Digestion Macromolecules: monomers, compartments

• Digestion involves breaking down macromolecules into monomers through hydrolysis.
• Proteins break down into amino acids, polysaccharides into monosaccharides, nucleic acids into nucleic acids, and fats into glycerol plus fatty acids.

Steps of Food Processing

• Ingestion: Eating.
• Digestion: Includes physical digestion (teeth + saliva) and chemical digestion (acids and muscle contractions).
• Absorption: Nutrients are absorbed, mainly in the duodenum of the small intestine, not the stomach.
• Elimination: Removal of unabsorbed waste.

Producers vs. Consumers

• Producers are autotrophs, like photoautotrophs that use light.
• Consumers include herbivores, carnivores, omnivores, scavengers, and traditors.

Feeding Mechanisms

• Suspension/Filter Feeders: They capture food from the surrounding medium by filtering, most aquatic animals. (Ex. Whale)
• Substrate Feeders: They live in or on their food source (Ex. Caterpillars).
• Fluid Feeders: They take liquid from a host, which exemplify parasitism (Ex. Mosquitoes).
• Bulk Feeders: Eat large pieces of food (Ex. Humans).

Digestion Compartments

• Digestion occurs in specialized compartments designed for breaking down specific nutrients.
• Alimentary Canal: Food passes one direction (Ex. Humans).
• Gastrovascular Cavities: Basic organisms have a single opening where food enters and exits without an alimentary canal.
• Crops and Gizzards: Involved in food storage and breakdown.

Digestive System Parts

• The digestive system includes the mouth, small and large intestines, stomach, esophagus, gallbladder, rectum, and anus.

Mouth

• Teeth: Incisors, canines, premolars, molars, and wisdom teeth.
  • Flat teeth shear, wide flat teeth crush, and canines rip. Adults have 32 teeth.
• Saliva: Contains amylase (for carbohydrate breakdown), mucus (protects from acids), antibacterial compounds, buffers (neutralize acids), and glycoproteins (form food into a bolus).
• Tongue: Forms food into a bolus and has tastebuds.
• Uvula: Might prevent food from going up.
• Tonsils: Help protect against infections.

Throat (Pharynx)

• The throat is where food and air passages meet.
• Trachea: The windpipe.
• Food Pipe: The esophagus.
• Bolus: Mashed food mixed with chemicals.
• Epiglottis: Blocks the trachea and larynx during swallowing.
• Esophageal Sphincter: A block over the esophagus.
• Esophagus: Uses muscular contractions to move food down; involuntary with no digestion.
• Cardiac Sphincter: Located at the bottom of the esophagus. Acid reflux occurs when stomach acid enters the esophagus causing heartburn.

Stomach

• The stomach is a muscular area with ridges (rugae).
• It contracts about every 20 seconds for mechanical breakdown.
• Gastric juices convert bolus into chyme, which enters the small intestine.
• It produces hydrochloric acid with a pH of about 2.
• Pepsin: Pepsinogen converts to pepsin by stomach acid and breaks down proteins.
• Hydrochloric Acid Cells: Parietal cells make hydrochloric acid to kill bacteria and denature proteins.
• Chief Cells

Digestive System Facts

• Digests food over a period of 24-36 hours.

Accessory Glands

• Salivary Glands
• Liver: Makes bile
• Gallbladder: Stores and modifies bile; bile is secreted into the small intestine to break down fats.
• Pancreas: Produces pancreatic juice with bicarbonate ions to neutralize acidic chyme.

Small Intestine

• Nutrients enter via passive and some active transport.
  • Duodenum: Digestion occurs here; connected to accessory glands where chyme mixes with bicarbonate, pancreatic juices, and bile.
  • Jejunum and Ileum: Most absorption occurs here.
  • Villi + Microvilli: Folds and ridges on the surface to increase surface area for absorption.

Enzymes in the Small Intestine

• Pancreatic Amylase: Digests carbohydrates.
• Bile Salts: Digests Fat
• Nucleases: Digests DNA and RNA.
• Trypsin, Chymotrypsin: Digests Polypeptides.

Liver

• Hepatic Portal Vein: Carries blood from digestive organs to the liver.
• Converts monosaccharides to glycogen for storage.
• Detoxifies alcohol and drugs.

Large Intestine

• Absorbs water, minerals, and vitamins.
• Contains gut bacteria.
• Electrolytes and water are removed.
• Forms feces, which is pushed to the rectum.
• Two sphincters control waste excretion; the first is uncontrollable, the second is controllable.
• Improper water absorption leads to diarrhea (too little) or constipation (too much).
• Fiber, made of cellulose, aids in bowel movements.

Digestive vs. Metabolic Waste

• Digestive waste is feces.
• Metabolic waste is CO2 and water from cellular respiration.

Energy in Food Measurement

• Calories: Energy to raise 1g of water by 1 degree Celsius.
• 1 gram of fat is 9 calories.
• 1 gram of protein/carbs is about 4 calories.
• 1 gram of alcohol is 7 calories.
• Metabolic Rate: Total energy used for all activities.
• Basal Metabolic Rate: Minimum kcal to maintain basic processes like cell maintenance, breathing, and heartbeat; more active = higher BMR.

Essential Nutrients

• Essential Fatty Acids: Linoleic and alpha-linoleic acids, which come from plants.
• Essential Amino Acids: Eight come from food, such as meat and beans.
• Essential Vitamins: 13 vitamins which are water-soluble (B and C) and fat-soluble (A, D, E, K).
• Essential Minerals: 10 essential minerals include iron (for blood), calcium (for bones), and copper.

Dietary Deficiencies

• Anorexia: Self-starvation.
• Bulimia: Eating followed by vomiting.

Explore macromolecule digestion and corresponding monomers. Learn about nutrient uptake during food processing. Discover the primary advantages of specialized digestive compartments and alimentary canals.