Download Digestion and Nutruition

Digestion and Nutrition
By Chaan Harris and Halainna Ramos
Digestive System

Digestion- the mechanical and
chemical breakdown of foods and
the absorption of the resulting
nutrients by cells

Digestive system-consists of the
alimentary canal

The alimentary system includes
the mouth, pharynx, esophagus,
stomach, small and large intestine,
and anus; extends about 8 meters
from the mouth to the anus
-The accessory organs include the
salivary glands, liver, gallbladder,
and pancreas
Structure of the Wall

The wall of the alimentary canal consists of four distinct layers that are developed
to different degrees from region to region: Mucosa, submucosa, muscular layer, and
serosa/serous layer

Mucosa/mucous membrane: Surface epithelium, underlying connective tissue and a
small amount of smooth muscle.

Submucosa: Consists of loose connective tissue as well as glands, blood vessels,
lymphatic vessels, and nerves organized into a network called plexus.

Muscular layer: This layer produces movement of the tube. It consists of two coats
of smooth muscle tissue and some nerves organized into a plexus. When the
circular fibers contract, the tube’s diameter decreases.

Serosa/Serous layer: The cells of the serosa protect the underlying tissues and
secretes serous fluid.
Movement

The mouth receives food and begins digestion by mechanically reducing the size of
solid particles and mixing them with saliva

Cheeks and Lips:


The cheeks consist of outer layers of skin, pads of subcutaneous fat, muscles
associated with expression and chewing.
Lips surround the mouth opening

Tongue:

The tongue nearly fills the oral cavity when the mouth is closed. Mucous membrane
covers the tongue; the membranous fold is called the frenulum which connects the
midline of the tongue to the floor of the mouth.

The body of tongue is mostly skeletal muscle. These muscles mix food articles with
saliva during chewing and move food toward the pharynx during swallowing.

Rough projections called papillae on the tongue surface provide friction; also
bears taste buds.

The posterior region, or the root of the tongue is anchored to the hyoid bode

Palate:

The palate forms the roof of the oral canal cavity and consists of a hard anterior
part and a soft posterior part.
In the back of the mouth, on either side of the tongue and closely associated with
the palate are masses of lymphatic tissue called palatine tonsils

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Teeth:

There are 2 different sets of teeth form during development.
-The first set, the primary teeth usually erupt through the gums at regular intervals
between the ages of six months and two to four years.
Teeth

Before the primary teeth shed, their roots are
resorbed. The pressure from the developing
secondary teeth push the primary teeth out of
their sockets.

Teeth begin mechanical digestion by breaking
pieces of food into smaller pieces
-This action increases the surface are of food
particles, allowing digestive enzymes to react
more effectively with the food molecules

Each tooth consists of 2 main portions: The
crown and the root

Glossy white enamel covers the crown. Enamel
consists of mainly calcium salts and is the hardest
substance in the body.
Teeth cont.


Dentin is a substance close to bone, but is much harder.

Surrounds the tooth’s central cavity which contains a combination of blood
vessels, nerves , and connective tissue called pulp.

Blood vessels and nerves reach this cavity through tubular root canals
extending into the root
A thin layer of bonelike material called cementum encloses the root. The
periodontal ligament surrounds the cementum. This ligament contains bundles of
thick collagenous fibers
Salivary Glands

The salivary glands secrete saliva. – The fluid moistens food particles, helps bind
them, and begins the chemical digestion of carbohydrates.

Within a salivary gland are two types of secretory cells: serous cells and mucous
cells

Serous cells produce watery fluid that contains that digestive enzyme amylse

When a person sees, smells, or thinks, parasympathetic nerve impulses elicit the
secretion of a large volume of watery saliva

Paratial glands- are the largest of the major salivary glands.
-Each gland lies anterior and somewhat inferior to the ear

Sybmandibular glands- located on the floor of the mouth on the inside surface of
the lower jaw
Pharynx and Esophagus

The pharynx connects the nasal and oral cavities with the larynx and esophagus. It
has 3 parts

Nasopharynx- communicates with the nasal cavity and provides a passageway
for air during breathing

Is posterior to the soft palate and inferior to the nasopharynx

Laryngophanrynx is inferior to the orophyrnx; pathway to the esophagus
Swallowing Mechanism

Food is mixed with saliva and forced into the pharynx

Involuntary reflex actions force the food into the esophagus

The soft palate raises, preventing food from entering the nasal cavity

The hyoid bone and larynx is are elevated. The epiglottis blocks off the
top of the larynx so the food doesn’t enter the trachea

Peristalis transports food to the stomach
Stomach
The stomach is divided into 4 parts:
Cardiac, fundic, body and pyloric
regions
-The cardiac region is a small area near
the esophageal opening.
The fundic region is a temporary storage
area
The body region is the main part of the
stomach and lies between the fundic
and pyloric portions
The pyloric region narrows and becomes
the pyloric canal as it approaches the
small intestine
Pancreas

The pancreas produces pancreatic juice that is secreted into a pancreatic duct

Pancreatic juice contains enzymes that split carbohydrates, proteins, lipids,
and nucleic acids

The carbohydrate digesting enzyme is pancreatic amylase, which splits the
molecules of starch/glycogen into double sugars

Pancreatic lipase is a fat digesting enzyme that breaks triglyceride molecules
to fatty acids and glycerol

Nucleases are enzymes that break down nucleic acid molecules into
nucleotides

Trypsin, chymotypsin and caboxypeptidase are protein splitting enzymes
Liver

The liver is located in the upper right quadrant of the abdominal cavity and is
inferior to the diaphragm


Functions: metabolizes carbohydrates, lipids and proteins
 Filters blood
 Destroys toxins
 Secretes bile
 maintaining normal concentration of blood glucose

transports fat to adipose tissue
The gallbladder stores bile between meals
Small/Large Intestine

The small intestine is a tubular organ that
extends from the pyloric sphincter to the
beginning of the large intestine. –fills most
of the cavity

Has 3 portions: the duodenum, jejunum
and the ileum

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The large intestine starts in the lower
right side of the abdominal cavity
where the ileum joins the cecum
(beginning of intestine). –It ascends
to the right, crosses left, and descends
into the pelvis
It opens to the outside of the body as
the anus
The narrow tube with a closed end is
called the vermiform appendix
**Fun Fact: the human appendix has
no known digestive function
-It absorbs water and electrolytes and
forms and stores feces
Small/Large Intestine
Vitamins/ Minerals

Vitamins are organic compounds other than carbs, lipids and proteins
- Fat-soluble vitamins are vitamins A, D, E and K; water –soluble are B and C

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Fat-soluble vitamins dissolve in fat which associates them with lipids and are
influence by the same factors that affect lipid absorption
-Fat-soluble vitamins can accumulate in various tissues and can lead to
overdose conditions.
Vitamin B help oxidize carbohydrates, lipids, and proteins; Vitamin C promotes
iron absorption
Dietary minerals are essential in human metabolism
 Some minerals are part of inorganic compounds, like calcium phosphate of
bone
 They play vital roles in nerve impulse production, muscle fiber contraction and
maintenance of the pH of body fluids
Carbohydrate, Lipid and Protein
Digestion

Carbohydrates are organic compounds used to supply energy for cellular processes

They can be ingested in a variety of forms: starch from grains and vegetables,
glycogen from meats, disaccharides from cane sugar, and monosaccharides from
honey and fruits.
-Liver enzymes catalyze reactions that convert fructose and galactose into
glucose, which is the carbohydrate form mostly used for cellular fuel
Digestion breaks down complex carbohydrates into monosaccharides which are
small enough to be absorbed

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Lipids: include fats, oils and fatlike substances; they supply energy for cellular
processes

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Mostly found in meats, eggs, milk, nuts and lard (both plant- and animal-based foods)
Proteins: Supply energy after digestion breaks them down into amino acids; they
control metabolic rates, clotting factors, elastin/collagen of connective tissue

Found in meats, fish, poultry, cheese/milk, eggs and cereals
Healthy Diets

An adequate diet provides sufficient energy, essential fatty acids, amino acids,
vitamins and minerals to support growth and repair body tissue

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Individual requirements for nutrients vary with age, sex, growth rate, amount of
physical activity, and levels of stress.

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If a person lacks essential nutrients, malnutrition can be a result. This can be due to
undernutrition (symptoms of deficiency diseases) or overnutrition (excess nutrient
intake)
A measurement called body mass index, or BMI is used to determine whether a person is
of adequate weight, overweight, or obese. *Obesity rates are increasing in the U.S and
raises the risk of developing cardiovascular disease, diabetes, and/or cancer
Food pyramids are used to organize foods according to suggested amounts (serving
size)
Adequate Diet

In order to have an adequate diet, an athlete would have to have a strict diet to
follow.
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They would have to load up on carbohydrates (it’s the main source of energy);

For muscle tone, eat about 5 oz. of proteins (but not too much; it doesn’t provide a
lot of energy, but its good for building muscle tissue; Calcium for bones (dairy)
-For long events like marathons, athletes eat a lot of unsaturated fat from
foods like nuts, vegetable oils and fatty fish.

A person with a heart condition however, won’t be able to eat the same foods, or
the same amount as athletes.
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They are more likely to eat low-sodium canned vegetables and fruits

Grains: Whole-Wheat flour, High-fiber cereal, oatmeal, ground flaxseed and brown
rice
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Proteins- Low-fat dairy products, egg whites, fish (mostly fatty, cold-water),
skinless poultry, soybeans and soy products
Diseases in the Digestive Sys.

There are many types of diseases in the digestive system:

Anorexia nervosa- self starvation
Cachexia-state of chronic malnutrition and physical wasting
Cholelithiasis- inflammation of the gallbladder
Dysphagia- Difficulty swallowing
Enteritis- Inflammation of the intestine
Gastrectomy- partial or complete removal of the stomach
Glossitis- inflammation of the tongue
Hyperalimentation- long-term intravenous nutrition
Pharynatitis- inflammation of the pharynx
Stomatitis- inflammation of the lining of the mouth
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Works Cited
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www.aokain.com/stomach-diagram-labeled/
Shier, David. Hole’s Essentials of Human Anatomy and Physiology. 9th Edition.
Boston: New York, 2006. 386-422. Print.
www.colgate.com/app.CP/US/EN/OC
www.enchantedlearning.com/subjects/anatomy/digestive/labeleasy/
En.wikipedia.org/wiki/Small _intestine
www.everythingessential.me/HealthConcerns/DigestiveDisorders.html
Jaret, Peter. “Top Nutrition Tips for Athletes”. WebMD. June 17, 2012. WebMD..
Web. April 29, 2014 http://www.webmd.com/fitness-exercise
Mayo Clinic Staff. “Heart-healthy diet: 8 steps to prevent heart disease”. 20 April
2014. Mayo Clinic. 20 April 20114. Web. <http://www.mayoclinic.org/diseasesconditions>
www.pwsausa.org/syndrome/foodpyramid.htm
www.sites.duke.edu/sofabkidsculinarycamp2013/
www.washingtonpost.com/wp-srv/nation/daily/graphics/diet_042005.html