Nutrition - 2.1 - Digestion: From Food to Fuel
The GI tract can be divided into 6 main parts
- mouth - esophagus - stomach - small intestine - large intestine - rectum
There are 3 processes the body can use to move nutrients from the GI tract into the blood/lymph system and eventually into the cells:
- passive diffusion - facilitated diffusion - active transport
Additionally, four main organs produce and secrete substances that aid in digestion, but they are not part of the GI tract:
- salivary glands - liver - gallbladder - pancreas
What are the 5 flavors that can be identified by taste buds?
- sweet - salty - sour - bitter - umami (meaty)
The small intestine is approximately
20 feet long
Where energy is required to move substances in or out of the cell. Nutrients move from low to high concentrations.
Active transport
are two types of bacteria that are considered important to our health. While some foods naturally contain these bacteria, other food products have the bacteria added to them.
Bifidobacterial and lactobacilli
is the resulting substance when food particles are mixed with stomach acids and enzymes.
Chyme
The outer layers of the GI tract, both which function to mix & move food along the GI tract.
Circular & longitudinal muscles
is the process of transforming food into basic nutrients that can be absorbed and used by the body.
Digestion
where the first portion of the small intestine is wider than the remainder of the small intestine.
Duodenum
released in the mouth & have specific functions (salivary amylase and lingual lipase)
Enzymes
Tube that connects the throat with the stomach
Esophagus
Where no energy is required, but a special protein carrier is required to help substances cross in or out of the cell. Nutrients move from high to low concentrations.
Facilitated diffusion
True or False: ENG is required for facilitated diffusion.
False, it is not
True or False: The vast majority of all digestion and absorption of nutrients occurs in the stomach
False: In the small intestine
True or False: passive transport requires the use of ENG in the form of ATP.
False; no ATP is needed for passive transport
True or False: Nutrients move from low to high concentrations in facilitated diffusion.
False; they move from high concentration to low concentration
a long hollow tube consisting of several layers of tissue that begins with the mouth and ends at the anus.
GI tract
Is produced when we begin to think about eating foods as well as during the actual ingestion of food.
Gastrin
hormone responsible for controlling the concentration of acid in the stomach.
Gastrin
What are the 2 hormones released by the pancreas to help with glucose regulation
Glucagon and insulin
The final section of the small intestine that connects the small and large itnestines
Ileum
is a vital glycoprotein produced in the stomach.
Intrinsic factor
The middle section of the small intestine
Jejunum
Secretes bile
Liver
Where substances move easily in and out of cells without the use of energy. Nutrients move from high to low concentrations.
Passive diffusion
refers to substances that stimulate bacterial growth in the large intestine.
Prebiotics
are foods that contain these good bacteria.
Probiotics
True or False: Active transport includes endocytosis
True
True or False: Notably, circular bands of muscle are most often found where one part of the tract connects to another, serving as valves to control the flow of the food particles.
True
True or False: Passive Transport includes osmosis and simple diffusion
True
True or False: Passive and Facilitated Diffusion are both considered passive transport
True
True or False: Relative to the small intestine, the large intestine does not play a major role in the digestion and absorption of nutrients.
True
True or False: The stomach is a continuation of the chemical digestion that began in the mouth
True
True or False: Undigested food cannot be absorbed in the small intestine.
True
True or False: both mechanical and chemical digestions take place in the mouth
True
True or False: some types of active transport require the use of protein carrier / transport molecules.
True
The function of the mouth is to ____ the food particles to prepare them to be ____ .
alter; swallowed
seeing the food
appearance
4 sections of the large intestine
ascending colon, transverse colon, descending colon, sigmoid colon
Once food passes through it on the way to the stomach, the sphincter muscle constricts (closes) and prevents the ____ of the stomach contents into the esophagus.
backflow
The ____ in the colon are necessary for breaking down the remaining food products that entered from the small intestine as well as for breaking down of some forms of fiber.
bacteria
Relative to digestion, enzymes ____ the chemical reactions required to break down food particles into smaller parts, which prepares the nutrients for absorption.
catalyze
However, it should also be noted that chemical aids may be present along the various stages of digestion. Enzymes, acid, bile, and mucus are all ___ means the body has at its disposal to further aid in breaking down food.
chemical
The epiglottis folds down over the trachea, or wind pipe, during swallowing to prevent food from entering the trachea. Without this mechanism, food would accidentally enter the trachea, resulting in
choking.
The sphincter muscle is a ____ muscle located at the end of the esophagus.
circular
thoughts about food can start the flow of saliva
cognition
Before food even enters the mouth, a cascade of events involving the nervous system and a variety of hormones are set off based on a variety of stimulus:
cognition, sound, odor, appearance, taste
large intestine is also called
colon
The gallbladder will store the bile until it receives a hormonal signal that fat has entered the small intestine. When this occurs, bile is released into the duodenum through the ____
common bile duct.
Without the process of ____, the nutrients we initially consume in food would be useless.
digestion
Why is it named the small intestine?
due to its small diameter
The bile begins to ____ the fat into smaller pieces that can be mixed with water.
emulsify (break down)
Movement of large molecules into a cell (where cell membrane folds around the molecules)
endocytosis
Notably, ___ are proteins that catalyze (speed up) chemical reactions.
enzymes
The acid in the gastric juice prepares proteins for digestion and activates
enzymes.
The role of the esophagus is to transport food to the stomach. During the swallowing process, food lands on a flap of tissue called the
epiglottis.
The gallbladder release bile when it receives a hormonal signal that ___ has entered the small intestine
fat
Lingual lipase breaks down
fats
As the food waste passes through the large intestine, a semi-solid mass known as ____ is produced.
feces
The stomach has a ____-cup capacity and can hold food for ____ hours, or longer, until it is ready to pass into the small intestine
four; two to three
Where bile is stored
gallbladder
As a continuation of the chemical digestion that began in the mouth, food particles in the stomach are mixed with
gastric juice and enzymes.
An enzyme that begins fat digestion
gastric lipase
Nutrient absorption occurs across the wall of the
gastrointestinal (GI) tract
Within the colon, there are also many mucus-producing cells, the function of which is two-fold: First, the mucus ____ the feces together. Second, the secreted mucus ____ the intestine from bacteria.
holds; protects
Connects small intestine to large intestine
ileocecal sphincter
Higher levels of good bacteria help to protect the body from disease-causing bacteria, and they are an important part of the
immune system.
In order for vitamin B-12 to be absorbed, what must be present?
intrinsic factor
The last section of the digestive tract
large intestine
This intestine is 5 feet long
large intestine
What are the several organs also associated with the small intestines?
liver, gallbaldder and pancreas
Fat-soluble nutrients go into the _____ , while other nutrients are absorbed into the ____ .
lymph system; blood stream
Once food enters the mouth, it begins to break down into smaller units in both ____ & ____ processes
mechanical; chemical
The beginning of the GI tract
mouth
The mechanical process begins in the ____with chewing.
mouth
Also called the intestinal wall
mucosa
The inner-most layer of the GI tract, and it's made of absorptive cells and glands
mucosa
The small intestine is lined with ____ , and it's folded over may times
mucosa
In conjunction with gastrin, ____ is also secreted to line and protect the stomach from its high level of acidity.
mucus
mixes w/ food, lubricating the particles and making it easier to swallow
mucus
The bicarbonate ____ the acidity of the chyme to protect the intestinal wall.
neutralizes
Once absorbed, these ____ can be used to fuel cellular growth, fight infections, and provide energy to our muscles and brain.
nutrients
smells stimulate a hunger response and influence its taste
odor
Chyme is a very watery mixture that slowly empties from the stomach into the small intestine. Depending on the size of the meal consumed, this process occurs over a period of ____ to ____ hours.
one; four
The pancreas releases a mixture of water, bicarbonate, and enzymes called ____ that breaks down carbohydrates, protein, and fats.
pancreatic juice
An enzyme that breaks down proteins
pepsin
What enzymes are in gastric juices
pepsin and gastric lipase
Once in the esophagus, the nervous system sends signals to the surrounding muscles in the GI tract to initiate ____, which propels the food forward.
peristalsis
The mechanical process begins in the mouth with chewing. From there, involuntary muscle contractions are used to move food mixtures along the tract, a process referred to as
peristalsis.
Fermented milk and yogurt are examples of ____ that can be marketed to improve your gut health and digestion.
probiotics
Another sphincter, known as the _____, controls the release of chyme into the small intestine.
pyloric sphincter
Its major role is to control the release of chyme into the small intestine.
pyloric sphincter
What sphincter connects the stomach to the small intestines?
pyloric sphincter
Feces remains in the ____—the end portion of the large intestine—until muscular contractions push it into the anus to be expelled.
rectum
In order to prevent the destruction of the stomach wall, the levels of stomach acid must be closely
regulated.
Enzymes released in the mouth include
salivary amylase and lingual lipase
Explain how chemical digestion occurs in the mouth:
salivary glands secrete saliva which contains mucus ( a lubricant) and enzymes to break down food
The vast majority of all nutrient are absorbed in the
small intestine
Connects the stomach to the large itnestine
small itnestine
hearing a description of the meal
sound
Neither passive nor facilitated diffusion require an initial input of energy to transport nutrients across a membrane. However, a ____ is required for facilitated diffusion.
specialized carrier (or gatekeeper) protein
Salivary amylase breaks down
starches
Role of the stomach is to ___ , ___, ____ & ____ of food.
store, mix, dissolve; continue digestion
The folds, villi, as well as absorptive cells that line the villi expand the absorptive ____ of the small intestine.
surface area
begins as the food enters your mouth and also how it feels
taste
The ____ on the tongue provide the pleasure sensation we experience when we eat.
taste buds
Explain how mechanical digestion occurs in the mouth:
the teeth break food into smaller particles.
As an important component of the mouth, the ____ gives us the ability to taste food.
tongue
The epiglottis folds down over the ____, during swallowing to prevent food from entering the trachea.
trachea (wind pipe)
The role of the esophagus is to
transport food to the stomach.
The expulsion of feces from the body is controlled by ___ anal sphincters.
two
Without the bicarbonate, the high level of acid would destroy the lining of the small intestine, resulting in the formation of an
ulcer.
Within the folds are finger-like projections called ____. ____ help trap food, and they are necessary for the processes of digestion and absorption.
villi
Within the folds of the small intestine are finger-like projections called
villli
What is inside pancreatic juice?
water, bicarbonate and enzymes
Relative to the small intestine, the large intestine does not play a major role in the digestion and absorption of nutrients. However, after leaving the small intestines, the remaining ___ & certain minerals (____, ___, & ___ )can be absorbed in the large intestine.
water; sodium; potassium; chloride