Digestive System

Villi

Fingerlike extensions in the intestinal wall that increase surface area

Mouth

Food mixes with saliva masticated(Chewed) Function of the Tongue: Tongue mixes food with saliva and initiates swallowing

esophagus

Literally a food chute; it has no digestive or absorptive role

Mechanical Digestion versus Chemical digestion

Mechanical Digestion-prepares food for chemical digestion. It begins in the mouth as food is chewed. Inside the stomach, mechanical digestion called peristalsis occurs, which are contractions that help churn the food. Chemical digestion begins with the salivary glands that release amylase enzymes that help digest carbohydrates. Chemical digestion also occurs in the stomach and small intestine. Chemical digestion is the process where acids, base and enzymes released in the digestive tract responds to semi-solid food lumps.

Alimentary Canal=digestive tract

mouth>pharynx>esophagus>stomach>small intestine>large intestine>anus

Ingestion:

food is placed into mouth before it can be otherwise acted upon by the body an active and voluntary process Organis in Play: Mouth

peristalsis

rhythmic wave like contractions that moves food to different processing stations in the digestive tract. Begins in the esophagus. The wave like motions of the mouth muscle to esophagus carry food to the stomach. Peristalsis continues in the small intestine and concludes in the large intestineMec.

Name the Accessory organs:

-Teeth -Salivary Glands -Pancreas -Liver & Gallbladder

4 stages of digestive system

1. Ingestion-the act of taking a substance such as food or liquid, into the body by the oral cavity (mouth) 2.Digestion-The physical and biochemical breakdown of food by the body. Food is mechanically broken down by teeth, turning it into smaller pieces. The stomach and instestines also churn and squeeze this food with their muscles to break it down physically. Chemical digestion happens when enzymes break down food into molecules the body can absorb. 3.Absorption- Cells absorb the small molecules of amino acids and simple sugars. Microvilli in the small intestine absorb nutrients 4> Elimination-undigested material passes out of the digestive system through the anus.

stomach

An anatomical region where mechanical digestion takes place Organ in which protein digestion begins Generally takes about 4 hrs for stomach to empty completely after a well-balanced meal. 6 hrs if it was high in fat.

pharynx

Common passage for food and air

Function:

Ingests food Digest food Absorb Get rid of what remains Alimentary Canal (GI Tract)-the whole passage along which food passes through the body from mouth to anus. It includes the esophagus, stomach, and intestines.(Mouth, Pharynx, Esophagus, Stomach, Small and Large Intestines and Anus.

Pancreas

Only organ that produces enzymes

anus

Opening through which feces are expelled from the body

Large intestine

Organ primarily involved in water absorption and feces formation It contains the colon's -Ascending colon -Transverse colon -Descending colon -Sigmoid colon Major functions: dry out indigestible food residue by absorbing water eliminate residues from body as feces 4 major parts Cecum Appendix Colon Rectum Cecum - sac/pouch that begins large intestine (where leftover food waste enters from small intestine Appendix - can get bacteria growing and can become inflamed (appendicitis) Colon is major part of Large intestine where most of liquid absorption occurs No villi in this section - food has been digested and absorbed already

Small Intestine

Organ responsible for absorption of most nutrients Organ into which the stomach empties Organ that receives pancreatic juice and bile Food absorption happens in the small intestine

Tongue

Organ that mixes food in the mouth

Salivary glands

Produce enzymes that beginn carbohydrate digestion

Liver

Produces Bile contains bile salts and phospholipids

Pancreas

Produces a juice that neutralizes stomach acid and contains digestive enzymes

Liver

Produces bile

Microvilli

Projections of the plasma membrane of a cell that increase the cell's surface area

Gall Bladder

Stores bile until it is secreted

Enzyme

Substance produced by a living organism that acts as a catalyst to bring about a biochemical reaction. digestive enzymes: items that increase absorption of materials, etc.

chyme

Thats what food is called after its been digested Chyme enters small intestine through pyloric sphincter

Cardiac Sphincter

The area where the stomach and esophagus meet

Explain how the small intestines are well adapted for absorption

The muscle wall of the small intestine is thin, with a large surface area. This allows absorption to happen quickly and efficiently. To get a big surface area, the inside of the wall of the small intestine is line with Villi. These stick out and give a big surface area. They also contain blood capillaries to carry away the absorbed food molecules.

View Slide 15

VIEW SLIDE 15!

Villi and Microvilli

Villi - projections of mucosa membrane Microvilli - projections of plasma membrane of mucosa cells plasma membranes have enzymes that complete the digestion of proteins and carbs in small intestine

Digestion

part 2 of digestion) large food molecules are chemically broken down into their building blocks by enzymes carbohydrates -> monosaccharides (glucose, fructose, galactose) proteins -> amino acids lipids -> fatty acids and glycerol nucleic acids -> nucleotides mostly in small intestine through pancreating nuclease enzymes Fiber is an example of types of carbs we cannot break down and get nutritional benefits from, but it helps move foodstuffs along our GI tract (ex: cellulose) Chemical Digestion: Saliva chemically breaks down the food Organs in Play: Mouth, Pharynx, Esophagus, Stomach, Small intestine and Large Intestine

rectum

store feces until they are excreted

Gallbladder

stores bile when not digesting

Propulsion:

to be processed by more than one digestive organ, foods must be propelled from one organ to the next Ex: swallowing, peristalsis can be voluntary (swallowing) and involuntary (peristalsis) Peristalsis - adjacent segments of intestine/organ alternately contract and relax thereby moving foods distally down the tract Segmentation - single segments of intestine alternately contract and relax. Active segments are separated by inactive ones. Food is therefore moved forward and backward. Food is mixed as opposed to being moved down the tract. (mostly occurs in small intestine which helps mix food with digestive juices and move food along the end of the digestive tract) MORE of an example of mechanical digestion. Organs in Play: Pharynx, Esophagus, Stomach, Small intestine and Large Intestine

Absorption

transport of end products of digestion to the blood or lymph mostly happens in the small intestine

Appendix

Blind sac hanging from the initial part of the colon

Small Intestine is a major digestion organ

Body's major digestive organ with 3 subdivisions duodenum, jejunum, ileum *true?* Chemical digestion starts in the small intestine Duodenum is shortest part but does lots of stuff! Enzymes from intestinal cells AND pancreas Bile enters from liver All comes together in alkaline fluid pyloric sphincter- Regulates how much food is going in. Enzymes from pancreas are more significant to digestion than ones secreted from the small intestine cells themselves

Pharynx and Esophagus

Pharynx (Throat) flows into the esophagus -Food passes through the pharynx and the esophagus -Esophagus goes THROUGH the diaphragm on its way to the stomach -Esophagus runs from pharynx to the stomach peristalsis: Mechanism of propulsion of food from pharynx down to esophagus

Mouth (Oral Cavity)

Region where mechanical digestion occurs

Saliva

Saliva - mixture of mucous and serous fluids mucous helps moisten and bind food together - forming the bolus (ball of food formed by mouth to prepare for swallowing) Serous fluid contains salivary amylase - begins process of starch digestion in the mouth Contains lysozyme and antibodies - inhibit bacteria helps dissolve food chemicals so they can be tasted

Defecation:

elimination of indigestible residues from GI tract via anus in the form of feces

Mechanical Digestion:

mechanical food breakdown (part 1 of digestion) Ex: mixing food in mouth by tongue & chewing, churning of food in stomach, squeezing food in small intestine prepares food for further digestion by enzymes, by physically fragmenting food into smaller pieces As food enters and fills the stomach, the walls of the stomach begin to stretch at this point, the three muscle layers of stomach become activated Chewing-Mouth Churning-Stomach Segmentation intestine Organs in Play: Mouth, Pharynx, Esophagus, Stomach, Small intestine and Large Intestine

4 organs/glands that are accessory in the digestive system

salivary glands, liver, gall bladder, and pancreas