DIGESTIVE SYSTEM: ANATOMY AND FUNCTIONS Flashcards
1
Q
HOW LONG IS THE GI TRACT OF A HEALTHY ADULT?
A
9m
2
Q
WHAT ARE THE SUPPORTING ORGANS OF THE GI TRACT?
A
SALIVARY GLANDS, LIVER, GALLBLADDER, PANCREAS
3
Q
WHAT ARE THE MAIN ORGANS OF THE GI TRACT?
A
MOUTH, ESOPHAGUS, STOMACH, SMALL INTESTINE, LARGE INTESTINE
4
Q
WHAT ARE THE PARTS OF THE SMALL INTESTINE?
A
DUODENUM (stomach exit), JEJUNUM, ILEUM
5
Q
WHAT ARE THE PARTS OF THE LARGE INTESTINE?
A
CECEUM, ASCENDING COLON, TRANSVERSE COLON, DESCENDING COLON, RECTUM, ANUS
6
Q
WHAT ARE THE LAYERS THAT LINE ALL PARTS OF THE GI TRACT EXCEPT FOR THE MOUTH CALLED?
A
THE MUCOSA, THE SUBMUCOSA, THE MUSCULARIS PROPRIA, THE SEROSA
7
Q
IN WHICH LAYER OF THE GI TRACT DOES THE ABSORPTIVE FUNCTION OCCUR?
A
THE MUCOSA
8
Q
WHAT IS THE STRUCTURE OF THE MUCOSA?
A
Single epithelial layer (inner layer facing the lumen made out of cells called enterocytes) attached to the lamina propria (connective tissue and lymph nodes) underneath which is the muscularis mucosae (smooth muscle cells)
9
Q
WHAT TYPES OF CELLS DOES SUBMUCOSA CONTAIN?
A
INFLAMMATORY CELLS, AUTONOMOUS NERVE FIBERS AND GANGLION CELLS
10
Q
WHAT DO THE GANGLION CELLS OF THE SUBMUCOSA DO?
A
CONTROL MUSCLE MOVEMENTS OF THE GI TRACT
11
Q
WHAT ARE THE TWO LAYERS OF MUSCULARIS PROPRIA?
A
2 layers made out of smooth muscle cells:
- circualr (inner)
- longitudinal (outer)
12
Q
HOW DOES MUSCULARIS PROPRIA PROPEL FOOD THROUGH THE GUT?
A
BY CONTRACTILE PERISTALTIC MECHANISMS WHICH ARE CONTROLLED BY THE MYENTERIC PLEXUS
13
Q
WHAT IS THE ROLE OF SEROSA?
A
TO PROTECT THE GI TRACT FROM EXTERNAL AGGRESSIONS
14
Q
DURING HUMAN EMBRYOGENESIS, WHEN DOES ESOPHAGUS DEVELOP?
A
AT 8-10 WEEKS
15
Q
MUSCULARIS PROPRIA OF WHICH GI ORGAN IS THE ONLY ONE WHICH HAS BOTH SMOOTH AND STRIATED MUSCLES?
A
ESOPHAGUS
16
Q
WHAT IS THE ESOPHAGEAL SEROSA CALLED?
A
ADVENTIA
17
Q
HOW DOES ESOPHAGUS ENSURE ITS UNI-DIRECTIONAL FUNCTION?
A
- it has 2 sphincters (1st one stops the food from getting into trachea, the second one prevents stomach reflux)
- it generates peristaltic movements (reflex contractions of longitudinal and circular muscles)
18
Q
WHAT IS CHYME?
A
SEMI LIQUID FLUID IN THE STOMACH AND SMALL INTESTINE
19
Q
WHAT IS BOLUS?
A
CHEWED FOOD IN THE MOMENT OF SWALLOWING
20
Q
WHAT IS FECES?
A
SEMI SOLID SUBSTANCE IN THE LARGE INTESTINE
21
Q
PERISTALTIC REFLEX IS ALSO CALLED THE…
A
MYENTERIC REFLEX
22
Q
WHICH PART OF NERVOUS SYSTEM CONTROLS THE MYENTERIC/PERISTALTIC REFLEX?
A
ENTERIC NERVOUS SYSTEM, REGULATED BY THE ANS
23
Q
DOES PARASYMPATHETIC NERVOUS SYSTEM INCREASE OR INHIBIT PERISTALSIS?
A
IT INCREASES PERISTALSIS
24
Q
PERISTALTIC REFLEX IS A COMBINATION OF WHICH TWO SEGMENTS AND WHAT ARE THEIR FUNCTIONS?
A
PROPULSIVE SEGMENT (constriction of the lumen and propulsion of the bolus) & RECEIVING SEGMENT (expansion of the lumen to receive the moving bolus)
25
WHEN DOES STOMACH DEVELOP DURING HUMAN EMBRYOGENESIS?
FROM 13 TO 39 WEEKS, BUT REGIONS PRESENT AT 14 WEEKS
26
WHAT IS THE NAME OF THE SPHINCTER THAT CONNECTS THE STOMACH AND DUODENUM?
PYLORIC SPHINCTER
27
ONE EXAMPLE OF STOMACH'S ENDOCRINE FUNCTION:
SECRETION OF HOROME GHRELIN WHICH REGULATES FOOD INTAKE
28
WHAT IS THE IMPORTANCE OF HCl SECRETION:
IT IS NECESSARY TO BREAK DOWN SECONDARY AND TERTIARY PROTEINS, TO KILL PATHOGENS AND TO ACTIVATE DIGESTIVE ENZYMES (e.g. PEPSINOGEN INTO PEPSIN)
29
WHAT IS THE ROLE OF SOMATOSTATIN IN THE GI SYSTEM?
IT REGULATES ACID PRODUCTION, REGULATES GLUCOSE LEVELS...
30
WHICH TYPES OF CELLS DO GASTRIC GLANDS IN THE MUCOSA CONSIST OF?
PARIETAL CELLS, NECK CELLS, PIT CELLS, CHIEF (ZYMOGENIC) CELLS AND ENDOCRINE CELLS
31
WHAT IS THE ROLE OF CHIEF (ZYMOGENIC) CELLS?
SECRETION OF DIGESTIVE ENZYMES (E.G. PEPSINOGEN, GASTRIC LIPASE AND AMYLASE)
32
WHAT IS THE ROLE OF NECK CELLS?
SECRETION OF BICARBONATE TO BUFFER THE pH
33
WHICH CELLS IN THE GASTRIC GLANDS IN THE MUCOSA PRODUCE HCl?
PARIETAL CELLS
34
WHAT IS THE STOMACH pH AT REST AND WHAT AFTER A MEAL?
4-5 AT REST, 1.5-3.5 AFTER A MEAL
35
MEALS HIGH IN WHICH OF THE MAIN NUTRIENTS REQUIRE A LOWER pH?
PROTEIN
36
WHAT PERCENTAGE OF CARBS ARE DIGESTED IN THE MOUTH?
5%
37
WHAT ARE AUTOANTIBODIES?
ANTIBODIES WHICH ATTACK OUR OWN BODY
38
WHAT DO EXCITATORY AND WHAT DO INHIBITORY MOTOR NEURONS RELEASE IN THE GI TRACT?
EXC: Ach and Substance P (induces contraction)
INH: NO and Vasoactive Intestinal Peptide (VIP) (induces relaxation)
39
WHEN THE BOLUS INDUCES A MECHANICAL STRETCH IN THE GUT WALL IT STIMULATES SECRETION OF WHAT FROM THE EPITHELIAL CELLS?
SEROTONIN (5HT)
40
WHAT DOES SEROTONIN DO IN THE GUT?
IT ACTIVATES SENSORY AFFERENT NEURONS OF THE MYENTERIC PLEXUS AND IT ALSO INHIBITS ITS OWN PRODUCTION IN THE EPITHELIUM (SO THERE AREN'T CONTINUOUS MOVEMENTS IN THE GUT EVEN WHEN THERE IS NO FOOD)
41
WHAT KIND OF STRUCTURES DOES THE MUCOSAL EPITHELIUM FORM AND WHAT ARE THEY CALLED?
FINGER-LIKE STRUCTURES, VILLI
42
WHICH PART OF THE GI TRACT DOES THE PERISTALTIC REFLEX START IN AND UP UNTIL WHICH POINT DOES IT CONTINUE?
STARTS IN THE ESOPHAGUS AND CONTINUES IN EVERY PART OF THE GI TRACT
43
HOW LONG IS THE SMALL INTESTINE?
7m
44
IN WHICH PART OF THE SMALL INTESTINE ARE ALL THE NUTRIENTS IN ITS FINAL FORM AND THE DIGESTION IS ALMOST COMPLETED?
DUODENUM
45
HOW LONG IS THE DUODENUM?
28cm
46
THE DUODENUM ENCIRCLES WHICH ORGAN?
THE PANCREAS
47
PANCREATIC JUICE FROM THE PANCREAS AND THE BILE JUICE FROM THE GALLBLADDER ARE DELIVERED TO WHICH PART OF THE SMALL INTESTINE?
DUODENUM
48
HOW MUCH OF THE SMALL INTESTINE IS JEJENUM?
2/5
49
WHAT ARE THE MAIN SITES OF ABSORPTION IN THE SMALL INTESTINE?
JEJENUM AND ILEUM
50
WHAT IS MESENTERY AND WHAT IS ITS FUNCTION?
IT IS A CONNECTING MEMBRANE BETWEEN THE SMALL INTESTINE AND THE ABDOMINAL WALLS. IT PROVIDES INSULATION (FAT) AND BLOOD SUPPLY!!!
51
HOW DOES BLOOD ENTER THE SMALL INTESTINE?
THROUGH ABDOMINAL AORTA (MESENTERIC ARTERY + HEPATIC ARTERY)
52
HOW DOES BLOOD LEAVE THE SMALL INTESTINE AND WHERE IS IT DRAINED TO?
VIA SUPERIOR MESENTERIC VEIN, DRAINS INTO THE LIVER
53
CONTRACTIONS IN THE SMALL INTESTINE GRADUALLY DECREASE IN WHICH DIRECTION?
FROM THE DUODENUM TO THE ILEUM
54
HOW BIG IS THE ABSORPTIVE SURFACE OF THE SMALL INTESTINE?
4500m2
55
SMALL INTESTINE DIAMETER?
3 to 4cm
56
WHAT ARE PLICAE CIRCULARES AND WHAT ARE THEY MADE OF?
THE MUCOSA OF THE SMALL INTESTINE IS ARRANGED IN PLICAE CIRCULARES, WHICH ARE CONCENTRIC FOLDS (5-6cm LONG, 3mm THICK), MADE OUT OF VILLI.
57
WHERE ARE THE PLICAE CIRCULARES THE LARGEST AND WHERE DO THEY DISAPPEAR?
LARGEST IN THE BOTTOM HALF OF THE DUODENUM, MISSING IN THE LAST PART OF ILEUM
58
HOW MANY PLICAE CIRCULARIS ARE THERE IN THE SMALL INTESTINE?
800
59
WHAT IS THE SIZE OF INTESTINAL VILLUS (VILLI)?
0.5-1.6mm
60
HOW ARE THE ENTEROCYTES IN THE SMALL INTESTINE CONNECTED?
WITH TIGHT JUNCTIONS
61
WHAT IS THE APICAL MEMBRANE OF ENTEROCYTES COVERED WITH?
MICROVILLI (CALLED THE BRUSH BORDER)
62
THE APICAL MEMBRANE OF ENTEROCYTES FACES THE LUMEN. WHAT DOES THE BASOLATERAL MEMBRANE FACE?
THE BLOOD VESSELS (HEPATIC VEIN) AND THE LYMPHATIC SYSTEM
63
WHAT IS THE APICAL MEMBRANE OF THE ENTEROCYTES COVERED WITH?
LITTLE PROJECTIONS CALLED MICROVILLI THAT FORM THE BRUSH BORDER
64
HOW DO MONOMERS TRAVEL FROM THE SMALL INTESTINE INTO THE BLOODSTREAM?
THE ENZYMES LOCATED AT THE BRUSH BORDER WILL BREAK DOWN NUTRIENTS INTO THEIR FINAL MONOMERS. THE APICAL MEMBRANE CONTAINS TRANSPORT SYSTEMS TO GET THE MONOMERS INSIDE THE ENTEROCYTES. THEY WILL THEN EXIT BY THE BASOLATERAL MEMBRANE AND INTO THE BLOOD.
65
WHAT ARE GOBLET CELLS?
A COMPONENT OF THE VILLUS, THEY SECRETE MUCIN; THE MAIN COMPONENT OF THE PROTECTIVE MUCUS
66
WHAT IS THE ROLE OF THE CRYPT STRUCTURE ON THE VILLI?
IT CONTAINS STEM CELLS FOR THE RENEWAL OF ENTEROCYTES
67
WHAT IS THE PROBABLE FUNCTION OF CELLS OF PANETH ON THE VILLUS?
THEY CONTAIN LYZOSOME AND Ig, SO THEY MAY BE INVOLVED IN THE IMMUNE FUNCTION OF THE INTESTINE
68
HOW LONG IS THE COLON?
1.5m
69
WHAT IS THE DIAMETER OF THE COLON?
6cm
70
ARE ENTEROCYTES POLARIZED OR UNPOLARIZED CELLS?
POLARIZED
71
WHAT ARE THE DIFFERENCES AND SIMILARITIES BETWEEN THE LUMEN OF THE COLON AND THE SMALL INTESTINE?
SIMILARITIES - BOTH HAVE CRYPTS, MUCUS GLANDS AND GOBLET CELLS
DIFFERENCE - THE COLON HAS NO VILLI
72
THE DIGESTION OCCURRING IN THE COLON IS PERFORMED BY? WHAT IS THE PRODUCT OF THIS DIGESTION?
GUT BACTERIA THAT DEGRADE FIBERS FOR THEIR OWN ENERGY PRODUCTION. THERE ARE SOME SUBSTANCES PRODUCED DURING THAT PROCESS SOME SUBSTANCES ARE ALSO PRODUCED, LIKE SHORT CHAIN FATTY ACIDS THAT ARE IMPORTANT FOR HEALTHY GUT FUNCTION.
73
HOW DOES BLOOD ENTER THE LARGE INTESTINE?
VIA MESENTERIC ARTERIES (+INTERNAL ILEAC ARTERY)
74
HOW DOES BLOOD LEAVE THE LARGE INTESTINE?
VIA THE MESENTERIC VEINS JOINING THE PORTAL VEIN
75
WHEN DOES THE MOTILITY START IN THE COLON?
AS SOON AS THE FOOD IS IN OUR MOUTH
76
APART FROM MASTICATION (CHEWING), WHAT ELSE STIMULATES THE COLON MOTILITY?
HORMONES PRODUCED BY THE SMALL INTESTINE AND THE STOMACH, LIKE GHRELIN AND CHOLECYSTOKININ (CCK)
77
WHAT ARE THE FUNCTIONS OF CCK?
Cholecystokinin stimulates the gallbladder to contract and release stored bile into the intestine. It also stimulates the secretion of pancreatic juice and may induce satiety.
78
WHAT ARE THE MAIN ROLES OF THE COLON?
- WATER REABSORPTION
- MAINTAINING OSMOLARITY; REABSORB ELECTROLYTES (like Na+ and Cl-)
- STORING OF FECAL MATERIAL
79
WHAT IS THE VOLUME OF THE CHYME ENTERING THE COLON AND WHICH VOLUME IS IT REDUCED TO?
1.5-2L UPON ENTRANCE, REDUCED TO 150ml
80
WHICH ENZYME IN THE SALIVA STARTS BREAKING DOWN STARCH?
AMYLASE
81
WHAT DOES SALIVA CONSIST OF?
WATER, ELECTROLYTES, DIGESTIVE ENZYMES, ANTIMICROBIAL ENZYMES AND PAIN KILLER AGENTS
82
CAN CARBOHYDRATES BE DIGESTED EVEN IF THE SALIVARY GLANDS ARE NOT WORKING PROPERLY AND WHY?
YES BECAUSE THERE ARE OTHER AMYLASES ALONG THE GI TRACT, BUT THE DIGESTION WILL BE INCOMPLETE.
83
CAN CARBOHYDRATES BE DIGESTED EVEN IF THE SALIVARY GLANDS ARE NOT WORKING PROPERLY AND WHY?
YES BECAUSE THERE ARE OTHER AMYLASES ALONG THE GI TRACT, BUT THE DIGESTION WILL BE INCOMPLETE.
84
WHAT IS THE TRANSITIONAL AREA BETWEEN THE MOUTH AND THE ESOPHAGUS CALLED?
PHARYNX
85
WHAT IS AT THE END OF PHARYNX?
EPIGLOTTIS
86
WHY DOES THE EPIGLOTTIS CLOSE DURING SWALLOWING?
TO BLOCK THE AIRWAY/ STOP THE FOOD FROM GOING INTO THE TRACHEA
87
WHICH ORGAN IS THE SITE OF CARB, PROTEIN AND FAT METABOLISM?
THE LIVER
88
WHAT GIVES THE YELLOWISH COLOUR TO THE BILE SECRETED BY THE LIVER?
BILIRUBIN
89
WHERE DOES BILIRUBIN COME FROM?
FROM THE BREAKDOWN OF ERYTHROCYTES
90
WHERE IS BILE STORED AFTER THE LIVER MAKES IT?
THE GALLBLADDER
91
WHAT IS LIVER'S WEIGHT, THICKNESS AND HOW IS IT DIVIDED (STRUCTURE)?
UP TO 1.6KG, 13cm thick, DIVIDED INTO 2 LOBES AND ORGANIZED INTO LOBULES THAT ARE MADE OUT OF SPECIALIZED CELLS HEPATOCYTES
92
WHAT ARE THE IMMUNE CELLS IN THE LIVER CALLED?
KUPFFER CELLS
93
WHICH CELL TYPE REPRESENTS 80% OF THE LIVER VOLUME AND CAN REGENERATE?
HEPATOCYTES
94
HOW DOES BLOOD GET INTO THE LIVER
BLOOD FROM THE HEART COMES VIA THE HEPATIC ARTERY AND BLOOD FROM ORGANS (PANCREAS, SPLEEN, STOMACH, SMALL AND LARGE INTESTINES) COMES VIA THE PORTAL VEIN (WHICH DIVIDES INTO PARTS GOING TO EACH OF THE HEPATIC LOBES)
95
HOW DOES BLOOD LEAVE THE LIVER?
VIA HEPATIC VEIN WHICH MERGES WITH VENA CAVA WHICH THEN GOES TO THE HEART
96
WHAT DO HEPATOCYTES SYNTHESIZE?
CHOLESTEROL AND PRIMARY BILE ACIDS (WHICH DERIVE FROM CHOLESTEROL)
97
WHAT IS THE VOLUME OF THE GALLBLADDER?
200ml
98
HOW MUCH OF PRIMARY BILE DOES THE LIVER MAKE DAILY?
1L
99
WHICH COMPONENTS ARE REABSORBED FROM THE BILE IN THE GALLBLADDER?
WATER, CHLORIDE AND BICARBONATE
100
WHAT IS BILE'S MAIN FUNCTION AND HOW DOES IT DO IT?
TO EMULSIFY LIPIDS. BILE FORMS MICELLES WITH THE LIPIDS AND THIS WILL HELP LIPASE TO BREAK THEM DOWN.
101
WHAT IS BILE'S COMPOSITION?
MOSTLY WATER AND BILE ACIDS (SALTS), AND ALSO BILIRUBIN, CHOLESTEROL AND LECITHIN
102
HOW AND WHERE ARE THE SECONDARY BILE ACIDS MADE?
THEY ARE MADE IN THE INTESTINE BY THE GUT BACTERIA
103
WHERE DO THE SECONDARY BILE ACIDS GO AFTER THEY'VE BEEN MADE IN THE INTESTINE?
THEY GO TO THE LIVER WHERE THEY ARE RECYCLED AND STORED IN THE GALL BLADDER AGAIN
104
WHEN THE PANCREATIC DUCT AND THE COMMON BILE DUCT MERGE, THEIR CONTENTS ENTER THE DUODENUM BY:
THE DUODENAL PAPILLA
105
WHICH CELLS REPRESENT 95% OF ALL PANCREATIC CELLS AND WHAT IS THEIR FUNCTION?
ACINAR CELLS, HAVE AN EXOCRINE FUNCTION; PRODUCE DIGESTIVE ENZYMES
106
WHAT ARE ZYMOGENS?
DIGESTIVE ENZYMES PRODUCED BY THE ACINAR CELLS OF THE PANCREAS IN THEIR INACTIVE/PRECURSOR FORM BEFORE SECRETION
107
WHICH HORMONES REGULATE ENZYME SECRETION FROM THE PANCREAS?
GASTRIN, Ach, VIP
108
WHAT IS THE NAME OF ENDOCRINE PANCREATIC CELLS AND WHAT ARE THEIR TYPES & FUNCTIONS?
ISLET CELLS: ALPHA (SECRETE GLUCAGON), BETA (INSULIN) AND DELTA (SOMATOSTATIN)
