unit 4 Flashcards
(109 cards)
1
Q
what do humans get from food
A
basic organic molecules to make atp, build tissues, and serve as cofactors and coenzymes
2
Q
what does digestion do to the macros
A
breaks the polymers into monomer building blocks via hydrolysis reactions
3
Q
what takes monomers into bloodstream to be used by cells
A
absorption
4
Q
-open at both ends
and is continuous with the environment
-considered “outside” the body
A
digestive tract
5
Q
materials that cannot be digested (cellulose)….
A
never actually “enter” the body
6
Q
what allows for specialization of function along the tract
A
one way transport (peristalsis)
7
Q
what is motility
A
movt of food thru the tract
8
Q
taking food into the mouth
A
ingestion
9
Q
chewing and mixing food with saliva
A
mastication
10
Q
swallow
A
deglutition
11
Q
wave like, one way movt thru tract
A
peristalsis
12
Q
churning and mixing while moving forward
A
segmentation
13
Q
what are the 6 functions of digestive system
A
-motility
-secretion
-digestion
-absorption
-storage and elimination
-immune barrier
14
Q
thesec ome from glands that help release substances that help break down food and facilitate absorption
A
exocrine secretion
15
Q
example of exocrine secretion
A
digestive enzymes, hydrochloric
acid, mucus, water, and bicarbonate
16
Q
hormones to regulate digestion
A
endocrine secretion
-gastrin, insulin, secretin
17
Q
breaking food down into
smaller units, both physically and
chemically
A
digestion
18
Q
passing broken-down food
into blood or lymph
A
absorption
19
Q
temporary
storage and subsequent elimination of
undigested food molecules
A
storage and elimination
20
Q
what are the immune barriers in dig sys
A
-simple columnar epi with tight junctions
-immune cells
21
Q
prevents swallowed pathogens
from entering body
A
simple col epi with tight junction
22
Q
—in connective tissue of the
tract promote immune responses
A
immune cells
23
Q
detects and responds to pathogens. the immune cells are part of this
A
galt
24
Q
30 ft long from mouth to anus
A
gastrointestinal tract
25
organs of GI
oral cavity, pharynx, esophagus, stomach, SI, LI, anus
26
main site of digestion
SI
27
Location: First section (about 10 inches long)
Function:
Receives chyme (partially digested food) from the stomach.
Mixes chyme with bile (from the liver) and pancreatic enzymes (from the pancreas) to begin the digestion of fats, proteins, and carbohydrates.
Neutralizes stomach acid with bicarbonate to protect the intestinal lining.
duodenum
28
Location: Middle section (about 8 feet long)
Function:
Main site for nutrient absorption (carbohydrates, amino acids, vitamins, and minerals).
Has many villi and microvilli to increase surface area for absorption.
jejunum
29
Location: Final section (about 12 feet long)
Function:
Absorbs vitamin B12, bile salts, and any remaining nutrients.
Transfers contents to the large intestine via the ileocecal valve.
ileum
30
accessory organs
teeth, tongue, salivary glands,
liver, gallbladder, pancreas
31
produce bile to emulsify fats
liver
32
store and release bile
gallbladder
33
secreted digestive enzymes and bicarbonate into si
pancrease
34
Location: Where the esophagus connects to the stomach (upper portion).
Function:
Receives food from the esophagus.
Contains the lower esophageal sphincter, which prevents acid reflux by closing after food enters.
cardia
35
Location: Dome-shaped area above the cardia, to the left.
Function:
Temporarily stores swallowed food and gas produced during digestion.
Fundus
36
Location: Largest central region of the stomach.
Function:
Main site of mechanical mixing and chemical digestion.
Secretes hydrochloric acid (HCl) and digestive enzymes (like pepsin) to break down proteins.
corpus
37
Location: Lower portion, leading to the small intestine.
Subdivided into:
Antrum (holds and mixes food)
Pyloric canal (leads to the pyloric sphincter)
Function:
Controls emptying of chyme into the duodenum through the pyloric sphincter.
Prevents backflow from the small intestine.
pylorus
38
Chewing breaks food down
into smaller pieces for deglutition and
mixes it with saliva
mastication
39
contains mucus, an antimicrobial
agent, salivary amylase to start digestion
of starch, and salivary lipase to begin fat
digestion.
saliva
40
layers of digestive tract
mucosa, submucosa, muscularis externa, serosa
41
like lysozyme- kill bacteria and defend pathogens in food
antimicrobial agent
42
salivary glands
parotid, submandibular, sublingual
43
func in starch digestion (amylase)
parotid gland
44
function in moistening food. this is majority of saliva
submandibular gland
45
function in lubricating and moistening
sublingual gland
46
lined with
skeletal muscles innervated by somatic motor
neurons
Mouth, pharynx, and upper esophagus
47
lined with smooth muscle
controlled by autonomic nervous system
lower esophagus
48
opens to allow food to pass into stomach. It stays
closed to prevent regurgitation
Lower esophageal sphincter (cardiac sphincter)
49
occurs when part of the normal
stratified squamous epithelium of the esophagus is
replaced by columnar epithelium
barretts esophagus
50
constitutes metaplastic tissue (metaplasia refers
to the abnormal replacement of cell types)
barretts esophagus
51
occurs because of injury to the esophageal
mucosa by gastroesophageal reflux disease
(GERD)
barretts esophagus
52
when stomach acid repeadely flows back into esophagus (heart burn)
-this is when LES is weak and allow acid to reflux into esophagus
gerd
gastroesophageal reflux disease
53
functions of stomach (5)
a. Stores food
b. Churns food to mix with gastric secretions
c. Begins protein digestion
d. Kills bacteria in the food (acid)
e. Moves food into small intestine in the form of
chyme
54
partially digested, semi liquid food mixture that forms in stomach after mechanical and chemical dig
chyme
55
these are at base of folds lead to gastric glands that contain several types of
secretory cells
gastric pits
56
types of secretory cells
mucous cell, parietal cell, chief (zygomatic) cell
57
secrete mucus to help
protect stomach lining from acid
mucus cell
58
secrete HCl acid and intrinsic
factor (helps small intestine absorb vitamin B 12 )
parietal cell
59
secrete pepsinogen,
the inactive form of a protein digesting enzyme
chief (zygomatic) cell
60
how does HCl form (3 steps)
-primary active transport of Hydrogen via H/K ATPase pumps
-facilitated diffusion of CL- coupled to downhill movt of bicarbonate
-parietal cells secrete CL- as well as H= into gastric juice while secreting bicarbonate into the blood
61
functions of HCL (3)
-drops pH to 2 (protein denaturation)
-pepsinogen converts to active pepsin (digests protein)
-serves as the optimal pH for pepsin activity
62
why do proteins begin digestion in stomach
bc of pepsin
-food enters= secrete HCl
-acidic env activates pepsinogen
-pepsin activated and break down pro into peptides
-moves into si and turns into amino acids
63
what begins digestion in mouth
starches
64
what activity stops in stomach and why
salivary amylase bc its not active at pH 2. too acidic
65
three parts of si
duodenum, jejunum, ileum
66
receives chyme from stomach and digestive enymes from pancreas
duodenum
67
major site for nutrient absorption
jejunum
68
absorb remaining nutrients, especially b12 and bile salts
ileum
69
these 3 things secrete enzymes
duodenum, jejunum, ileum
70
why are the si lined with microvilli and villi
more sa for absorption
71
function of si (3)
digest food, absorb nutrients, move food
72
what kind of food does si digest
pro, carbs, and fat with enzyme and bile
73
what nutrients does the duodenum absorb
aa, sugars, fatty acids, calcium, iron into duodenum and jejunum
74
the si absorb nutrients into the blood and lymoh, and the main regions resposnible are
duodenum, jejunum, and ileum
75
absorption happens in the wall of si thru structures like---- which contain---
villi and microvilli; capillaries and lacteals
76
these absorb sugars, AA, vitammins, minerals into the blood
capillaries
77
(lymph vessels) that absorb fat into the lymphatic system
lacteals
78
what nutrients does ileum absorb
bile salts, vitamin b12, water, electrolytes
79
the absorption of nutrients are very rapid due to
villi and microvilli
80
digestive enzymes found in the small intestine—specifically on the brush border (microvilli) of intestinal cells and in the intestinal juice. They complete the digestion of carbohydrates, proteins, and nucleic acids into absorbable units.
intestinal enzymes
81
examples of brush border enzymes
maltase, sucrase, lactase
82
these are mostly produced by cells that line the si or come from pancreas
intestinal enzymes
83
all brush border ezymes are a type of
intestinal enzyme
84
---- are not released into the lumen, but they stay attached to the plasma membrane with active site exposed to chyme, allowing them to directly digest nutrients at the surface of the microvilli
brush border enzymes
85
these hydrolyze disaccharides, polypeptides,a nd other subtrates to simple nutrient molecules
brush border enzymes
86
87
s made of 2 sugars
disaccharides
88
long chain of AA linked to peptide bonds
polypeptides
89
an inability to digest the disaccharide lactose
into glucose and galactose for absorption by the small
intestine
lactose intolerance
90
digestion of lactose requires the enzyme ---, one of the brush border disaccharidases.
lactase
91
symptoms of lactose in the intestines produce
abdominal gas, bloating, diarrhea, nausea
92
functions of li (3)
-absorption of water, electrolytes, vitamin k, and some b vitamins
-prod vitamin k and b vitamins via microbial organisms
-stores feces
93
bacterial fermentation, gut bacteria digests remaining fibers, prod gas and vitamins
microbial organisms
94
how long does li store feces
until defacation (elimination)
95
functions of liver (4)
processes nutrients, filters blood, produces bile, and supports immunity
96
how much bile per day does liver prod
250-1500mL
97
bile is composed of (5)
-bile pigment (bilirubin)
-bile salts
-phospholipids (lecithin)
-cholesterol
-inorganic ions
98
what is the main bile pigment
bilirubin
99
comes from heme (part of hemoglobin) after old rbc are broken down in spleen and liver
bilirubin
100
are waste products found in bile, primarily formed from the breakdown of hemoglobin in red blood cells
bile pigments
101
these blend/ emulsify fats. made from cholesterol in liver and stored in gallbladder. released into si to digest fats. after its job, reabsorbs in ileum and returns to liver
bile salts
102
Form micelles with polar groups toward
water and nonpolar groups inward toward
the fat
bile salts
103
Provides a greater surface area for fat digestion
by lipase
bile salts
104
Fats are emulsified by bile salts first, then enter ---for absorption.
micelles
105
The liver can remove hormones, drugs, and
other substances in three ways
1) Excreted into bile
2) Phagocytized by Kupffer cells lining sinusoids
3) Chemically altered by hepatocytes
106
most pancreatic enzymes are ---- until they reach si
inactive (zymogens)
107
what activates trypsinogen
enterokinase (on epithelium)
108
trypsin activates
other enzymes
109
trypsin does what
digests protein
