The digestive system

Gastrointestinal (GI) tract

- continuous two with two openings (mouth and anus) -does not enter the body until it is absorbed

Three reasons for secretion

-Breakdown food -balance pH level -liquefies food

What does the tongue do

-Helps to position the food during mastication(chewing) -gathers the chewed food and a ball (bolus) in preparation for swallowing it

Propulsion

-Movement of food along digestive tract -gets it from point a to point B -The major meaning of propulsion is peristalsis

Additional churning in stomach

-Occurs in small intestine through muscular construction of intestinal wall -this process, segmentation is similar to peristalsis

Mechanical digestion

-Process of physically breaking down food into smaller pieces -begins with chewing food and continues with muscular churning of stomach

Tongue

-define slower boundary of them out -tongue covered in papillae (small projections that help get the food-many bare taste buds)

Pharyngeal phase

-involuntary -uvula protect nasal cavity -epiglottis goes down and protect -food goes to the esophagus

Absorbtion

-movement of molecules from digestive track two adjacent blood and lymphatic vessels (by passive defusion/active transport) -entrance of the digested food in the body

Chemical digestion

-process of chemically breaking down food into smaller molecules -carried out by enzymes in the stomach and small intestine and mouth

Meaning of peristalsis

-process of moving food forward Series of alternating contractions and relaxtions of smooth muscle that lines the walls of the digestive organs and that forces you to move forward

Segmentation

-similar to peristalsis except rythmic timing of the muscle constrictions -process of moving food back-and-forth

Palate

-upper boundary of mouth -front part=hard -back part=soft

Buccal phase

-voluntary -Tongue makes bolus -pushes bolus and to throat

Large intestine

5 to 6 feet long, 2.5 inches wide, last 7 to 8 inches is rectum -major iron absorbed: soldium -no chemical digestion occurs -absorbs vitamins for metabolic process

Three phases of swallowing

Buccal, pharyngeal, esophageal

Bile duct

Comes from gallbladder, enzymes enter through the ducks in the laws of gland and from pancreas

Parts of small intestine

Duodenum, jejenum and ileum

Jejenum an ileum

Finishes digestion but mainly absorption and small intestine

Saliva

Has water, enzymes, lysosomes, proteins, anti-bodies -lubricates mouth, softens food when chewing, protects mouth against pathogens, begins chemical digestion

Villi and microvilli

Increases surface area and contains capillaries and lymphatic vessels

Seven steps

Ingestion propulsion secretion mechanical digestion chemical digestion Absorption defication

Esophagus

Long tube that begins at laryngopharynx all the way down thru the cavity between the lungs, moves food down

Teeth

Lower and upper jawbone -incisors; biting -canine; tearing -premolars and molars; grinding and crushing

Liver

Makes bile, Controls breakdown of sugar, vitamin storage, remove drugs and hormones from body

Pancreatic duct

Merges into hepatopancreatic ampulla

Process of the G.I. tract

Mouth -> pharynx -> esophagus -> stomach -> small intestine -> large intestine

Controlled release

Movement of chyme into smaller intestine is regulated by The valve pyloric sphincter

Vestibule

Narrow region between the cheek and Teeth and between the lips and teeth

Gastric juices

Needed to activate enzymes, helps break down food into smaller pieces

Bile

Neutralizes stomach acids

Ingestion

Process of eating

Defication

Process of eliminating undigested material through the anus

Chemical breakdown

Proteins chemically breakdown by enzyme pepsin. It doesn't self digest do to mucus layer

Function of large intestine

Reabsorbs water and ions and compact feces

Duodenum

Receives spurts of chyme released from stomach through the pyloric sphincter

Pancreas

Secretes pancreatic juices to help break down food into tiny pieces

Secretion

Secretion Of digestive enzymes and other substances liquefies, Adjust the pH of, and chemically break down the food

Mixing

Stomach mixes the food with water and gastric juice to make chyme

Five functions of the stomach

Storage, mixing, physical breakdown, chemical breakdown, controlled release

Feces

Stores and compacts undigested material

Gallbladder

Stores bile until needed

Accessory organs

Teeth, tongue, salivary glands, liver, gallbladder, pancreas

Uvula

Tell writes back of pilot, prevents food going into your nasal passage while swallowing

Storage

The rugae lets the stomach expand

Physical breakdown

Three layers of smooth muscle churn contents of the stomach, physically breaking down food into smaller particles

Muscles

Three layers of smooth muscle, helps churn food

pharynx

Throat, receives food from mouth during swallowing

What does HCL do

Unfolds proteins and loosens The cementing substances between the cells that HCl also kills most bacteria that may accompany the food

Esophageal phase

When esophageal sphincter closes food passes thru larynx, when food reaches the end cardiac sphincter opens to let food goni to the stomach

Hepatopancreatic ampulla

Where the pancreatic duct and bile duct meat

Importance of temporary storage

You eat faster than you digest food and absorb its nutrients