CHAPTER 17: DIGESTIVE SYSTEM

KEY CHAPTER 17: DIGESTIVE SYSTEM
OBJECTIVES
1. Name the organs and function of the digestive system.
ORGANS
FUNCTION
To breakdown food into substances that
Mouth
can be absorbed and used for energy.
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Salivary glands
Pancreas
Liver
Gallbladder
2.
Define the term digestion and explain its significance.
The breakdown of food or nutrients to small substances that can be absorbed for cellular
respiration = energy.
3.
Distinguish between mechanical (i.e. physical) digestion and chemical digestion.
Mechanical – mouth with chewing and breaking into smaller pieces; stomach with
mixing
Chemical – digestion of macromolecules by enzymes into smaller building blocks.
4.
Discuss the five digestive processes that overview the many functions of the digestive
system.
Ingestion, Mechanical digestion( mouth, stomach), Propulsion (swallowing, peristalsis),
Chemical digestion, Absorption, Defecation.
5.
Distinguish between the alimentary canal and digestive accessory organs, and label each
on the diagram below.
Alimentary canal – from mouth to anus: Oral cavity, pharynx, esophagus, stomach, small
intestine, large intestine. These organs “see” the food.
.
Accessory organs – Salivary glands, liver, gallbladder, and pancreas. These organs
secrete enzymes or substances into “food” to assist with its chemical digestion.
6.
Name two synonyms for the alimentary canal.
Digestive Tract , GI Tract
7.
Name the four layers that compose the wall of the alimentary canal from innermost
(lining lumen) to outermost, and label each in the diagram below.
Mucosa
Submucosa
Muscularis
Serosa
submucosal
Copyright 2011 Dr. Mary Cat Flath
myenteric
8.
Compare and contrast the four layers of the alimentary canal wall (named above) in terms
of their structure, function, and any distinguishing features.
Mucosa- Epithelium, CT, Smooth muscle- protection, secretion, absorption.
Submucosa- LACT, Blood Vessels, Lymphatic Vessels, Nerves - nourishes mucosa and
carry away absorbed nutrients.
Muscularis- two layers of smooth muscle, inner circular and outer longitudinal =
movement of tube through mixing and peristalsis.
Serosa- SSET over LACT- lubrication and cushioning.
peritoneum.
Also called the visceral
9.
Name the layer of the alimentary canal that is synonymous with visceral peritoneum.
Serosa- function in lubrication and cushioning
10.
Explain the significance of mesentery or peritoneal extensions.
The small intestine is suspended in the abdominal cavity by mesentery
11.
Describe how food is moved through the length of the alimentary canal (b below) and
name the layer responsible for these actions.
a. Mixing – mechanical digestion in mouth and stomach
b. Peristalsis – interaction between circular and longitudinal layers which move food
through the alimentary canal
12.
Define the term digestive sphincter muscle, describe the structure of these muscles, name
the function of these muscles, and denote the major five locations of digestive sphincter
muscles in the diagram below.
A sphincter muscle is a circular muscle that prevents regurgitation of food between
portions of the alimentary canal.
-
Gastroesophageal Sphincter lies between the esophagus and stomach/
-
Pyloric Sphincter lies between the stomach and small intestine.
-
Ileocecal valve lies between the small and large intestine.
-
Anal Sphincters - Internal and External, lie between anus and outside
13.
Name two synonyms for the mouth.
Oral Cavity
Buccal Cavity
14.
Describe the overall structure and function of the mouth, and label the major parts in the
diagram below.
The mouth is structured as a food receptacle and it’s surrounded by powerful cheek
muscles and the tongue. It houses teeth which mechanically digest ingested food.
It is also the first site of carbohydrate digestion: Salivary amylase- chemically digests
polysaccharides (glycogen and starch) into disaccharides.
.
15.
Discuss the three portions of the palate, in terms of location (these should already be
labeled above) and give an overall function for the palate.
Hard Palate, Soft Palate, Uvula
The palate separates the oral cavity from the nasal cavity.
16.
Name the tissue that composes the tonsils, label them above, and name the overall
function of tonsils.
Palatine tonsils- masses of lymphatic tissue- lateral to palate
Pharyngeal tonsils- adenoids lymphatic on posterior pharynx
Tonsils function to filter out and destroy debris and foreign agents ingested. They are
part of the lymphatic system which controls disease.
17.
Name the two sets of teeth we possess as humans, discuss the general structure of a tooth
and label each in the lower diagram below, and describe the four types of teeth we
possess according to their location and function, and label each in the upper diagram.
Deciduous Teeth
Permanent Teeth
0. Number 20
1. Number 32
1. Erupt from 6-22 months
2. Erupt from 6yrs- adult hood
2. Lost between 6-12 years
Function: To break food into smaller
Pieces (mechanical digestion)
18.
Name and locate the three sets of salivary glands in humans (see below), name and
describe the secretions from these glands, and name the two types of cells that compose these
glands.
Parotid- largest lies over masseter, mostly serous cells - clear, watery serous fluid (with
amylase).
Submandibular- floor of mouth lateral, mix of serous (with amylase) and mucous cells
Sublingual- floor of mouth, medially, mostly mucous cells
19.
Discuss the enzyme "salivary amylase", in terms of its digestive function, location of its
activity, and secretory gland.
Enzyme – salivary amylase breaks polysaccharides into disaccharides
A. Starch – disaccharides B. Glycogen – disaccharides
20.
Explain the process of deglutition using the diagram below.
Deglutition- swallowing
A) The tongue forces bolus of food into pharynx
B) The soft palate and larynx are raised, the tongue is pressed against palate, and the
epiglottis closes.
C) Superior constrictor muscles contract and force food into the esophagus.
D) Peristaltic wave move food through the esophagus to the stomach
21.
Name the function of the epiglottis, and label it in the diagram above.
The epiglottis closes off the airway during swallowing.
22.
Define the term peristalsis and explain its digestive function.
A) Accomplished by movements down the longitudinal muscle layer propelling
action. B) As food passes, one section of the tube relaxes opening next section
food moves on.
23. Name the tube that carries food from the mouth to the stomach and label it in the diagram
below.
Esophagus
24.
Define the term gastric.
Stomach
25.
Describe the macroscopic structure of the stomach and locate each portion in the diagram
below and on the torso model.
J- shaped pouch like organ contains extra oblique layer in muscularis under diaphragm
left side.
Proximal cardiac region, ballooned fundic region, and distal pyloric region. Greater
curvature versus lesser curvature and bulk is called the body.
26.
Name the term used to describe the mucosal folds of the stomach lining and explain their
significance.
Rugae
27.
Discuss the histology of the stomach wall.
Gastric villi form gastric pits are lined by gastric glands with Chief cells, (pepsin),
Parietal cells (HCl and Intrinsic Factor), Mucous cells (mucus) and G-Cells (gastrin).
28.
Name the five types of cells that compose gastric glands, name the secretion(s) that each
cell produce(s) that together compose gastric juice, identify each on the diagram below,
and give the function of each component of gastric juice.
Gastric pits are lined by gastric glands. Gastric glands secrete gastric juice; Gastric glands
are composed of four types of cells: 1) chief cells secrete enzyme pepsin. 2) Parietal cells
secrete hydrochloric acid and intrinsic factor. 3) Mucous goblet cells secrete mucus. 4)
G- cells secrete hormone Gastrin.
29.
Define the term chyme.
Food plus mixing with gastric juices.
230.
Name one substance that is absorbed through the gastric mucosa.
Toxins, alcohol, some vitamins are absorbed.
31.
Name the hormone that regulates the release of gastric juice, circle it in the diagram
below, name the cell that secretes it, explain when it is released, and the results of its
action.
When food enters the stomach, G-cells secrete the hormone gastrin. Gastrin travels
through the bloodstream and targets gastric glands. Gastrin stimulates glands to release
more gastric juice rich is pepsin, HCl, etc. It also stimulates mixing action and constricts
the gastroesophageal sphincter and over time, relaxed the pyloric sphincter.
32.
Using anatomical terminology, describe the location of the pancreas in the abdominal
cavity, and label it below.
Pancreas is posterior to stomach.
Copyright 2011 Dr. Mary Cat Flath
(of Vater)
(of Oddi)
33.
Explain how the pancreas aids in digestion by listing the components in pancreatic juice,
and naming the action of each of those components.
The pancreas secretes pancreatic juice containing amylase, proteinases, lipases, and
nucleases into duodenum. These enzymes work in the duodenum and break down
polysaccharides, proteins, triglycerides, and nucleic acids, respectively.
34.
Name the site of pancreatic enzyme action, and label it in the diagram above.
Duodenum
35.
Name the regulatory hormone responsible for the release of pancreatic juice into the
duodenum, explain when it is activated, and circle its name in the diagram below.
Secretin. It is released from the intestinal mucosa when acidic chime enters. It travels
through the bloodstream and targets the pancreas to release of its bicarbonate rich
pancreatic juice into duodenum.
Copyright 2011 Dr. Mary Cat Flath
36.
Define the term hepatic.
37.
liver
Using anatomical terminology, describe the location of the liver in the abdominal cavity,
and label it in the diagram below.
Upper right quadrant below diaphragm.
38.
Name the functional unit of the liver and describe its general structure as seen in diagram
(a) below.
The functional unit of the liver is the hepatic lobule.
39.
Define the terms hepatocyte and liver sinusoids, and label each in diagram (b) above.
Hepatocytes- liver cells; which provide most functions.
Liver sinusoids- liver capillaries. Blood enters and hepatocytes remove oxygen,
nutrients, poisons, worn cells, and debris.
40.
Describe the many functions of the liver.
Produces bile (digestive function = emulsification of fat), filter blood of toxins and
debris, metabolizing of all simple nutrients, and storage of glycogen, iron, and more.
41.
Name the two blood vessels that supply the liver lobules with blood and track the flow of
blood into and out of the liver lobule.
Hepatic Artery
Hepatic portal vein
Hepatic Artery
(Oxygenated Blood)
from aorta)
Hepatic Portal Vein
(Deoxygenated Blood with
newly absorbed nutrients
from Small intestine, etc.)
Liver Sinusoids
(Exchange)
Central Vein of Hepatic Lobule
Hepatic Vein
Inferior Vena Cava
42.
Name the components of a portal triad, and label them in the diagram 38b above.
Branch of hepatic artery, branch of hepatic portal vein, and a bile duct.
43.
Explain the significance and location of Kupffer's cell.
Macrophages in liver tissue which filter and destroy debris and worn cells from blood
through phagocytosis. They are part of the lymphatic system and help control disease.
44.
Define the term emulsification and explain its role in digestion.
Emulsification = breaking large fat globules into small fat droplets, increasing surface
area so lipases can work more effectively. Bile is released into duodenum through
common bile duct. It emulsifies fat and also aids in absorption of fat and fat soluble
vitamins.
45.
Using anatomical terminology, describe the location of the gallbladder in the abdominal
cavity and label it in diagram 36 above and in the diagram below.
Inferior to liver.
46.
Name the function of the gallbladder.
Stores bile between meals.
47.
Name the "common" route that bile travels from either the liver or gallbladder, name the
site where bile is deposited, and label each in the diagram below.
Bile is deposited into duodenum from either the liver or gallbladder. The cystic duct
from the gallbladder and the hepatic duct from liver come together to form the common
bile duct. There is a valve that keeps the common bile duct closed until it is stimulated
with CCK below.
48.
Name the regulatory hormone that is responsible for the release of bile into the duodenum
explain when it is activated, and circle its name in the diagram below.
When fatty chyme enters the duodenum the intestinal mucosa release the hormone
cholecystokinin (CCK) into the bloodstream. CCK targets the gallbladder and causes
contractions that cause the deposition of bile into the duodenum.
49.
Name the three parts of the small intestine, and locate each on the diagram below and on
the torso model.
Duodenum
Jejunum
Ileum
50.
Discuss the histology of the small intestinal wall.
Macroscopic villi with mucosa, submucosa, muscularis, and serosa. Mucosa lining is
simple columnar epithelium and contains goblet cells and microvilli = protection,
secretion, and absorption. Submucosa with blood vessels carries away absorbed
nutrients. Muscularis functions in peristalsis. Serosa (SSET/LACT) provides lubrication
and cushioning.
51.
Name the digestive enzymes that are secreted by the mucosa of the small intestines and
explain the action of each.
Duodenal mucosa secretes lactase, sucrase, and maltase, which break disaccharides into
monosaccharides; peptidases which break peptides into amino acids; lipases which
continue to clip two fatty acids off triglycerides, leaving monoglyceride and 2 fatty acids.
52.
Identify the simplest forms of food that are absorbed through the mucosa of the small
intestine, name the transport process by which each is absorbed, and describe the fate of
each absorbed nutrient.
Monosaccharides are absorbed by facilitated diffusion (and active transport). They are
carried away by submucosal blood capillaries into the bloodstream (i.e. mesenteric vein
to hepatic portal vein to liver).
Amino acids are absorbed by active transport. They are carried away by submucosal
blood capillaries into the bloodstream (i.e. mesenteric vein to hepatic portal vein to liver).
Fatty acids and monoglyceride are absorbed by simple diffusion into intestinal mucosa.
They are recombined into chylomicrons that are absorbed by a lacteal into the lymphatic
system.
53.
Define the term lacteal, explain its significance, and be able to identify the lacteal below.
Lymphatic capillaries in each intestinal villus that absorb dietary fat.
54.
Distinguish between the duodenum and the distal small intestine (i.e. jejunum and ileum)
in terms of function. Review the location of each in diagram 48 above.
Duodenum (proximal) = site of completion of digestion.
Jejunum = bulk of intestinal length = site of absorption of simple nutrients.
Ileum (distal) = distal end which meets with cecum of large intestine.
55.
Name the four parts of the large intestine and locate each on a diagram or torso model.
1. Cecum
3. Rectum
2. Colon
56.
3. Anus
Name the four parts of the colon and locate each on the diagram below and on the torso
model.
Ascending colon (right side)
Transverse Colon (across from right to left)
Descending Colon (left side)
Sigmoid Colon (back to center)
57.
Identify the major functions of the large intestine.
Reabsorption of water and electrolytes.
58.
Explain how the movements in the large intestine differ from those throughout the rest of
the alimentary canal.
Mass movements only 2-3 times daily. Peristaltic waves of large intestine move residual
chyme toward anal sphincter muscles.
59.
Define the terms feces and defecation.
Feces = undigested and unabsorbed material.
Defecation = emptying of solid wastes from rectum.
60.
Name the sphincter muscles that open to the outside and explain how their action is
controlled.
Internal and External anal sphincters.
61.
List the four major organic macromolecules that we ingest, and explain how each is
broken down by various enzymes within the alimentary canal. Be sure to include enzyme
names, the location of enzyme action, and the breakdown products that result from the
enzymatic action, and explain any hormonal control of the breakdown. Finally, explain
how and where these simplest food forms are absorbed into the bloodstream or lymphatic
system.
DIGESTIVE SYSTEM SUMMARY TABLE II (Keyed at the end of this exercise)
MACROMOLECULE
INGESTED
SITE OF
DIGESTION
DIGESTIVE
ENZYME(S)
END-PRODUCT(S)
SITE AND MODE
OF ABSORPTION
ABSORBED INTO
BLOOD OR
LYMPH
REGULA-TION
MACROMOLECULE
INGESTED
CARBOHYDRATES
PROTEINS
FATS (TRIGLYCERIDES
OR TG)
NUCLEIC
ACIDS
SITE OF
DIGESTION
1.MOUTH
2.DUODENUM
3.DUODENUM
1.STOMACH
2.DUODENUM
3.DUODENUM
1. DUODENUM
2. DUODENUM
DUODENUM
DIGESTIVE
ENZYME(S)
1. SALIVARY
AMYLASE
2. PANC.
AMYLASE
3. SUCRASE,
LACTASE,
MALTASE
1.PEPSIN
(HCl)
2. PANC.
PROTEASES
3.
PEPTIDASES
1.
PANCREATIC
LIPASES
*BILE
2. DUODENAL
LIPASES *BILE
PANCREATIC
NUCLEASES
END-PRODUCT
(S)
1 & 2.
STARCH AND
GLYCOGEN
TO DISACCHARIDES
1. HCl
DENATURES
PROTEINS
1 & 2.
PROTEINS TO
PEPTIDES
3. PEPTIDES
TO AMINO
ACIDS
BILE
EMULSIFIES
TG’S.
PANCREATIC
LIPASES
BREAK TG’S
INTO FATTY
ACIDS &
MONOGLYCERIDES;
DUODENAL
LIPASES
BREAK TG’S
INTO FATTY
ACIDS
GLYCEROL
NUCLEOTIDES
3. DISACCHARIDES TO
MONOSACCHARIDES
SITE AND MODE
OF ABSORP-TION
DISTAL SM.
INTESTINE ;
FACILITATED
DIFFUSION
DISTAL SM.
INTESTINE;
ACTIVE
TRANSPORT
DISTAL SM.
INTESTINE
SIMPLE
DIFFUSION
DISTAL SM.
INTESTINE
ABSORBED INTO
BLOOD OR LYMPH
BLOOD
BLOOD
LYMPH BY
LACTEAL
BLOOD
REGULATION
SECRETIN
GASTRIN ;
SECRETIN
CCK FOR BILE;
SECRETIN ;
SECRETIN