Ch 26 Digestive

Question 1

What are the six essential activities of the GI tract? Broadly define each.

Answer 1

ingestion:food into dig tract
propulsion:swallow and Peristalsis (contrac/relax organ muscles)
mechanical digestion:chewing/churning/mixing
chemical digestion:food catabolic breakdown
absorption:nutrients move to blood/lymph
defecation:elimation of indig solid waste

Question 2

Describe the 3 regulations of digestion.

Answer 2

Mechan/chem stim:stretch recep, osmolarity, ph, substrate presence, end prod of dig.
(initiates activ/inhib dig gland, or mix lumen and move)
Intrinsic:nerve plexus (short reflexes) and short reflex (mediated by gutbrain)
Extrinsic: long reflex within/out gi tract, CNS centers and autonomic nerves

Question 3

What is the double layer of peritoneum? What does it provide?

Answer 3

Mesentery
~vascular/nerve supplies to viscera
~hold organs in place/store fat

Question 4

Identify the diff between peritoneal and retroperitoneal organs.

Answer 4

peritoneal: organs within peritoneal cavity
retro: organs behind (kidney, pancreas)

Question 5

What is the splanchnic circulation? This includes:

Answer 5

arteries branched off abd aorta (to supply guts)

• celiac trunk (hepatic, spenic, L gastric): liver, spleen, stomach
• Inf/sup mesenteric arteries: sm/lg intestines
• Hep portal circulation: collects from venous dig viscera, delivers to liver (metabolic proc and storage)

Question 6

Name the 4 tunics of the alimentary canal in order from the lumen outward.

Answer 6

mucosa
submucosa
muscularis externa
serosa (adventia)

Question 7

What are the major functions of the mucosa of the alimentary canal? Tissue type? Layers?

Answer 7

Moist epithelial 
-secretes mucus
-absorbs end prod of dig
-protects against infec dz
Layers:lining epi, lamina propria, muscularis mucosae

Question 8

When referring to the epi layer (1 of 3 layers) of the mucosa in the alimentary canal, what type of cells are here? What are the mucus secretions? And it contains what 2 important cells?

Answer 8

Simple columnar and mucus secreting goblet cells
Mucus sec:
protect dig orgs from dig self, ease food along
Stomach and sm inte mucosa contain:
enzyme secreting cells, hormone secreting cells (locally)

Question 9

The other 2 layers of the mucosa, Lamina propria and muscularis mucosae are made up of, functions as, contains?

Answer 9

LP-loose areolar/ret conn
nourish epi/absorb nutrients
lymph follicles (defense for bacteria)

MM-border of mucosa and sub

Question 10

Explain the 3 other sublayers of the alimentary canal. (submuc, mus ext, serosa)

Answer 10

sub-dense conn w/ elastic fib, blood, lymph vess/node and nerves (strength)
Mus ext-inner circ smooth musc, outer longi smooth musc (seg and peristalsis)
Serosa-protective visceral peritoneum

Question 11

What are the two major intrinsic nerve plexus’s of the dig sys?

Answer 11

submucosal nerve plexus-reg gland/smooth mus (speed of dig)

myenteric nerve plexus-mobility (btween circ/long layers contraction)

*seg/peristal automatic by local reflex arcs
*link to CNS by long autonomic reflex arc
(PNS increase dig, SNS decrease)

Question 12

What are the muscles categories of the tongue. to what do these control?

Answer 12

Intrinsic-shape of tongue
Extrinsic-position (location)
Lingual-securing down in mouth

Question 13

What are the papillae of the tongue and their location?

Answer 13

filiform: roughness/friction
fungiform: scattered, reddish hue
foliate: folds laterally on edge
circumvallate: v shaped in back

Question 14

What are the three pairs of extrinsic glands? and the intrinsic?

Answer 14

Ex: parotid, submandibular, sublingual (phys stim)
In:throughout oral mucosa (in cheek always keeping damp)

Question 15

What consists of both the alimentary canal and accessory digestive organs?

Answer 15

AC-mouth, pharynx, esophagus, stomach, sm/lg intestine

ADO-teeth, tongue, gb, salivary glands, liver, pancreas

Question 16

What are dental carries?

Answer 16

Demineralization of enamel and dentin by bacterial action.

acid produced by bacterial diminishes mineral salt,
flossing prevents caries

Question 17

what is gingivitis and periodontitis?

Answer 17

Ging-calcified plaque forming calculus (tartar)
disrupts seal between gingiva and tooth.
Perio-gum dz resulting from immune sys attacking intruders and body tissue carving pockets around tooth dissolving bone.

Question 18

Where does the esophagus join the stomach?

Answer 18

cardiac orifice and surrounding cardiac sphincter (gastroesophageal sphincter)

Question 19

When the esophagus is empty it does what? its glands secrete? and has muscle that changes how?

Answer 19

Folds longitudinally and flattens
glands secrete mucus (nonker strat squa epi) as bolus moves

muscularis changes from skeletal to smooth (inferiorly)

Question 20

After food is ingested, mechanical digestion occurs, what is deglutition, and the buccal phase?

Answer 20

swallowing (coodinated by tongue, soft palate, pharynx, esoph, and muscle groups)

bolus is forced into the oropharynx

*salivary amylase begins chemical breakdown of starch

Question 21

What is the pharyngeal-esophageal phase?

Answer 21

(controlled by medulla and low pons)
Peristalsis moves food through the pharynx to the esophagus.

all routes closed except to dig tract
tongue blocks mouth, soft palate blocks nasopharynx, epiglottis covers trachea

Question 22

Muscularis of the stomach is made up of, and does what?

Answer 22

longitudinal and circular muscle layers and additional oblique layer that:
allows stomach to mix and break down

Question 23

Discuss the epithelial lining and gastric pits of the stomach.

Answer 23

Goblet cells product alkaline mucus coat (this traps bicarbonate rich fluid beneath)

Pit contain gastric glands that secrete gastric juice, mucus, and gastrin.

Question 24

Name and describe the secretory cells of the gastric glands.

Answer 24

Parietal cells:secrete HCL and intrinsic factor (stomach protein that binds b12)
Chief Cells:produce pepsinogen (activated into pepsin when HCL added from the stomach. Pepin can activate more itself too.)
Enteroendocrine cells: secrete gastrin histamine

Question 25

What is the purpose of the mucosal barrier of the stomach?

Answer 25

bicarbonate mucus on wall neutralizes acid
Epi cells joined by tight junctions (mitotic)
Gastric glands impermeable to HCL

Question 26

What regulates the gastric secretion?

Answer 26

Neural and hormonal mechs.
Stimulatory and inhib events:
Cephalic (reflex) Phase-prior to food
Gastric phase-food into stomach
Intestinal Phase-part dig food into duodenum

Question 27

What are the excitatory and inhibitory events in the celiac phase of gastric secretion regulation?

Answer 27

Ext-site/thought of food. Taste/smell receptor stimulation.

Inb-appetite loss/depression. low parasym stim

Question 28

What are the excitatory/inhib events of the gastric phase?

Answer 28

Excit-stomach stretch, neural activation of stretch recep, active chemoreceps by peptides, caffeine, and rising ph. release of gastrin to blood.
Inhib-ph below 2, emotions (override parasym)

Question 29

What are the excit/inhib events of the intestinal phase?

Answer 29

excit-low ph, part dig. food entering duodenum pushes gastric gland activ.
inhib-stretch of duodenum, presence of fatty, acidic, or hypertonic chyme, irritants in duodenum(stops stomach release tempor)
`This inhibits local reflex and vagal nuclei (intest not ready for food yet), closes pyloric sphincter, releases enterogastrones inhibiting gastric secretion.

Question 30

HCL secretion is stimulated by ___, ___, and ____ through 2nd messenger systems.
Release of Hydrochloric Acid is low if…or high if…
Antihistamines block ___ receptors and decrease ____ release.

Answer 30

ACH, Histamine, Gastrin
low if only one ligand binds to parietal cell
high if all three ligands bind to parietal cell
H2, HCL

Question 31

Stomach filling reflex mediated events include:

Answer 31

receptive relaxation-food traveling in the esoph causes stomach to relax.
Adaptive relax-stomach dilates in reponse to gastric filling

Question 32

What is Plasticity (stomach filling)?

Answer 32

Intrinsic ability of smooth muscle to exhibit the stress-relaxation response (able to stretch w/o increasing tension)

Question 33

What do cells of cajal do?

Answer 33

Pacemaker cells (BER) for peristalsis towards pylorus

Question 34

What is Emesis, how can it be caused?

Answer 34

Vomiting
overeating (extreme stretching)
spicyfood/irritants (bac. toxin/alcohol)
bloodborne chems irritating emetic center in medulla (nausea)

Question 35

Ulcers are a breach in?

Answer 35

mucosal barrier of stomach.

Question 36

The small intestine that runs from pyloric sphincter to ileocecal valve has three subdivisions named what? And their basic concern.

Answer 36

duodenum-mix
jejunum-absorb
ileum-reg deliv in L intes

Question 37

What 3 factors increase surface area in the small intestines?

Answer 37

Plicae circulares-deep circular folds of mucosa and submucosa
villi-fingerlike extentions of the mucosa
Microvilli-tiny projections of absorbative mucosal cells plasma membranes

*increased surface area more absorption

Question 38

The epi of the mucosa of the small intestine is made of:

Answer 38

absorptive cells goblet cells (Prevent cell diges)
Enteroendocrine cells (histamine, gastrin)
Interspersed T cells (intraepithelial lymphocytes) (fight infection w/ cytokines)

Question 39

What other cells are found throughout the sm intestine?

Answer 39

Intestinal crypt cell-secrete watery mucus
Paneth cells (in crypts)-secrete antimicrobial chems (defensin, lysozyme)
Peyers Patches (submucosa)
Brunners glands (duodenum) secrete alkaline mucus (bicarb fluid to neutral acidic chyme)

Question 40

Name the 4 lobes of the liver. and assoc ligaments.

Answer 40

R, L, caudate, and quadate.

Falciform Ligament-seps r/l. suspends liver from diaphragm and ant. abd. wall.
Ligamentum teres-remnant of umbilical vein

Question 41

hexogonal shaped liver lobules are composed of?

Answer 41

Hepatocyte plate-radiate outward from central vein
Portal triad at 6 corners of lobule:consist of:
-bile duct
-Hepatic artery;supplies o2 blood to liver
-hepatic portal vein; carries venous blood with nutrients from dig viscera

Question 42

What are liver sinusoids and kupffer cells?

Answer 42

enlarged leaky caps between hepatic plates

hepatic macrophages in sinusoids

Question 43

What are the functions of hepatocytes?

Answer 43

Production of bile. Processing blood-borne nutrients. Storage of fat soluble vitamins. Detoxification.

• secreted bile flows between hepatocytes toward the bile ducts in the portal triads.

Question 44

What is bile composed of?

Answer 44

A yellow green, alkaline solution containing bile salts, bile pigments, cholesterol, neutral fats, phospholipids, and electrolytes.

Question 45

Bile salts are cholesterol derivatives that?

Answer 45

Emulsify fat (mix with water). Facilitate fat and cholesterol absorption. Help solubilize cholesterol.

Question 46

What recycles bile salts?

Answer 46

Entero hepatic circulation

Question 47

The chief bile pigment is _________, a waste product of heme.

Answer 47

Bilirubin

Question 48

What is the purpose of the gallbladder? Where does it release its contents?

Answer 48

Thin-walled green muscular sac on the surface of the liver that stores and concentrates bile by absorbing its water and ions.

Releases bile via the cystic duct which flows into the bile duct.

Question 49

Cholecystokinin and secretin are released into the bloodstream because?
This then stimulates the liver to?
Causing weak contractions of?

Answer 49

Acidic, fatty chyme causes duodenum to release.
Produce bile.
Gallbladder.

Question 50

What are the exocrine and endocrine functions of the pancreas?

Answer 50

EXOC:
Secretes pancreatic juice (breaks down food).
Acini (clusters of secretory cells) contain zymogen granules with dig enzymes
ENDO:
Release of insulin and glucagon for blood sugar regulation.

Question 51

What is the composition and function of pancreatic juice?

Answer 51

Water solution of enzymes and electrolytes.(bicarb)

Neutralizes acid chyme. Provide optimal environment for pancreatic enzymes.
Enzymes are released in inactive form and activated in the duodenum so pancreas is not digested.

Question 52

What are some examples of the pancreatic juices?

Answer 52

Trypsinogen activated to trypsin.
Procarboxypeptidase activated to carboxypeptidase.
Active Enzymes secreted:
Amylase – carb/starch – sugar
Lipases – fat/lipid – fatty acid, glycerol
Nucleases – nucleic acid – nucleotides

Question 53

What induces secretion of enzyme rich and bicarbonate rich pancreatic juices?

Answer 53

CCK – enzyme rich

Secretin – bicarbonate rich.

Question 54

Virtually all nutrient absorption takes place in the? The most common motion of this area is?

Answer 54

Small intestines. Segmentation.(initiated by the cajal cells)

Question 55

What are the three unique features of the large intestine?

Answer 55

Teniae coli-three bands of longitudinal smooth muscle in muscularis
Haustra-pocket like sex cause by the tone of the teniae coli
Epiploic appendages: fat filled pouches of visceral peritoneum.

Question 56

Colon mucosa and anal canal have what type of tissue cells? Why?
What is the purpose of the anal sinuses?
How are hemorrhoids occurred?

Answer 56

Colon-simple columnar epithelium (absorption)
Anal-stratified squamous
* has deep Crypts lined with goblet cells for drying out feces.
Anal sinuses excuse mucus and compress feces.

Inflammation of superficial venous plexus is in anal canal cause hemorrhoids.