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Cell to Cell
Communication: Chemical and Electrical Signaling
| Question | Answer |
|---|---|
| 4 components required for communication | sender, signal, medium and receiver |
| Name 2 types of homeostatic signals | Chemical and Electrical |
| What are chemical signals? | Proteins, lipids or gasses secreted by cells that prompt an effect in neighboring or distant cells |
| What are electrical signals? | change in overall balance of negative and positive ions inside and outside of cell that transmit signals along cell membrane |
| True or False: Messages can be carried by a series of electrical AND chemical signals | TRUE |
| Define Hormone | Chemical messenger produced by endocrine gland Travels through bloodstream to act on distant cells |
| Define Neurohormone | Chemical released be a nerve cell into blood Meant to act on distant cells |
| Define Neurotransmitter | Chemical released by nerve cell bridges the synaptic cleft to turn electrical signals into chemical ones |
| Define Paracrine Factor | Chemical signal released by body cells Travels by diffusion through extracellular fluid Act on nearby cells |
| Describe ligand-gated channel receptor | Gates that allow ions to cross cell membrane |
| Describe enzyme-linked receptor | Has 2 parts When extracellular part is bound, it activates an enzyme that activates another enzyme and keeps going until one activated enzyme induces a functional change in the cell |
| Describe G-Protein coupled receptor | membrane receptors that utilize second messengers to spread intracellularly an extracellular signal |
| Define second messenger | small molecule that transmits a cell surface signal to cytoplasm or nucleus |
| What is the role of a G-Protein | regulates the production of a specific second messenger |
| What is a ligand? | Chemical signals |
| What is a receptor? | A receiver that binds to a ligand |
| what receptor protein are enzymes a part of? | Enzyme linked receptors |
| True or False: ligands can cause different responses in various cells | True- because different cells have different receptors |
| What is the role of a dendrite? | convey electrical signals from another cell TOWARD the neuron cell body |
| What is the role of the cell body of a neuron? | Most of the neuron mass Contains nucleus |
| What role do axons in a neuron? | Convey electrical signals AWAY from cell body and to other cells |
| What is the function of a collateral? | Provide regulation of the cells firing pattern. |
| Role of meylin sheaths? | help accelerate the transmission of electrical signals |
| Define endogenous ligand | naturally occurring ligand for a particular receptor (endo=within; genous=body) |
| Define exogenous ligand | originates outside of the body |
| True or False: A Neuron can have only one dendrite and many axons | False: A neuron can have many dendrites but only one axon |
| What is an electrical gradient? | different number of anions and cations of either side of the cell membrane is found in every cell and is the basis of electrical communication |
| What is a membrane potential? | fluid inside a cell membrane compared to the fluid just outside |
| Characteristics of Action Potentials | - has depolarizing and re-polarizing phase - always the same magnitude - signal strength is determined by the frequency - travels long distances - occurs when man voltage gated sodium channels are opened |
| Characteristics of Graded Potentials | - can be depolarizing or hyperpolarizing - can be combined to create a larger signal |
| Where is sodium more concentrated? | Outside of the cell |
| Where is potassium more concentrated? | Inside of the cell |
| 3 important ions channels | Leak channels, ligand gated channels and voltage gated channels |
| Describe a leak channel | always open, allowing ions to "leak out" , most cells have more potassium leak channels than sodium channels |
| Describe a ligand gated channel | open in response to a chemical signal, help with turning a chemical signal into an electrical signal |
| Describe a voltage gated channel | open in response to a change in membrane potentials, responsible for long distance electrical signals |
| What 2 things are needed for ion movement by facilitated diffusion? | A) a gradient B) an open ion channel |
| What 2 things determine a resting membrane potential? | A) potassium is concentrated inside cell B) potassium channels are always open |
| Name the four phases of action potential | -resting state - graded potential - depolarization - re-polarization |
| Describe the resting state of an action potential | -inside of cell is negatively charged -no change in membrane potential - Na+ ions outside of cell - K+ ions inside of cell - Voltage gated channels are closed |
| Describe the graded potential phase of action potential | - Membrane potential is slightly depolarized - some Na+ ions enter the cell by opening of voltage-gated channels - K+ ions are still leaving via the leak channel |
| Describe the depolarization phase of an action potential | -Membrane potential continues to depolarize -many Na+ ions enter due to opening of more voltage-gated channels -K+ ions continue to leave via leak channel, voltage-gate channels are closed until polarization reaches peak |
| Describe the re-polarization of an action potential | -Cell membrane begins to re-polarize - Na+ voltage-gated channels are closed, blocking their entry - K+ ions leave via leak channels and newly opened K+ voltage gate channels |
| Define action potential | Large change in membrane potential that can travel long distances |
| Sodium ions entering the cell cause what reaction? | Depolarization |
| Potassium ions leaving the cell cause what reaction? | repolarization |
| What part of the neuron do action potentials happen? | nodes |
| Define anatagonist | chemical that blocks or slows down the effect of a ligand |
| In which body systems are electrical signals most important? | Nervous and muscular system |
| What is the resting membrane potential for muscle and nerve cells | -70mV |
| A strong graded potential has a greater... | magnitude |
| a stronger action potential has a greater... | frequency |
| The process by which myelnated neurons move electrical signals quickly is called... | saltatory conduction |
| what channels are opened during the repolarization phase of an action potential | voltage gated potassium channels |
| G-protein coupled receptors stimulate the production of.... | phospholipids |
| Graded potentials travel over ______ distances and action potentials travel over _______ distances | graded: short action: long |
Created by:
efoote
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