Download Period 1 - Digestive System

Digestive System - Period 1
Oral Cavity, pharynx, salivary glands, tongue, and teeth
1.the oral cavity is the first part of the digestive tract. It contains the mouth, teeth, gums, top and bottom of
mouth and cheeks.
2. The salivary glands produce saliva a liquids substance which moistens the mouth, lubricates the
passageway for food and helps to break down carbohydrates.
3.the tongue functions include helping chewing and swallowing, speech and tasting.
4.a small rounded mass of a substance, especially of chewed food at the moment of swallowing.
(the chewed food that you're about to swallow)
5. The hard palate is located on the roof of the mouth. The soft palate is also located on the roof of the mouth
but contains no bone. The function of the soft palate is closing off the nasal passages when swallowing and
closing off the airway. The hard palate spans the arch formed by the upper teeth.
6. Mechanical digestion starts as the food is being chewed. Chemical digestion breaks down food into simpler
nutrients. Chemical digestion starts when food mixes with saliva
7. The epiglottis is a lid-like structure that covers the larynx during swallowing to prevent food from entering the
airway.
8. An adult normally has 32 teeth.
Esophagus and Stomach
Function:
(BM) Esophagus- carries food, liquids and saliva to the stomach.
(Rm)Stomach- break down and digest foods, and extract nutrients from your food needed for your body's
everyday needs. Also produces multiple enzymes.
Questions 1-4 (BM)
1. What is peristaltic movement and how does it function in the esophagus?
 An involuntary movement of the contraction and relaxation of muscles. In the esophagus, it works by
propelling a ball of food down to the stomach by creating a wave like motion. It can also occur in the
stomach and small intestine.
 (ND) What is peristaltic movement and how does it function in the esophagus? Peristaltic
movements are involuntary movements of muscles that come in the form of waves. In the esophagus,
peristaltic waves begin at the top of the tube, and they push the food down to your stomach.
2. Does any digestion of food occur in the esophagus?
 No, the esophagus is simply the tube that carries food down to the stomach.
 The esophagus is where the swallowed food is pushed. The esophagus connects the throat to the
stomach.
3. What are the primary functions of the stomach?
 When food enters the stomach, the opening at the bottom, closes and food enters the stomach. It
begins breaking down food by secreting acids and enzymes that break down food. As it secrets the
acids the stomach then contracts to mix the acid and enzymes with the food. Because acid could harm
the stomach it creates a sticky neutralizing substance that lines the walls. The stomach can also store
food. It can store up to about a quart of food.
4. What is chyme and how does the stomach mix this material?
 Chyme is the acidic fluid composed of partially digested food that travels to the small intestine. The
stomach mixes this by combining food, enzymes and gastric juices. (Clear fluid produced by the
stomach)
 Chyme is a thick semi-fluid of partially digested foods do digestive secretions that forms in the stomach
and intestine during digestion. Muscle contractions of the stomach walls help mix food and digestive
substances together, forming chyme.
(RM) 5. What role does the stomach play in decontaminating the incoming food matter?
 The stomach releases enzymes that kill bacteria in your food and balance pH.
 The stomach releases protease enzymes that kill most bacteria and balance pH.
(RM) 6. Why doesn't gastric juice digest the inside of the stomach?
 The stomach wall is made up up of mostly proteins, without it being protected the acid in our stomachs
would eat right through it.
 The stomach wall is made up mostly of protein. If left unprotected the gastric juices would eat through
the walls of the stomach. Fortunately, the stomach walls have a lining that contains epithelial cells that
secrete a protective layer of mucus and bicarbonate.
(RM) 7. What are sphincters and how are they related to the stomach?
 Sphincter at the opening into and out of the stomach. They open and close when needed to allow food
into the stomach or allow digested food out of the stomach. So the lower esophageal sphincter
(entrance) regulates food passing from the esophagus into the stomach and prevents contents from the
stomach from reentering the esophagus. Pyloric sphincter (exit) governs the passage of food out of the
stomach out of the stomach and to the small intestine.
 A sphincter is a ring of muscle surrounding and serving to guard or close an opening of a tube. There
are 2 sphincters in the stomach, one at the top, called the cardiac sphincter, and the one at the bottom,
called the pyloric sphincter.

(RM) 8. What mechanical and chemical digestion occurs in the stomach?
A type of mechanical digestion that occurs in the stomach is churning. A type of chemical digestion that
occurs in the3 stomach is the role of gastric acid. Mechanical digestion is when the stomach churns to
break down food. Chemical digestion is when the stomach releases enzymes to break down food (
gastric enzyme, lipase, pepsin, HCL).
 Digestion in the stomach includes the the stomach walls contracting to “mash” the food and break it
down. Chemical Digestion includes the chemicals being churned in the stomach using acids and
enzymes, to break it down into more digestible forms.
Small intestineConsist of three parts:
 Duodenum (Connects to stomach)- Where food from the stomach enters to be mixed with bile, first part
of absorption of nutrients begins here
 Jejunum (middle part of small intestine)- Most nutrients are absorbed here before being passed to the
ilum for further absorption
 Ileum (Connects to collon)- Made up of folds that absorbs bile salts that are sent to liver and absorbs
whatever is left (TG)
PH levels and how it is maintained…
Within the small intestine the pH level gradually increases in the small intestine, from about 6 pH in the
duodenum to about 7.4 in the ileum. PH level, when measured at a higher level means it has more of an
alkalinity (capability of water neutralizing acidity), while a lower measure means higher acidity. This level is
maintained through the pancreas, gallbladder, and the lining of the small intestine which secretes a base
(alkanin) to act as a buffer which lowers the acidity levels. (TG)
The duodenum gets pancreatic enzymes from the pancreas. The liver and gallbladder send bile to the
duodenum. Both of the fluids are sent through the opening called the Sphincter of Oddi. (CC)
The walls of the intestines are made of muscle, the organs are also hollow. The movement of these organs is
called peristalsis. When the organs move, they push along the food to the other parts of the body.(CC)
The small intestine is where most of the chemical digestion happens. Some of the enzymes that help break
down the food are produced in the pancreas, and then are sent to the smaller intestine to aid digestion. When
food enters the small intestine, a hormone is released, signalling the enzymes that help break down the food to
be released. Some of the enzymes that help break down the food are lipase for lipids, nuclease and
nucleosidase for breaking down nucleic acid, trypsin and peptidases for breaking down proteins, pancreatic
amylase and finally, maltase for the breaking down of carbohydrates.(CC)
More about the Small Intestine
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Duodium
 Connects the small intestine to the stomach
Jejunum
 Absorbs nutrients
Ilium
 Absorbs the rest of the nutrients left over from jejunum like vitamins and bile salt then transports
it to large intestine
PH levels
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Range from 5.7 to 7.4
A major gastrointestinal hormone secretin is released because of possible HCl presence in the duodenum
Entering the small intestine
 Bile
 Comes from liver which enter the duodenum through an opening called the sphincter of Oddi
 Pancreatic enzymes
 Comes from pancreas which enter the duodenum through an opening called the sphincter of Oddi
Movment
 Walls contain muscles that push the food through
 Movement is called peristalsis
Ensymes
 Pancreatic amylase
 Completes digestion of carbohydrates, producing glucose
 Maltase
 Starch is partially converted to maltose, maltase converts maltose to glucose
 Trypsin
 Helps absorb protein
 Peptidases
 Breaks big molecules into smaller ones
 Nuclease
 Breaks bonds
 Nucleosidases
 Realeases purines and pyrimidine bases
 Lipase
Large Intestine

MN - The major function of the large intestine is to absorb water from remaining indigestible food and
transmit useless waste from the body.

MN - The way it maintains water balance is by absorbing water from food. If this water is not being
absorbed, then you develope something known as hyponatremia, or low sodium levels, because they
have been diluted by the water in your body. Hyponatremia can lead to the swelling of the cells, which
can be expressed through symptoms like nausea, vomiting, headache, confusion, fatigue, restlessness;
and can cause muscle weakness, spasms, cramps, seizures, and coma. If there is not enough water being
taken in through food in the first place, this can cause a difficulty in regulating body temperature and
metabolism, slowed blood circulation and detoxification. Too little water absorbed can lead to diarrhea,
and too much can lead to constipation.

HC-Ions and nutrients released by gut bacteria and dissolved in water are absorbed by the large
intestine.
Ascending colon: Carries feces to the transverse colon.
Transverse colon: To extract water and nutrients from digested food. It is also the connection to the
descending colon.
Descending colon: To store remains to be sent to the rectum.
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Pancreas
Size: The of the pancreas is about 6 inches long across the back of the abdomen. Located on the
right side of the abdomen, connected to the
First section of the small intestine by a tube called the pancreatic duct. Located by the stomach and
liver.
Functions of the pancreas and how it is directly related of digestion: The pancreas is directly
connected to the digestive system by producing enzymes or digestive juices, the pancreas secretes
into the small intestine to further the digestion of food after going through the stomach. This gland
also produces a hormone insulin which enters the bloodstream to regulate glucose/ sugar levels.
How does the pancreas connect to the rest of the digestive system?
The pancreas produces digestive enzymes that enter into the small intestine, these enzymes break
down food into energy. It also produces an insulin with regulates blood sugar levels in the blood and
keeps your body in homeostasis.
What enzymes are produced by the pancreas and what are their functions?
There are many enzymes that the pancreas produces one of these pancreatic proteases that helps
breaks down proteins. Another enzyme is pancreatic amylase which helps digest sugars or
carbohydrates. The last enzyme pancreatic lipase which helps digest lipids. The pancreas also
creates hormones that play a part in the digestive system. One of the most important hormones is
insulin, which regulates blood sugar levels. Another hormone similar to insulin is glucagon which also
regulates blood sugar. The last hormone that the pancreas creates is gastrine which helps with
digesting in the stomach. -EP
How is insulin related to the digestive system?
After food is digested the energy and nutrients are absorbed and spread throughout the body. One of
these used in the body for energy is glucose which is sugar. When you eat a starchy or sugary food
you digest in and then this sugar enters the bloodstream. This sends a signal to your pancreas to
send out insulin. Insulin is the hormone that allows the glucose to be used as energy in your body.
Without insulin to balance out the glucose your body would not be able to maintain homeostasis. -EP
Liver and Gallbladder
The gallbladder is a small pouch that sits just under the liver and stores bile produced by the liver. After meals
the gallbladder may be full of biles and become about the size of a small pear.
1. What is the size of the liver and where is it located?
o The size of the liver is about the size of a football,located above the stomach and below the
diaphragm
2. How does the liver function in relation to digestion?
o The liver has more than one function,but the main function of the digestive system is to process
the nutrients that are in the small intestines.the bile from the liver released into the small
intestines that also has an important role in the digesting fat, also the liver is the body’s chemical
“factory”
3. What are other functions of the liver in the body? (SB)
o The liver filters blood coming from the digestive tract before the blood leads to the rest of the
body. It also detoxifies chemicals and metabolizes drugs inside the blood stream. The liver also
creates proteins that helps with blood clotting for the platelets in the blood. While doing this, the
liver creates bile to be stored into the gallbladder to be used for digestive purposes in the small
intestine.
4. What is the relationship between the liver and the gallbladder? (SB)
o The liver creates bile, which is required to digest food in the small intestine. The two lobes of the
liver contain cells called hepatocytes, which create bile and secretes them into bile ducts that lead
to the gallbladder. The gallbladder stores and concentrates bile until it is used by the small
intestine for digestion
5. What is the function of bile and where does it enter the digestive tract? (SB)
o Bile enters the digestive tract through the duodenum in the small intestine. As stated before, bile
is stored in the gallbladder. After meals, bile that is being stored goes through the cystic duct, to
the common bile duct, and finally to the duodenum, where the bile enters the small intestines for
digestion. The flow of bile into the duodenum is regulated by layers of muscle, known as the
sphincter of Oddi. The sphincter of Oddi is closed between meals and opens during and after the
consumption of food until food is fully digested.