Levels of Organization and Human Body Systems

Posted on Aug 24, 2024 in Biology

Levels of Organization: Complexity in Living Matter

Atomic and Molecular Level

Matter is made up of atoms, which come together to form molecules held by chemical bonds. Atoms in living matter are called bioelements. Molecules in living things are biomolecules.

Inorganic Molecules

These have a simple chemical structure and include water and minerals. They are found in both living and non-living matter.

Organic Biomolecules

These are found in living things and contain carbon. They are usually polymers and include:

  • Carbohydrates or sugars
  • Lipids
  • Proteins
  • Nucleic acids

Cellular Level

The cell is the basic unit of life, capable of performing vital functions. Molecules join together to form cells.

Organism Level

A tissue is a group of coordinated cells performing a function. Tissues are grouped into organs, organs join to form systems, and systems together form a human being.

The Human Cell

The Cell

The cell is the most basic part of a living organism capable of performing the three vital functions: nutrition, interaction, and reproduction. It can be heterotrophic or autotrophic.

1. The Plasma Membrane

A thin, flexible covering that separates the cell from the outside. It has two main functions:

  • Transport: Regulates the passage of substances in and out of the cell.
  • Interaction: Detects changes in the outside and enables the cell to react.

2. The Cytoplasm

The substance containing the cell’s organelles: mitochondria, ribosomes, the endoplasmic reticulum, the Golgi apparatus, vesicles, lysosomes, the cytoskeleton, and centrioles. Many vital chemical reactions take place in the cytoplasm.

3. The Cell Nucleus

The main structures are:

  • Nuclear Envelope: A double membrane with pores, regulating the passage of substances between the nucleus and cytoplasm.
  • Chromatin: Comprises the cell’s genetic material (DNA). During reproduction, chromatin coils up to form chromosomes.
  • Nucleolus: A spherical structure where ribosomes are produced.

The nucleus controls the cell’s function through DNA, containing information on a person’s characteristics. During cell division, DNA is transmitted to daughter cells.

Functions of Cell Organelles

1. Endoplasmic Reticulum (ER)

Manufactures proteins using ribosomes attached to its membrane. The ER stores or transports them to the Golgi apparatus.

2. Ribosomes

Made up of two subunits, ribosomes manufacture the cell’s proteins.

3. Mitochondria

Where cellular respiration takes place. Nutrients are burned in the presence of oxygen to obtain energy, releasing CO2.

4. Centrioles

Direct chromosome separation during cell reproduction. Also involved in creating structures for cell movement, like flagella.

5. Cytoskeleton

A network of filaments providing structural support to organelles, giving the cell its shape, and involved in cell movement.

6. Golgi Apparatus

Collects substances and uses vesicles to transport them to different parts of the cell.

7. Lysosomes

Vesicles from the Golgi apparatus containing digestive substances for cell digestion.

8. Vesicles

Small membrane-bound sacs that store waste and substances incorporated into the cell.

Tissues: Groups of Specialized Cells

1. Epithelial Tissue

Made up of tightly packed cell layers.

  • Covering Epithelium: Covers and protects external surfaces and internal cavities (e.g., mucous membrane, endothelium, epidermis).
  • Glandular Epithelium: Forms glands that secrete substances.

2. Connective Tissue

Made up of cells separated by an intercellular substance called the matrix. Supports and binds other tissues and organs.

  • Connective Tissue Proper: Fills organs and spaces, forms ligaments and tendons.
  • Cartilage: Flexible and strong, found in ears, trachea, and joints.
  • Adipose Tissue: The body’s largest energy reserve, provides insulation.
  • Bone Tissue: The main element of the skeleton, supports and protects vital organs.
  • Blood: A connective tissue with a liquid matrix called plasma, containing suspended blood cells.

Nutrition: Obtaining Matter and Energy

Nutrition is the process of obtaining matter and energy for growth and vital functions.

Nutrients

  • Water: Acts as a solvent, transports substances, and regulates body temperature.
  • Minerals: Form structures and regulate body functions.
  • Carbohydrates: Provide immediate energy (sugars and polysaccharides).
  • Proteins: Chains of amino acids, essential for cell and tissue formation and growth.
  • Lipids: Insulate the body, help construct cell membranes (cholesterol and phospholipids).
  • Vitamins: Essential for proper body function in small amounts.

Diet: Healthy vs. Unhealthy

A balanced diet provides the body with necessary energy and nutrients.

Food Wheel

  1. Foods rich in carbohydrates (grains, potatoes, sugar)
  2. Foods rich in lipids (butter, oil)
  3. Foods rich in protein (meat, eggs, fish, legumes)
  4. Foods rich in protein and calcium (milk, dairy)
  5. Foods rich in vitamins and minerals (leafy greens, vegetables)
  6. Foods rich in vitamins and minerals (fresh fruit)

Characteristics of a Healthy Diet

  1. Varied: Includes foods from all groups in the right amounts.
  2. Provides Energy: Meets the body’s energy needs based on activity level and age.
  3. Macronutrient Ratio: 55-60% carbohydrates, 25-30% fats, 10-15% proteins.
  4. Healthy Fats: Primarily from plant sources and oily fish.
  5. Protein Intake: No more than 40% of nutrients should be protein.
  6. Dietary Fiber: Important for digestion.
  7. Hydration: Water should be the main drink (1.5 liters daily).
  8. Exercise: Combine a healthy diet with daily exercise.

Mediterranean Diet

A healthy, balanced diet rich in plant-based foods, grains, fruits, vegetables, legumes, olive oil, fish, moderate dairy, white meat, eggs, and small amounts of red meat.

Atlantic Diet

Similar to the Mediterranean diet but with different proportions. Includes large amounts of fish and shellfish, grains, potatoes, legumes, fruits, leafy greens, eggs, dairy, moderate meat, and olive oil as the main fat source.

Food-Borne Illnesses

Food-Borne Infections

Result from eating food contaminated with infectious microorganisms.

1. Salmonellosis

Caused by Salmonella bacteria found in contaminated water or food (e.g., eggs, mayonnaise). Symptoms include headache, vomiting, and diarrhea. Serious in children and the elderly.

2. Botulism

Caused by Clostridium botulinum bacteria in inadequately preserved foods. Produces botulinum toxin.

3. Toxoplasmosis

Caused by the protozoan Toxoplasma gondii found in raw meat. Symptoms include swollen lymph nodes, fever, and headache.

4. Trichinosis

Caused by eating raw meat (pork) infested with Trichinella larvae. Symptoms include abdominal pain, vomiting, diarrhea, and fever. Serious in the elderly.

5. Anisakiasis

Caused by eating raw or undercooked fish containing the Anisakis worm. Symptoms include abdominal pain, vomiting, and diarrhea.

Food Labels: Information for the Consumer

  1. Brand name and product name
  2. Manufacturer identification
  3. Batch number
  4. Volume or net weight
  5. List of ingredients and additives
  6. Best-before or use-by date
  7. Storage conditions and cooking instructions

Food Preservation Methods Using High Temperatures

1. Sterilization

Heating food at 135°C for 2-3 seconds to destroy microorganisms. Allows for long-term storage.

2. Pasteurization

Heating food to 65-75°C for a short time and then cooling quickly.

3. Dehydration/Drying

Using heat to remove water from food, either completely or partially.

Food Additives

Substances added to food to preserve flavor, smell, color, change characteristics, or extend shelf life.

Types of Food Additives

  • Food Coloring: Enhances the visual appeal of food.
  • Preservatives: Prevent microorganism growth and spoilage.
  • Antioxidants: Prevent food oxidation.
  • Texture Modifiers: Change food consistency.
  • Flavor Enhancers: Enhance the existing flavor of food.

Accessory Glands of the Digestive System

Located outside the digestive tract but secrete digestive juices containing enzymes that break down food.

1. Salivary Glands

Three pairs of glands that secrete saliva into the mouth.

2. Liver

The largest gland, produces bile to aid in lipid digestion, stores glucose, iron, and vitamins, and eliminates toxins.

3. Pancreas

Secretes pancreatic juices into the intestine for digestion and releases substances into the bloodstream (endocrine function).

How the Respiratory System Works

1. Inhalation

The diaphragm contracts, lungs expand, and air enters through the mouth or nasal passages, where it is warmed before traveling to the alveoli.

2. Gas Exchange

Oxygen diffuses from the alveoli into the blood, and carbon dioxide diffuses from the blood into the alveoli to be expelled.

3. Exhalation

The diaphragm relaxes, lungs reduce in volume, and air containing CO2 is expelled.