Upgrade to remove ads
Terms in this set (50)
The building blocks of our bodies and the foods we eat. These are linked by chemical bonds to form molecules.
Made of atoms that are linked by chemical bonds.
The smallest unit of life - made of molecules. Cells of similar structure and function are organized into tissue, and tissue into organs.
A group of organs that work together to perform a particular function.
The digestive system:
The organ system primarily responsible for the movement of nutrients into the body proper.
Organs of the digestive system include:
Gastrointestinal tract (GI tract) and the four accessory organs including salivary glands, liver, gallbladder and pancreas.
The time between the ingestion of food and the elimination of the solid waste from that food. In a healthy adult, 24-72 hours.
Structure of the Gut Wall (Small Intestine):
The wall of the small intestine has four layers: Mucosa, connective tissue, smooth muscle layers and the outer connective tissue layer
The digestion of food and the absorption of nutrients in the lumen of the GI tract are aided by the secretion of muscus and enzymes
How Gastrointestinal Activity Is Regulated
The passage of food and secretion of digestive substances are regulated by nervous and hormonal signals
Digestion and Absorbstion
The processes of digestion and absorbtion begin in response to the smell or sight of food (cephalic phase) and continue as food enters the digestive tract at the mouth
Where food is broken down into smaller pieces by the teeth and mixed with saliva. The chemical digestion of carbs is begun here by the enzyme salivary amylase.
Where food passes after the mouth before it reaches the esophagus.The rhythmic contractions of peristalsis propel food down the esophagus to the stomach. When the weight of the weight of the bolus presses on the lower esophageal sphincter (aka gastroesophageal sphincter and cardiac esophageal sphincter) it will open to allow the bolus into the stomach
Acts as a temporary storage site for food where the muscles mix the food into a semiliquid mass called chyme
How the structure of the stomach supports its function
The lining of the stomach is covered with gastric pits which house the gastric glands that produce the components of gastric juice
A mixture of water, mucus, hydrochloric acid, and the inactive enzyme called pepsinogen, which is activated in the presence of the hydrochloric acid in the stomach into pepsin.
-Pepsin digests protein
In the small intestine, bicarbonate from the pancreas neutralizes stomach acid, pancreatic and intestinal enzymes digest the macronutrients
The digestion of fat in the small intestine is aided by bile from the gallbladder
The main site of digestion of food and the absorption of nutrients.
How Nutrients are absorved
-The absorbtion of fat across the intenstinal muscoa occurs by several different processes.
-Simple diffusion, osmosis, and facilitated diffusion do not require energy, but can only move substances from an area of higher concentration to an area of lower concentration
-Active transport requires energy, but can transport substances against a concentration gradient
Populated by bacteria, collectively termed the intestinal microflora, that digest some of the unabsorbed materials, such as fiber, producing small amounts of nutrients and gas. Components of chyme that are not absorbed in the small intestine pass on to here, where water and nutrients are absorbed. The remaining unabsorbed materials are excreted in the feces.
Health of the GI tract:
Is essential to overall health. Immune system cells and tissues located in the GI tract help eliminate disease-causing organisms or toxins.
Sources of food allergens:
Seafood, peanuts, tree nuts, fish, soy, wheat, milk, eggs.
-Abnormalities in immune function are the cause of food allergies
A condition in which the protein gluten, which is found in wheat, barley, and rye, triggers an immune response that damages the villi of the small intestine.
Heart burn & GERD:
Common digestive problems that are caused by the leakage of stomach contents into the esophagus.
Caused by infections with Helicobacter pylori, GERD, or medications that damage the mucosa.
Occurs wen the lining of the small intestine is inflamed so nutrients and water are not absorbed.
Caused by a diet that is low or high in fiber, but low in fluids.
The lymphatic system:
-A system that is important for fluid balance, immune function and the absorption of fat-soluble products of digestion. Nutrients absorbed via this system enter the blood circulation w/out first passing through the liver. Lymphatic System: Absorbs and transports atty acids and fats. It transports white blood cells
How stomach activity is regualted
stomach emptying is regulated by the amount and composition of food consumed and regulated by nervous and hormonal signals from the stomach and the small intestine
How the structure of the small intestine maximizes function:
The small intestine contains large circular folds, villi, and microvilli, all of which increase the absorptive surface area
Motility and secretions in the small intestine
Chyme is propelled through the small intestine by peristalsis and mixed by the contractions of segmentation.
Immune function of gastrointestinal tract
Immune system cells and tissues located in the GI tract help eliminate disease-causing organisms or toxins
Pancreatic and Gallbladder Problems
Gallstones can cause pain and interfere with fat digestion and absobtion
Can be delivered by a narrow tube passed through the nasal passages and into the stomach or intestine so that a liquid diet can be deliverd
IF a person's GI tract is not functional, total parenteral nutrition can deliver a solution providing all of the essential nutrients directly into the bloodstream through a large vein in the upper arm or chest
Delivering Nutrients to the Body
Nutrients absorved into the muscosal cells of the intestine enter the blood circulation by either the hepatic portal circulation (water-soluble pathway) or the lymphatic system (fat-soluble pathway)
Most nutrients go directly to the liver
-The products of carbohydrate and protein digestion and the waer-soluble products of fat digestion enter the capillaries in the intestinal villi and are transported to the liver via hepatic portal circulation
-The liver serves as a processing center, removing the absorbed substances for storage, converting them into other forms, or allowing them to pass unaltered
-The lymphatic system is important for fluid balance, immune function, and the absorption of fat-soluble products of digestion
-Lipid transport particles are absorbed into lacteals in the intestinal villi, which join larger lymph vesssels
--the nutrients absorbed via the lymphatic system enter the blood circulation without first passing through the liver
How nutrients enter body cells
All human cells are surrounded by a cell membrane, and most contain a nucleus, mitochondira, lysomes, endoplasmic reticulum, ribosomes in their cytosol
-Cells are the final destination of absorbed nutrients
Metabolism of nutrients
Each of the absorbed nutrients plays a unique role in metabolism
Anabolic and Catabolic Pathways
Within the cells, glucose, fatty acids, and amino acids absorbed from the diet can be broken down by catabolic pathways, which release energy in the form of ATP, or used in anabolic pathways, which use ATP to build body compounds.
The reactions that completely break down macronutrients in the presence of oxygen (aerobic) produce water, carbon dioxide, and ATP are referred to as cellular respiration
-Glucose, fatty acids, and amino acids can all be broken down into two-carbon molecules that form acetyle-COA
-The reactions of the citric acid cycle and the electron transport chain complete the breakdown of acetyl-CoA to form carbon dioxide and water and generate ATP
The reactions that completely break down macronutrients in the presence of oxygen (aerobic) to produce water, carbon dioxide, and ATP.
Sythesizing New Molecules
Dietary, glucose, fatty acids and amino acids are used to synthesize structural, regulatory, or storage molecules
Elimination of metabolic wate
Metabolic wastes such as carbon dioxide, nitrogen and wtaer which are generate by nutrient metabolism must be removed from the body
Respiratory system and skin
-Carbon dioxide is eliminated in exhaled air with water lost via the lungs and skin
Where water and small molecules are filtered out of the blood through the working of the nephrons.
-Some filtered substances are reabsorbed into the blood and those that are not are excreted in urine.
The gallbladder is a small organ where bile is stored before it is released into the small intestine.
-Bile or gall is produced by the liver and aids the digestion of lipids in the small intestine
Bile or Gall
-Bile or gall is produced by the liver and aids the digestion of lipids in the small intestine
The pancreas is an organ in the digestive system and endocrine system.
-It is an endocrine gland producing several important hormones, including insulin, glucagon, somatostatin, and pancreatic polypeptide which circulate in the blood
-Pancreas is also a digestive organ secreting pancreativ juice containing digestive enzymes that assist digestion and absorbtion in the small intestine.
-These enzymes help to further break down carbohydrates, proteins, and lipids in the chyme
Metabolism is usually divided into two categories:
-Catabolism that breaks down organic matter and harbests energy by way of cellular respiration
-Anabolism that uses energy to construct components of cells such as proteins and nucleic acids
Recommended textbook explanations
Anatomy and Physiology
Essentials of Human Anatomy & Physiology
Elaine N. Marieb
Human Anatomy & Physiology
Elaine N. Marieb, Katja Hoehn
Laboratory Manual for Hole's Essentials of Human Anatomy & Physiology
Terry R. Martin
Sets found in the same folder
Water-Soluble Vitamins Chapter 8
Chapter 10: water/electrolytes
Ch. 7 How Cells Harvest Energy
Understanding Nutrition Chapter 1
Sets with similar terms
chapter 3 notes - digestion
Nutrition CH.3 Digestion
9. The Digestive System
Visualizing nutrition chapter 3
Other sets by this creator
Authors of Articles/Area of Focus
Animal Behavior Review Guide Questions
Electrolytes, Major, and Trace Minerals
Nutrition Final Exam-Learning Obj.-Review Question…
Other Quizlet sets
Midterm Study Guide PSYC 201 Lifespan Development
American Democracy Jeopardy
Film Final Exam
Internal Assessment: Bildbeschreibung