Term
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Definition
| changes in a cell's membrane potential |
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Term
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Definition
| molecules secreted by cells into the ECF |
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Term
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Definition
| cells that respond to electrical or chemical signals |
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Term
| 3 types of local communication |
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Definition
1. gap junctions (direct cytoplasmic transfer of electrical & chemical signals between adjacent cells)
2. contact-dependent signals (surface molecules on one cell membrane bind to surface molecules on another cell's membrane)
3. chemicals that diffuse through the ECF to act on cells close by |
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Term
| long-distance communication |
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Definition
| uses a combination of chemical & electrical signals carried by nerve cells & chemical signals transported in the blood |
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Term
| cell adhesion molecules/CAMs |
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Definition
| first known for cell-to-cell adhesion, now known to act as receptors in cell-to-cell signaling; linked to the cytoskeleton or intracellular enzymes; transfer signals in both directions across cell membranes |
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Term
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Definition
| acts on cells in the immediate vicinity of the cell that secreted the signal |
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Term
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Definition
| a chemical signal that acts on the cell that secreted it |
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Term
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Definition
| chemical signals that are secreted into the blood & distributed all over the body by the circulation; how the endocrine system communicates |
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Term
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Definition
| chemicals secreted by neurons |
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Term
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Definition
| a neurocrine molecule that diffuses from the neuron across a narrow extracellular space to a target cell & has a rapid-onset effect |
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Term
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Definition
| a neurocrine that acts more slowly as an autocrine or paracrine signal |
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Term
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Definition
| a neurocrine molecule that diffuses into the blood for body-wide distribution |
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Term
| A cell can respond to a particular chemical signal only if the cell _____ |
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Definition
| has the appropriate receptor protein to bind that signal |
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Term
| 4 features shared by all signal pathways |
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Definition
1. the signal molecule is a ligand that binds to a protein receptor
2. ligand-receptor binding activates the receptor
3. the receptor in turn activates one or more intracellular signal molecules
4. the last signal molecule in the pathway creates a response by modifying existing proteins or initiating the synthesis of new proteins |
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Term
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Definition
| the process by which an extracellular signal molecule activates a membrane receptor that in turn alters intracellular molecules that create a response |
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Term
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Definition
| a devices that converts a signal from one form into a different form |
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Term
| 3 steps of biological signal transduction |
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Definition
1. an extracellular molecule binds to & activates a membrane receptor
2. the activated membrane receptor turns on its associated proteins & starts an intracellular cascade of second messengers
3. the last second messenger in the cascade acts on intracellular targets to create a response |
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Term
| 2 things that membrane receptors & their associated proteins can do |
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Definition
1. activate protein kinases (enzymes that transfer a phosphate group from ATP to a protein)
2. activate amplifier enzymes that create intracellular second messengers |
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Term
| 3 things second messenger molecules can do |
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Definition
1. alter the gating of ion channels
2. increase intracellular calcium
3. change enzyme activity, especially of protein kinases or protein phosphatases (enzymes that remove a phosphate group) |
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Term
| The steps of a signal transduction pathway form a _____ |
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Definition
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Term
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Definition
| turning one signal molecule into multiple second messenger molecules |
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Term
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Definition
| turned on by the receptor-ligand complex; activates several molecules which in turn each activate several more molecules as the cascade proceeds |
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Term
| The activation of _____ initiates the most rapid intracellular responses of all receptors |
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Definition
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Term
| The _____ are a large & complex family of membrane-spanning proteins that cross the phospholipid bilayer 7 times |
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Definition
| G protein-coupled receptors (GPCRs) |
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Term
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Definition
| a three-part membrane molecule to which the cytoplasmic tail of GPCRs are linked |
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Term
| What was the first identified signal transduction pathway? |
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Definition
| G protein-coupled adenylyl cyclase-cAMP system |
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Term
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Definition
| converts a membrane phospholipid into two lipid-derived second messenger molecules (diacylglycerol & inositol triphosphate) when a signal molecule activates the "phospholipase C" G-protein coupled pathway |
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Term
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Definition
| a nonpolar diglyceride that remains in the lipid portion of the membrane & interacts with protein kinase C (PKC) |
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Term
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Definition
| a Ca2+-activated enzyme associated with the cytoplasmic face of the cell membrane |
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Term
| inositol triphosphate (IP3) |
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Definition
| a water-soluble messenger molecule that leaves the membrane & enters the cytoplasm |
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Term
| 2 regions on a receptor-enzyme |
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Definition
1. a receptor region on the extracellular side of the cell membrane
2. an enzyme region on the cytoplasmic side |
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Term
| Guanylyl cyclase is the amplifier enzyme that converts GTP to _____ |
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Definition
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Term
| 4 types of modified proteins that control cell responses |
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Definition
1. metabolic enzymes
2. motor proteins for muscle contraction & cytoskeletal movement
3. proteins that regulate gene activity & protein synthesis
4. membrane transport & receptor proteins |
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Term
| 5 types of calcium-dependent events that occur in the cell |
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Definition
1. Ca2+ binds to the protein calmodulin
2. calcium binds to other regulator proteins & alters movement of contractile or cytoskeletal proteins such as microtubules
3. Ca2+ binds to regulatory proteins to trigger exocytosis of secretory vesicles
4. Ca2+ binds directly to ion channels to alter their gating state
5. Ca2+ entry into a fertilized egg initiates development of the embryo |
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Term
| The best-known gaseous signaling molecule is _____ |
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Definition
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Term
| _____, a gas known mostly for its toxic effects, is also a signal molecule produced in minute amounts by certain cells |
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Definition
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Term
| The newest gaseous signal molecule to be described is _____ |
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Definition
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Term
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Definition
| an enzyme that produces arachidonic acid from membrane phospholipids |
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Term
| 2 major groups of arachidonic acid-derived paracrine molecules |
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Definition
1. leukotrienes (produced by the action of the enzyme lipoxygenase on arachidonic acid)
2. prostanoids (produced when the enzyme cyclooxygenase acts on arachidonic acid) |
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Term
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Definition
1. prostaglandins
2. thromboxanes |
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Term
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Definition
| a competing ligand to a primary ligand that binds & elicits a response |
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Term
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Definition
| a competing ligand to a primary ligand that binds & blocks receptor activity |
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Term
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Definition
| a decrease in receptor number |
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Term
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Definition
| when the target cell inserts more receptors into its membrane |
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Term
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Definition
1. the nervous system has a role in preserving the "fitness" of the internal environment
2. some systems of the body are under tonic control
3. some systems of the body are under antagonistic control
4. one chemical signal can have different effects in different tissues |
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Term
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Definition
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Term
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Definition
| the disturbance or change that sets the reflex pathway in motion |
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Term
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Definition
| AKA sensory receptor; continuously monitors its environment for a particular variable |
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Term
| When activated by a change, the sensor sends an _____ to the integrating center for the reflex |
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Definition
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Term
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Definition
| part of a reflex pathway that compares the input signal with the setpoint |
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Term
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Definition
| the desired value of a given variable |
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Term
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Definition
| an electrical and/or chemical signal that travels to the target |
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Term
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Definition
| the cell or tissue that carries out the appropriate response to bring the variable back within normal limits |
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Term
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Definition
| the minimum stimulus needed to set the reflex response in motion |
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