Term
| What are the 2 different types of cell communication? |
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Definition
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Term
| What is a type of direct communication? |
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Definition
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Term
| What are 6 types of indirect communication? |
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Definition
-Paracrine
-Autocrine
-Cytokine
-Neurotransmitter
-Hormones
-Neurohormones |
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Term
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Definition
| Type of chemical messenger that communicates w/ neighboring cells by simple diffusion |
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Term
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Definition
| Type of chemical messenger for which the secretory cell and target cell are the same. |
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Term
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Definition
| Peptides or proteins that are usually secreted by immune cells in response to a stimulus. |
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Term
| Define neurotransmitters. |
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Definition
| Chemical messenger released from the axon terminal of a neuron. |
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Term
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Definition
| Chemical messenger released from endocrine cells or glands into the interstitial fluid, where they then diffuse into the blood and travel to target cells. |
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Term
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Definition
| Special class of hormones released by neurosecretory cells. |
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Term
| It is the nature of the ________ that determines the cell action, not the ________. |
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Definition
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Term
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Definition
| Conversion of the energy form of a stimulus into an electrical signal in the form of changes in membrane potential. |
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Term
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Definition
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Term
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Definition
| Any cell selectively affected by a particular agent, such as a hormone or drug. |
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Term
| What are the 5 chemical classifications of messengers? |
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Definition
-Amino Acid messengers
-Amine messengers
-Peptide/protein messengers
-Steroid messengers
-Eicosanoid messengers |
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Term
| 2 characteristics of amino acid messengers. |
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Definition
-They function as neurotransmitters in brain and spinal cord
-Lipophobic (disolve in water but do NOT cross the plasma membrane) |
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Term
| 3 characteristics of amine messengers. |
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Definition
-Derived from amino acids
-Possess an amine group (-NH2)
-Lipophobic (except thyroid hormones) -> disolve in water but do NOT cross the plasma membrane. |
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Term
| 2 characteristics of peptide/protein messengers. |
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Definition
-Most chemical messengers are these
-Lipohobic (dissolve in water but do NOT cross the cell membrane) |
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Term
| 2 characteristics of steroid messengers |
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Definition
-Derived from cholesterol
-Lipophilic (do NOT dissolve in water and DO cross the cell membrane) |
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Term
| 2 characteristics of eicosanoid messengers. |
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Definition
-Function as paracrines.
-Lipophilic (do NOT dissolve in water and DO cross the cell membrane) |
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Term
| What is the difference between lipophilic (hydrophobic) and lipophobic (hydrophilic) messengers? |
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Definition
Lipophilic messengers will react inside the cell's cytosol or nucleus. Acts on protein synthesis.
Lipophobic messengers do NOT passively cross the plasma membrane. They require a carrier and secondary active transport. |
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Term
| How are lipophilic and lipophobic messengers secreted by a cell? |
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Definition
Lipophilic- By diffusion across the lipid bilayer
Lipophobic- By exocytosis. Formed in cell by ribosome of the rough ER. |
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Term
| How are lipophilic and lipophobic messengers transported in blood? |
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Definition
Lipophilic- Bound to carrier proteins in plasma
Lipophobic- Dissolved in blood plasma |
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Term
| What is the half-life of lipophilic and lipophobic messengers? |
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Definition
Lipophilic- long half-life
Lipophobic- Short half-life |
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Term
| The receptors that lipophilic and lipophobic messengers bind to are located where? |
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Definition
Lipophilic- Cytosol
Lipophobic- Plasma membrane |
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Term
| The cellular effects elicited of lipophobic and lipophilic messengers? |
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Definition
Lipophilic- Stimulate protein synthesis
Lipophobic- Affects ion channel activity w/ gated channels |
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Term
| What are the 4 properties of a receptor? |
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Definition
-Specificity (receptors generally bind to only 1 msgr or a single class of msgrs)
-Affinity and competition (strength of binding between hormone and receptor - influences the strength of the response)
-A single target cell may have receptors for more than 1 type of msgr
-The binding of msgrs (receptors produce a response in a cell through a variety of mechanisms) |
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Term
| Describe the secondary messenger system. |
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Definition
| Extracellular messenger (1st messenger) binds to a receptor on the cell membrane which stimulates an intracellular messenger (2nd messenger) which initiates a cell response. |
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Term
| Describe the action of G-Proteins. |
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Definition
| When a messenger binds to a G-Protein receptor, the G-protein alpha subunit releases GDP. G-protein alpha subunit then binds to GTP, which activates the G-Protein. Alpha subunit seperates from G-protein and moves laterally to cause a change in an effector. |
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Term
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Definition
| A single activated receptor can activate phosphorelation of hundreds of target proteins. |
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