Bio: Digestive system

pancreatic juice

- Mostly water, also contains bicarbonate ions and enzymes

Maltose

A disaccharide or double sugar made of two glucose molecules

Pancreas

A large elongated gland responsible for secreting insulin and enzymes to help digest food. In small intestines

Explain action of bile.

Bile is made in liver, stored in gall bladder and acts as an emulsifier of fats (breaks up/disperses fat molecules). Not an enzyme! Lipase is enzyme that further breaks down emulsified fats molecules.

What is the major role of the digestive system?

Break down food particles to a size (molecules) that can be absorbed into the blood stream for later use Storage of fats which can store large amounts of energy

Jejunum

Middle portion of the small intestine

Parts of the digestive tract

Mouth Pharynx Esophagus Stomach Small Intestine Large Intestine

List in order the structures of the digestive track..

Mouth, oesophagus, stomach, pyloric sphincter, small intestines, large intestines, colon, rectum, anus.

Two types of waste

Solid Waste - from the Digestive System in the form of feces. Metabolic Wastes - produced by chemical reactions like respiration, hydrolysis, synthesis and neutralization. CO2

Large intestine function

Waste is pushed into the expanded portion (rectum) of the large intestine. Solid waste stays in the rectum until it is excreted through the anus as feces. Appendix hangs on the right side of the large intestine.

Digestive enzymes

are special proteins that help break up large molecules of food into very tiny molecules that can be absorbed and used by the cells in the form of nutrition.

Stomach enzymes

pepsin/protease lipase

List any pH changes that occur throughout digestive track.

7.0 pH (neutral)in saliva, 1-3 pH (acidic) in stomach juices, 8 pH (basic) small intestines

Esophagus

A straight muscular tube that is about 10 inches (25 cm) long which connects the mouth with the stomach Food takes about 4 to 8 seconds as it passes through to the stomach. Its walls contain smooth muscles that contracts in wavy motion ( Peristalsis ). Peristalsis propels food and liquid slowly down the esophagus into the stomach. Cardiac Sphincter (ring-like valve) relaxes to allow food into the stomach.

Bile duct

A tube that carries bile from the liver and gallbladder to the intestine

Pyloric sphincter

A valve between the stomach and the small intestine that regulates the flow of chyme into the small intestine.

Organs of excretion skin

Allows water, salt and urea to diffuse from the blood (capillaries) into the sweat glands. Releases sweat from the sweat glands through the sweat ducts out to the skin pores.

Bile

An emulfier produced by the liver that breaks down fat molecules into fat droplets

Liver

Breaks down toxins, such as alcohol and processes nutrients into forms easier for the rest of your body to use. Digestive Helper that helps with bile that is sent to the small intestine to break down lipids into fatty acids.

Chemical digestion

Changes the chemical composition of food with the aid of digestive enzymes Carbohydrate Protein Lipid

Mechanical/physical digestion

Changes the physical form of food (mouth, churning of stomach) Chew Tear Grind Mash Mix

Ileum

END PORTION OF THE SMALL INTESTINE

Removal of wastes

Egestion removal of digestive waste. Excretion removal of metabolic waste.

Duodenum

First part of the small intestine

Mouth

Food enters in the mouth or oral cavity Tasting Mechanical breakdown of food Secretion of salivary glands (salivary amylase) Structures Teeth - cut, tear, crush and grind food. Salivary glands - produce and secrete saliva into the oral cavity. Saliva moistens food and contains amylase which begins breakdown of carbohydrates

Villi

Has folded inner walls covered with fingerlike projections ( villi ; sing. - villus) Each villus has tinier projections called microvilli that absorbs digested food. Villi and microvilli increases the surface area of the small intestine for greater absorption.

Phases of digestion

Ingestion Movement Digestion Absorption Further digestion

Stomach

J-shaped muscular sac Has inner folds that increases the surface area of the stomach. Churns and grinds together the bolus into smaller pieces. Food is mixed with gastric juices (hydrochloric acid and enzymes) secreted by the stomach walls. HCL (Hydrochloric acid) helps break down food and kills bacteria that came along with the food.

Liver

Largest gland of the body Stores vitamins A,D,E,K Stores sugar and glycogen Produces bile (watery, greenish substance) Secretes bile to the gall bladder via the hepatic duct and cystic duct.

Small intestines

Long (20 ft), coiled tube beneath the stomach. Has three parts: Duodenum - upper part; about 10 in; connected to the stomach. - where the digestive juices from the pancreas and the liver combine with chyme making it thin and watery. Jejunum - about 8 ft Ileum - about 12 ft Peristalsis moves the undigested food to the large intestine.

Organs of excretion kidneys

Major excretory organs of the body which removes most of the body wastes. Purify blood by filtering out water, salts, digested food particles and urea in the form of urine. Urine passes out through the urinary tract.

Accessory parts

Organs that are not in the digestive tract but helps in the digestion Teeth Tongue Salivary glands Liver Gall bladder Pancreas

Organs of excretion liver

Part of the digestive, circulatory and excretory systems. Removes excess amino acids from the body. Breaks down the amino acids through deamination to form the urea which is excreted in the urine.

Contents of stomach

Pepsin - major enzyme; converts proteins into peptides in the presence of HCL. Mucus - lubricates food and protects the gastric lining from strong digestive juices. Converts the bolus into a liquid ( chyme ) after 4 hrs of mechanical and chemical digestion Chyme passes through the pyloric sphincter into the small intestine.

Function of digestion

Produces various chemicals to break down the food. Filters out harmful substances. Gets rid of solid wastes (egestion)

Secretions from pancreas

Protease, amylase, lipase, bicarbonate

List enzymes that occur in specific areas of digestive track.

Stomach juices-Protease-protein Saliva-amylase-carbohydrates Small intestines-Lipase-fats/amylase

Gall bladder

Stores and releases bile and bile breaks down fat

Gall bladder

Stores bile in between meals Secretes bile to the duodenum through the bile duct during mealtime. Bile contains bile salts, pigments, cholesterol and phospholipids. Bile is an emulsifier NOT an enzyme. Emulsifier - dissolves fat into the watery contents of the intestine.

What features of the digestive system allow for maximum absorption?

The VILI in the small intestines absorbs molecules into blood stream. Surface area for absorption. Lining of small intestines thin for quick absorption. Finger-like projections along wall.

Digestion

The chemical breakdown of complex biological molecules into their component parts. Lipids to fatty acids Proteins to individual amino acids Carbohydrates into simple sugars

Pancreatic duct

The main duct of the pancreas.Carries the secretions of the pancreas (enzymes and bicarbonate) travel through the duct into the small intestine (dueodenum).

Large intestine

a.k.a. Colon larger diameter, but shorter (5 ft) Water is absorbed from the undigested food making the waste harder until it becomes solid. Waste stays for 10 - 12 hours.

Emulsifiers

help keep fats evenly dispersed within foods. (bile)

Intestinal juices

moisten the chyme, helps buffer acids, and dissolves digestive enzymes and the products of digestion

Amino peptidase

releases free amino acids from the amino end of short chain peptides