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.