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