Nutrition and Digestion Lecture Notes

Flashcards to help learn about nutrition and digestion

Nutrition

The process of ingesting, digesting, and absorbing nutrients.

Essential Nutrients

Chemical energy which is converted into ATP and powers processes in the body and are required by cells and must be obtained from the diet. Essential nutrients must be obtained in preassembled form; cannot be made by cells

Four Classes of Essential Nutrients

Essential amino acids, essential fatty acids, vitamins, and minerals.

Essential Amino Acids

Animals require 20 amino acids and can synthesize 12 of them from molecules in their diet, The remaining 8 amino acids, the essential amino acids, must be obtained from food in preassembled form

Protein Deficiency

Caused by a diet that provides insufficient essential amino acids.

Complete Proteins

Meat, eggs, and cheese.

Essential Fatty Acids

Animals can synthesize most of the fatty acids they need, The essential fatty acids are certain unsaturated fatty acids that must be obtained from the diet

Vitamins

Organic molecules required in the diet in small amounts.

Two Categories of Vitamins

Fat-soluble and water-soluble.

Minerals

Simple inorganic nutrients, usually required in small amounts.

Herbivores

Eat autotrophs / plants and algae.

Carnivores

Eat other animals.

Omnivores

Regularly eat animals and autotrophs.

Ingestion

The act of eating.

Suspension Feeders

Sift small food particles from the water

Substrate Feeders

Animals that live in or on their food source.

Fluid Feeders

Suck nutrient-rich fluid from a living host.

Bulk Feeders

Eat relatively large pieces of food.

Digestion

The process of breaking food down into molecules small enough to absorb.

Enzymatic Hydrolysis

Splits bonds in molecules with the addition of water.

Absorption

Uptake of nutrients by body cells.

Elimination

Passage of undigested material out of the digestive compartment.

Specialized Compartments

Reduce the risk of an animal digesting its own cells and tissues.

Intracellular Digestion

Food particles are engulfed by endocytosis and digested within food vacuoles (lysosomes).

Extracellular Digestion

The breakdown of food particles outside of cells.

Gastrovascular Cavity

Functions in both digestion and distribution of nutrients = digestive sac with one opening: mouth/anus.

Complete Digestive Tract / Alimentary Canal

A digestive tube with two openings, a mouth and an anus.

Mammalian Digestive System

Consists of an alimentary canal and accessory glands that secrete digestive juices through ducts.

Peristalsis

Rhythmic contractions of muscles in the wall of the canal.

Sphincters

Regulate the movement of material between compartments.

Mechanical Digestion

The teeth physically break down food into smaller particles, The tongue allows taste and shapes food into a bolus and provides help with swallowing

Salivary Glands

Mucus to lubricate food and salivary amylase, initiating breakdown of glucose polymers.

The Pharynx

A junction that opens to both the esophagus and the trachea (windpipe)

Epiglottis

Small cartilaginous flap; swallowing causes the epiglottis to block entry to the trachea, and the bolus is guided into the esophagus.

The Esophagus

Conducts food from the pharynx down to the stomach by peristalsis = rhythmic waves of involuntary smooth muscle contractions.

The Stomach

Stores food, churns, and secretes gastric juice.

Gastric Juice

Hydrochloric acid, Pepsin, and Mucus

Gastric Ulcers

Lesions in the lining which are caused mainly by the bacterium Helicobacter pylori

Small Intestine

The longest section of the alimentary canal, It is the major organ of digestion and absorption

Duodenum

The first portion of the small intestine

Jejunum and Ileum

The second and third portions of the small intestine

Duodenum Functions

Receives acidic chyme from the stomach little by little through pyloric sphincter, mixes with digestive juices from the pancreas, liver, and gallbladder

Pancreatic Secretions

Produces a mixture of digestive enzymes – trypsin digests proteins, Lipases digest fats, Pancreatic amylase digests starch, Nucleases digest nucleic acids

Liver

Produces bile

Gallbladder

Stores bile

Bile

Aids in digestion and absorption of fats; emulsifier which solubilizes fats into an aqueous solution for digestion.

Digestion and Absorption in the Small Intestine

Enzymatic digestion is completed as peristalsis moves the chyme and digestive juices along the small intestine.

Jejunum and Ileum

Huge surface area, due to villi and microvilli that are exposed to the intestinal lumen; the enormous surface area greatly increases the rate of nutrient absorption.

Villus

A network of blood vessels and a small lymphatic vessel called a lacteal.

Hepatic Portal Vein

Delivers blood to the liver and then on to the heart; the liver is the “gate keeper of the blood” and blood with newly absorbed nutrients must be checked by the liver before being sent into general circulation.

The Colon / Large Intestine

Is connected to the small intestine, aids in the fermentation of plant material and connects where the small and large intestines meet.

Major Functions of the Colon

Reabsorb water that has entered the alimentary canal; wastes of the digestive tract, the feces, become more solid as they move through the colon, removal of digestive waste

Colon

Houses strains of the bacterium Escherichia coli, some of which produce vitamins.