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