Life Maintenance Systems: Nutrition and Excretion Notes

Life Maintenance Systems: Nutrition and Excretion

Objectives

• Understand nutrients and their role in nourishing the body.
• Comprehend the processes of digestion and excretion in humans.

Nutrition: Intake and Conversion

• Definition: Nutrition is the intake of food and its conversion into living matter.
• Importance: Provides energy and materials necessary for growth and development.

Types of Organisms Based on Nutrition

• Autotrophs (Producers):

• Produce their own food using inorganic materials.

• Method: Photosynthesis (e.g., plants, algae, some bacteria).

• Heterotrophs (Consumers):

• Cannot produce their own food; obtain nutrients by consuming other organisms.

• Examples: Animals, fungi, and most bacteria.

Types of Consumers

• Herbivores: Eat only plants.
• Carnivores: Eat only meat.
• Omnivores: Eat both plants and meat.
• Detritivores: Feed on dead organic material.

Macronutrients & Micronutrients

• Macronutrients (needed in large amounts):

• Carbohydrates

• Proteins

• Fats

• Micronutrients (needed in small amounts):

• Vitamins

• Minerals

Explanation of Carbohydrates

• Known as sugars; primary energy source for organisms.
• Can also be converted into nucleic acids, lubricants, and fats.
• Calorie Measurement:
• 1 kcal = 1000 calories.

Digestion in Animals

• Digestive System: Processes that break down food into nutrients.
• Types of Digestion:
• Intracellular: Food particles engulfed by cells.
• Extracellular: Breakdown of food outside the cells.

Digestion Mechanisms

• Suspension Feeding: Filter feeding; captures suspended particles.
• Substrate Feeding: Organisms live on or in food sources.
• Fluid Feeding: Sucking nutrient-rich fluids from a host.
• Bulk Feeding: Ingesting large food pieces.

Nutrient Absorption Methods

• Endocytosis: Engulfing substances by cells.
• Phagocytosis: Engulfing large particles or cells.
• Pinocytosis: Engulfing fluids and dissolved substances.
• Receptor-mediated endocytosis: Specific molecule binding triggers vesicle formation.

Energy Needs

• Average adult requires ~2000 kcal per day.
• Varies with age, sex, and activity level.

Metabolism and Energy

• Metabolism: All chemical reactions in the body.
• Basal Metabolism: Energy required at rest.
• Affected by climate, size, age, sex.

Energy Requirements Breakdown

• Female in her early 20s: ~1800 - 2000 calories/day.
• Male in his early 20s: ~2200 - 2500 calories/day.

Examination of Nutrients

• Proteins:

• Comprised of amino acids; essential for growth and repair.

• Function: Enzyme and hormone synthesis.

• Fats:

• Provide double the energy of carbohydrates; stored as excess.

• Vitamins:

• Critical for functions, must be ingested (except Vitamin D).

• Types: Fat-soluble (A, D, E, K) and water-soluble varieties.

Minerals & Water

• Minerals: Inorganic substances crucial for body functions; includes calcium, potassium, iron.
• Water: Vital solvent; must be replenished regularly.

Fiber

• Indigestible material from fruits/vegetables; promotes gut health and aids digestion.
• Important for preventing constipation.

Stages of Food Processing in Animals

1. Ingestion: Intake of food.
2. Digestion: Mechanical and chemical breakdown of food.
3. Absorption: Nutrients absorbed into cells.
4. Elimination: Removal of waste materials.

Digestion Process in Human Alimentary Canal

• Starts in the mouth and continues through specialized structures (esophagus, stomach, small intestine, large intestine).
• Oral Cavity: Physical and chemical breakdown of food.

Digestive Glands

• Salivary Glands: Produce saliva to aid in digestion.
• Pancreas: Produces enzymes and insulin.
• Liver: Produces bile for fat digestion.

Elimination of Waste Materials

• Feces Composition: Unabsorbed material, dead bacteria, digestive juices.
• Egestion/Defecation: Removal of feces from the body.

Excretion: Waste Removal Processes

• Lungs: Excrete carbon dioxide and water vapor.
• Skin: Releases excess water and nitrogenous wastes as sweat.
• Kidneys: Filter blood to eliminate toxins and maintain body’s fluid and electrolyte balance.
• Urea: Less toxic waste formed from ammonia in the liver.

Kidney Functions & Filtration Process

1. Filtration at Glomerulus: Removes waste using blood pressure.
2. Reabsorption/Secretion: Important nutrients reabsorbed in renal tubules.
3. Urine Collection: Remains is collected and transported for elimination from the body.

Kidney Health & Disorders

• Kidney Failure: Failure to filter blood effectively.
• Dialysis: Artificial filtration method.
• Transplants: Finding compatible donors can be challenging.
• Kidney Stones: Semi-solid mineral formations in the urinary tract; causes may include oversaturation of minerals.

Conclusion

• Nutrition, digestion, and excretion are crucial for maintaining homeostasis and supporting biological functions in animals. Understanding these processes assists in the promotion of health and well-being.