Digestive System Walkthrough Powerpoint

Digestive System Digestive System Walkthrough Walkthrough

November 18 2008 Mark Ealy

Digestion Digestion

Digestion Digestion and its 3 Functions and its 3 Functions

Digestion is the process of breaking larger food particles into smaller particles that can pass through the plasma membrane.

Every cell in the body needs nutrients Absorption- The circulation of nutrients in

the bodyElimination- Undigested waste material

Digestive Tract

Mouth/ Oral Cavity Mouth/ Oral Cavity

Receives Food Breaks food into smaller particles by

chewingSalivary glands in the mouth secrete saliva to

help lubricate the food Saliva also has a digestive enzyme named

Salivary amylase, which jump starts starch digestion

Tongue aids in chewing and swallowing and is a muscular organ, that contains taste buds that differentiate taste of different foods.

TeethTeeth

Also housed in the mouth/oral cavity. 32 in a complete set for adults Are used to break food down into smaller

particles for absorption Covered in enamel the hardest substance

in body to keep

Pharynx/ Throat Pharynx/ Throat

Separated into parts Oropharynx- contains the tonsils and is

visible when you look into the mouthNasopharynx – upward to the nasal cavity Laryngeal Pharynx- Downward Extend The Tongue pushes food into the pharynx,

swallowing is involuntary and happens quickly

Soft Palate and uvula raise to prevent food from entering nose cavity

Food enters Esophagus

Esophagus Esophagus

Muscular Tube Measuring about 25 cm No additional digestion occurs in the

esophagus Food is lubricated with mucus and moved

by peristalsis into the stomach Must pass through the Esophageal Hiatus

located in the Diaphragm before connecting with the stomach

Stomach Stomach

J Shaped organ in upper left region of the abdominal cavity.

Has an Angled layer that aids in the grinding of food and mixing of digestive juices.

Contains Sphincters that regulate the size of the opening

Pylorus- Leads to the sphincter that regulates how fast food moves into the small intestines

Functions as a digestive organ, churn, and storage pouch.

Can stretch to hold one half of a gallon of food or water Gastric Juice formed by special cells in the lining of the

stomach

Stomach Cont.Stomach Cont.

Active components of Gastric Juice are :Hydrochloric acid- strong acid that helps break

down protein and destroy foreign organisms Pepsin- Inactive form of protein digesting enzyme

only activated when food enters stomach and HCl is produced

Chyme- Highly Acidic , mixture of gastric juice and food that leaves stomach and enters small intestine.

The Small Intestine The Small Intestine

Longest part of digestive tract! Larger than larger intestines but smaller in diameter average width of

2.5 cm Duodenum- first 2mcm of the small intestines Jejunum- next 2/5 cm Ileum- the remaining portion Mucus protect the intestine from the highly acidic chyme from the

stomach. Most digestion occurs here, due to the juices secreted by many

glands that help aid in the breakdown of carbs and proteins. Most absorption of digested food, water, and minerals also occur

here. Microvilli- increase the surface area of absorption in the small

intestines Contains a specialized lymphatic capillary called a lacteal, which

absorbs fats.

The Large Intestine The Large Intestine

Named for its wide diameter Cecum- first part small pouch Ileocecal valve- between the ileum of the small intestines a

sphincter that prevents food from traveling backward into the small intestines

Veriform- blind tube containing lymphoid tissue Contains the colon that empty in the rectum Rectum- temporary storage area for indigestible or

nonabsorbable food Narrows into the anal canal, which leads to the outside of

the body called the anus

The Large Intestines Cont. The Large Intestines Cont.

Secretes a great amount of mucus, but no enzymes.No food is digested, but some water is reabsorbed

and undigested food is stored and formed into solid waste, called feces and eliminated

Propels solid waste toward the rectum , aided by voluntary contractions defecation is achieved.

Contains an anal sphincter that provides voluntary control over defecation

Some bacteria that live in the colon produce vitamin k and some B complex vitamins

The Accessory Organs The Accessory Organs

The Salivary Glands The Salivary Glands

Food mixes with salvia in the mouth which moistens the food and facilitates chewing and swallowing

Contains antibodies and lysozyme that help reduce bacterial growth

Contains salivary amylase which begins the digestive process by converting sugar to starch.

Manufactured in 3 pairs of glands.

Liver Liver

Body's largest glandular organ Manufactures bile- substance needed for digestion of fats Stores Glycogen and coverts it to glucose to restore normal

blood sugar levels Stores some vitamins and iron Destruction of red blood cells and recycling or elimination

of their breakdown products Synthesis of urea- waste product of protein metabolism Detoxification of harmful substances such as alcohol and

drugs The main digestive function of the liver is the production of

bile, breaks fats into smaller droplets that can be acted upon by digestive enzymes

The Gallbladder The Gallbladder

Muscular sac on the inferior surface the liver that stores bile

Contracts and squeezes bile through the cystic duct and into the common bile duct, when chyme enters the duodenum

Stores bile because the body only needs it a few times a day.

The Pancreas The Pancreas

Long gland that extends from the duodenum to the spleen Produces enzymes that digest fats, proteins, carbohydrates,

and nucleic acids Protein digesting enzymes are produced in inactive form and

must be converted into active forms in the small intestines Produces Alkaline fluid, that balances the acidic chyme

protecting the lining of the SI Can also function as an endocrine gland, producing insulin and

glucagon to regulate sugar metabolism

Enzymes/ WaterEnzymes/ Water

Enzymes are proteins that are catalyst, that speed the rate of chemical reactions

Highly Specific in its action Water – is added to nutrient molecules as they are split by

enzymes. Hydrolysis- digestion by water 7 liters of water are secreted into the digestive tract each

day, in addition to 2 liters taken in with food and drink Helps dilute food to move more easily through tract

Hormones Active In Digestion Hormones Active In Digestion

Gastrin- Stimulates release of gastric Juice Gastric-Inhibitory Peptide- Stimulates insulin release from

pancreas when glucose enters duodenum; inhibits release of gastric juice

Secretin- Stimulates release of water and bicarbonate from pancreas, stimulates release of bile from liver: inhibits the stomach

Cholecystokinin- Stimulates release of digestive enzymes from pancreas, stimulates release of bile from gallbladder inhibits the stomach.