Ch. 3 Digestion, Absorption, and Transport Flashcards
1
Q
GI tract
A
23-foot-long muscular tube, makes up organs of the digestive tract
2
Q
5 organs of GI tract
A
- mouth
- esophagus
- stomach
- small intestine
- large intestine
3
Q
Sphincters
A
allow food to pass from one organ to the next
4
Q
4 accessory organs
A
- liver
- pancreas
- gallbladder
- salivary glands
5
Q
Bolus (formation and where it enters)
A
- tongue rolls chewed and moistened food into this
- enters pharynx to be swallowed
6
Q
Esophagus function
A
transports food and fluids from mouth to stomach
7
Q
Two sphincters in esophagus
A
- Upper esophageal sphincter
- Lower esophageal sphincter (LES)
8
Q
Upper esophageal sphincter function
A
allows bolus to enter the esophagus
9
Q
Lower esophageal sphincter (LES) function (3)
A
allows bolus to enter the stomach
- loosens after swallowing
- shrinks to prevent stomach contents from returning to esophagus
10
Q
Epiglottis up…
A
trachea open
11
Q
Epiglottis down…
A
trachea closed
12
Q
Stomach function (chemical and mechanical)
A
- mixes food with gastric juices to chemically break it down into smaller pieces
- mechanical digestion: muscles of stomach mix, churn, and push content with gastric juices
13
Q
How much does the stomach hold?
A
empty: holds 1 cup
expanded: up to 1 gallon
14
Q
Chyme
A
semiliquid, partially digested food mass that leaves stomach and enters small intestine
15
Q
How much chyme leaves the stomach?
A
1 tsp of chyme leaves the stomach and enters small intestine every 30 seconds
16
Q
Pyloric sphincter
A
allows chyme to enter small intestine from the stomach
17
Q
Goblet cells (location and function)
A
cells in GI tract produce mucus
18
Q
Parietal cells (3)
A
- secrete HCl
- intrinsic factor
- digestion and absorption of vitamin B12
19
Q
Innermost layers of stomach contain (2)
A
- goblet cells
- gastric pits
20
Q
Gastric pits function
A
contain gastric glands that produce gastric juices
21
Q
Chief cells
A
produce pepsinogen, an enzyme that breaks down proteins
22
Q
Small intestine (3)
A
- long chamber (three chambers)
- important in finishing process of food digestion and nutrient absorption
- food is in here for 3 to 10 hours
23
Q
Segments of small intestine (length) (3)
A
- duodenum (10 inches)
- jejunum (8 feet)
- ileum (12 feet)
24
Q
Mechanical and chemical digestion in small intestine
A
- muscular contractions push chyme forward
- digestive secretions break down nutrients
25
Villi (2)
small projections that line interior of small intestine
| - maximize absorption
26
Lumen
hollow interior of small intestine; contains circular folds
27
Enterocytes
absorptive epithelial cells that line the walls (villi) of the small intestine
28
Microvilli (2)
tiny projections on the villi in small intestine
| - maximize nutrient absorption
29
Crypts (2)
- glands that secrete intestinal juice
| - contain stem cells that produce younger cells
30
How does chyme enter large intestine?
ileocecal valve (leaving ileum, part of cecum)
31
Large intestine size
5 feet long, 2.5 inches diameter
32
3 segments of large intestine
- cecum: beginning
- colon: large part
- rectum: final 8-inch portion
33
Large intestine function
site of water, sodium, potassium, and chloride absorption (indigestible food)
34
Cecum function
receives waste from small intestine
35
Ileocecal valve
sphincter that separates small intestine from large intestine
36
Bacteria produce what vitamins in colon? (5)
vitamin K, thiamin, riboflavin, biotin, and vitamin B12
| - only biotin and vitamin K absorbed
37
Ferment in colon (3)
- undigested and unabsorbed carbs fermented into simpler compounds: methane gas, carbon dioxide, and hydrogen
- intestinal gases produced
- fermented fiber produces short-chain fatty acids
38
Large intestine fluid/fecal ratio
1 liter of fluid material reduced to 200 grams feces
39
Time spent in large intestine
12 to 70 hours depending on person's health, age, diet, and fiber intake
40
Stool
propelled from large intestine to rectum
41
Anus (2)
opening of rectum/end of GI tract
| - feces voluntary released here
42
Final stage of defecation (2)
voluntary release of stool
| - influenced by age, diet, medications, health, and abdominal muscle tone
43
Salivary glands (3)
- dissolve small food particles to make swallowing food easier
- body produces 1 quart of saliva daily
- saliva contains water, mucus, electrolytes, and enzymes
44
Liver size and functions (6)
- largest internal organ (weights 3 pounds)
- helps with digestion, absorption, and transport of nutrients
- makes proteins
- makes bile used to digest fats
- carbohydrate metabolism
- site of alcohol metabolism; removes and degrades toxins and excess hormones
45
Gallbladder (3)
- receives bile from liver through hepatic duct
- concentrates and stores bile
- releases bile into small intestine through common bile duct
46
Pancreas (3)
produces enzymes and hormones
- Endocrine function: releases hormones insulin and glucagon to maintain blood glucose levels
- Exocrine function: secretes digestive enzymes into small intestine
47
How is food propelled through GI tract?
muscular contractions
48
Peristalsis (3)
- occurs in esophagus, stomach and small intestine
- squeezes food forward through GI tract
- mechanical digestion
49
Segmentation (3)
- occurs in small and large intestines
- shifts food back and forth along GI tract in the intestines
- allows contact with surface of small and large intestines and increases absorption
50
Chemical digestion (3)
carried out by digestive enzymes
- regulated by hormones
- finished by the time food reaches large intestine
51
Enzymes (2)
proteins that drive digestion
| - catalyze hydrolysis
52
Hydrolysis (2)
chemical reaction that uses water to split chemical bonds of digestible nutrients
- hydroxyl group (OH) joins one molecule, hydrogen ions (H) joins the other molecule
53
3 conditions for enzymes to work
1. Compatible enzyme and nutrient must be present
- enzymes compatible with specific substrate
- ex. sucrase (enzyme) hydrolyzes sucrose (substrate)
2. pH of environment
- enzymes work best in certain acidity and alkalinity
3. Temperature of environment
- low temperature: slow activity
- high temperature: activity halted
54
Enzyme in action (3)
1. substrate binds to active site
2. hydrolysis: bond is broken between two molecules
3. products released, process repeated
55
Enzyme in saliva (2)
salivary amylase
| - begins digestion of starch/carbohydrates
56
Enzyme in stomach (protein)
pepsinogen with substrate pepsin
| - beings hydrolysis of polypeptides
57
Enzyme in stomach (lipids)
gastric lipase
| - begins digestion of lipids
58
Enzyme in pancreas (carbs)
pancreatic amylase
| - digests starch
59
Where does most absorption take place?
small intestine
60
Passive diffusion (4)
nutrients move from high to low concentration
- NO energy required
- nutrients pass through cell membrane
- simplest diffusion
61
Facilitated diffusion (2)
nutrients move from high to low concentration with help of carrier protein
- NO energy required
62
Active transport
nutrients move from low to high concentration with the help of a carrier protein
- energy required
63
Endocytosis
cell forms a vesicle to surround and engulf nutrient
| - whole molecules engulfed by cell membrane
64
Where are water and salt absorbed?
large intestine
65
How is water absorbed by cell membrane?
passive diffusion
66
How is salt absorbed by cell membrane?
active transport
67
Endocrine and nervous systems function
coordinate digestion, absorption, and excretion of waste
68
Enteric nervous system
nerve fibers that supply the nerves of the GI tract, pancreas, and gallbladder
69
Enteric nerves function
monitor stomach contractions after eating and secretions of the cells in GI tract
70
Hormones functions (3)
- release gastric and pancreatic secretions
- peristalsis
- enzyme activity
71
Enterogastrones (2)
produced and secreted by cells lining the stomach and small intestine
- influence GI motility, stomach emptying, gallbladder contraction, intestinal absorption, and hunger
72
Types of hormones (4)
- Gastrin
- Secretin
- Cholecystokinin (CCK)
- Gastric inhibitory peptide (GIP)
73
Gastrin
stimulates HCl production and release of gastric enzymes
74
Secretin
stimulates pancreas to release bicarbonate to small intestine; pH is raised
75
Cholecystokinin (CCK) (3)
- stimulates pancreas to release lipase
- stimulates gallbladder to release bile
- slows down gastric motility
76
Gastric inhibitory peptide (GIP)
inhibits gastric motility and stomach secretions
77
Nervous system function in digestion
tells you when to eat and drink, and when to stop
78
Extrinsic nerves (function and locations)
- communicate changes in GI tract and stimulate motility
| - brain and spinal cord
79
Intrinsic nerves (function and locations)
- receive message from extrinsic nerves and respond by stimulating release of digestive juices
- found in linings of esophagus, stomach, and small and large intestines
80
Ghrelin
signals when you're hungry
81
Peptide YY (PYY)
keeps you feeling full
82
Nutrient transportation in body
absorbed through bloodstream or lymphatic system
83
Water-soluble nutrients transport (3)
1. absorbed into cardiovascular system (GI tract capillaries)
2. through hepatic portal vein (portal vein)
3. to the liver
84
Hepatic vein
substances leave intestine through here
85
Fat-soluble nutrients transport (3)
absorbed into lymphatic system (fat-soluble vitamins, long-chain fatty acids, and proteins too large to be transported through capillaries)
1. Lymph capillaries
2. Lymphatic vessels
3. Thoracic duct
86
Excretory system (2)
waste products that remain after nutrient absorption removed here
- kidneys filter blood, waste products excreted through urine
87
Gastroesophageal Reflux Disease (GERD)
- indigestion or acid reflux
| - LES doesn't close properly, HCl from stomach enters esophagus
88
Esophageal cancer (3)
- cancer of digestive tract
- males over 50, urban areas, smoke and drink heavily
- treatment: surgery, radiation, and chemotherapy
89
Belching (2)
- caused by swallowing air
| - eating too fast, drinking carbonated beverages, anxiety, chewing gum, and smoking
90
Stomach flu (2)
- symptoms: nausea, vomiting, diarrhea, and abdominal cramping
- treatment: rest, rehydration, and eating soft foods
91
Foodborne illness (2)
- consuming food contaminated with E. coli, salmonella, or campylobacter
- treatment: rest and rehydration
92
Ulcers (5)
- sore or erosion lining lower region of stomach or upper part of duodenum
- cause: Helicobacter pylori (bacteria)
- symptoms: vomiting, fatigue, bleeding, weakness, and burning pain
- treatment: drugs, dietary changes, surgery
- untreated: can cause peritonitis, scar tissue that blocks food and causes vomiting and weight loss
93
Gallbladder disease (3)
- women and older Americans
- obesity and rapid weight loss
- unhealthy gallbladder = gallstones
94
Gallstones (3)
- form from cholesterol in gallbladder or bile duct
- treatment: surgery for gallbladder removal, medication, shock-wave therapy
- body adapts to removal of gallbladder by secreting bile into duodenum
95
Celiac disease (4)
- genetic autoimmune disease
- damages small intestine when foods with gluten are eaten
- causes villi in small intestine to flatten out, causing nutrient malabsorption
- abnormal reaction to protein gluten found in rye, wheat, and barley
96
Celiac disease symptoms (7)
- abdominal bloating
- cramping/gas
- diarrhea
- foul-smelling stool
- weight loss
- anemia
- bone or join pain
97
Celiac disease risk, diagnosis and treatment
- increase risk: osteoporosis, diminished growth, and seizures
- diagnosis: blood test and tissue biopsy of small intestine
- treatment: gluten-free diet
98
Flatulence (3)
- results from formation of intestinal gas
- released 10 to 20 times a day
- causes: foods high in fiber and starch, eating fast, soda, not exercising, smoking
99
Diarrhea (cause and treatment included) (4)
- releasing watery, loose stools more than 3 times a day
- cause: bacterial, viral, or parasitic infections that cause food/fluids to pass through colon too quickly
- can lead to dehydration and death (children and elderly)
- treatment: fluid and electrolyte replacement
100
Constipation (cause and treatment included)
- dry, hardened stool
- cause: not enough fiber or water intake, stress, inactivity, smoking, and various illnesses
- treatment: exercise, normal eating patterns, rest, laxatives
- avoid colon cleansing (enema) as treatment
101
Hemorrhoids
swelling of veins in rectum and anus
- can lead to bleeding, itching, pain
- causes: straining to poop, pregnancy, constipation, diarrhea, aging
- treatment: increase fiber and fluid intake
102
Irritable bowel syndrome (IBS)
changes in colon rhythm
- overresponse to colon stimuli, changes patterns of diarrhea, constipation, and abdominal pain
- treatment: increase dietary fiber, stress management, and drugs
103
Ulcerative colitis (4)
- chronic inflammation of large intestine, causing ulcers in lining of the colon
- runs in families
- men and women ages 15 to 30
- treatment: drug therapy, surgery
104
Crohn's disease
similar to ulcerative colitis, but ulcers occur in GI tract
- treatment: drug therapy, surgery
- change diet/lifestyle
105
Colon cancer (4)
- third leading cause of cancer, most curable if detected early
- begins with small polyps in lining of colon, can be surgically removed (can turn into cancerous tumors)
- treatment: radiation, chemotherapy, surgery
- survival rates: depend on age, treatment response, and stage cancer
106
Mechanical digestion
breaking down food through chewing, grinding, squeezing and moving food through GI tract by peristalsis and segmentation
107
Chemical digestion
breaking down food through enzymatic reactions
108
Saliva (3)
- dissolves small food particles
- contains enzyme amylase, which begins breakdown of carbs
- in adults, no other chemical digestion occurs in mouth
