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Questions and Answers
What initiates the opening of voltage-gated channels?
What initiates the opening of voltage-gated channels?
In carrier-mediated facilitated diffusion, how does the carrier transport the solute?
In carrier-mediated facilitated diffusion, how does the carrier transport the solute?
Which of the following substances typically uses carrier-mediated facilitated diffusion?
Which of the following substances typically uses carrier-mediated facilitated diffusion?
What drives the passive process of osmosis?
What drives the passive process of osmosis?
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Which statement is true regarding active transport?
Which statement is true regarding active transport?
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What initiates the negative feedback mechanism for regulating body temperature when it exceeds the set point?
What initiates the negative feedback mechanism for regulating body temperature when it exceeds the set point?
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What role do blood vessels play when body temperature rises above the set point?
What role do blood vessels play when body temperature rises above the set point?
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What distinguishes active transport from passive transport mechanisms?
What distinguishes active transport from passive transport mechanisms?
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What is a key characteristic of a positive feedback system compared to a negative feedback system?
What is a key characteristic of a positive feedback system compared to a negative feedback system?
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Which of the following correctly describes simple diffusion?
Which of the following correctly describes simple diffusion?
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During the process of temperature regulation, what happens when the body temperature decreases below the set point?
During the process of temperature regulation, what happens when the body temperature decreases below the set point?
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What is the primary function of ion channels in facilitated diffusion?
What is the primary function of ion channels in facilitated diffusion?
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Which of the following best describes the function of the control center in the body’s temperature regulation?
Which of the following best describes the function of the control center in the body’s temperature regulation?
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Which statement about facilitated diffusion is false?
Which statement about facilitated diffusion is false?
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What is a characteristic of gated channels in facilitated diffusion?
What is a characteristic of gated channels in facilitated diffusion?
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What happens when a stimulus disrupts a controlled condition?
What happens when a stimulus disrupts a controlled condition?
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In a negative feedback system, what is the role of the effector?
In a negative feedback system, what is the role of the effector?
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Which statement most accurately describes the afferent pathway in the feedback system?
Which statement most accurately describes the afferent pathway in the feedback system?
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Which component of the feedback system evaluates input and generates output based on the received signals?
Which component of the feedback system evaluates input and generates output based on the received signals?
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What is the primary function of baroreceptors in the context of blood pressure regulation?
What is the primary function of baroreceptors in the context of blood pressure regulation?
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Study Notes
Transport across the Cell Membrane
- Substances move across cellular membranes via passive or active transport
- Passive transport occurs along a gradient, without energy expenditure
- Active transport moves substances against a gradient, using energy
- Passive transport includes simple diffusion and facilitated diffusion
Simple Diffusion
- Substances move freely through the lipid bilayer
- Permeable to lipid-soluble substances (e.g., oxygen, carbon dioxide)
- Also permeable to small, uncharged polar molecules (e.g., water, urea)
Facilitated Diffusion
- Channel-mediated facilitated diffusion
- Small, inorganic ions use membrane channels
- Selective permeability (each channel permits only certain ions e.g. sodium, potassium)
- Slower than simple diffusion
- Carrier-mediated facilitated diffusion
- Larger water-soluble molecules use carrier proteins (transporters)
- Solute binds to carrier, changes carrier shape, releases solute
- Examples include glucose, fructose, galactose, amino acids, and some vitamins
Osmosis
- A type of diffusion where water moves across a semipermeable membrane
- From an area of higher water concentration to lower water concentration
- Passive process
Active Transport
- Movement of substances against a gradient, requiring energy
- Primary Active Transport
- Energy directly from ATP hydrolysis (e.g., sodium-potassium pump)
- Secondary Active Transport
- Energy from an ionic gradient (e.g., coupled transport of glucose and Na+)
Types of Active Transport Carriers
- Symporters: carry two substances in the same direction
- Antiporters: carry two substances in opposite directions
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