10.2 Structure and Function of the Digestive System Flashcards
1
Q
Organisms that are too big to diffuse nutrients and water for survival must have ___________
A
a digestive system
2
Q
What are the 4 stages of food processing?
A
Ingestion
Digestion
Absorption
Elimination
3
Q
what kind of specialized organ does a sea anenome have?
A
digestive sac
4
Q
what kind of specialized organ does a nematode have?
A
digestive tract
5
Q
explain ingestion
A
Ingestion is the act of eating or drinking.
6
Q
explain digestion
A
Digestion is the process of breaking food down into molecules that are small enough for the body to absorb
7
Q
mechanical digestion
A
(chewing) chops and grinds food into
smaller pieces, increasing its surface area.
8
Q
chemical digestion
A
breaks the chemical bonds within the large
molecules of carbohydrates, fats, and proteins and produces smaller molecules during hydrolysis
9
Q
hydrolysis
A
process that breaks bonds in food molecules by adding water to them in the presence of specific
enzymes
10
Q
if a protein was a macromolecule, what would the components be? (what would the protein-digesting enzymes turn it into)
A
amino acids
11
Q
if fat was a macromolecule, what would the components be? (what would the fat-digesting enzymes turn it into)
A
glycerol and fatty acids
12
Q
give an example of chemical digestion
A
protein (macromolecule) uses protein digesting enzymes to turn into amino acids
13
Q
give an example of a chemical digestion with fat
A
fat (macromolecule) uses fat digesting enzymes to turn into glycerol and fatty acids
14
Q
explain absorption
A
-occurs in the small intestine, where the cells absorb small molecules, such as amino acids and simple sugars
-from the small intestine, the molecules enter the circulatory system
-the molecules are transported in the blood to body cells, where they join to make bigger molecules or are broken down to provide energy
-if there are more molecules than are needed
immediately, they are converted to fat for storage
15
Q
explain elimination
A
Elimination is the process of removing from the digestive tract any undigested materials.
-These materials travel through the large intestine and are eliminated as feces.
16
Q
In more complex animals, digestion occurs in a tube called
A
an alimentary canal
17
Q
alimentary canal
A
-digestive tract with two openings, a mouth and
an anus.
-food enters through the mouth at one end of the canal and is churned and mixed as it travels along the tube
-further along the tube, nutrients are absorbed from the digested food and then the wastes are disposed of through the anus
18
Q
Why is an alimentary canal more
efficient than a digestive sac for obtaining nutrients from food?
A
because an alimentary canal has more specialized regions for processing food
19
Q
Another name for the alimentary canal is the _______
A
gastrointestinal tract
or GI tract
20
Q
The length of an animal’s alimentary canal is often correlated with _____
A
diet
21
Q
In general, herbivores and omnivores have ___ alimentary canals, relative to their body size, than carnivores.
A
longer
22
Q
Why do herbivores and omnivores have longer alimentary canals than carnivores?
A
Vegetation is more difficult to digest than meat because it contains cell walls. A longer alimentary
canal provides more time for digestion and more surface area for absorption of nutrients
23
Q
What are two advantages of a longer alimentary canal?
A
provides more time for digestion and more surface area for absorption of nutrients
24
Q
Most animal species
process food in specialized organs, an adaptation that avoids the risk of __________
A
self-digestion
25
In humans, six main organs make up the alimentary canal:
the mouth, pharynx, esophagus, stomach, small
intestine, and large intestine
26
Accessory glands and organs include:
the salivary glands, pancreas, liver, and gallbladder
27
function of accessory glands and organs in the alimentary canal
secrete digestive juices into the alimentary canal
28
the mouth
-Beginning of digestion
-Teeth and tongue: mechanical digestion
-Incisors, cuspids, bicuspids cut into and tear food
-Molars grind food into a paste
-Salivary glands secrete saliva
-Watery liquid that contains digestive enzymes,
mucus, and other chemicals
29
Composition of saliva
1.) Enzymes :
-Amylase
-breaks down chemical bonds in starches to form
sugars
-Lysozyme
-helps fight infection by digesting cell walls of
bacteria
2.) Mucus
-coats and lubricates food
3.) Buffers
-protects teeth from acidic foods (swings in pH)
30
Pharynx
-Upper part of the throat
Shared by digestive and respiratory system
-The tongue pushes chewed up food (bolus) down the throat
-Epiglottis: cartilaginous flap seals off the airway
-prevents food from moving into the
passageway as it passes through the pharynx
into the esophagus
31
bolus
food that has been chewed and mixed in the mouth with saliva
32
epiglottis and function
Epiglottis: cartilaginous flap seals off the airway
-prevents food from moving into the passageway as it passes through the pharynx into the esophagus
33
esophagus
-Long, muscle-encased tube
Connects pharynx to stomach
-Gravity is not the reason your food travels downward
-Peristalsis: muscle contractions
-contract in a wave like fashion forcing bolus into
the stomach
-Once food is in the stomach, a valve called a sphincter closes the esophagus, preventing stomach contents from going back up the esophagus
-If the muscle opens at an inappropriate time, acid from the stomach can flow backward, causing heartburn
34
peristalsis
when food is pushed through the esophagus by a series of muscle contractions
35
sphincter
Once food is in the stomach a valve called a sphincter closes the esophagus, preventing stomach contents from going back up the esophagus
36
what happens if the sphincter muscle opens at an inappropriate time?
acid from the stomach can flow backward causing heartburn
37
mechanical vs. chemical digestion
Mechanical Digestion
-physical change
-chops and grinds food into smaller pieces
-increases surface area
Chemical digestion
-chemical change
-breaks the chemical bonds within the large molecules of carbohydrates, fats and proteins
-produces smaller molecules during hydrolysis
38
give an example of a polymer and monomer in chemical digestion
polymer (fat)
monomers (glycerol and fatty acids)
39
if amino acid is a monomer in a chemical digestion, what is the polymer
protein
40
stomach
-Elastic, muscular sac
-Cardiac/lower esophageal and pyloric
-Mechanical and chemical digestion
-Contains accordion-like folds, is elastic (can stretch)
41
mechanical digestion in the stomach
-Muscles in the stomach wall churn the food
-This action turns the bolus into a nutrient-rich
liquid called chyme
-force into small intestine
-pyloric sphincter regulates flow of chyme
-typically, it takes 2-6 hours for the stomach to empty
42
chyme
the acidic fluid which passes from the stomach to the small intestine, consisting of gastric juices and partly digested food
43
chemical digestion in the stomach
Gastric Juice:
secreted when you see, smell, or taste food; a message from your brain stimulates gastric glands
secreted by glands in the stomach lining.
-HCl: breaks down cells in food and kills bacteria
-Pepsin: enzyme that breaks large protein -
molecules
-Mucus: lubricates the stomach and prevents the
stomach from digesting itself
-Every 3 days, enough new stomach cells are created to replace the entire stomach
44
gastric juice
-secreted when you see, smell, or taste food; a message from your brain stimulates gastric glands
-secreted by glands in the stomach lining
45
hydrochloric acid
HCl: breaks down cells in food and kills bacteria
46
pepsin
enzyme that breaks large protein molecules
47
mucus
-lubricates the stomach and prevents the stomach from digesting itself
-every 3 days enough new stomach cells are
created to replace the entire stomac
48
absorption
-Cells absorb monomers
-Amino acids, simple sugars
-Small intestine 🡪 diffuse to blood in circulatory
system
1.) go to body cells
2.) join to make polymers OR
3.) broken down to provide energy
-If there are more molecules than are needed, they are converted to fat for storage
49
small intestine
-Chyme enters through pyloric sphincter
-moves via peristalsis (6m long, 2.5cm in diameter)
-3-5 hr process
-Absorption of most nutrients
-Digestion in 1st part (duodenum) absorption in rest
50
what 3 structures make up the small intestine?
duodenum, illeum and jejunum
51
duodenum
-U-shaped structure and is the shortest and the widest of all of the sections
-Pancreatic and bile ducts open into the duodenum making it extremely important for further chemical and mechanical breakdown of partially digested food.
52
jejunum
-2.5 m long and contains more folds and intestinal glands than the duodenum
-Breaks down remaining proteins and carbohydrates
53
illeum
-3m long contains fewer and smaller villi
-To absorb nutrients as well as to push remaining undigested material into the large intestine
54
function of small intestine
absorption
55
small intestines- villi form
-Finger-like projections inside intestines
-Each villus has microvilli
-Contain capillaries and lymph vessels (lacteals – carry fluid away)
56
lacteals
carry fluid away
57
small intestines- villi function
-Fatty acids and glycerol are absorbed by intestinal cells, they are recombined into fats and then transported into the lymph vessel
-Sugars and amino acids are absorbed into the bloodstream via the blood vessels in each villus
-From the bloodstream they travel to the liver where most nutrients are converted into other useable forms
-Liver detoxifies and cleanses materials before entering the heart
58
the large intestine (colon)
-Undigested food passes cecum to here
-Food passes by appendix which contains white
blood cells and thusly, we think has an immune
function
-absorbs rest of water
-Between sm. and lg. intestine, 90% of water ingested is reclaimed
-As water is absorbed the remains of the digested food becomes more solid
-Wastes move along colon via peristalsis (12-24 hours)
-Undigested food material is called feces
-Feces are stored in the final portion of the colon called the rectum
-2 sphincters (1 voluntary, 1 involuntary)
regulate the opening of the anus
59
what happens after the water is absorbed in the large intestine?
-As water is absorbed the remains of the digested food becomes more solid
-Wastes move along colon via peristalsis (12-24 hours)
-Feces are stored in the final portion of the colon called the rectum
60
duodenum
The first section of the small intestine
61
bile
-Bile is a yellow or greenish alkaline liquid produced outside of the small intestine by the body’s largest internal organ, the liver.
-Bile is stored in a sac-like structure called the
gallbladder until it is secreted into the duodenum. --Although bile contains no enzymes, it has substances that help prepare fats for hydrolysis
62
pancreatic juice
-Pancreatic juice is a clear alkaline liquid that neutralizes the acidic chyme and contains enzymes
that further break down carbohydrates, proteins, and fats.
-Pancreatic enzymes, along with enzymes secreted by the lining of the small intestine, complete the chemical digestion of food.
63
completing digestion in the small intestine
-carbohydrates are broken down to form sugars, which provide your cells with a source of energy
-these sugars are also a source of chains of carbon atoms that your body can use to construct other molecules containing carbon.
-The complete digestion of proteins results in amino acids that your cells use to build proteins
-The complete digestion of fats results in molecules of fatty acids and glycerol.
-Your cells use these molecules to build fats.
64
villi
-The wall of the small intestine is folded into many small, finger-like projections called villi (singular, villus).
-The cells lining each villus have microscopic projections called microvilli
65
lymph vessels
-Lymph vessels are structures that carry fluid away
from cells.
-After fatty acids and glycerol are absorbed by intestinal cells, these building blocks are recombined into fats that are then transported
into the lymph vessel
66
Undigested food material and
other waste products are called
feces
67
Feces are stored in the final portion of
the colon, the _______, until they can be eliminated
rectum
68
what is the cause of gas in the digestive system
results from swallowed air or the breakdown
of undigested food in the colon
69
endoscopy
-a narrow tube is inserted into the throat and passed into the esophagus, stomach, and upper intestine
-a small camera in the narrow tube enables the doctor to see the internal structures and to identify abnormalities
-Sometimes, the tube has tiny scissors that are used to cut a small piece of tissue for viewing under a microscope.
70
what is the cutting procedure using an endoscopy called?
biopsy
-used to determine if the cells are normal and can also identify the presence of the Helicobacter pylori bacteria, which burrow into the stomach wall and cause inflammation
71
colonoscopy
-During a colonoscopy, a thin, lighted tube with an attached camera is inserted through the rectum
-If an unusual growth is detected, the doctor may choose to perform a biopsy.
-If the biopsy indicates that the cells are abnormal or cancerous, it is sometimes possible to surgically remove those cells during the diagnostic procedure
72
Gastroesophageal reflux disease (GERD)
Gastroesophageal reflux disease occurs when acid
from the stomach spills back up into the esophagus
so frequently that it harms the lining of the
esophagus.
73
diagnosis and treatment for Gastroesophageal
reflux disease (GERD)
-Since smoking, drinking alcohol, and excess eating
seem to make this condition worse, doctors suggest that they be avoided.
-Antacids are prescribed to neutralize the stomach acid.
-Sometimes surgery is needed to strengthen the muscle that sits at the junction between the esophagus and the stomach.
74
ulcer
-If the stomach lining is broken down it becomes
irritated by gastric acid.
-The gastric acid can also spill into other parts of the digestive system and irritate the tissues of nearby organs.
-Sores found in the stomach lining, esophagus or the upper small intestine are called peptic ulcers
75
diagnosis + treatment of ulcers
-In order to properly diagnose an ulcer, a doctor may order a number of diagnostic tests including a blood test, feces or stool test, barium X-ray, and endoscopy.
-Barium is a white metallic liquid that coats the
digestive system and makes the ulcer more visible
in the radiograph produced by the X-ray.
-The blood and stool tests are used to identify the presence of H. pylori bacteria, the cause of most ulcers.
76
Inflammatory bowel disease (IBD)
-In inflammatory bowel disease, the intestines become irritated and inflamed and develop many ulcers, causing abdominal pain and diarrhea.
-Two common inflammatory bowel diseases are ulcerative colitis and Crohn’s disease.
-Ulcerative colitis is found in continuous sections of the intestine and rectum.
-Crohn’s disease may occur anywhere in the digestive tract.
77
diagnosis + treatment of Inflammatory bowel disease (IBD)
-The exact cause of inflammatory bowel disease
is still being researched.
-It is thought that the presence of foreign substances in the intestines may cause the body to attack itself in order to rid itself of the foreign invaders.
-This allergic type of reaction causes inflammation, which results in the development of ulcers.
78
Constipation
-Constipation occurs when peristalsis moves the feces along too slowly or when the colon absorbs too much water and the feces become too compacted.
-Constipation is usually a temporary condition
resulting from a diet that does not include enough
plant fibre.
-Constipation sometimes results from surgery, medication, air travel, and pregnancy.
79
diagnosis + treatment of constipation
To prevent constipation:
*Eat a healthy diet that contains a lot of fibre, such as fruit, vegetables, and grains.
-Fibre adds softness and bulk to the waste in the colon.
-As a result, the waste can pass through the colon more easily.
* Get plenty of exercise.
* Drink at least 1 L of water every day
80
Diarrhea
-If the lining of the colon is irritated — by a viral or
bacterial infection, for instance — the colon is less
effective in reclaiming water, and diarrhea may
result.
-Severe diarrhea can cause dehydration and
become life-threatening without treatment.
81
diagnosis + treatment of diarrhea
A healthy patient usually recovers from diarrhea
within several days, given enough clean water
and nutritious food. However, diarrhea can also
be a symptom of more serious disease, such as
infl ammatory bowel disease.
82
Compare and contrast the terms “mechanical
digestion” and “chemical digestion”:
(a) in the mouth
MD-teeth
CD- saliva + enzymes
83
Compare and contrast the terms “mechanical
digestion” and “chemical digestion”:
(b) in the stomach
MD- churns and mixes food
CD-enzymes break food smaller
84
How is a bolus formed?
After ingestion, the solid hard materials are broken down into smaller pieces or chewed with the help of teeth. These food materials get mixed with the digestive juice called saliva secreted from the salivary gland by the movement of the tongue. Thus, this moist mixture forms ball-like structures called a bolus.
85
What happens during hydrolysis?
a process that breaks bonds
in food molecules by adding water to them in the presence of specific
enzymes
86
(a) Define peristalsis.
(b) Describe its role in the digestive system
-food is pushed through the esophagus by a series
of muscle contractions
-forces the bolus of food toward the stomach
87
What is chyme?
mechanical digestion turns the bolus into an acidic, nutrient-rich liquid called chyme
88
(a) What is bile?
(b) What is the role of bile in digestion?
Bile is a yellow or greenish alkaline
liquid produced outside of the small intestine by the body’s largest internal organ, the liver
-has substances that help prepare fats for hydrolysis and separates small fat droplets, which enables digestive enzymes to break down the fats more efficiently
89
Explain the process of chemical digestion in
the duodenum
-As chyme enters the duodenum, it mixes with several digestive juices (e.g. bile)
-Bile is stored in a sac-like structure called the
gallbladder until it is secreted into the duodenum.
-Although bile contains no enzymes, it has substances that help prepare fats for hydrolysis.
-Fats tend to clump together, making it difficult for enzymes to reach the molecules.
Bile separates small fat droplets, which enables digestive enzymes to break down the fats more efficiently
90
(a) State four locations where sphincters are
found in the digestive system.
(b) What is the role of a sphincter?
1) where the stomach and esophagus meet (cardiac)
2) where the duodenum and stomach meet (pyloric)
3) where the small intestine meets the large intestine (ileocecal)
4) end of anus (anal sphincter)
-circular muscles that open and close passages in the body to regulate the flow of substances
91
anal sphincter
internal anal sphincter prevents uncontrolled movement of contents through the anus
92
pyloric sphincter
opens to allow partially digested food to pass from the stomach into the duodenum where it will be exposed to bile and other digestive enzymes
93
malfunction of pyloric sphincter can cause...
A malfunction of the pyloric sphincter can cause bile (a digestive enzyme produced by the liver) to back up into the stomach and sometimes the esophagus. Symptoms of bile reflux are indistinguishable from those of acid reflux.
94
ileocecal sphincter
involuntary sphincter located where the small intestine and large intestine (colon) meet.
There is not much known about this sphincter. It is thought to regulate the movement of partially digested food from the ileum (the last section of the small intestine) to the large intestine.
95
anal sphincter
regulates defecation (the evacuation of stool from the body).
The anal sphincter has both inner and outer muscles:
The inner sphincter is involuntary and prevents stool from leaking out.
The outer sphincter is predominantly voluntary and allows you to pass or hold stool on demand.
96
malfunction of anal sphincter can cause...
loss of bowel control
97
cardiac sphincter
closes the esophagus and prevents the contents of the stomach from flowing back into the esophagus
98
malfunction of cardiac sphincter can cause...
If the muscle opens at an inappropriate time, such
as caused by overeating, acid from the stomach
can flow backward into the esophagus, creating
a burning sensation called heartburn.
99
(a) Carbohydrates are broken down to form_____ , which provide your cells with_________ .
sugars; a source of energy
100
Proteins are broken down to form _____ that
your cells use to _____.
amino acids; build proteins
101
Fats are broken down to produce
molecules of _______and_____ that your cells
use to build _______.
fatty acids; glycerol; fats
102
How do the villi and microvilli maximize the
ability of the intestine to absorb nutrients?
The cells on the villi are packed full of tiny hairlike structures called microvilli. This helps increase the surface of each individual cell, meaning that each cell can absorb more nutrients.
103
What is a major function of the large intestine?
absorbs remaining water
104
(a) What is a colonoscopy
(b) Why is it important?
During a colonoscopy, a thin, lighted tube with an attached camera is inserted through the rectum
If an unusual growth is detected, the doctor may choose to perform a biopsy that can remove cancerous cells
105
What does the abbreviation “GERD” stand for?
Gastroesophageal reflux disease (GERD)
106
(a) What is an ulcer?
(b) What causes an ulcer?
-Sores found in the stomach lining, esophagus or the upper small intestine are called peptic ulcers.
-If the stomach lining is broken down it becomes
irritated by gastric acid. The gastric acid can also
spill into other parts of the digestive system and
irritate the tissues of nearby organs.
107
peptic ulcers
Sores found in the stomach lining, esophagus or the upper small intestine are called peptic ulcers.
108
explain why saliva is a very important
bodily fluid
Saliva contains special enzymes that help digest the starches in your food (amylase breaks down starches into sugars, which your body can more easily absorb + lingual lipase, which breaks down fats)
it also moistens the mouth for comfort, lubricates as you chew and swallow, and neutralizes harmful acid
109
Why might an individual with gallbladder
disease have difficulty digesting ice cream?
-produces bile that helps break down fats through hydrolysis and since ice cream is full of fat, it won't be able to properly digest it
