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1191: anatomy 2 > ch 20: digestive system > Flashcards

ch 20: digestive system Flashcards

1
Q

what does the digestive system consist of

A

alimentary canal and accessory glands

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2
Q

what are the main parts of the human alimentary canal

A

oral cavity, esophagus, stomach, small
intestine, large intestine, rectum and
anus.

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3
Q

what are the accessory digestive glands?

A

salivary glands, gallbladder and pancreas

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4
Q

All the following are considered organs of
the gastrointestinal tract EXCEPT
a) pharynx
b) small intestine
c) gallbladder
d) stomach
e) esophagus

A

gallbladder because it’s an accesory organ

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5
Q

what are the different kinds of the peritoneum (thing that covers organs) in the digestive system

A

◦ Serous membrane of the
abdominal cavity
* Visceral peritoneum covers the
abdominal organs
* Parietal peritoneum lines the
abdominal wall
* Serous fluid between visceral
and parietal peritonea prevents
friction and adhesion

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6
Q

folds of the peritoneum: falciform ligament

A

: attaches liver
to anterior abdominal wall and diaphragm

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7
Q

GREATER OMENTUM

A

from the transverse
colon, it covers the folds of the small intestine.
Contains much adipose tissue (beer belly). Contain
many lymph nodes (part of the immune system)

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8
Q

lesser omentum

A

connects the
stomach and duodenum to the liver.
Pathway for blood vessels entering the liver

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9
Q

the mesocolon

A

binds the large intestine to the
posterior abdominal wall.
Contains blood and lymphatic vessels.

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10
Q

the mesentery

A

binds small
intestine to posterior wall.
Contains lots of adipose tissue
and contributes extensively to
the large abdomen in obese
individuals. Contains multiple
blood and lymphatic vessels,
as well as lymph nodes.

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11
Q

what is peritonitis and what is it caused by?

A

Inflammation of the peritoneum
Most often due to infection by microorganisms
◦ life-threatening
◦ could be due to surgery
◦ could be due to perforation of intestine
Can be due to rubbing of inflamed peritoneal surfaces
◦ not life-threatening, but still painfu

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12
Q

Which of the following peritoneal folds
suspends the liver in place?
a) Greater omentum
b) Falciform ligament
c) Lesser omentum
d) Mesentery
e) Mesocolon

A

B

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13
Q

The mesentery
a) binds the transverse and sigmoid colon to the posterior
abdominal wall
b) drapes over the transverse colon and coils of the small intestine
c) extends from the posterior wall to wrap around the small
intestine
d) suspends the stomach and duodenum from the liver

A

c) extends from the posterior wall to wrap around the small
intestine

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14
Q

layers of the GI tract: mucosa

A

: The inner lining of the
tract; is a mucous membrane
consisting of an epithelium
moistened by glandular secretions
and a lamina propri

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15
Q

layers of the GI tract: submucosa

A

A layer of areolar
connective tissue that
surrounds the mucosa; has large
blood vessels and lymphatic
vessels; in some regions also
contains exocrine glands that
secrete buffers and enzymes
into the lumen of the digestive
tract. Contains extensive
network of neurons

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16
Q

muscularis

A

Is dominated by
smooth muscle cells - an inner
circular layer and an outer
longitudinal layer – that play an
essential role in mechanical
processing and in the movement of
materials along the digestive tract

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17
Q

serosa

A

A layer of visceral
peritoneum that covers organs
along most portions of the
digestive tract; attaches the
digestive tract to adjacent
structures; Connective tissue
contains blood vessels and nerves

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18
Q

where is simple stratified squamous mucosa found and what is its function?

A

stratified squamous in mouth, pharynx, esophagus and anal canal
◦ offers protection against abrasion

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19
Q

where is simple columnar mucosa found and what is its function

A

simple columnar in stomach and intestines
◦ secretes enzymes and absorbs nutrients
◦ specialized cells (goblet) secrete mucous onto cell surfaces

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20
Q

describe the lamina propria in mucosa

A

thin layer of areolar connective tissue
◦ contains blood vessels, nervous tissue, glands and immune cells

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21
Q

describe muscularis mucosae

A

thin layer of smooth muscle
◦ causes folds to form in mucosal layer to increase surface area

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22
Q

Stretching of the GI tract by chyme will
activate a gastrointestinal reflex pathway.
a) True
b) False

A

a) True

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23
Q

what are the 2 sets of nervous systems that innervate the GI tract

A

enteric nervous system (ENS-intrinsic) and autonomic nervous system (ANS-extreinsic)

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24
Q

describe the enteric nervous sytem that regulates the neural innervation of the GI tract

A

◦ “Brain of the gut” – can function
independently
◦ Myenteric plexus
◦ Located between the longitudinal and
circular smooth muscle layers
◦ Controls GI tract motility
◦ Submucosal plexus
◦ Located within the submucosa

controls secretions of organs in GI tract

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25
Q

describe how the autonomic nervous system regulated the innervation of the GI tract

A

◦ Regulate neurons of the ENS
◦ Parasympathetic (CN X; sacral
nerves) – increase ENS activity
◦ Sympathetic (thoracic and upper
lumbar nerves – decrease ENS

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26
Q

what kins of sensory receptors are involved in the enteric nervous system

A

mechanoreceptors,

chemoreceptors

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27
Q

describe the oral cavity

A

oral cavity formed by cheeks, hard and soft palates and tongue
* mouth opens posteriorly into
oropharynx

hard palate separates oral from nasal cavity

soft palate moves up to
block entrance to nasal
cavity during swallowing

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28
Q

sublingual glands vs submandibular glands bs parotid glands

A

sublingual: deep to the tongue in the floor of the mouth. Secretes mucus that serves as buffer
\
Submandibular: medial in inferior body of mandible, secretesalivary amylase and mucuc

Paratoid: inferior/anterior to the ears b/w skin and masseter, secrete watery liquid with salivary amylase

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29
Q

The parotid glands are found
a) in the tongue
b) between the skin and the masseter muscle
c) in the floor of the mouth
d) beneath the tongue
e) in the palate

A

B

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30
Q

Sympathetic nerve impulses
a) promote continuous secretion of a moderate amount of saliva
b) stimulate production of saliva in response to the feel and taste of
food
c) decrease salivation in times of stress
d) A and B are both correct.
e) A, B, and C are all correct.

A

C

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31
Q

describe the composition of saliva

A

Saliva is 99.5% water and 0.5% solutes
◦ Ions (Na+, K+, Cl-, HCO3-, phosphates)
◦ Dissolved gases
◦ Organic substances such as urea (waste) , uric acid (waste), mucus, IgA,
lysozyme, salivary amylase

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32
Q

what are the functions of saliva?

A

*Wet food for easier swallowing
*Dissolves food for tasting
*Bicarbonate and phosphate ions buffer acidic foods
*Chemical digestion of starch (salivary amylase)
*Chloride ions activate salivary amylase
*Removal of metabolic wastes (urea and uric acid)
*Enzyme (lysozyme) → helps destroy bacteria
*IgA = antibodies that prevent attachment of microbes to epithelium

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33
Q

what are the different kinds of digestion in the mouth

A

mechanical digestion and chemical digestion

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34
Q

describe mechanical digestion in the mouth

A

(mastication or chewing)
◦ breaks into pieces
◦ mixes with saliva so enzymes can access food molecules
◦ forms a bolus

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35
Q

describe chemical digestion in the mouth

A

Salivary amylase
◦ begins starch digestion (pH 6.5 or 7.0 in mouth)
◦ inactivated by gastric juices (pH 2.5)
◦ Lingual lipase
◦ Although it is secreted in the mouth, it begins the digestion of triglycerides
in the stomach

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36
Q

describe the pharynx

structure

A

tube of skeletal muscle lined by mucous membrane

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37
Q

deglutition (swallowing) steps

A
  1. Bolus is forced into the oropharynx by
    tongue movement
  2. Soft palate moves up, blocking the nasal cavity
  3. Epiglottis blocks the
    trachea, preventing
    food from entering
  4. Food moves
    from the pharynx
    to the esophagus
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38
Q

describe deglutition (swallowing)

2 stages

A

It consists of voluntary and involuntary stages
Voluntary stage begins when the bolus is forced into the oropharynx by tongue
movement
Receptors in oropharynx stimulate deglutition center in brain
Soft palate moves up, blocking the nasal cavity and epiglottis blocks the trachea – prevents food entry (involuntary)
Food moves from the pharynx to the esophagus

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39
Q

what does the esophagus do?

A

squeezes food along to the stomach

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40
Q

what does peristalsis do?

A

moves food boluses into the stomach

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41
Q

what does the cardiac sphincter do?

A

(lower esophageal
sphincter) regulates the passage of food through
the esophagus and into the stomach.

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42
Q

describe the layers of the esophageal wall (upper sheet region)

A

The mucosa and submucosa form large folds
that allow for expansion during the passage
of a large bolus; tone in the walls keeps the
lumen closed, except when you swallow.

Muscularis externa contains
skeletal muscle fibers in the
superior portion of the esophagus;
the lower portion of the esophagus
contains smooth muscle tissue

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43
Q

describe the mucosa, submucosa and muscularis in the esophagus

A

Mucosa = stratified squamous epithelia
Submucosa = large mucous glands
Muscularis = upper 1/3 is skeletal,
middle is mixed, lower 1/3 is smooth
muscle
◦ esophageal sphincters are prominent
circular muscles that control the entry
and exit of food

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44
Q

what tissue does the esophagus have instead of serosa?

A

Adventitia instead of serosa =
connective tissue without epithelium.
Attaches esophagus to surrounding
structures

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45
Q

what is Gastroesophageal reflux disease (GERD)

A

When the lower esophageal sphincter fails to close adequately after food has
entered the stomach
stomach content (acidic) can reflux (go back up) into the inferior portion of the
esophagus
causes burning sensation (heartburn)

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46
Q

Which of the following statements is FALSE?
a) The upper esophageal sphincter contains smooth muscle.
b) The upper esophageal sphincter controls movement of food
from the pharynx into the esophagus.
c) The lower esophageal sphincter contains smooth muscle.
d) The lower esophageal sphincter controls movement of food from
the esophagus into the stomach.
e) Gastroesophageal reflex disease may be due to a defect in the
lower esophageal sphincter.

A

A

47
Q

describe the stomach

A

he stomach churns the food (Gentle
mixing waves every 15 to 25 seconds)
with gastric juice to form a mixture called
acid chime (a thin liquid).
The stomach is closed at either ends by
cardiac sphincter and pyloric sphincter.
◦ The pyloric sphincter opens to allow
the passage of chyme into the small
intestine.
Emptying of the stomach into the small intestine occurs ~3ml at a time

48
Q

describe the layers of the muscularis externa in the stomach

A

strengthens the stomach wall and assists in the mixing and churning activities essential to the formation of chyme

49
Q

how does the pyloric sphincter relate to the stomach

A

Empties as small squirts of
chyme leaves the stomach
through the pyloric sphincter

50
Q

how is extensive stretching possible in the stomach

A

die to rugae

51
Q

describe the mucosa of the stomach wall

A

simple columnar epthelium
Produces an alkaline carpet of mucus
that covers the interior surfaces of
the stomach and protects epithelial
cells against the acid and enzymes in the gastric lumen.

52
Q

The myenteric plexus
a) controls the contractile strength and frequency of the muscularis
b) supplies the secretory cells of the mucosal epithelium
c) contains sensory neurons which function as chemoreceptors
d) regulates secretion by gastrointestinal organs.
e) supplies the mucosal epithelium

A

A

53
Q

what are gastric pits and gastric glands?

A

epithelial cells that extend down into the lamina propria

54
Q

gastrin

A

hormone
released by G cells in
the stomach when food
arrives to stimulate
additional secretion of
gastric juice

55
Q

Hydrochloric acid is secreted in the stomach
by
a) parietal cells
b) chief cells
c) G cells
d) mucous neck cells
e) surface mucous cells

A

a) parietal cells

56
Q

Pepsinogen is an active protease in the stomach. (protein breakdown)
a) True
b) False

A

b)

57
Q

how does protein digestion occur in the stomach

A

Protein digestion begins in the stomach
◦ HCl denatures (unfolds) protein molecules
◦ HCl turns pepsinogen (inactive) into pepsin (active) which breaks peptide
bonds between certain amino acids

58
Q

how does fat digestion occur in the stomach?

A

gastric and lingual lipases split triglycerides

59
Q

how are the stomach walls protected from being digested

A

Mucous cells protect stomach walls from being digested with layer of
mucous 1-3mm thick

60
Q

what is peptic ulcer disease and what are the 3 causes? treatment?

A

Ulcer (craterlike lesion in a membrane) exposed to
gastric juices can cause bleeding (sometimes severe)
* 3 causes:
* infection with Helicobacter pylori
* bacteria secrete compounds that protect
them from acidity of stomach, but also
destroys mucus
* antibiotics are effective treatment
* use of non-steroidal anti-inflammatory
drugs (NSAIDs)
* hypersecretion of HCl (in certain tumors)

61
Q

where does nearly all chemical digestion take place?

A

in the small intestine

62
Q

describe the pancreas and the liver functions

in terms of digestion what are they and what do they do

A

The pancreas and the liver are two
accessory glands that are necessary for
chemical digestion to take place in the small
intestine

63
Q

describe pancreatic juice

A

Pancreatic juice contains enzymes that digest
◦ starch (pancreatic amylase)
◦ fats (pancreatic lipase)
◦ nucleic acids (ribonuclease and deoxyribonuclease)
◦ proteins (trypsinogen** [trypsin], chymotrypsinogen, [chymotrypsin],
procarboxypeptidase [carboxypeptidase], proelastase** [elastase])
◦ **These enzymes are all inactive in the pancreas and get activated when they
reach the duodenum
sodium bicarbonate from pancreas converts acid chyme to an alkaline pH (7.1-8.2)
◦ promotes activity of pancreatic enzymes

64
Q

Pancreatic juice does all the following EXCEPT
a) buffer gastric juice
b) provide protein-digesting enzymes in inactive form
c) provide starch-digesting enzymes
d) provide glucagon
e) stop the action of pepsin

A

d) provide glucagon

65
Q

describe the liver

structure

A

Second largest organ after skin
◦ Completely covered by
visceral peritoneum
◦ Two lobes separated by
falciform ligament

66
Q

describe the gallbladder

A

Pear-shaped sac that stores
bile until needed for digestion

67
Q

Bile breaks down fats into monoglycerides
and fatty acids.
a) True
b) False

A

b) false

68
Q

Secretions from the liver and gallbladder are united in
the common bile duct and enter the duodenum
through the sphincter of the hepatopancreatic
ampulla.
a) True
b) False

A

a) true

69
Q

what are the different functions of the liver

A

*Role in lipid homeostasis (cholesterol synth.,
lipoprotein synth., break down fatty acids to
generate ATP)
*Synthesis of bile salts from cholesterol; Fats
emulsification
*Role in glucose homeostasis
*Detoxify toxic substances and excrete drugs into bile
*Storage of vitamins (A, B12, D, E, K) and minerals
(iron, copper)
*Phagocytosis of worn out red and white blood cells
and bacteria

70
Q

describe blood supply to the liver

A

The liver receives a double supply of blood – Oxygenated blood from the hepatic artery – Deoxygenated blood from hepatic portal
vein; blood in hepatic portal vein comes
from the esophagus, stomach, small
intestine and most of large intestine. It
contains newly absorbed nutrients, drugs,
microbes and toxins from the GI tract.
* All blood eventually leaves the liver via
the hepatic vein

71
Q

what does the portal triad include

A

Bile Duct
Branch of Hepatic Portal Vein
Branch of Hepatic Artery

72
Q

where are liver lobules and what do they do?

A

arteries and veins of each portal triad deliver
blood to the sinusoids of adjacent liver lobules

73
Q

steps in blood supply to liver

A
  1. Blood enters the liver sinusoids (highly
    permeable capillaries) from small branches of
    the hepatic portal vein and hepatic artery
  2. As blood flows through liver sinusoids, hepatocytes regulate solute and nutrient levels and
    absorb or secrete molecules such as plasma proteins
  3. Phagocytic cells, stellate reticuloendothelial
    cells (Kupffer cells), engulf pathogens, cell debris,
    and damaged blood cells. They are also store iron,
    lipids, and heavy metals (tin or mercury) that are
    absorbed by the GI.
  4. The central vein collects blood from the sinusoids of
    the lobule. All central veins merge to form the hepatic
    veins, which then empty into the inferior vena cava.
  5. Hepatocytes secrete bile into narrow
    spaces called bile canaliculi. They extend
    outward, away from the central vein.
  6. Bile canaliculi carry bile to bile ducts in the
    nearest portal triad. Bile plays an important role
    in the digestion of fats in the small intestine
74
Q

through which structures does blood flow in liver?

A
75
Q

Which of the following correctly details the
flow of blood through the liver?
a) hepatic artery > liver sinusoids > central vein > hepatic vein > hepatic portal vein
b) hepatic artery > hepatic portal vein > liver sinusoids > central vein > hepatic vein
c) hepatic artery > central vein > hepatic portal vein > liver sinusoids > hepatic vein
d) hepatic artery and hepatic portal vein > liver sinusoids > central vein >
hepatic vein
e) hepatic artery and hepatic portal vein > liver sinusoids > hepatic vein > central vein

A

d)

76
Q

what is hepatitis

A

inflammation of the liver that can be caused by:
◦ viruses
◦ drugs
◦ chemicals (including alcohol)
can lead to cirrhosis
◦ liver loses its functions because liver cells die and the tissue gets replaced by
scar tissue
◦ remember, scar tissue cannot perform same function

77
Q

how do gallbladder and bile work?

A

The gallbladder functions in storing
and concentrating bile
* Bile can flow through the cystic duct in
both directions
* Bile salts emulsify fats and help in
absorption of lipids in duodenum of
small intestine
* Bile contains water, bile salts,
pigments (bilirubin from broken down
RBC), and several ions

78
Q

describe gallstones

A

if bile contains insufficient bile salts or excessive cholesterol, cholesterol may
crystallize to form gallstones
partially or completely block ducts

79
Q

describe the small intestine.
What are the 3 anatomical and physiological regions

A

The small intestine is the major organ of chemical digestion and nutrient absorption
It is divided in 3 anatomical and physiological regions

duodenum, jejunum and ileum

80
Q

what is the function of the duodenum in the small intestine

A

Shortest segment of small intestine (~ 25 cm).
Begins at the pyloric sphincter and merges with jejunum.
Receives and neutralizes the acid chime,
Mixes contents and secretions from pancreas and liver

81
Q

what is the function of the jejunum in the small intestine?

A

Digestion of most nutrients

82
Q

what is the function of the ileum of the small intestine

A

absorption of bile salts and some vitamins (B12)
Joins to the large intestine at the ileocecal sphincter.

83
Q

why does the small intestine have a large surface area for absorption?

A

Folds of the intestinal lining, villi, and microvilli all contribute to the large
surface area
The absorptive surface
area of the small
intestine is about 250 m2 – the size of a tennis
court!

84
Q

describe the intestinal villus of the small intestine

A
  1. Intestinal villus (plicae circulares)– folds of the mucosa and submucosa– cannot stretch out like rugae in the stomach
85
Q

describe the villi in the small intestine

A
  1. villi– Finger-like projections of mucosa– lamina propria contains blood and
    lymph capillaries– lined with simple columnar epithelium
86
Q

describe the microvilli in the small intestine

A
  1. microvilli– Finger-like projections of the plasma membrane on
    individual cells
87
Q

describe the histology of each of the 3 segments of the small intestine

deudenum, jejunum and illium

A
88
Q

describe the muscularis of the small intestine

structure

A

formed by two layers of smooth muscle: outgoing longitudinal and inner circular

89
Q

serosa of the small intestine

A

CT and epthelial layer - forms portion of visceral peritoneum

90
Q

where are the lymphati nodules (peyer’s patches) found in the small intestine

A

found in the lamina propria of the ileum

91
Q

describe intestinal juices

A

◦ water and mucus, slightly alkaline
◦ provides a liquid medium to aid for absorption
◦ intestinal enzymes (brush border enzymes) break down foods at the cell
membrane
* Carbohydrate-digesting enzymes
* Protein-digesting enzymes
* Nucleic acid-digesting enzymes

92
Q

what are the different movements in the small intestine

A

Segmentation
◦ major movement of the small intestine
◦ localized contraction in areas containing food
◦ Serves for mixing, not moving food along
Peristalsis
◦ propels the chyme onward through the
intestinal tract

93
Q

describe chemical digestion in the small intestine

A

Chyme entering the small intestine contains only partially digested
carbohydrates, proteins and lipids.
These compounds need to be broken down into their respective monomers in
order to be absorbed by the small intestine
The completion of the digestion of these compounds is a collective effort of
pancreatic juice, bile and intestinal juice from the small intestine

94
Q

how are carbohydrates digested?

A

(oral cavity) salivary amylase breaks down
polysaccharides (glycogen, starch) to
oligosaccharides and disaccharides

(small intestine) pancreatic amylase continues
breaking down glycogen and
starch to smaller oligosaccharides

( small intestine) brush border enzymes → -dextrinase,
maltase, sucrase and lactase act on
oligosaccharides and produce monosaccharides
(fructose, glucose and galactose)

95
Q

how are proteins digested

A

(stomach)- HCl denatures proteins- pepsin turns proteins into peptides

(small intestine) proteolitic enzymes (trypsin, carboxypeptidase,
chymotrypsin, elastase) split peptide bonds
between specific amino acids (creates peptides)

(small intestines) brush border enzymes break down
peptides to single amino acids/dipeptides

96
Q

digestion of lipids

A

Lingual lipase (secreted in mouth, active
in stomach) and gastric lipase (stomach)
digest triglycerides to diglycerides,
monoglycerides and fatty acids- happens in stomach
– all the rest occur in the small intestine)
emulsification of fat globules
by bile (mechanical digestion)

pancreatic lipase splits triglycerides
into fatty acids & monoglycerides

no brush border enzymes
break down triglycerides

97
Q

digestion of nucleic acids.

A

nucleic acid digestion only
happens in the small intestine

Pancreatic juice contains 2 nucleases: -ribonuclease which digests RNA
into nucleotide-deoxyribonuclease which digests
DNA into nucleotide

Nucleotides are further digested
by brush border enzymes: -nucleosidase and phosphatase
digest nucleotides into pentose,
phosphate & nitrogenous
bases

98
Q

how are nutrients absorbed?

A

Nutrients pass into epithelial cells of villi in the jejunum of the small intestine
Fatty acids and glycerol are recombined into fats and transported into lymph

Other absorbed nutrients such
as amino acids and sugars pass
into the blood, which then flows
directly to the liver

99
Q

how are small fatty acids absorbed?

A

Small fatty acids enter and exit cells by simple diffusion

100
Q

how are larger lipids absorbed?

A

Larger lipids exit the lumen only within micelles (bile salts coatin)
◦ Lipid-soluble vitamins get packaged along in micelles
◦ lipids enter cells by simple diffusion leaving bile salts behind
◦ Bile salts reabsorbed into blood & recycled into bile by liver

101
Q

what are the final steps in the absorption of lipids

A

Inside epithelial cells, fats are rebuilt and coated with protein to form chylomicrons
Chylomicrons leave intestinal cells by exocytosis into a lacteal (lymphatic capillary)
◦ travel in lymphatic system to reach subclavian veins
◦ removed from the blood by the liver and adipose tissue

102
Q

Most proteins are absorbed as amino acids
through _________, while dietary lipids are
absorbed through __________.
a) facilitated diffusion; active transport
b) active transport; facilitated diffusion
c) facilitated diffusion; simple diffusion
d) simple diffusion; active transport
e) active transport; simple diffusion

A

e) active transport; simple diffusion

103
Q

describe the absorption of water

A

> 9 liters of fluid enters GI tract each day
Small intestine reabsorbs > 8 liters
Large intestine reabsorbs 90% of that last liter
Reabsorption is by osmosis through cells into
capillaries in villi

104
Q

describe digestion in the large intestine

A

*Undigested material passes to the large intestine or colon.
*No enzymes are secreted - only mucus
*Absorption of some ions (Na+ and Cl-) and vitamins
*Absorption of water (90% in small intestine, ~10% in large intestine)

105
Q

describe how bacteria contribute to digestion in the large intestine

A

ferment undigested carbohydrates; produces carbon dioxide and methane gas
* ferment undigested proteins into simpler substances → odor
* turn bilirubin into simpler substances → color
* produce vitamin K and B in colon

106
Q

describe the rectum of the large intestine and its function

A

The rectum is a muscular organ at the end of the large intestine
The rectum stores feces until they can be eliminated

107
Q

what is feces

A

dead epitheleal cells, undigested food such as cellulose, bacteria (both live and dead)

108
Q

describe the two sphincters in the large intestine

A
  • Involuntary
    Opens from the large intestine to the rectum.
  • Voluntary
    Opens into the anus.
109
Q

describe the eptithelium of the large intestine

A

smooth tube,
no villi or folds

simple columnar
epithelia (absorptive
cells) cells absorb
water (have microvilli)

Goblet cells
secrete mucus

110
Q

what is haustral churning in the large intestine

A

When the distension of a haustrum reaches a certain point, the walls
contract and squeeze the contents into the next haustrum

111
Q

peristalsis vs mass peristalsis

A

◦ Strong peristaltic wave begins at the middle of the transverse colon, quickly
driving the content into the rectum

112
Q

defecation is a reflex. explain

A

mass peristalsis causes filling of the rectum
* stretching of the rectal wall initiates the
defecation reflex
* The internal anal sphincter (involuntary)
relaxes
* the external anal sphincter can be
voluntarily controlled (except in infants) to
allow or postpone defecation
* voluntary contractions of the diaphragm
and abdominal muscles aid in defecation

113
Q

The descending colon empties into:
a) Transverse colon
b) Sigmoid colon
c) Cecum
d) Rectum
e) Anal canal

A

b) Sigmoid colon

114
Q
A

1191: anatomy 2 (18 decks)

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