Biology Chapter: Organisation in Living Organisms

Organisation in Living Organisms

• Multicellular organisms are complex, with cells organised into tissues.
• Groups of tissues form organs, which work together in organ systems.
• Different organ systems cooperate to maintain the organism's homeostasis.
• Examples include the digestive, respiratory, circulatory, and nervous systems.
• Specialized cells perform specific functions within the organism facilitating efficient interactions.

Cell Structure and Function

• Cells are the basic units of life.
• Cells exhibit various structures, like the cell membrane, nucleus, mitochondria, and ribosomes, each with a specific function.
• The cell membrane regulates what enters and leaves a cell.
• The nucleus contains genetic material (DNA).
• Mitochondria are the powerhouses of the cell, responsible for energy production.
• Ribosomes are the sites of protein synthesis.
• Plant cells are distinguished by having cell walls and chloroplasts.
• Specialized cells, such as nerve cells, muscle cells, and blood cells, have adapted structures to perform specific tasks.

Infection and Response

• Pathogens cause disease by invading and damaging the host's tissues.
• Examples of pathogens include bacteria, viruses, fungi, and parasites.
• The immune system defends the body against pathogens.
• A primary function of the immune system is recognizing and destroying these pathogens through various mechanisms.
• Non-specific defences like skin and enzymes provide a first line of defense.
• Specific defences target particular pathogens through immune responses, including antibody production and cell-mediated immunity.
• Vaccines work by stimulating the immune system to produce immunity to particular pathogens without causing disease.
• Infectious diseases can be transmitted directly or indirectly.
• Some diseases are endemic, some epidemic, and some pandemic.
• Understanding disease transmission and the use of antibiotics and other medicines against pathogens are important elements of public health.
• Understanding the immune system and its complexity allows for the development of vaccines, antiviral medications, and therapies to combat infectious diseases.

Disease and Disorders

• Diseases can be caused by various factors, e.g., genetic predisposition, lifestyle, environment or pathogens.
• Some diseases can be inherited.
• Some disorders arise from a lack of a certain enzyme, leading to a metabolic problem.
• Lifestyle choices can also cause certain diseases (e.g., heart disease related to poor diet and lack of exercise).
• Diagnosing and managing diseases involves a blend of medical knowledge, technology, and patient care.
• Different types of diseases necessitate different approaches to both prevention and treatment.
• Examples of diseases include cancers, cardiovascular diseases, autoimmune disorders, and specific genetic disorders and syndromes.