Human anatomy and physiology

 

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Writing Assignment One: What to recall from BIO201

You are expected to understand and apply the following information throughout the Spring 2012 semester in BIO202. 1. Describe the different methods of membrane transport: simple diffusion, facilitated diffusion, primary active transport, secondary active transport, and osmosis.   simple diffusion  – the movement of a solute from a high concentration of that solute to a low concentration of that solute across a biological membrane   facilitated diffusion  – the movement of a solute from a high concentration of that solute to a low concentration of that solute across a biological membrane with the help of a protein channel, pore or carrier   primary active transport  – the movement of a solute from a low concentration of that solute to a high concentration of that solute across a biological membrane through a protein pump. This method requires energy in the form of ATP.

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  concentration secondary active transport  the movement of a solute from a lowacross a of that solute to a high concentration of that solute biological membrane through a protein carrier. This method does not require ATP energy, but utilizes the energy of a sodium gradient.   osmosis  – the movement of a solvent (water) from a low concentration of solutes to a high concentration of solutes across a biological membrane through a protein pore (aquaporin). Another definition is the movement of a solvent (water) from a high concentration of the solvent to a low concentration of the solvent across a biological membrane through a protein pore.

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2. Describe the relationship between H+ concentration and pH. +

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  pH is a measure of H  ions in a solution. An increase in H  in solution results in a decrease in pH. This is more acidic.

3. Describe the sliding-filament sliding-fi lament model of muscle contraction. Include in your answer the roles of actin, myosin, troponin, tropomyosin, ATP and calcium.   When calcium enters the cytoplasm from the sarcoplasmic reticulum (SR), it binds to troponin. The troponin/tropomyosin complex changes shape, exposing the active sites on actin. Myosin heads then bind to the active sites, and using ATP, pull the filaments along each other, resulting in shortened sarcomeres and muscle contraction.

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Name ____________________________________

4. Describe action potentials in either nervous or muscle tissue. Include in your answer the roles of sodium, potassium, calcium and voltage-gated channels (for all relevant ions).   An action potential is a brief reversal in the charge on the membrane. In response to an initial depolarization, if threshold is reached, voltage gated Na+ channels open, allowing Na+ to flow into the cell, resulting in

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a steep depolarization, that moves the charge on the membrane from negative to positive. Then voltage gated K+ channels open, allowing K+ to leave the cell, repolarizing the cell membrane and even overshooting the resting membrane potential with a brief hyperpolarization. 5. Describe the resting membrane potential and how the polarization of the membrane changes in response to depolarization, hyperpolarization and repolarization.   All cellular membranes are charged or polarized. The inside of the membrane is negative with respect to the outside. This is considered the resting membrane potential.   Depolarization results in the charge on the membrane becoming less negative or more positive.   Repolarization is the change change in charge that results in the membrane being restored to the resting membrane potential.   Hyperpolarization results in the charge on the membrane become more negative. 

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