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A&P 1
(2) Ligands, Receptors, Ion Channels
| Question | Answer |
|---|---|
| ligand refers to... | chemicals made by the body that can bind complementary receptor on target cells to send a signal to that cell to do something |
| 2 primary ligands include | hormones and neurotransmitters |
| hormones are chemicals secreted by | endocrine glands directly into the circulatory system |
| what base are hormones | either amino acid or steroid based (derived from cholesterol) |
| true or false: hormones can travel long distances before encountering and binding to a complementary receptor on its target cell | true |
| are hormones considered metabotropic | yes |
| neurotransmitters are ligands secreted by... | axon terminal knobs into a synaptic cleft |
| when is a neurotransmitter considered ionotropic | if binding to a receptor DIRECTLY opens an ion channel |
| when is a neurotransmitter considered metabotropic | if binding to a receptor results in changing cells metabolism and INDIRECTLY opens ion channels |
| what are receptors and where are they found | cluster of molecules, found at surface of cell (ion channel linked receptors and G protein linked receptors) or intracellular |
| true or false: when ligand binds to the receptor, it triggers a specific change in the target cell | true |
| what are the 2 kinds of surface receptors | ion channel linked receptors, G protein linked receptors |
| when a neurotransmitter that is ionotropic binds to an ion linked receptor... | it directly opens/closes the ion channel |
| where are ion linked receptors | bound to an ion channel within the plasma membrane |
| where are G protein linked receptors | parts of the receptor extend through the plasma membrane |
| true or false: G protein linked receptors can be used by both neurotransmitters and hormones | true |
| structure and activity of a G protein linked receptor | ligand binds to receptor, receptor changes shape and interacts w G protein, G protein changes shape and interacts w adenylate cyclase, adenylate cyclase converts ATP to Cyclic AMP, cyclic AMP activates other enzymes to initiate metabolic change in cell |
| true or false: a neurotransmitter that is metabotropic binds to G protein receptor and the effect is to indirectly open an ion channel | true |
| amino acid based hormones binds to G protein linked receptors with a variety of results such as... | stimulate mitosis, protein synthesis, secretion, etc. |
| intracellular receptors locations | in cytoplasm or nucleus of target cell |
| intracellular receptors are only used by | steroid based hormones (and other that are fat soluble). (ex. estrogen, testosterone) |
| intracellular receptor activity | hormone passes through plasma membrane of target cell and binds to receptor, hormone-receptor complex binds to area on the DNA and "turns on" a gene to initiate protein synthesis. |
| what are ion channels | large proteins that float in cell membrane and selectively allow ions into/out of the cell |
| types of ion channels | passive (leakage channels), gated ion channels (Active) |
| true or false: passive (leakage) channels are always open, allowing ions to flow freely through them | true |
| where are passive channels located | all over surface of a neuron |
| what do passive channels control | distribution of ions across cell membrane when neuron is at rest |
| what are the 3 types of passive (leakage) channels | chloride channels, potassium channels, sodium channels |
| what are gated ion channels | ion channels that open or close in response to a stimulus |
| what are the 4 types of gated ion channels | chemically (ligand) gated, voltage gated, mechanically gated, light gated |
| chemically gated ion channels | open in response to a chemical (neurotransmitter or hormone) binding to a receptor |
| where are chemically gated ion channels located | dendrites and cell bodies of neurons |
| voltage gated ion channels | open or close when there is a change in voltage across the cell membrane |
| where are voltage gated ion channels located | on axons and terminal knobs of neurons |
| mechanically gated ion channels | open in response to mechanical distortion of cell membrane (cell is pressed, bent, or stretched) |
| where are mechanically gated ion channels located | on receptive ending of pseudounipolar neurons |
| light gated ion channels | respond to changed in light levels (photons) |
| where are light gated ion channels located | in rods and cones of the retina |
Created by:
katiew0