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9 Cards in this Set
- Front
- Back
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What is a ligand? |
Substances that can create or cause a response in a cell. Ex. Hormones-PTH which causes an increase in osteoclasts, calcitonin which causes a decrease in osteoclasts. Other exs include neurotransmitters and ACh. Can increase/decrease activity, open/close doors in cell membrane and can turn genes on/off. |
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What is specificity in regards to ligands and target cells? |
Only cells with specific receptors can respond to a ligand. A cell can only respond to a ligand that it has specific receptors for. |
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What are the 2 types of receptors? |
1. Membrane bound receptors: responds/binds to ligands that CAN NOT enter/pass through the cell membrane. (Lipid ligand) - the ligand open/closed cell membrane door or uses a SECOND MESSENGER to do it for them. 2. Intracellular receptors: responds/binds to ligands that CAN pass through the cell membrane. (Protein ligand) - proteins are huge and cannot pass through the cell membrane on their own, has to use a membrane bound receptor to get in. |
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What are intracellular receptors responsible for? |
Direct gene activation, enter the cell, go to the nucleus and turn genes on or off. |
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What is the protein like ligand that will open ligand-gated NA+ channels on the cell membrane of skeletal muscles? |
Acetylcholine (ACH, ach, ACh) |
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What are the 3 types of channels? |
1. Ligand-gated in channels: (chemically gated) which opens/closes because of a ligand. Ex. Key to a door, key is the ligand, lock is the receptor. 2. Voltage-gated upon channels: which open/close because of an electrical event. Ex. Garage door 3. Non-gated in channels: door is always open and cant be closed. Ex. Archway with no door |
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What is the sodium-potassium pump? |
A protein active transport mechanism located in the cell membrane. Allows passage from the intracellular (cytoplasm) to the extracellular, etc. - always 2/3 more NA+ than K+ on the extracellular side than the intracellular. Ex. 2 K+ = 3 NA+, 6 K+ = 9 NA+ -90mv less positive that extracellular, -90mv more positive that intracellular side. RMP - resting membrane potential |
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What can we use to open up a sodium-potassium pump? |
ACh (which is a ligand) |
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Why do we pump out all the NA+ out of the cell? |
Just so they can come back in. We use the ligand-gated NA+ channels to pump NA+ back into the cell so they can create a force (voltage) which gives voltage-gates in channels the energy to open up for more NA+ to enter. |
