Chapter 9B

Question 1

gastric phase (the end)

The pH of the stomach chyme in/decreases and the distension of
the stomach walls lessens because chyme
has passed into the small intestine,
suppressing secretion of gastric juice
(positive/negative feedback loop)

Answer 1

decreases, negative

Question 2

HORMONAL REGULATION: gastric secre>on during the gastric phase is regulated by the
hormone X

Answer 2

gastrin

Question 3

Gastrin is released from the X cells
of the gastric glands in response to:

1. distension of the stomach by
   chyme
2. partially/fully digested proteins in
   chyme
3. low/high pH of chyme
4. caffeine in gastric chyme
5. acetylcholine released from
   parasympathetic/sympathetic neurons

• Once released, gastrin enters the
  bloodstream and finally reaches its
  target organs in the digestive system

Answer 3

G cells
partially
high

Question 4

Gastrin functions:

1. stimulates gastric glands to
   secrete gastric juice
2. strengthens the contraction of the
   X sphincter to
   prevent reflux of acid chyme into
   the esophagus
3. promotes gastric emptying by
   increasing motiity of the stomach
   and relaxing the pyloric sphincter

Answer 4

lower esophageal

Question 5

Gastrin secretion is inhibited when the
pH of gastric juice drops below/rises above 2.0 and
is stimulated when the pH decreases/rises.

Answer 5

drops below
rises

Question 6

Intestinal phase:
* It begins once food enters the small intestine.
* In contrast to reflexes initiated during the cephalic and gastric phases, which
stimulate stomach secretory activity and motility, those occurring during the
intestinal phase have inhibitory effects that slow X

Answer 6

the exit of chyme from the
stomach. This prevents the duodenum from
being overloaded with more chyme
than it can handle.

Question 7

These activities of the intestinal phase
of digestion are regulated by X and X mechanisms.

Answer 7

NEURAL
and HORMONAL

Question 8

Distension of the duodenum by
the presence of chyme causes
the X reflex.

• Stretch receptors in the
  duodenal wall send nerve
  impulses to the medulla
  oblongata, where they inhibit
  parasympathetic stimulation
  and stimulate the sympathetic
  nerves to the stomach.
• As a result, ……..

Answer 8

enterogastric
gastric motility is inhibited and there is an
increase in the contraction of the pyloric sphincter, which decreases gastric emptying.

Question 9

HORMONAL REGULATION: The intestinal phase of digestion is mediated by two
major hormones secreted by the small intestine:

1. Cholecystokinin (CCK): is
   secreted by the CCK cells of
   intestinal glands in the small
   intestine in response to chyme
   containing X and X
2. Secretin: is released from the S
   cells of the intestinal glands in
   the small intestine in response
   to X entering the
   duodenum .

Answer 9

amino acids from
partially digested proteins and
fatty acids from partially
digested triglycerides.

acidic chyme

Question 10

• Functions of CCK:
  1. produces hunger/satiety (acts on
  hypothalamus)
  2. slows/rapids gastric emptying by promoting
  contraction of the pyloric sphincter
  3. stimulates secretion of pancreatic
  juice (rich in digestive enzymes)
  4. promotes normal growth and
  maintenance of the pancreas
  5. contraction of the wall of the
  gallbladder (squeezes stored bile out)
  6. relaxation of hepatopancreatic
  ampulla sphincter (Oddi sphincter)
  allowing pancrea2c juice and bile to
  flow into the duodenum
  7. enhances the effects of secre2n

Answer 10

satiety
slows

Question 11

Functions of secretin:

1. stimulates the flow of
   X juice that is rich in
   bicarbonate (HCO3 −) ions to
   buffer the acidic chyme that
   enters the duodenum from the
   stomach
2. inhibits secretion of X
   juice (slows production of acid
   in the stomach)
3. promotes normal growth and
   maintenance of the pancreas
4. enhances the effects of CCK

Answer 11

pancreatic
gastric

Question 12

The opening from the ileum into the large intestine is guarded by a fold of mucous
membrane called the X (valve), which allows materials from the
small intestine to pass into the large intestine.

Answer 12

ileocecal sphincter

Question 13

Structurally, the four
major regions of the
large intestine are:

Rectum
Cecum
Anal canal
Colon

put in right order

Answer 13

1. Cecum
2. Colon (ascending,
   transverse and
   descending)
3. Rectum
4. Anal canal

Question 14

The opening of the anal canal to the
exterior (anus), is guarded by:
* Internal anal sphincter of
smooth muscle (involuntary)
and
* External anal sphincter of
skeletal muscle (voluntary).
* These sphincters keep the anus
closed except during the elimination
of feces.

Answer 14

ok

Question 15

Large intestine:

The epithelium contains mostly X cells (water absorption) and goblet cells
(secrete mucus that lubricates)

• Both cells are located in long, straight, tubular intestinal glands (crypts of
  X) that extend the full thickness of the mucosa.
• Solitary lympha>c nodules are also found.
• Large intes>ne does not have circular folds or villi; however, microvilli are present on
  the absorp>ve cells.

Answer 15

absorptive
Lieberkühn

Question 16

Muscularis consists of an external layer of longitudinal smooth muscle (teniae
coli) and an internal layer of circular smooth muscle.
* Tonic contractions of the bands gather the colon into a series of pouches
called X which give the colon a puckered appearance.
Small pouches of visceral peritoneum filled with fat and attached to teniae
coli are called omental (fatty) appendices

Answer 16

haustra

Question 17

The passage of chyme from the ileum into the cecum is regulated by X which is normally partially closed.
* After a meal, a gastroileal X intensifies peristalsis, opens the ileocecal valve
and forces chyme from the ileum (small intes<ne) into the cecum (large
intes<ne).
* It works with the gastrocolic reflex to s<mulate the urge to defecate
* The hormone gastrin also relaxes the sphincter.

Answer 17

ileocecal sphincter
reflex

Question 18

When substances pass the ileocecal sphincter, movements of the colon begin:

1. Haustral churning: when walls contract, squeeze the contents into the next
   haustrum.
2. Slow peristalsis also occurs.
3. Mass peristalsis due to the X reflex: strong peristaltic wave that
   begins at about the middle of the transverse colon and quickly drives the
   contents of the colon into the rectum.

Answer 18

gastrocolic

Question 19

The X reflex involves
an increase in motility of the
colon in response to stretch in
the stomach and the
byproducts of digestion in the
small intestine.

• This reflex is responsible for
  the urge to defecate following
  a meal.

Answer 19

gastrocolic

Question 20

Mucus and enzymes are secreted by the gland of the large intestine

true/false

Answer 20

false: no enzymes

Question 21

The final stage of diges(on occurs in the colon through the ac>vity of X that
inhabit the lumen: ferment any remaining carbohydrates and proteins

Answer 21

bacteria

Question 22

Large intes>ne also absorbs water (osmosis), ions (sodium and chloride), and some
bacterial products such us vitamins B and K

Answer 22

ok

Question 23

By the >me chyme has remained in the large intes>ne 3–10 hours, it has become solid
or semisolid because of water absorp>on and is now called X

Answer 23

feces

Question 24

Func>ons of the large intes>ne:

1. Haustral churning, peristalsis, and mass peristalsis drive contents of colon into
   rectum.
2. Bacteria in large intes>ne convert proteins to amino acids, break down amino
   acids, and produce some B vitamins and vitamin K.
3. Absorp>on of some water, ions, and vitamins
4. Forma>on of feces.
5. Defeca>on (emptying rectum).

Answer 24

ok

Question 25

large intestine: Mass peristaltic movements push fecal material into the rectum. * Distension s>mulates stretch receptors, which ini>ates a defeca(on reflex: * Receptors send sensory nerve impulses to the sacral spinal cord. * Motor impulses from the cord travel along parasympathe>c nerves back to the descending colon, sigmoid colon, rectum, and anus.

Answer 25

ok

Question 26

* The resulting contraction of the longitudinal rectal muscles shortens the rectum, thereby increasing the pressure within it. * This pressure, along with voluntary contractions of the diaphragm and abdominal muscles, plus parasympathetic stimulation, opens the internal anal sphincter. * If the anus is voluntarily constricted, defecation can be postponed.

Answer 26

ok