Understanding Human Health: Infections and Body Functions

Infectious Diseases

Bacteria: Single-celled organisms that can cause diseases through toxins.

Mushrooms: Unicellular or multicellular organisms causing fungal infections, thriving in moist environments.

Protozoa: Single-celled parasites found in aquatic environments.

Viruses: Non-cellular entities requiring a host cell to reproduce.

Modes of Transmission

Direct contact, inanimate objects, contaminated water or food, airborne pathogens, animal transmitters.

Internal Defenses

Nonspecific: Phagocytes acting against any microorganism.

Specific: Lymphocytes producing antibodies against specific microorganisms.

Noninfectious Diseases

Body System Dysfunctions

Respiratory: Asthma, chronic bronchitis.

Bones and Joints: Osteoarthritis, osteoporosis, cancer.

Deficiencies

Caused by poor diet, lack of nutrients (hypovitaminosis, goiter).

Traumatic

Accidents.

Endocrine and Metabolic

Hormonal secretion issues (obesity, diabetes).

Mental Disorders

Thought, behavior, and emotion disorders.

Genetic Disorders

Inherited gene-related conditions.

Nutritional Needs

Energy Needs: Obtained from glucose and fats.

Structural Needs: Proteins and lipids are essential.

Functional and Regulatory Needs: Vitamins and minerals.

Digestion Process

Mastication

Food is crushed to facilitate digestion. Teeth structures: incisors (cutting), canines (tearing), molars and premolars (crushing).

Salivation

Saliva mixes with food, forming a bolus. Functions of saliva:

• Facilitates swallowing.
• Starts starch digestion.
• Destroys some bacteria in food.

Swallowing

The bolus passes through the pharynx, esophagus, and into the stomach.

In the Stomach

The bolus mixes with gastric juice (4 hours). Gastric juice contains:

• Pepsin: Enzyme for protein digestion.
• Hydrochloric acid: Activates pepsin and breaks down fiber.

In the Small Intestine

Chyme enters the duodenum, contacting digestive secretions from the pancreas and liver.

Liver

Produces bile (stored in the gallbladder), aiding digestion with bile salts.

Pancreas

Produces hormones regulating glucose and pancreatic juice containing digestive enzymes.

Nutrient Absorption

Nutrients are absorbed in the small intestine. Water is absorbed in the intestine. Villi increase absorption surface.

In the Large Intestine

Water absorption and waste compaction occur, forming feces.

Stomach

Bag-like organ with cardia (inlet) and pylorus (outlet).

Small Intestine

Tube (6-7 meters) divided into duodenum, jejunum, and ileum.

Liver

Large organ with multiple functions, including blood filtration.

Pancreas

Elongated gland behind the stomach.

Large Intestine

Sections: cecum (with appendix), colon (ascending, transverse, descending), and rectum ending at the anus.