Covers biological coordination systems, contrasting quick electric signals (Nervous System) with sustained chemical messages (Hormones). Emphasis placed on mechanisms like negative feedback (glucose homeostasis) and comparison of coordination methods across animals and plants.
Uses of Energy Released by Respiration Cells use the energy released during respiration for various essential life processes: Energy Use Description Muscle contraction Energy for movement and physical activity Protein synthesis Building proteins from amino acids for growth and repair Cell division Energy required for mitosis and reproduction Active transport Moving substances against concentration gradients Growth Building new cells and tissues Nerve impulses Electrical signals for communication Body temperature Maintaining metabolic heat Aerobic Respiration Definition Aerobic respiration is using oxygen to break down nutrients for energy. ...
Introduction Gas exchange in humans is the process by which oxygen enters the body and carbon dioxide is removed. This occurs primarily in the lungs through a system of specialized structures optimized for efficient gas transfer. Features of Gas Exchange Surfaces Four Essential Features For effective gas exchange, the surface must have four key characteristics: Feature Purpose How it Works Large surface area More area for gas exchange Many alveoli create large total area (~70 m² in adult lungs) Thin surface Short diffusion distance Alveoli and capillary walls are one cell thick (~0.5 μm) Good blood supply Maintain concentration gradient Capillaries carry away O₂, bring CO₂ Good ventilation Maintain concentration gradient Breathing brings in O₂, removes CO₂ How These Features Work Together Large surface area = more sites for O₂ and CO₂ to cross Thin surface = faster diffusion (shorter distance) Good blood supply = blood constantly removes O₂, loads with CO₂ Good ventilation = fresh air constantly replaces stale air ...
Pathogens and Disease What is a Pathogen? A pathogen is a disease-causing organism. It enters the body, multiplies, and causes harmful effects. Types of Pathogens Pathogen Type Examples Diseases Caused Bacteria Salmonella, Mycobacterium Food poisoning, tuberculosis Viruses Influenza, HIV, SARS-CoV-2 Flu, AIDS, COVID-19 Fungi Ringworm, Candida Fungal infections Parasites Malaria parasite Malaria Transmissible Disease A transmissible disease is one where a pathogen is passed from one host to another. This can spread within populations and cause epidemics or pandemics. ...
Circulatory System Overview Components of the Circulatory System The circulatory system consists of three main components working together: Vessels - Tubes that carry blood throughout the body Pump - Heart that pushes blood through vessels Valves - Ensure one-way flow of blood Types of Circulation Single Circulation (Fish) Blood passes through heart once per complete circuit Path: Heart → gills → body → heart Less efficient - blood pressure drops significantly after gills Double Circulation (Mammals) Blood passes through heart twice per complete circuit Pulmonary circulation: Heart → lungs → heart Systemic circulation: Heart → body → heart More efficient - maintains higher blood pressure to body tissues Advantages of Double Circulation Higher blood pressure to body tissues Separate oxygenated and deoxygenated blood flow More efficient delivery of oxygen and nutrients Supports higher metabolic rates needed for active lifestyles Heart Structure and Function Heart Structure The heart is a muscular organ with four chambers and internal structures: ...