Electric Circuits and Gas Exchange

Circuit

• An electric circuit is a closed path that allows electric current to flow.
• It consists of a power source (like a battery), conducting wires, and a load (like a light bulb).
• Current flows from the positive terminal of the power source, through the load, and back to the negative terminal.
• Components are connected in series (one after the other) or in parallel (multiple paths).
• In series circuits, current is the same throughout, but voltage is divided across components.
• In parallel circuits, voltage is the same across all components, but current is divided amongst branches.
• Ohm's Law (V = IR) relates voltage (V), current (I), and resistance (R) in a circuit. Higher resistance results in lower current.
• Circuit breakers and fuses are safety devices that prevent circuit overload and potential fires.

Gas Exchange

• Gas exchange is the process by which organisms take in oxygen and release carbon dioxide.
• This process occurs in various locations, depending on the organism.
• In humans, gas exchange primarily takes place in the lungs.
• Lungs contain alveoli, tiny air sacs surrounded by capillaries.
• Oxygen diffuses from the alveoli into the capillaries, and carbon dioxide diffuses from the capillaries into the alveoli.
• Oxygenated blood is then transported throughout the body.
• Efficiency of gas exchange depends on the surface area available for diffusion, and the concentration gradients of the gases.
• Other organisms, including plants, have different mechanisms for gas exchange tailored to their specific needs and environment.

Electric Circuit

• A basic circuit needs a source (battery or power supply), conducting wires, and a component to use the electricity (light bulb, resistor).
• The path must be complete for continuous current flow.
• The flow of electric current is measured in amperes (amps).
• Resistance affects the current flow; higher resistance leads to lower current.
• Voltage is the potential difference driving electric current between two points in the circuit.
• Kirchhoff's laws are key concepts relating current and voltage in multiple components (nodes and loops): "The sum of currents entering a junction equals the sum of currents leaving it" (junction rule), and "The sum of voltage changes around any closed loop in a circuit is zero" (loop rule).
• AC (alternating current) and DC (direct current) circuits are different types of circuits; DC current flows in one direction, while AC current reverses direction periodically.
• Different circuit connections (series and parallel) influence how current and voltage behave.