Exam 2- rest of digestive system

Question 1

what are irons not used in?

a. hemoglobin, myoglobin
b. fatty acid, ubiquinone
b. cytochrome, cytochrome oxidase
c. peroxidase, catalase

Answer 1

b.

Question 2

what are 3 ways irons are handled?

a. iron bind with an intracellular storage protein, called ferritin
b. iron bind with a plasma transport protein called apotransferrin to form transferrin, which is transported in the plasma .
c. regulated in the intestinal rate of iron absorption via up/down-regulating the ferritin gene by the hormone (hepcidin)
d. all of above

Answer 2

d.

Question 3

what is the function of hepcidin?

Answer 3

in high iron conc - it bind to the membrane transporter (ferroportin), leading to degradation of ferroportin inside the cell. This prevent iron from leaving and get sequestered inside cell.

Question 4

what is iron found associated with when it’s being transported from the small intestine to blood to liver, back to blood then red blood cells?

Answer 4

Fe+2 is is excreted daily from the plasma.
Fe is absorbed in the small intestine that enter the enterocytes.
a. it combines with transferrin to be carried in the blood toward liver tissues.
b. it is unloaded there as free iron that get stored as ferritin
c. it can be used for hemoglobin in red blood cells. once Hb is degraded, macrophages can salvage the free irons.

Question 5

how is iron absorbed? choose all that apply

a. enter the SI mucosal epithelial cells via protein DMT1 in the luminal PM
b. exit the enterocytes via protein ferroportin, and is then moved in blood capillaries.

Answer 5

a and b

Question 6

Excess iron from the blood and in the body are stored in what 2 organs?

a. heart and brain
b. muscle and lungs
c. liver hepatocytes and bone marrow reticuloendothelial cells

Answer 6

c

Question 7

what form is it refers to when small amounts of iron are stored in a very insoluble form?

Answer 7

hemosiderin

Question 8

3 ways that iron rate is regulated genetically and hormonally during high iron and low iron levels?

Answer 8

1. body has enough iron (increased level of free iron in blood and SI epithelial cells) leads to INCREASED transcription of the gene encoding FERRITIN protein in SI epthelial cells.
   a. with more ferritin made – more iron are stored and less is released into blood.
2. low iron- less ferritin is produced in intestinal epithelial cells. then, less iron is stored in ferrtin and more iron is released into the blood
3. iron is controlled by hepcidin, a hormone produced by liver, secondly by ferroportin (control the exit of iron from cells into blood).
   a. high systemic iron storage and concentration– hepcidin is released. Hepcidin binds to ferroportin, whereas fp is moved inside cell and degraded.
   hepcidin- prevent iron from leaving to the blood and get sequestered inside the cells

Question 9

1. a deficiency of irons leads to what condition?

2. an excess of iron cause what condition?

Answer 9

1. anemia (lack of rbc production)

2. hemochromatosis- result in abnormal skin pigmentation, diabetes, liver disease, and heart/reproductive problems.

Question 10

Instead of regulating the ECF, where does the GI system exert its control on? Lumen conditions are governed by what 2 factors in the lumen?

Answer 10

GI regulate conditions in the LUMEN OF THE TRACT, rather than in ECF.
-Lumen conditions are governed by volume and composition of the lumen, rather than the nutritional state of body.

Question 11

where are the GI receptors mostly located at?

what are the 4 stimuli from the GI lumen that the receptors respond to?

Answer 11

-most receptors are located in the wall of GI tract itself.

• distension of the lumen wall
• osmolarity or acidity of the chyme,
• products of digestion (amino acids, fatty acids, monosaccharides, etc.)

Question 12

what are the 3 different types of receptors that trigger the reflexes and the 2 main effectors it act on?

Answer 12

• reflexes are triggered by activation of mechano (stretch), osmo-, and chemoreceptors.
• influence the muscles in GI tract wall and the EXOCRINE glands that secrete into its lumen

Question 13

what are the 5 components of a GI negative feedback reflex/GI control relexes?

Answer 13

1. chemo-, osmo- or mechanoreceptors recognize the stimulus coming from GI lumen
2. receptor send signals to the nerve plexuses or secrete hormones in the blood to the integration center
3. the integration center respond by sending a signal along the motor pathway to the effectors
4. smooth muscle or glands will contract or secrete more hormones, respectively
5. this produce a response that negate the problem

Question 14

purposes of the reflex:

a. prevent large changes in the variable that initiate them
b. maintains the optimal luminal conditions for MAXIMUM digestion and absorption.
c. it does no such thing!
d. a and b are correct

Answer 14

d.

Question 15

what are the 2 nerves plexuses making up the local nervous system exist in the GI tract, and what it refers as?

Answer 15

-GI has its own local nervous system, the ENTERIC NERVOUS SYSTEM, in the form of myenteric and submucosal nerve plexues

Question 16

what are the interactions between the neurons and its effectors for impulses to go both up and down in the GI tract?

Answer 16

-neurons from sympathetic (mainly postganglionic) and parasympathetic (preganglionic) synapse with each other, and with the GI tract muscles, glands and epithelial cells that allow for impulses traveling up and down the tract.

Question 17

traveling GI impulses permit neural reflexes within the tract that are DEPENDENT of the central NS. T/F

Answer 17

False

Question 18

sympathetic and parasympathetic neurons synapse with neurons of both plexuses, allowing the CNS influence on GI tract motility and secretions. T/F

Answer 18

True

Question 19

what are the transmitters released by enteric neurons?

a. nor-epi
b. acetylcholine
c. nitric oxide
d. ATP
e. several neuropeptides
f. all of above

Answer 19

f. all of above

Question 20

what does long reflex vs. short reflex involve?

what is a typical number of neuron chain that goes from CNS to effector?

Answer 20

long reflex- CNS route
short reflex- nerve plexuses
-a 2 neuron chain from CNS to effector

Question 21

what are the stimuli not originated from the GI lumen (outside of the GI tract) that also set off the reflex?

a. hunger
b. emotional state
c. sight or smell of food
d. none of the above
e. the first 3 stimuli

Answer 21

e. the first 3 stimuli

Question 22

where does the reflex occur with stimuli coming from outside the GI tract?

Answer 22

in the gut or nasal cavity

Question 23

hormone-secreting cells of GI tract:

a. are scattered throughout the tract’s mucosal epithelium
b. clustered into discrete organs
c. are scattered and produced on the needs of the body

Answer 23

a.

Question 24

luminal surface of hormonal-secreting cells is exposed to and stimulated by some chemical in the chyme. As a response, what substance does the cells-not facing lumen secrete into the blood?

Answer 24

this cause hormone to be released into the blood from the cell’s outer surface.

Question 25

the released hormones enter blood capillaries through what mechanism to reach the different target cells via circulation?

Answer 25

-hormones diffuse into blood capillaries

Question 26

what are the 3 hormones from stomach and small intestine that were secreted into the blood? what organs secreted what?

Answer 26

1. gastrin from the stomach

2. secretin and cholecystokinin (CCK) from the small intestine

Question 27

stimulus from GI lumen cause endocrine cell to secrete hormones to be released in the blood.
what are 3 mode of actions/effectors that hormones released from blood can act on?

Answer 27

1. hormones leave blood and act on smooth muscle or exocrine gland to produce a response
2. hormones leave blood and stimulate the same luminal facing endocrine cell to secrete hormones.
   These hormone can either:
   -activate the exocrine gland located on non-luminal side of GI tract wall to produce a response exert its effect in the lumen or
   -stimulates smooth muscle or exocrine gland within the GI wall to produce a response.
3. hormones leave blood and stimulate exocrine gland located on non-luminal side to produce a response in the lumen.

Question 28

chewing (mastication) occurs via what muscles and regulated by what type of neurons?

Answer 28

skeletal muscles

-regulated by SOMATIC neurons

Question 29

pressure of food against the palate, tongue, and gums reflexively activate _____ contractions and inhibit or activate? the muscles holding the jaw closed.

Answer 29

• rhythmic contractions

- inhibit

Question 30

how many and what are the salivary glands that produce saliva?

a. 2 parotid, 2 sublinguar glands
b. 4 parotid, 2 submandibular
c. 2 parotid, 2 submandibular, and 2 sublinguar glands

Answer 30

c

Question 31

unlike with other organs, these salivary glands secretion receive input from both sympathetic and parasympathetic, with parasympathetic being more potent. T/F

Answer 31

True

Question 32

taste stimulus on the tongue communicate with ____ nerve and tractus solitarius that get sent to __/__ salivatory nuclei, respectively. then are synapse onto submandibular ganglion that stimulates submandibular and sublingual salivary glands to secrete saliva.

Answer 32

• glossopharyngeal nerve - superior

- tractus solitarius- inferior

Question 33

Control reflexes are initiated by various stimuli, they are:

a. sight and smell of food
b. mechanoreceptors (detect pressure) in the mouth
c. chemo/taste receptors in the mouth, esp one that detect acid
d. all of above
e. b and c

Answer 33

d. all of above

Question 34

can reflex be modified by input from other brain regions (ie. appetite area of the hypothalamus) to the salivatory nuclei in the brainstem? Y/N

Answer 34

Yes

Question 35

describe the 5 components of reflex arc when it is modified by input from other brain regions? describe each component.

Answer 35

1. receptor
2. sensory pathways
3. integration center
4. motor pathways
5. effectors
6. sight, smell, taste and pressure of food stimulates eyes, smell receptors, taste buds, and mouth mechanoreceptors, respectively.
7. receptors transmit signals and communicate with sensory neurons in cranial nerves ie. optic nerve, olfactory nerve
8. the info get funneled into salivatory nuclei in brainstem
9. send signals to parasympathetic neurons in facial and glossopharyngeal nerves
10. reach the salivary glands
11. response: increase saliva secretion

Question 36

what is the stimulus that pressure receptors in the pharynx wall detect?
what center in the medulla oblongata does the sensory impulses travel to?

Answer 36

• stimulated by food forced into the pharynx/posterior oral cavity
• send to swallowing center in the medulla oblongata

Question 37

swallowing center’s 1st output include:

a. impulse in somatic to smooth muscle
b. both impulses in somatic motor neurons to skeletal muscles and in autonomic neurons to smooth muscles
c. impulse in autonomic to smooth muscles

Answer 37

b.

Question 38

swallowing center's 2nd output: 
temporarily \_\_\_ respiration and \_\_\_\_ the glottis.
a. activates, closes
b. activates, opens
c. inhibits, closes
d. inhibits, opens

Answer 38

c.

Question 39

swallowing center’s 3rd output deals with preventing food from entering the nose, by elevating what structure?

Answer 39

elevates the soft palate (uvula)

Question 40

list the consequential 3 outputs from swallowing center that’s followed by impulses, respiration and glottis, and nose.

Answer 40

1. relaxes the upper esophageal sphincter
2. cause PERISTALTIC WAVES of muscle contraction that force food toward the stomach.
3. opens the lower esophageal sphincter

Question 41

swallowing depends on gravity not by muscle contraction (peristalsis). T/F

Answer 41

False

Question 42

food that did not reach the stomach:

a. are vomited
b. stays in the esophagus until more food pushes it down
c. cause distension in esophageal wall that stimulates sensory receptors in the wall to initiate reflexes, resulting in repeated contractile waves called secondary peristalsis
d. only a and b are correct

Answer 42

c.

Question 43

what is the name of the condition referring to when the lower esophageal sphincter is unable to prevent stomach contents from splashing into the esophagus, leading to gastroesophageal reflux.

Answer 43

“heart burn!”
technically, it’s a burn in esophageal wall, not in the heart. heart is like why do I get blamed for this?? lol.
stomach content is very acidic and will burn other tissues.

Question 44

what is the characteristics of stomach mucosal epithelium?

a. multiple cell layer that doesn’t from any tubular glands
b. a single cell layer that invaginated into the mucosa to form many tubular glands
c. neither of these

Answer 44

b.

Question 45

what are the 4 different molecules that are secreted by gastric (oxyntic) gland with the respective cells in the gland?

Answer 45

1. parietal (oxyntic) cells- secrete hydrochloric acid and intrinsic factor
2. chief (peptic) cells- secrete pepsinogen
3. mucous neck cells- secrete mucus

Question 46

Parietal cell contains “invagination of the luminal membrane” that secrete contents into the lumen are called what?

Answer 46

canaliculi

Question 47

what are the 2 molecules the pyloric glands secrete?

Answer 47

1. mucus- provide protection from acids and enzymes

2. hormone, gastrin, into the blood, not into the lumen.

Question 48

Hcl secretion. describe how H+ and K+ are being pumped out into the canaliculi lumen and into the cells, respectively. what carrier does it used?
what does K+ use to exit the parietal cell into the stomach lumen?

Answer 48

H+ is derived from the breakdown of water.

a. Using an ATP-using active transporter carrier, that is a countertransporter, pumps H+ out of cells into lumen and K+ into the cell from the stomach lumen
b. K+ then leaks back into the lumen through ion channels

Question 49

how do cells facing the interstitial fluid handle Cl- and bicarbonate movement into and out of the cell? what type of carrier?
what does Cl- use to exit the parietal cell into the stomach lumen?

Answer 49

Cl- is exchanged for bicarbionate ions.
Cl- move into the cell from interstitial fluid and hc03- out of cell into interstitial fluid using a non-energy using countertransporter.
Cl- movement inside the cell builds up a Cl gradient that allow it to diffuse out of parietal cell and into the stomach lumen via ion channels (similar to K+ exit)

Question 50

what are the 3 messenger molecules that stimulate the stomach to increase its acid secretion into its lumen?

Answer 50

1. acetylcholine
2. gastrin
3. paracrine histamine

Question 51

What effect does the 3 messengers-acid secretion induced have on the parietal cells in the luminal membrane?

Answer 51

the messengers induce the parietal cells to insert additional H+/K+-energy using countertransport proteins into the luminal membrane

Question 52

what is the 1 messenger that signals the reduction of acid secretion into the stomach lumen?

Answer 52

somatostatin, a paracrine, acting on parietal cells

Question 53

what cell secrete histamine?

Answer 53

enterochromaffin-like cells (ECL)