. Digestion of fats

Front 59

Sphincter of Oddi

Back 59

Where pancreatic duct & bile duct empty into.

Front 60

Duodenal enterokinase

Back 60

Activates pancreatic zymogen trpsinogen to trypsin.
**Duodenal enzyme

Front 61

Trypsin

Back 61

Enzyme that catalyzes protein ------> polypeptide reaction.
**differs from pepsin that it's active in basic envt. Secreted by pancreas and activated in SI

Front 62

Brush border enzymes

Back 62

Work on inside or surface of duodenum (NOT secreted). Hydrolyze smallest carbohydrates & protein ---> monosaccharide & a.a.

Front 63

3 duodenal hormones

Back 63

1. Cholecystokinin (CCK)
2. secretin
3. enterogastrone - decreases stomach emptying.

Front 64

4 functions of Cholecystokinin (CCK)

Back 64

1. secreted in response to fat.
2. causes pancreas to secrete digestive enzymes.
3. stimulates gallbladder contraaction (bile release)
4. decreases gastric motility.

Front 65

3 roles of secretin

Back 65

released in response to acid in duodenum.
2. causes pancreas to release high-pH buffer (HCO3- in H2O, very basic secretion)
3. Neutralizes HCl from stomach.

Front 66

Duodenal pH must be

Back 66

neutral or slightly basic for pancreatic enzyme to function.

Front 67

2 functions of colon (muscular tube, 3-4 ft)

Back 67

1. absorb water & minerals
2. form/store feces

Consists of cecum and rectum

Front 68

Appendix

Back 68

Composed of lymphatic tissue

Front 69

2 parts of anal sphincter that controls defecation and their description

Back 69

1. internal: smooth muscle, autonomic control
2. external: skeletal muscle, voluntary control

Front 70

Gas

Back 70

From undigested materials metabolized by colonic bacteria (normal flora).

Front 71

2 importance of normal flora

Back 71

1. colony competition: keep dangerous bact from proliferating.
2. supply of Vitamin K: essential for blood clotting.

Front 72

3 enzymes of exocrine pancreas

Back 72

1. pancreatic amylase
2. pancreatic lipase
3. Nucleases: hydrolyze dietary DNA/RNA
4. pancreatic proteases

Front 73

Nervous system vs. pancreatic secretion

Back 73

Sympathetic nervous system: decreased pancreatic secretion.
Parasympathetic: increased pan. secretion.

Front 74

1. Islets of Langerhans
2. What hormones does each cells in it secrete?

Back 74

1. small regions within the pancreas containing three types of cells: alpha, beta, & sigma.
2. Glucagon, insulin, and somatostatin

Front 75

3 characteristics of glucagon (secreted by alpha cells)

Back 75

1. secreted in response to low blood sugar.
2. stimulates liver to hydrolyze glycogen & release glucose into bloodstream.
3. stimulates adipocytes to release fats into bloodstream.

Front 76

3 characteristics of insulin (by beta cells)

Back 76

1. secreted in response to high blood sugar.
2. effect: opposite of glucagon.
3. stimulates removal of glucose from blood for storage as glycogen & fat.

Front 77

Somatostatin (by sigma cells)

Back 77

inhibits many digestive processes.

Front 78

Body in response to high blood glucose does what?

Back 78

releases insulin, which causes sugar removed and stored.
** diabetics: high blood pressure
** excess glucose destroys many physiological system.

Front 79

Body in response to low blood glucose:

Back 79

releases:
1. glucagon (polypeptide hormone from pancreas)
2. epinephrine (a.a. derivative from adrenal medulla)
3. cortisol (steroid from adrenal cortex)

Front 80

3 hormones: raise blood glucose level.
1 hormone: lowers blood glucose level.
Why difference in number?

Back 80

Low blood glucose level: immediately fatal.
High blood glucose level: harmless in short term.

Front 81

5 functions of liver

Back 81

1. secretes bile
2. stores sugar as glycogen
3. makes proteins from a.a.
4. renders toxins harmless
5. produces most of the blood proteins that circulate in plasma

Front 82

2 functions of gallbladder

Back 82

1. stores bile from liver until fatty meal's eaten
2. contracts in response to CCK and parasympathetic stimulation

Front 83

monosaccharides and a.a. from SI to bloodstream

Back 83

1. Na+ leaves the cell thru basolateral Na/K ATPase, creating a concentration gradient.
2. Monosac & a.a. taken into the ep. cell with Na+ (symport).
3. monosac & a.a. reach the bloodstream by facilitated diffusion down the gradient (uniport)

Front 84

1. Chyme in duodenum causes:
2. Trypsin activates:

Back 84

1. secretion of CCK and secretin.
2. proteases: polypeptide --> dipeptides

Front 85

How's fat broken down? 4 steps.

Back 85

1. Not broken down in stomach.
2. In duodenum CCK hormone released.
3. Lipase cannot digest clump of fats. CCK causes bile secretion; bile solubilizes fat.
4. Lipase works.

Front 86

fat from SI to blood.

Back 86

1. triglycerides ---> monoglyceride & fatty acid by pancreatic lipase.
2. into ep cells by simple diffusion.
3. Inside ep cells, converted back to triglycerides, which are packaged into chylomicrons.
4. chylomicrons enter lacteals (tiny lymphatic capillaries).
5. lacteals --> larger lymphatics --> thoracic duct --> large vein near heart.

Front 87

Lipoprotein lipase

Back 87

enzyme contained in adipose (fat cells) and liver tissues, which hydrolyzes chylomicron --> monoglycerides and free fatty acids.

Front 88

2 types of vitamin

Back 88

1. Fat soluble: require bile acids for solubilization & absorption. Stored in adipose tissue.
2. Water soluble: excreted in urine by kidneys.

Front 89

4 Fat-soluble vitamins and their function.

Back 89

A: visual pigment
D: stimulates Ca2+ absorption from the gut and deposition in bones.
E: Prevents oxidation of fats
K: Necessary for blood coagulation

Front 90

5 types of water-soluble vitamin B

Back 90

B1: for enzymatic decarboxylations
B2: made into FAD, electron transporter
B3: made into NAD
B6: protein & a.a. metabolism
B12: nucleotides --> deoxynucleotides

Front 91

Other three water soluble vitamins

Back 91

C: collagen formation; prevents scurvy.
biotin: CO2 transport
folate: transport of methylene groups, synthesis of purines & thymines, required for fetal nervous system development.