2/19-mastication & digestion

Question 1

what are the 4 muscles of chewing and what does each one do?

Answer 1

1. masseter- a large, strong, crushing muscles; aids in bitin down
2. temporalis- also a crushing muscle, provides a different crushing angle
3. buccinator- in cheeks, keeps food from pocketing pushing it midline
4. pterygoid- attach in the middle to the pterygoid plates in the skull; allows for circulatory chewing and side to side grinding

Question 2

what causes one to chew?

Answer 2

a reflex arc in the chewing center of the brain which is hooked to to the taste buds through the facial nerve (CN VII). if the taste buds sense food, it will cause you to chew.

Question 3

1. what happens in the act of chewing regarding receptors?

2. what type of contraction is this?

Answer 3

1. stretch receptors information is sent via the facial nerve as the jaw relaxes; then the trigeminal nerve (V) sends a message to the muscles to contract
2. rebound contraction

Question 4

how is food turned into chyme:

1. what does saliva do?
2. what type of cells are in the salivary glands
3. what does acinar do that is different from the duct cells

Answer 4

1. glues the food into a ball while moisturizing it
2. salivary glands have acinar glands (glands with ducts)
3. duct cells secrete fluid; acinar glands secrete enzymes

Question 5

why are glandular cells (especially carcinomas) called adeno?

Answer 5

because all glands embryonically come from the GI tube (even if in the lungs i.e. adenocarcinoma).

Question 6

how are the taste buds set up as far as how and where information is sent:

1. first 2/3 of the tongue?
2. last 1/3 of the tongue?
3. what branches of CNIX go where and what happens?

Answer 6

1. first 2/3 of the tongue has taste buds that send info to the lingual nerve; which sends information to the facial nerve (CN VII) (adding sensory and motor innervation to the first 2/3 of the tongue).
2. the last 1/3 sends information via the glossopharyngeal nv. (CN IX)
3. one branch will go to the gustatory cortex in the parietal lobe which tells you the taste has been sensed; another branch goes to the salivation center which will send a message back down through the facial nerve.

Question 7

1. when the information is coming back down to the salivary glands from the salivation center, what nerve does it go down and where does it go next?
2. what nerve deals with what 2 salivary glands?

Answer 7

1. the glossopharyngeal nerve deals with the parotid glands

2. the facial nerve deals with the 2 “subs” (i.e. submandibular and sublingual).

Question 8

(A & B) what is the difference between what the parotids and the “subs” secrete?

Answer 8

1.A) parotids secrete a watery and serous solution

B) submandibular and sublingual secrete a serous and mucous sectetion

Question 9

what does the mucous from the “subs” do?

Answer 9

lubricate and glue; rather than have small bits falling down your throat, you have a bouls but if it has sharp potato chips in it, they will be lubricated so that it doesnt scratch your esophagus.

Question 10

what else does the parotid gland secrete (besides watery and serous fluid)?

Answer 10

amylase; which breaks polysaccharides (starches, glucycogen) into into smaller oligosaccharides (turns “many to few”).

Question 11

what do duct cells release (3 antimicrobials)

Answer 11

1. IgA (duct cells bathe teeth with antibodies decreasing cavity causers)
2. cytosome (a form of lysosome which kills bacterial cells)
3. thiocyanate (a sulfer-cyanide poison that kills bacteria).

Question 12

how do the duct cells keep mouth acid down?

1. why does chloride leave?
2. what is chloride exchanged for? what benefit does this have?

Answer 12

1. the sodium and potassium channels bring in sodium and kick out potassium (chloride is a whore, so she goes with K+).
2. in cells, if you want to bring chloride in, it must exchange for somthing, this will be bicarbonate ion- which goes out and buffers the acid biproduct of bacteria feeding on sugar.

Question 13

what does amylase need to work?

Answer 13

K+ and Cl-

Question 14

what triggers the swallowing reflex?

1. what triggers the initial signal?
2. what receptors sense the signal, where are they located?
3. thru what nerves is this info sent, to where?

Answer 14

1. tongue presses against hard palate
2. cause stretch on endothelial swallowing stretch receptors in palatopharyngeal folds
3. stretch info is sent via trigeminal and glossopharyngeal nerves to swallowing center of brain
4. motor info is sent via trigeminal to pharynx and via glossopharyngeal to esophageal sphincter and pharynx; and Vagus to esophagus, stomach and small intestine.
5. soft palate rises to block off nasopharynx
6. palatopharyngeal folds squeeze in medially to funnel small food boluse only
7. epiglottis closes off airway
8. upper esophageal sphincter opens up like a funnel and rises to catch food bolus

Question 15

how is the esophatus divided (as far as smooth and skeletal muscle)?

Answer 15

upper 1/3 is skeletal, last 2/3 is smooth

Question 16

how is glanduar tissue of esophagus divided (the first 1/3 is ??? mucosa, etc…)?

Answer 16

upper 1/3 of submucosa is simple (only one fold), as it goes down the esophagus, it transitions to compound (branched) submucosa (looks like a hand with 20 fingers)

Question 17

what does the compound mucosa do that the simple mucosa does not? why?

Answer 17

secretes more mucous and starts to secrete bicarbonate. because it is closer to the the acids of the stomach.

Question 18

1. how many kinds of peristalsis are there?

2. what are they (describe them):

Answer 18

1. two kinds- primary and secondary
2. A) primary is all or nothing, somthing is swallowed and it goes all the way donw
   B) secondary kicks in when receptors in the esophagus are stretched from residual food (stuck), this causes dilation distally to allow for food to be pushed down.

Question 19

1. what kind of venous supply services the esophagus

2. what kind of arterial flow?

Answer 19

1. venous supply is a valveless plexus that drains into the liver (so back up from the liver causes esophageal varices that bleed out).
2. the arterial supply is segmented

Question 20

1. what happens to the larynx and hyoid bone during swallowing?
2. what does this do?

Answer 20

1. strap muscles pull them up

2. closes the airway

Question 21

1. what kind of pressure is in the lower esophageal sphincter (high or low)?
2. what is Barrett’s Esophagitis?

Answer 21

1. high
2. when high pressure causes acid reflux changes in esophageal tissue to gastric like tissue, this metamorphasis predisposes the patient to cancer.

Question 22

parts of the stomach

Answer 22

Can-Fran-Bake-Apple-Pie?

1. cardium (with cardiac sphincter)
2. fundus
3. body
4. antrum
5. pylorus (with pyloric sphincter)

Question 23

1. what type of cells are in the fundus?

2. what do they secrete

Answer 23

1. parietal cells

2. hydrochloric acid

Question 24

1. what type of cells are on the lower side of the body of the stomach?
2. what do they secrete?
3. what cells are on the upper side of the body of stomach?
4. what do they secrete?

Answer 24

1. chief cells
2. pepsinogen
3. G-cells
4. secrete gastrin (hormone) into the blood

Question 25

1. in what structure are parietal cells, chief cells and G cells located? 2. what are theses pits and what else do they secrete?

Answer 25

1. gastric pits inside the rugae | 2. are very tight tight with mucous neck cells at the top which secrete bicarb and mucous (to protect the tissue)

Question 26

1. what are enterochromaffin cells, what do they secrete (what does that cause)? 2. how do they get their name?

Answer 26

1. cells that secrete histhamine which stimulates the parietal cells to secrete HCL- and intrinsic factor (which allows the blood to pick up B-12 vitamins). 2. they stain "silver" on histology stains

Question 27

what does lack of B-12 cause

Answer 27

pernicious anemia

Question 28

1. what is inside the parietal cells? 2. what is inside these? 3. why are they important (what does this create)?

Answer 28

1. clear canals called canaliculi 2. carbonic anhydrase is inside the canaliculi. when activaed by Histhamine, they are pushed up and the carbonic anhydrase is pushed out 3. the carbonic anhydrase causes HCO3- to go out (this is always traded for Cl-), when the Cl- comes in, it mixes withe H+ to make HCL- which is pumped out at the anterolateral membrane

Question 29

1. what stimulates the G-cell? 2. what does the G-cell do? 3. what does the hormone released do (what cell does it go to and what does that cell release)? 4. what other place does the hormone go and what does it cause?

Answer 29

1. presence of peptides and amino acids 2. secretes gastrin into the blood 3. gastrin goes to the entero-chromaffin cells telling them to release histhamine 4. gastrin also goes to the ileocecal valve causing it to relax and allow food into it.

Question 30

1. what is IBD caused by (in general) | 2. what can trigger the cascade of gastrin release ...?

Answer 30

1. an imbalance of the gastrin, histhamine cycle | 2. the mere thought of food causes release of Ach which triggers the G-cell as well.

Question 31

1. what do chief cells use HCL for? | 2. what pH does pepsin work at?

Answer 31

1. to cleave pepsinogen to pepsin | 2. a ph of 2

Question 32

1. what is pepsin? | 2. how does pepsin keep from digesting the stomach?

Answer 32

1. pepsin is a protein that breaks down other proteins/ collagen for digestion 2. pepsin will eventually digest itself, ending the digestion

Question 33

what are the different gastric cells and wherer are they located from top to bottom ?

Answer 33

1. enterochromaffin cells=histhamine- location unkonwn 2. parietal cells= HCL & intrinsic-located in fundus 3. g cells=gastrin-located in upper body of stomach 4. chief cells= pepsinogen- located in lower body of stomach "PG chief"

Question 34

1. what happens when you get 1 liter of food in stomach? | 2. what is aded

Answer 34

1. it will stretch and stary churning the chyme down the middle and up the sides of the stomach 2. adding HCL from parietal cells

Question 35

what are gastric reflex arcs called?

Answer 35

vagal vagus reflex arcs (because vagus is 80% sensory and 20% motor).

Question 36

what controls the vago-vagal reflex arcs?

Answer 36

myenteric plexus

Question 37

name 3 of the myenteric plexus reflec arcs (and what they do): 1. 2. 3.

Answer 37

1. gastro-enteric: relaxes pyloric sphincter for gastric emptying 2. gastro-ileal: relaxes ileocecal sphincter to allow ileum to empty 3. gastro-colic: sends message to colon to make room

Question 38

name 2 other reflexes:

Answer 38

1. entero-gastric: intestines tell stomach to stop emptying into intestine 2. duodenal-colic: duodenum tells colon to start moving cause food is coming

Question 39

1. what is cck? | 2. what causes its secretion?

Answer 39

1. secreted from "I" cells in the presence of fats, | 2. slows stomach down, stimulates pancrease to secrete enzymes and proteases

Question 40

what are the pancreatic proteases and what do they do? 1. 2. 3.

Answer 40

1. trypsinogen -is turned to trypsin 2. chymotripsinogen 3. pre-carboxypeptidase

Question 41

1. what enzyme keeps trypisn from digesting the pancreas | 2. what enzyme activates the pancreatic proteases?

Answer 41

1. trypsin inhibitor | 2. enterokinase

Question 42

small intestinee: 1. what are plicae 2. what is contained on them

Answer 42

1. plicae are shelf like structures in the intestine (similar to rugae of stomach) 2. in the microvilli of the plicae there are small pits called Krypts of Liberkin where mitsis occurs, pushing new cells up the krypt and old cells off the tip of the plicae into the intestine

Question 43

What 3 ncranial nerves control peristalsis

Answer 43

Trigeminal Glossopharyngeal Vagus