The Human Digestive System

6 Questions

Match the following structures in the mouth with their functions:

Incisors = Cutting and biting Canines = Piercing and tearing Premolars = Crushing and grinding Molars = Grinding and crushing

Match the following substances in saliva with their functions:

Amylase = Breaks down carbohydrates Lipase = Breaks down fats Mucus = Moistens food for swallowing Enzymes = Breaks down proteins

Match the following processes in the esophagus with their descriptions:

Peristalsis = Wave-like muscle contractions that propel food downwards Swallowing = Food is pushed to the back of the mouth by the tongue Gastric emptying = Partially digested food enters the small intestine Gastric digestion = Mixing of food with stomach acid and enzymes for 1-2 hours

Match the following substances in the stomach lining with their functions:

Hydrochloric acid (HCl) = Denatures proteins and activates digestive enzymes Pepsin = Breaks down proteins into peptides and amino acids Mucus = Protects the stomach lining from acid and enzymes Saliva = Moistens food for swallowing

Match the following processes in the small intestine with their descriptions:

Absorption = Absorption of nutrients into the bloodstream Digestion = Breakdown of proteins and absorption of nutrients Gastric emptying = Partially digested food enters the small intestine Gastric digestion = Mixing of food with stomach acid and enzymes for 1-2 hours

Match the following functions in the large intestine with their descriptions:

Water absorption = Reabsorbed into the bloodstream Electrolyte absorption = Reabsorbed and regulated Waste storage = Feces are formed and stored in the rectum Absorption of nutrients = Absorption of nutrients into the bloodstream

Study Notes

Digestive System

Mouth and Teeth

Primary function: mechanical breakdown of food into smaller particles (chewing)
Teeth:
- Incisors: cutting and biting
- Canines: piercing and tearing
- Premolars: crushing and grinding
- Molars: grinding and crushing
Saliva:
- Produced by salivary glands
- Contains enzymes (amylase and lipase) to break down carbohydrates and fats
- Moistens food for swallowing

Esophagus and Swallowing

Muscular tube that transports food from the mouth to the stomach
Peristalsis: wave-like muscle contractions that propel food downwards
Swallowing process:
1. Food is pushed to the back of the mouth by the tongue
2. Food enters the pharynx (throat)
3. Epiglottis closes the trachea (windpipe) to prevent food from entering the lungs
4. Food enters the esophagus and is propelled to the stomach

Stomach Acid and Digestion

Primary function: chemical breakdown of proteins and absorption of nutrients
Stomach lining secretes:
- Hydrochloric acid (HCl) to denature proteins and activate digestive enzymes
- Pepsin: breaks down proteins into peptides and amino acids
- Mucus: protects the stomach lining from acid and enzymes
Gastric digestion: mixing of food with stomach acid and enzymes for 1-2 hours
Gastric emptying: partially digested food (chyme) enters the small intestine

Small Intestine Absorption

Primary function: absorption of nutrients into the bloodstream
Long, thin, and highly folded to increase surface area
Finger-like projections (villi) and microvilli increase surface area for absorption
Absorption of:
- Carbohydrates: broken down into glucose
- Proteins: broken down into amino acids
- Fats: broken down into fatty acids and glycerol
Absorbed nutrients enter the bloodstream and are transported to the liver for processing

Large Intestine and Waste Removal

Primary function: water absorption, electrolyte absorption, and waste storage
Also known as the colon
Water and electrolyte absorption:
- Water is reabsorbed into the bloodstream
- Electrolytes (e.g., sodium, potassium) are reabsorbed and regulated
Waste storage:
- Feces are formed and stored in the rectum
- Defecation: waste is eliminated from the body through the anus