Nutrition Exam #2. Chapter 3 Digestion

Active Transport

Low-high concentration. Requires Energy (ATP). A carrier molecule and energy as ATP shuttle nutrients from low-high concentration. Allows absorption of nutrients even when the concentration outside the absorptive cell is lower than inside the cell. Glucose and amino acids are examples of nutrients absorbed by active transport.

Fluid Absorption in the Large intestine

Majority of nutrients have been absorbed when chyme enters the large intestine Water and salt are absorbed in the large intestine Water: Passive diffusion Sodium: active transport

3.1 Digestion in the Stomach

Mechanical digestion: process mixes and churns the bolus with acid, enzymes, and fluid into a liquid called chyme Chemical Digestion: Pepsin begins digestion of proteins Absorption: A few fat-soluble substances are absorbed through the stomach wall

3.1 Digestion in the Small Intestine

Mechanical digestions and propulsion: Segmentation mixes chyme with digestive juices; peristaltic waves move it along the tract Chemical Digestion: Digestive enzymes from pancreas and brush border digest most classes of food Absorption: Nutrients are absorbed into blood and lymph through enterocytes

What are the major components (organs) of the digestive system?

Mouth, esophagus, stomach, small and large intestines

Segmentation (contractions)

Muscular contractions of the small intestine that move food back and forth, breaking the mixture into smaller and smaller pieces and combining them with digestive juices

Mechanical digestion in the Small intestine

Muscular contractions squeeze the chyme forward while digestive secretions from the pancreas, gallbladder, and intestinal lining chemically break down the nutrients

What organelles are the CEO of the cell?

Nucleus Mitochondria

Extrinsic nerves

Originate in the brain or spinal cord - smell food or have an empty stomach

What does the uvula do?

Prevents food from the going through the nasal cavity

3.1 Accessory Organs: Salivary Glands

Produce saliva, a mixture of water, mucus, enzymes, and other chemicals

3.1 Accessory Organs: Liver

Produces bile to digest fats

3.1 Accessory Organs: Pancreas

Produces digestive enzymes and bicarbonate ions that are released into the small intestine via the pancreatic duct

3.1 Digestion in the Pharynx and Esophagus

Propulsion: swallowing and peristalsis move the bolus from mouth to stomach

Gastrin

Released in the stomach and releases hydrochloric acid.

Undigested food Excreted

Removed by the digestive system Water and bile salts absorbed by large intestines, concentrating the chyme to feces.

Endoplasm Reticulum

Sit of protein synthesis; also involved in lipid synthesis and ethanol metabolism (Rough)

Segmentation function/action

Small and large intestines shifts food back and forth along the intestinal walls, moving it further down the intestinal tract

villi

Small finger-like projections that line the interior of the small intestine

Define Chief Cells

Specialized cells in the stomach that secrete on inactive protein- digesting enzyme called pepsinogen Chemical breakdown of protein

Define Parietal Cells

Specialized cells in the stomach that secrete the gastric juices hydrochloric acid and intrinsic factor. Intrinsic Factor absorbs vitamin B12

3.1 GI Tract process: Sphincter function

Sphincters along the way allow food to pass from one organ to the next. These muscular rings act like one-way doors, allowing the mixture of food and digestive juices to flow into one organ but not back out. Actual definition: A circular ring of muscle that opens and closes in response to nerve input

Rectum

Stool is propelled through the large intestine until it reaches the final 8-inches of the large intestine called the rectum

3.1 Accessory Organs: Gallbladder

Stores bile before release into the small intestine through the bile duct

enzymes

Substances, mostly proteins, that increase the rate of chemical reactions; also called biological catalysts

Define Pharynx

The area of the GI tract between the mouth and the esophagus; also called the throat

Lumen

The channel or inside space of a vessel such as the intestine or artery. The hollow interior of the intestine, creating a velvety appearance. Cause chyme to spiral forward through the small intestine, maximizing its exposure to the villi

3.1 The Process: Elimination

The excretion of undigested and unabsorbed food through the feces

Peristalsis (contractions)

The forward, rhythmic motion that moves forward through the digestive system. Peristalsis is a form of mechanical digestion because it influences motion, but it does not add a chemical

Liver

The largest organ in the body. Located just below the rib cage functions as the major player in digestion, absorption and transport of nutrients.

What are the 3 conditions required for enzymes to be digested?

1. Compatible enzyme and nutrient are present - enzymes are compatible only with specific compound or nutrient (substrate) - Named according to the substrate they act upon Example: sucrase hydrolyzes sucrose 2. Ph of the surrounding environment must fall within correct range. - most active when within a certain range. -outside the range: activity is decreased/halted 3. The temperature of the environment must be optimal. - enzyme is slowed w too low of a temp. halted when the temp. is too high.

How many layers of the stomach are there?

4

Hydrolysis

A chemical reaction that breaks the bond between two molecules with water. A hydroxyl group is added to one molecule and a hydrogen ion is added to the other molecule. Most food molecules are digested by this process.

Pancreas

A large gland located behind the stomach releases digestive enzymes after a meal. The pancreas also secretes the hormones insulin and glucagon, that control blood glucose

3.1 The GI Tract Description

A muscular tube, approximately 23 feet long in an adult that extends from the mouth to the anus

Substrate

A substance or compound that is altered by an enzyme. When a substrate binds to the active site of the enzyme the bond is hydrolyzed.

Absorption in the Large intestine

Absorbs water (1 liter - 4/5 cups) Electrolytes like Sodium, potassium, and chloride. Large intestine also produces a mucus that protects the cells and acts as a lubricant for fecal matter.

Enterocytes

Absorptive epithelial cells that cover villi and have smaller projections than micro villi and they line the walls of the small intestine. ABSORB THE NUTRITION

Ph scale

Acid= Lower pH higher in hydrogen ions Basic= higher pH higher hydroxide ions Neutral 7 pH

Cytoplasm

All your organelles are laid out

Colon

Another name for the large intestine: is the largest portion, further subdivided into ascending, transverse, descending, and sigmoid regions that are long and straight.

Organization of Life: in order

Atom, molecule, cells, tissue, organelle, organ, organ system, organism Smallest unit of life is a cell

3.1 Define Mechanical Digestion

Breaking down food by chewing, grinding, squeezing, and moving food through the GI tract by peristalsis and segmentation

3.1 Define Chemical Digestion

Breaking down food through enzymatic reaction

What does each villi contain?

Capillaries and lymphatic vessels called lacteal that pick up digested nutrients absorbed through the enterocytes and transporting them throughout the body

Essential roles of liver

Carbs metabolism, produces proteins, and manufactures bile salts used to digest fats. Bile is secreted from the liver and stored in the gallbladder. Liver is also the site for alcohol metabolism and removes and degrades toxins and excess hormones from the circulation.

Define Epiglottis

Cartilage at the back of the tongue that closes off the trachea during swallowing

What are the three segments of the Large Intestine?

Cecum, colon, and rectum

What are the segments to the Large intestine?

Cecum: beginning Colon: a. Ascending b. Transverse c. descending d. sigmoid Rectum Internal and External Sphincters

Define goblet cells

Cells throughout the GI Tract that secrete mucus Located on the innnermost layer of the stomach. Protects the body from Hydrochloric Acid

3.1 Digestion in the Large Intestine

Chemical digestion: Some remaining food residues are digested by bacteria Absorption: Salts, water, and some vitamins are reabsorbed Propulsion: Compacts waste into feces

Contact time in the small intestine

Depending on the amount and type of food eaten, the contact time is between 3 and 10 hours. Usually by the time you sit down to dinner, your breakfast is just about reaching the end of the small intestine

Define Gastric Pits

Ducts that are indentations or small puts in the stomach lining where the gastric glands are located; gastric glands produce gastric juices Located on the innermost layer of the stomach

What are the 3 segments and their lengths in the small intestine?

Duodenum 10 inches long, jejunum 8 feet long, ileum 12 feet long

3.1 Digestion in the Rectum

Elimination: Feces are temporarily stored before voluntary release through the anus

Peristalsis function/action

Esophagus, stomach, and small intestine squeezed the food and propels it forward

CCK

Fats and proteins in the duodenum secreted from the small intestine. stimulates the gallbladder and pancreas to secrete bicarbonate ions and enzymes

The stomach acts as a __________ _____.

Holding tank

3.1 Digestion in the Mouth:

Ingestion: Food enters the GI tract via mouth Mechanical digestion: (CHEWING) Mastication tears, shreds, and mixes food with saliva forming a bolus Chemical digestion: Salivary amylase begins carbohydrate breakdown (SALIVA ENZYME)

Intrinsic nerves

Interwoven in the linings of the esophagus stomach, and the small and large intestines. Receive the message from the extrinsic nerves and respond by stimulating the release ghrelin

Intestinal time Process

Intestinal matter takes up to 12-70 hours to pass through the colon depending on person's age, health, diet, and fiber intake.

What is the stomach's capacity?

It can hold one cup when it's empty and 1 gallon or 4 liters at most

Define Small Intestine

The long coiled chamber that is the major site of food digestion and nutrient absorption

Large intestine definition

The lowest portion of the GI tract, where water and electrolytes are absorbed and waste is eliminated. 5 feet long, 2 inch diameter Does not have villi or micro villi, does not produce enzymes, and is not tightly coiled

Define Upper esophageal sphincter

The muscular ring located at the top of the esophagus. Allows the bolus to enter the esophagus

Define Lower Esophageal Sphincter

The muscular ring located between the base of the esophagus and the stomach. Allows food to pass into the stomach. Function: closes to prevent the stomach contents from regurgitating backward into the esophagus.

The anus

The opening of the rectum, or end of the GI tract connected to the rectum and controlled by 2 sphincters: internal and external. usually closed. Final stage of defacation is influenced by age, diet, prescription medicines, health, and abdominal muscle tone.

Digestion Definition

The process in which chemicals and mechanical processes break the bonds and reduce food into individual molecules

3.1 The process: Digestion

The process of breaking down food into individual molecules small enough to be absorbed through the intestinal wall

3.1 The Process: Transport

The process of moving absorbed nutrients throughout the body through the circulatory and lymph systems

3.1 The Process: Absorption

The process of moving nutrients from the gastrointestinal tract (GI) into the circulatory system Class definition: The entry of nutrients into the body and entering the cell

3.1 Define propulsion

The process that moves food along the gastrointestinal tract during digestion

Define Chyme

The semi-liquid, partially digested food mass that leaves the stomach and enters the small intestine. Lower portion of the stomach. Contains digestive secretions and original food

ileocecal valve

The sphincter that separates the small intestine that receives waste from the small intestine

Microvilli

Tiny projections on the villi in the small intestine provide additional surface area and maximize nutrient absorption. Known as brush border. Also secrete digest specific nutrients

Define Esophagus

Tube that connects the mouth to the stomach

Excretion

Unabsorbed nutrients Removed by the excretory system The kidneys filter the blood, allowing waste products to be concentrated in the urine and excreted

How are nutrients transported throughout the body?

Vascular (blood) system Lymphatic sytem both are in each villi

Bacteria in the colon produces what?

Vitamin K thiamin riboflavin biotin Vitamin B12 Only Vitamin K and biotin can be absorbed in the colon.

Stool

Waste produced in the large intestine also called feces. Consists of undigested food residue as well as sloughed off cells from the GI tract and a large quantity of bacteria., Brown color is unabsorbed iron mixing with a yellowish-orange substance called bilirubin. The greater iron content the darker the feces.

Cecum

a pouch at the beginning of the large intestine that receives waste from the small intestine. chyme from the small intestine passes through the ileocecal valve into the cecum before entering the colon.

Water-soluble nutrients

absorbed in the cardiovascular system through the hepatic portal vein to the liver. Carbs, amino acids, and water soluble vitamins. Vascular system

How much chyme is released every 30 seconds?

approximately 1-2 mL or 1 teaspoon

Function of the pancreas

both endocrine (endo= inside) and exocrine (exo=outside). Endocrine organ: releases hormones to maintain blood glucose levels. Exocrine: produces and secretes digestive enzymes into the small intestine.

Ghrelin

brain and appetite control stimulates hunger

Nucleus

contains genetic info ~ DNA

What do nerve cells do?

control the GI system

Lysosomes

digestive systems

Secretin

duodenum in small intestine, stimulates the pancreas to release bicarbonate ions

What systems regulate digestion?

endocrine and nervous system

Fat-soluble nutrients

fat-soluble vitamins, long-chain fatty acids, and proteins are too large to be transported via the capillaries Absorbed into the lymphatic system. Enter the blood stream at the subclavian vein through the thoracic duct.

Prebiotics

food for bacteria that encourage their growth Example: fiber

Facilitated Diffusion

high - low concentration. Requires a carrier protein. Does not require energy. Fructose is an example of a nutrient that needs a carrier to move across a membrane.

Simple or Passive diffusion

high-low concentration does not require energy or a carrier molecule. The process of absorbing nutrients freely across the cell membrane. Water, small lipids, a few minerals, and Vitamin C are examples of nutrients absorbed via this.

Function of villi

increase the surface area to maximize absorption and they help mix partially digested chyme with intestinal secretions.

Endocytosis

large molecules: a type of active transport in which the cell membrane forms an indentation, engulfing the substance to be absorbed. Occurs when a cell forms a vessicle to surround and engulf a nutrient. Inside the nutrient is dissolved in water; "cell drinking" allows whole proteins like immunoglobulin from breast milk to be absorbed intact

Probiotics

living microorganisms found in food. Example: yoghurt

Salivary Glands

located beneath the jaw and under and behind the tongue release saliva in response to the sight, smell and taste of food.

Gallbladder

located beneath the right side of the liver. PEar shaped organ receives bile from the liver through the common hepatic duct, concentrates it, and secretes bile into the small intestine through the common bile duct.

Ferment

metabolize sugar into carbon dioxide and other gases. Bacteria also ferment undigested dietary carbs: methane gas, carbon dioxide, and hydrogen. This process is the major source of intestinal gas.

Golgi Apparatus

packaging site of protein (UPS)

Mitochondria

powerhouse- energy produce in this is called ATP

What does the Pyloric Sphincter do?

prevents chyme from exiting too soon and blocks the intestinal contents from returning to the stomach.

Ribosome

protein synthesis

What does the endocrine system do?

secretes hormones

Short-chain fatty acids

some of the colon's bacteria break down undigested fiber and produce various short-chain fatty acids and other chemical compounds.