Download Digestive System Lab Handout

BIOLOGY 165 DIGESTIVE SYSTEM LAB MANUAL
NOTE: You may be asked to identify any structure, cell, tissue, or organ labeled in the pictures within this lab
manual. In addition, you may be asked to name one function of each labeled item if a function is described in
the manual. You are only responsible for the specific information contained within this lab manual. Although
the pictures in this packet show a particular model, you should look at all similar models we have in the lab;
any model in lab can be used during the practical.
INTRODUCTION
The digestive system consists of the gastrointestinal tract (G.I. Tract) and the accessory organs listed below:
I. Gastrointestinal tract organs:
a. Mouth - with the following accessory organs:
i. Teeth - mechanically masticates (grinds-up) the food.
ii. Tongue - manipulates the food to help form a bolus, secretes the enzyme lingual lipase
(in infants) which starts the digestion of fats, assists in the voluntary phase of deglutition.
iii. Salivary glands - secretes saliva necessary for the formation of a bolus, secretes the
enzyme salivary amylase which starts the digestion of starches.
iv. Hard palate - separates the oral cavity from the nasal cavity, aids in formation of the
bolus.
v. Soft palate (including the uvula) - blocks off passage to the nasopharynx during
swallowing, contains tactile receptors that initiate the pharyngeal phase of swallowing.
b. Esophagus - transports the bolus to the stomach during the esophageal phase of swallowing.
c. Stomach - receives the bolus from the esophagus, mechanically breaks up the bolus, secretes an
acid (HCl) and enzymes that digest proteins and milk (in infants), to form a paste-like mixture
called chyme.
d. Small intestine - absorbs nutrients from food. Associated with the following accessory organs:
i. Pancreas - production and secretion of digestive enzymes through the pancreatic duct and
accessory pancreatic duct into the duodenum; production and secretion of an alkaline
fluid to neutralize the acidity of the chyme entering the duodenum from the stomach.
ii. Gall bladder - stores and ejects bile into the duodenum for the emulsification of fats.
iii. Liver - production of bile, storage of iron and copper, conversion of glucose and storage
of glycogen; synthesis of certain vitamins; production of urea; detoxification of harmful
substances.
e. Large intestine (colon) - absorbs water and electrolytes; forms and stores feces, and expels them
through defecation.
The Oral Cavity (Mouth)
There are three pairs of salivary glands that empty their contents into the oral cavity to lubricate and moisten
materials in the mouth and dissolve materials in food to stimulate the taste buds.
1) The parotid salivary glands secrete a watery saliva containing the enzyme salivary amylase. The saliva
from these glands passes through the parotid ducts and empty into the oral cavity adjacent to the upper
second molar.
2) The sublingual salivary glands empty into the oral cavity next to the lingual frenulum.
3) The submandibular salivary glands empty into the oral cavity just behind the incisors of the mandible.
1
Seen below: Lateral view of the face. Be able to identify the structures shown below, using any similar model
we have in lab.
Seen below: Oral cavity. Be able to identify the structures shown below, using any similar model we have in
lab.
Tongue
2
Seen below: Sagittal section of head. Be able to identify the structures shown below, using any similar model
we have in lab.
Tongue
Seen below: Mandible. Be able to identify the structures shown below, using any similar model we have in lab.
Mandible
3
Seen below: Tooth structure. Be able to identify the structures shown below, using any similar model we have
in lab.
Seen below: Light photomicrograph of taste buds. Be able to identify structures shown below.
s
4
Seen below: GI Tract organs. Be able to identify the structures shown, using any similar model we have in lab.
Esophagus
Liver
(the ridges)
Seen below: Light photomicrograph of stomach. Be able to identify the structures shown below.
s
5
The Liver, Pancreas, Small Intestine, and Large Intestine
The ducts of the liver (right hepatic, left hepatic, cystic, and common hepatic ducts) transport bile secreted by
the liver to the gall bladder to be stored until needed, and through the common bile duct, the major duodenal
papilla, and into the duodenum when fat is present there.
Seen below: Liver and gall bladder. Be able to identify the structures shown below, using any similar model
we have in lab.
Seen below: Liver. The liver is divided into lobes and is anchored in place by ligaments. Be able to identify
the structures shown below, using any similar model we have in lab.
6
Seen below: Spleen, pancreas, and part of the small intestine (duodenum). The pancreas secretes sodium
bicarbonate into the duodenum via the pancreatic duct and accessory pancreatic duct, through the major and
minor duodenal papilla (respectively) to neutralize the acidic chyme coming from the stomach. It also secretes
digestive enzymes that chemically digest the chyme. Be able to identify the structures shown below, using any
similar model we have in lab.
Seen below: Part of the small intestine (duodenum) and pancreas. The small intestine is divided into three
segments: the duodenum, jejunum, and ileum. Be able to identify the structures shown below, using any
similar model we have in lab.
Accessory pancreatic duct
Minor Duodenal Papilla
Major Duodenal Papilla
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Seen below: Parts of the large and small intestines. Be able to identify the structures shown below, using any
similar model we have in lab.
Ascending Colon
Ileum
Appendix
Seen below: Light photomicrograph showing a cross-section of the small intestine. Be able to identify the
structures shown below.
Villi
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Seen below: Light photomicrograph showing a longitudinal section of the small intestine. Be able to identify
the structures shown below.
Seen below: Parts of the small and large intestines. Be able to identify the structures shown below, using any
similar model we have in lab.
Ileum
Ileocecal valve
Ascending colon
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Seen below: Organs of the lower GI Tract. Be able to identify the structures shown below, using any similar
model we have in lab.
Jejunum
Ileum
Ileocecal valve
Cecum
Appendix
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