Wk 6 GI Flashcards
1
Q
Except for chewing, swallowing, and defecation, how are the movements of the digestive system (GI motility) controlled?
A
Autonomic nervous system (sympathetic & parasympathetic) & hormones
2
Q
What are the 4 layers of the GI tract? (inside to outside, include the sublayers)
A
Mucosa, submucosa, muscularis, & serosa
Mucosa (epithelium, lamina, muscularis mucosae)
Submucosa
Muscularis (Circular muscle layer, longitudinal muscle layer)
Serosa (connective tissue layer, peritoneum)
3
Q
What are the 3 enteric nerve plexuses and their locations?
A
Submucosal plexus, myenteric plexus, & subserosal plexus
Submucosal plexus (Meissner plexus) - in the muscularis mucosae
Myenteric plexus (Auerbach plexus) - in btwn circular & longitudinal muscle layers
Subserosal plexus - beneath the serosa
4
Q
How many permanent adult teeth in the mouth?
A
32
5
Q
What are the 3 salivary glands?
A
Parotid, submandibular, & sublingual
6
Q
How much saliva is secreted per day?
A
1 L
7
Q
What is saliva made up of?
A
Mucus
Electrolytes (sodium, bicarbonate, chloride, potassium)
Ptyalin (salivary alpha-amylase)
8
Q
What is ptyalin?
A
Salivary amylase - an enzyme that digests carbohydrates in mouth and stomach
9
Q
What stimulates and inihibits salivary glands?
A
ANS controls salivation.
Cholinergic parasympathetic fibers & beta-adrenergic sympathetic fibers stimulate
Atropine (anticholinergic agent) inhibits salivation & makes it dry
10
Q
Are salivary glands regulated by hormones?
A
No
11
Q
How does saliva prevent tooth decay?
A
Bicarbonate has pH of 7.4 = neutralizes bacterial acids
IgA (immunoglobulin A) prevents infection (also found in saliva)
Exogenous fluoride (fluoride in drinking water) absorbed & excreted in saliva
12
Q
How does swallowed food move from the mouth to the stomach?
A
Esophageal peristalsis
13
Q
What is peristalsis?
A
Coordinated sequential contraction & relaxation of the outer longitudinal & inner circular layers of muscles.
14
Q
Describe the muscles and nerves in the esophagus.
A
Upper = striated muscle innervated by motor neurons
Middle = mix of striated & smooth muscle
Lower = smooth muscle innervated by preganglionic cholinergic fibers frm the vagus nerve
15
Q
How is peristalsis in the esophagus stimulated?
A
As food passes & causes stretching of the walls, afferent fibers sense changes in the wall tension.
The greater the tension, the greater the esophageal contraction.
16
Q
Name & descibe the function of the esophageal sphincters.
A
Upper esophageal sphincter (cricopharyngeal muscle) & lower esophageal sphincter (cardiac sphincter)
Upper esophageal sphincter (Cricopharyngeal muscle) - prevents entry of air into the esophagus during respiration.
Lower esophageal sphincter (Cardiac sphincter) - prevents regurgitation frm the stomach.
17
Q
How is swallowing controlled?
A
Swallowing center in the brainstem
18
Q
Name & describe the 2 phases of swallowing.
A
Oropharyngeal & esophageal
Oropharyngeal (voluntary) phase - food bolus forced posteriorly by the tongue toward the pharynx. Superior constrictor muscle of the pharynx contracts, preventing movement of food into the nasopharynx. As respiration is inhibited, the epiglottis slides downard to prevent the bolus frm entering larynx & trachea.
Esophageal (involuntary) phase - food bolus enters the esophagus. Primary peristalsis occurs. If bolus of food b/comes stuck, 2ndary peristalsis occurs. Peristalsis = wave of relaxation (allows food to pass & reduces resistance), then wave of contraction (pushes food along).
19
Q
What is partially digested food called?
A
Chyme
20
Q
Describe the anatomic structure of the stomach.
A
Boundaries of the stomach: lower esophageal sphincter (cardiac sphincter), greater & lesser curvatures, pyloric sphincter
Functional areas of the stomach: fundus (upper portion), body (middle portion), & antrum (lower portion)
21
Q
Name the 3 smooth muscle layers of the stomach (inside to outside)
A
Oblique layer
Circular layer
Longitudinal layer
22
Q
Which parts of the stomach does the muscle layers become progressively thicker?
A
Body & antrum b/c ths is where food is mixed, churned, & pushed out to tthe duodenum
23
Q
What artery supplies blood to the stomach?
A
Celiac artery
24
Q
Describe the veins of the stomach
A
Splenic vein drains R side of stomach
Gastric vein drains L side of stomach
25
Describe the innervation of the stomach.
Extrinsic - originate outside stomach & controlled by vagus nerve & branches of the celiac plexus --\> parasympathetic fibers frm vagus nerve & sympathetic fibers frm the celiac plexus
Intrinsic - originate w/in stomach & respond to local stimuli --\> myenteric plexus
26
Can the stomach absorb substances? Give ex. of what the stomach absorbs.
Few substances can be absorbed in stomach - mucosa impermeable to water.
Can absorb alcohol & aspirin.
27
What action causes the fundus to relax making it more ceptive to receive a bolus of food?
Swallowing
28
What 2 intestinal hormones increase gastric motility/contraction? How?
Gastrin & motilin - make the threshold potential of muscle fibers less negative
29
Does the vagus nerve increase or inhibit gastric motility?
Increase
30
What inhibits gastric motility by making the threshold potential more negative?
Sympathetic activity & secretin (intestinal hormone)
31
What is gastrin? Include source, action, stimulus for secretion
Source: G cell of stomach's mucosa
Action: a hormone stimulates parietal cells to secrete hydrochloric acid (gastric acid) and chief cells to secrete pepsinogen; promotes gastric motility & regulates gastroileal reflex
Stimulus for secretion: partially digested proteins in stomach
32
What is motilin? Include source, action, & stimulus for secretion.
Source: small intestine
Action: a hormone that increases GI motility
Stimulus for secretion: acid or fat in the duodenum
33
When does the pyloric sphincter open during digestion?
Trick question: pylorus is always open about 2mm
It opens wider during antral contraction - normally no regurgitation frm duodenum to stomach.
34
What increases the rate of gastric emptying?
Larger volumes of food --\> increases gastric pressure, peristalsis, & rate of emptying
35
What decreases gastric emptying?
Solids, fats, & nonisotonic solutions
36
What hormone inhibits gastric motility & decreases gastric emptying?
Cholecystokinin
37
What is cholecystokinin? Include source, action, & stimulus for secretion.
Source: small intestine
Function: stimulates gallbladder to eject bile & pancrease to secrete alkaline fluid; decr. gastric motility & delays gastric emptying so that fats are not emptied into the duodenum at a rate that exceeds the rate of bile & enzyme secretion. Inhibits gastrin; constricts pyloric sphincter; regulates gastroileal reflex
Stimulus for secretion: presence of chyme (acid, partially digested proteins, fats) in the duodenum
38
How is the stomach's peristaltic activity affected by blood glucose levels?
Low blood glucose levels stimulate vagus nerve & gastric smooth muscles to increase peristalsis, but not emptying --\> stimulates the sensation of hunger pains.
39
What is the function of mucus in the stomach? Stimulus?
Protective barrier against acid & proteolytic enzymes
Stimulus: prostaglandins & nitric oxide --\> also stimulate bicarb & inhibits secretion of acid, further protecting the stomach.
40
What are gastric glands and gastric pits? Location.
**Location:** stomach's mucosa
**Gastric pits:** depressions in the epithelial lining of the stomach --\> a duct where gastric glands empty into.
**Gastric glands:** found at the bottom of gastric pits - tubular in nature --\> chief cells secrete gastric juice, parietal cells secrete stomach acid.
41
What are parietal cells? Location & function.
Location: stomach mucosa, fundus & body
Function: cells w/in the gastric gland that secrete hydrochloric acid (gastric acid) & intrinsic factor
42
What are chief cells? Location & function.
Location: stomach's mucosa, fundus & body
Function: cells w/in the gastric gland that secrete pepsinogen & gastric juices
43
What is pepsinogen and pepsin? Source, action, & stimulus in the GI system?
Source: chief cells in stomach
Pepsinogen: enzyme precursor to pepsin; turns into pepsin at pH of 2
Pepsin: enzyme in gastric juice that degrades food proteins into peptides
Stimulus: acetylcholine through vagal nerve stimulation during cephalic & gastric phases
44
What are G cells? Location & function
Location: stomach's mucosa in the gastric pit, part of gastric gland; toward the antrum
Function: Secretes gastrin
45
What are enterochromaffin-like cells? Location & function.
Location: stomach's mucosa in the gastric pit, part of gastric gland
Function: secrete histamine
46
What are D cells? Location & function.
Location: stomach's mucosa in in the gastric pit, part of gastric gland
Function: secrete somatostatin
47
What is somatostatin? Source, action, & stimulus in the GI system?
Source: D cells of stomach's mucosa
Action: a hormone that inhibits release of GI hormones (gastrin, motilin, cholecystokinin); inhibits gastric acid; decreases rate of gastric emptying; decreases muscle contractions
Stimulus: acid in the stomach
48
What are the major functions of gastric acid? What stimulates acid secretion? Source.
1) dissolve food fibers
2) bactericide against swallowed orgs
3) convert pepsiongen into pepsin
Source: parietal cells in stomach's mucosa
Stimulated by: acetylcholine (neurotransmitter), gastrin (hormone), & histamine (biochemical mediator)
49
What is histamine? Source, action, & stimulus in the GI system?
Source: Enterochromaffin cells in stomach's mucosa
Action: a biochemical mediator that stimulates acid secretion
Stimulus: gastrin & acetylcholine
\*Note histamine receptors in gastric mucosa = H2 receptors vs H1 in bronchial mucosa
50
What is gastric lipase? Source, action, & stimulus in the GI system?
Source: chief cells in stomach's mucosa in fundus
Action: enzyme found in gastric juices that helps break down fat into lipids
Stimulus: food bolus in stomach & most effective in acid environment
51
What is intrinsic factor in the GI system? Source, action, & stimulus in the GI system?
Source: parietal cells in the stomach's mucosa
Action: a mucoprotein that combines w/ vitamin B12 in the stomach so that B12 can be later absorbed by the ileum
52
Describe the 3 phases of gastric juice secretion.
Cephalic phase, gastric phase, & intestinal phase
## Footnote
**Cephalic phase**: anticipatory sensory experiences of food & swallowing. Vagus nerve --\> myenteric plexus --\> acetylcholine --\> parietal cells secrete acid, chief cells secrete pepsinogen, G cells in antrum secrete gastrin into blood stream. Gastrin travels through blood stream to gastric glands --\> acid & pepsinogen secretion.
**Gastric phase**: begins w/ arrival of food in the stomach. Distention of stomach & presence of digested protein = secretion of gastric juices.
**Intestinal phase**: begins w/ movement of chyme frm stomach into the duodenum. Gastric secretory response slows down & mediated by entero-oxyntin. Gastric inhibitory peptide decr. gastric motlity & secretion of acid & pepsin. Acidic chyme in duodenum inhibits gastric acid secretion & gastric motility.
53
What is entero-oxytin? Source, action, & stimulus in the GI system?
Source: small intestine mucosa
Action: delays gastric emptying
Stimulus: chyme in the duodenum
54
What are the parts of the small intestine?
Duodenum, jejunum, & ilem.
Duodenum begins at pylorus & ends at the Treitz ligament where it joins the jejunum. The end of jejunum & beggining of ileum not distinguished by anatomic marker, but jejunum slightly larger lumen than the ileum.
55
What is the Treitz ligament?
Suspensory muscle of the duodenum - connects the duodenum to the diaphragm.
Important anatomical landmark of duodenojejunal junction
56
What is the ileocecal valve/sphincter?
Location: btwn ileum & cecum of large intestine.
Controls flow of chyme & prevents reflux into the small intestine
Normally closed but peristaltic waves cause it to open, allowing small amt of chyme to pass through
Intrinsically regulated
57
What is the peritoneum? What are the 2 types?
Serous membrane surrounding the organs of the abdomen & pelvic cavity
Visceral peritoneum - lies over organs
Parietal peritoneum - lines walls of abdominal cavity
58
What is the peritoneal cavity?
The space btwn the visceral & parietal peritoneum.
Contains fluid to lubricate 2 layers & prevent friction during organ movement.
59
How are the 3 parts of the small intestine suspended or attached?
Duodenum: lies behind the peritoneum (retroperitoneal cavity) & attached to posterior abdominal wall.
Ileum & Jejunum: suspended in loose folds frm the posterior abdominal wall by the mesentary.
60
What is the mesentery? Location.
Location: abdominal cavity
A peritoneal membrane that suspends the ileum & jejunum loosely frm the posterior abdominal wall.
Facilitates intestinal motility & supports blood vessels, nerves, & lymphatics.
61
What artery supplies blood to the small intestine?
Duodenum - gastroduodenal artery
Jejunum & ileum - superior mesenteric artery
62
Where does the superior meseneteric vein empty into?
The superior mesenteric vein & splenic vein empties into the portal circulation to the liver.
63
How is the small intestine innervated?
ANS system
Parasympathetic nerves mediate secretion, motility, pain, & intestinal reflexes (relaxation of lower esophageal sphincter)
Sympathetic nerves inhibit motility & vasoconstricts.
Myenteric plexus (Auerbach plexus) & submucosal plexus (Meissner plexus) = intrinsic motor innervation.
64
Describe the muscles of the small intestine
Smooth muscles of small intestine = circular inner layer & longitudinal outer layer
65
What is plica? Location
Location: small intestine
Mucosal folds that slow the passage of food = more time for digestion & absorption
66
What are villi? Discuss location, function, & anatomy
Location: small intestine mucosa
Function: Cover the plica (mucosal folds) and secrete enzymes for digestion & absorb nutrients. At sites called tight junctions (where the columnar cells closely adhere to each other), water & electrolytes are absorbed.
Anatomy: composed of enterocytes (absorptive columnar cells) & goblet cells (mucus-secreting)
Each columnar cell has microvilli --\> increases surface area for absorption.
67
What is the brush border? Location.
Location: small intestine
Simple columnar epithleium covered by microvilli.
Has a coating of unstirred layer of fluid important for absorbtion of substances other than water & electrolytes.
68
What is the lamina propria? Location & function
Source: connective tissue layer of the intestine's mucous membrane, lies beneath the epithelial cells of the villi
Function: Contains lymphocytes & plasma cells. Plasma cells produce immunoglobulins & macrophages.
69
What is a lacteal? Location & function
Location: within the villi of the small intestine.
Function: a lymphatic channel that absorbs & transports fat molecules.
70
What are crypts of Lieberkuhn? Location & function.
Location: space between the bases of the villi of the small intestine.
Function: extend to the submucosal layer; where undifferentiated (stem cells) & secretary cells & Paneth cells are located.
71
What happens to the stem cells of the crypts of Lieberkuhn?
Stem cells = precursor of columnar epithelial & goblet cells. --\> eventually rise frm the base of the crypt & move toward the tip of the villus, maturing in shape & function as they progress. After functioning for a few days, they are sloughed into the intestinal lumen & digested.
72
Why are the sloughed epithelial cells of the intestine important?
They are a source of endogenous protein.
73
How often is the entire epithelial population of the small intestine replaced?
Every 4-7 days
74
What are Paneth cells? Location & function.
Location: at the bottom of the crypts of Lieberkuhn found in btwn villi of the small intestine.
Function: produce defensins & other abx peptides & proteins.
75
Describe how chyme is digested in the small intestine.
Chyme passes iinto the duodenum & digestion is continued in the proximal portion of the small intestine --\> pancreatic enzymes, intestinal brush border enzymes, & bile salts break food down further.
Nutrients, vitamins, & electrolytes absorbed across the intestinal mucosa & into the blood by active transport, diffusion, or facilitated diffusion.
76
Where do proteins, carbohydrates, & fats go after absorption?
**Protein & carbohydrates** broken down to amino acids & monosaccharides --\> **villus capillary --\> hepatic portal vein --\> liver**
**Fat** broken down to monoglycerides & long-chain fatty acids --\> **lacteals --\> thoracic duct --\> systemic circulation --\> liver**
**Fat** broken down to short-chain fatty acids & glycerol --\> **villus capillaries --\> portal vein --\> liver**
77
What major nutrients are absorbed at different sites of the digestive tract?
Stomach - alcohol & fluoride
Duodenum - Fats, proteins, sugars, water, iron, vitamins, calcium, magnesium, sodium
Jejunum - sugars, proteins
Ileum - bile salts, vit B12, chloride
Colon - water, electrolytes
78
How is water transported in the small intestine?
Transported through the tight junction & intercellular spaces vs across cell membranes
Diffuses passively according to hydrostatic pressure & in relation to osmotic gradients of electrolytes
79
The epithelial cell membranes are made up of lipids. What are the implications w/ the transport of water?
Hydrophobic - repels water
80
Approx. how much of the water that enters the GI tract is absorbed by the small intestine?
85-90%
81
Describe how protein, fat, and carbohydrates are absorbed/transported across the epithelial cell of the villus.
Protein broken down to **amino acids** --\> **active transport or 2ndary active transport w/ Na** --\> villus capillaries --\> portal vein --\> liver
Protein broken down to **dipeptides & tripeptides** --\> **2ndary transport w/ H+** --\> --\> villus capillaries --\> portal vein --\> liver
Carb broken down to **glucose & galactose** --\> **2ndary active transport with Na** --\> villus capillaries --\> portal vein --\> liver
Carb broken down to **fructose** --\> **facilitated diffusion** --\> villus capillaries --\> portal vein --\> liver
Fat emulsified to **short-chain fatty acids & glycerol** --\> **simple diffusion** --\> villus capillaries --\> portal vein --\> liver
Fat emulsified into micelle (makes it water-soluble) which turns into **long-chain fatty acids & monoglycerides** --\> **simple diffusion** --\> b/comes a triglyceride in the cell which turns into a chylomicron --\> lacteal of a villus --\> thoracic duct --\> eventually reach the liver through systemic circulation
82
How is sodium transported across the epithelial cell of the small intestine?
Diffuses through tight junctions --\> proximal part of intestine more permeable than distal part
Active transport --\> transported into intestinal cells in exchange for hydrogen at brush border. To maintain electroneutrality in the ileum, chloride actively enters cell in exchange for bicarbonate.
Secondary active transport --\> Sodium pump at basolateral membrane --\> glucose transport enhances sodium absorption.
83
What are the enzymes that break down carbohydrates? Discuss source & site of action.
**Salivary amylase** (breaks down starch to dextrins & oligosaccharides) --\> **source: mouth**, **site of action: mouth**
**Pancreatic amylase** (breaks down dextrins & oligosaccharides to lactose, maltose, & sucrose) --\> **source: pancreas**, **site of action: small intestine**
**Lactase, Maltase, & Sucrase** (breaks down lactose, maltose, & sucrose to galactose, glucose, & fructose) --\> **source: brush-border of small intestine**, **site of action: small intestine**
84
What are the enzymes that break down protein? Discuss source & site of action.
**Pepsin** (breaks down protein to proteases & peptones) --\> **source: stomach** in presence of hydrochloric acid, **site of action: stomach**
**Trypsin, Chymotrypsin, Carboxypeptidase** (breaks down proteases & peptones to small polypeptides & dipeptides) --\> **source: pancrease**, **site of action: small intestine**
**Aminopeptidases & dipeptidases** (breaks down polypeptides & dipeptides to amino acids) --\> **source: brush-border of small intestine**, **site of action: small intestine**
85
What agents & enzymes break down fats? Discuss site of action & source
**Bile acids** (emulsifies fat) --\> **source: liver**, **site of action: small intestine**
**Pancreatic lipases** (breaks triglycerides into monoglycerides & long-chain fatty acids OR glycerol & short-chain fatty acids)--\> **source: pancreas**, **site of action: small intestine**
86
What is emulsification?
When emulsifying agents (bile salts, fatty acids, monoglycerides, lecithin, cholestrol, & protein) in the intestinal lumen cover small fat particles & prevent them frm re-forming into fat droplets.
Readies fat for lipolysis
87
What is a chylomicron?
Triglycerides covered w/ phospholipids, lipoproteins, & cholesterol
Formed when fat is absorbed into the epithelial cell & resynthesized into triglycerides & phospholipids.
Travel to the basolateral membrane of the columnar epithelial cell & get into the lacteals of the lymphatics.
88
Calcium is absorbed throughout the small intestine, but here is calcium primarily absorbed?
Ileum
89
What is the recommended intake of calcium in adults?
1000-1500 mg/day
90
What enhances calcium absorption by indirectly facilitating absorption of Vit. D?
Bile salts
91
How is calcium absorbed in the small intestine?
Passive diffusion --\> when concentration is \> 5mmol/L
Active transport --\> when concentration \< 5 mmol/L; binds to carrier protein that requires active form of Vit. D3
92
How is magnesium absorbed in the small intestine?
Active transport --\> 50% absorbed this way
Passive diffusion --\> 50% absorbed this way in the jejunum & ileum
93
How is phosphate absorbed in the small intestine?
Passive diffusion
Active transport
94
What is the recommended intake of magnesium for adults?
300-350 mg/day
95
What is the average intake of iron? How much is absorbed?
Avg intake of iron: 15-30 mg/day
Menstruating women absorb 1-1.5 mg
Men absorb 0.15 to 1 mg
96
What is the primary source of iron?
Heme from animal protein
97
Where is iron primarly absorbed in the small intestine?
Duodenum
98
What vitamin increases iron absorption?
Vit C
99
What reduces absorption of iron in the intestinal lumen through binding?
Calcium phosphate & phosphoproteins (milk & antacids)
100
How does the small intestine absorb iron?
Iron bound to **intestinal transferrin** in small intestine --\> absorbed in epithelial cell & bound to **ferritin** --\> transported to blood by **plasma transferrin**
101
How is iron absorption in the small intestine regulated?
If body has **less need for iron** --\> iron remains in the enterocyte as ferritin, then carried into intestinal lumen & sloughed frm the end of the villus
**Hepcidin** - protein synthesized in liver, inhibits apical uptake of iron by enterocytes & modulates iron trafficking.
102
What 2 movements of intestinal motility promote digestion & absorption? Describe.
Segmentation & intestinal peristalsis
Segmentation: localized rhythmic contractions of cricular smooth muscles --\> occurs more freq. than peristalsis & frequency regulated by the myenteric plexus of longitudinal smooth muscle
Intestinal peristalsis: invovles short segments (10 cm) of contraction of longitudinal smooth muscle --\> wave of contraction moves slowly to allow time for digestion & absorption.
103
Name & describe the 3 intestinal reflexes. How are they regulated?
Ileogastric reflex, intestinointestinal reflex, & gastroileal relfex.
**Ileogastric reflex**: inhibits gastric motility when ileum b/comes distnded; prevents movemnt of chyme into already distended intestine --\> **extrinsic innervation**
**Intestinointestinal reflex**: inhibits intesintal motility when 1 part of the intestine overdistended --\> **extrinsic innervation**
**Gastroileal reflex**: stimulates increase in ileal motility & relaxation of ileocecal sphincter; empties ileum & prepares it for more chyme --\> **regulated by gastrin & cholecystoknin & activated by increase in gastric motility & secretion**
104
What are the parts of the large intestine?
Cecum, appendix, colon, rectum, & anal canal
105
What is the cecum? Location.
Location: part of the large intestine
A pouch that receives chyme frm the ileum & attached to it is the vermiform appendix
106
What are the 4 parts of the colon?
Ascending colon, transverse colon, descending colon, & sigmoid colon.
107
What is the O'Beirne sphincter? Location.
Location: Colon
Controls movement of wastes frm sigmoid colon into the rectum
108
What is the internal & external anal sphincter? Location & innervation.
**Location**: end of anus, part of the large intestine
**Internal anal sphincter**: involuntarilty regulates fecal passage; part of the inner surface of the anal canal; composed of circular muscle layers --\> **innervated by parasympathetic fibers**
**External anal sphincter**: --\> voluntarily regulates fecal passage; part of the encircling outside wall of the anal canal & canal opening; composed of striated muscle --\> **innervated by pudendal nerve (carries motor & sensory fibers)**
109
Name the sphincters & location of the digestive system from the mouth to the anus?
**Upper esophageal sphincter (Cricopharyngeal muscle)** - prevents entry of air into the esophagus during respiration.
**Lower esophageal sphincter (Cardiac sphincter)** - prevents regurgitation frm the stomach.
**Pyloric sphincter** - stomach to duodenum
**Ileocecal sphincter** - ileum to cecum of large intestines
**O'Beirne sphincter** - sigmoid colon to rectum
**Anal sphincter** (internal/external)
110
What are teniae coli? Location
Source: cecum & colon
3 longitudinal bands in the longitudinal muscle layer that are shorter than the colon, giving the colon it's "gathered appearance"
111
What are haustra (singular haustrum)? Location
Location: cecum & colon
Outpouchings of the circular muscles of the colon
112
Describe the mucosa of the colon.
There are **rugae (folds) btwn the haustra**.
Lieberkuhn crypts, **but no villi**
Mucosa made up of: **columnar epithelial cells** that absorb fluids & electrolytes & **goblet cells** that secrete mucus to lubricate the mucosa
113
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