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Flashcards in digestion Deck (53)
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1

List three sensory structures involved in mastication reflexe

-proprioceptors in the temporomandibular joint
-proprioceptors in the muscles of mastication
-proprioceptors in the periodontal ligaments

2

Masticationreflexesareintegratedinthe________

medulla oblongata

3

Twoeffectorsofmasticationreflexesinclude_______________________and
_________________________.

temporalis muscle and masseter muscle

4

Listthreecomponentsofsaliva(inadditiontowater)andthefunctionofeach.

amylase, an enzyme that digests starch
-electrolytes, like Na+, function not completely understood
-mucin, protein that absorbs water and acts as a lubricant
-also others

5

Outlinethebasicmechanismofdeglutition

-voluntary contraction of tongue muscles pushes the bolus upwards and activates pressure receptors in the pharynx
-sensory impulses are transmitted along the glossopharyngeal nerve to the medulla oblongata where the swallowing reflex is triggered
-pharyngeal constrictor muscles contract pushing the bolus of food down the pharynx
-the posterior part of the epiglottis moves downwards to cover the glottis and the bolus slides over it into the upper part of the esophagus

6

Describe the movement of a bolus down the esophagus: the main structures and
forces involved and how they are controlled (3

-the upper esophageal sphincter relaxes to allow the bolus to enter the esophagus
-the bolus moves down the esophagus because of a wave of peristalsis
-peristalsis is partly the result of local reflexes and partly the result of parasympathetic reflexes controlled by the medulla oblongata
- the lower esophageal sphincter relaxes for the bolus to enter the stomach

7

Name a medical procedure that eliminates the swallowing reflex.

-deep anesthesia

8

cribe the characteristics of mixing waves in the stomach.

-peristatic waves
-mostly in body of stomach
-move back and forth
-about 3 per minute

9

Ingesta spends about _____________ (time) in the stomach.

2-4 hours

10

Describe the secretions of the stomach and the digestion that occurs there (2
marks).

mucus, hydrochloric acid, pepsinogen and water
-proteins are converted to peptides by pepsin

11

Label a stomach showing the general positions of cardiac, oxyntic and pyloric glands
and indicate which area produces gastrin and which area produces acid and proteins
(2 marks).

-cardiac region is near the opening to the esophagus - its wall contains glands that produce mucus
-the pyloric region is near the opening to the duodenum-its wall contains glands that produce mucus and the hormone gastrin
-the body is between the pyloric and cardiac regions-its wall contains oxyntic glands that produce hydrochloric acid and pepsinogen, as well as mucus

12

Describe the roles of enterochromaffin cells, chief cells and parietal cells and how
each is regulated.

-enterochromaffin cells produce histamine in response to stimulus by gastrin
-chief cells secrete pepsinogen when stimulated by acetylcholine from the vagus nerve
-parietal cells secrete hydrochloric acid when stimulated by either the vagus nerve or histamine from enterochromaffin cells

13

intrinsic factor is produced in the ________________________; its function is to
____________________________.

parietal cells of oxyntic glands...promote the absorption of vitamin B12 from the intestines

14

Describe the mechanism for acid secretion by cells of the stomach and list two
chemicals that stimulate the process (4 marks).

-parietal cells contain the enzyme carbonic anhydrase the catalyzes the conversion of carbon dioxide to bicarbonate ion and hydrogen ion
-bicarbonate diffuses out of the cell into the blood, in exchange for chloride ion
-hydrogen ion is pumped out of the cell into the lumen of the stomach, in exchange for potassium ion
-histamine and the neurotransmitter acetylcholine stimuate acid production

15

Explain how mixing waves are generated in the stomach and list two factors that
increase their activity (3 marks).

-interstitial cells of Cajal act as a pacemaker and start the mixing waves as wall as conduct them through the stomach
-they increase in response to stimuation by vagus nerve and the hormone gastrin

16

Describe two ways in which the rate of gastric emptying is regulated (2

any 2 of the following ways:
1) stimulation by vagus nerve
2) gastrin released by stomach
3) secretin released by the small intestine
4) cholecystokinin released by the small intestine

17

List two kinds of digestive processes that occur in the stomach and the enzymes
responsible.

1) conversion of protein to peptides by pepsin
2) coagulation of milk proteins in the stomach of infants by rennin

18

Describe the kinds of substances that are absorbed from the stomach and the
mechanism for this process.

-water, osmosis
-lipid soluble substances such as alcohols, diffusion

19

Describe what each of the following is and its role in digestion.
a) bolus

-a ball shaped piece of macerated food mixed with saliva
-it is size and consistency the enables it to be swallowed and propelled down the esophagus

20

b) gastrin

-a polypeptide hormone, produced by the stomach in response to the presence of food, that stimulates digestive processes in the stomach

21

c) pepsin

-an enzyme that is present in the stomach that converts proteins to polypeptides

22

d) chyme

-liquid ingesta that is formed in the stomach and propelled into the small intestine

23

e) secretin

-a polypeptide hormone, is produced in the small intestine in response to the presence of nutrients, that stimulates digestive acttivities of the liver and pancreas

24

f) cholecystokinin g) trypsin

-a polypeptide hormone, produced in the small intestine in response to the presence of nutrients, that stimulates digestive activities of the pancreas and movement of bile into the duodenum.....-an enzyme, produced by the pancreas, that converts proteins to peptides

25

h) chymotrypsin

-an enzyme, produced by the pancreas, that converts proteins to peptides

26

i) carboxypeptidase

-an enzyme, produced by the lining of the small intestine, that remains attached to the tips of microvilli and converts peptides to amino acids

27

j) rennin

-an enzyme produced by the stomach's of infants that catalyzes the coagulation of mild proteins

28

k) amylase

-enzyme, produced by the pancreas as well as salivary glands, that catalyzes the conversion of starch into maltose and oligosaccharides

29

m) maltase

-a brush border enzyme that catalyzes the conversion of maltose into glucose

30

n) sucrose

-brush border enzyme that catalyzes the conversion of sucrose to glucose and fructose