Term
| What do chemoreceptors sense? |
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Definition
| Taste, smell, blood levels of 02 and pH |
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Term
| What do mechanoreceptors sense? |
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Definition
| Hearing, proprioception, touch, pain, blood pressure |
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Term
| What do photoreceptors sense? |
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Definition
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Term
| Bioelectricity involves charge movements. How is this accomplished in the body? |
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Definition
| Through movements of inorganic ions, including Na+, K+, Ca2+ and Cl- |
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Term
| What is the ratio at which sodium-potassium pumps exchange K+ for Na+? |
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Definition
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Term
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Definition
| Membrane potential. Caused by separation of ions across the impermeable membrane. This is the voltage difference across the cell membrane, ranging from -10 mV (RBCs) to -90 mV (heart cells). |
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Term
| What is an action potential? |
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Definition
| A transient change in Vm caused by ion movement across the cell membrane. |
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Term
| Which has a longer AP duration: skeletal muscle, nerve or cardiac muscle? |
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Definition
| Cardiac muscle. Another key difference: tension overlaps with AP in cardiac but NOT in nerve/skeletal muscle. |
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Term
| What is the main determinant of resting membrane potential? |
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Definition
| The concentrations of potassium (inside and outside the cell) and the permeability of the cell membrane to potassium. K+ is #1 for RMP! |
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Term
| What percentage of the body's water weight is in the intracellular fluid? |
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Definition
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Term
| About 40% of the water weight is in the extracellular fluid. What comprises this? |
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Definition
| Interstitial fluid (11 liters) and Plasma (3 liters). |
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Term
| Is the lipid bilayer of the cell membrane a good or bad conductor? |
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Definition
| It is a bad conductor! (A good insulator) |
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Term
| What is conductance? How is this related to resistance? |
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Definition
| It is the ease with which ions traverse the membrane driven by a transmembrane voltage gradient. It is the reciprocal of resistance. Higher conductance = easier ion passage. |
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Term
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Definition
| Net rate of movement of ions across the membrane (in quantity/time). Flux = (ease of movement)(driving force) |
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Term
| A net flux of zero means what? |
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Definition
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Term
| The total driving force acting on ions is what? |
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Definition
| The electrochemical gradient |
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Term
| When cations flow INTO the cell, what type of current is generated? |
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Definition
| An INWARD ionic current with a NEGATIVE sign. (Can also be produced when anions flow OUT of the cell) |
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Term
| When an electrochemical equilibrium has been reached, what is the membrane potential called? |
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Definition
| Potassium equilibrium potential (Vm). This is the energy available in the concentration gradient, expressed as voltage. |
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Term
| Why do real cells differ from the hypothetical cells we use for calculations? |
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Definition
| Real cells are leaky! But only to sodium. This depolarizes the cell just a little. |
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Term
| When you increase potassium outside the cell, what happens to the inward electrical gradient? How is this solved? |
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Definition
| The inward electrical gradient is now greater than the concentration gradient. This causes more K+ to rush IN and the cell depolarizes slightly. |
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