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biology final
Biology #3 section
| Question | Answer |
|---|---|
| Neurons | are the functional unit of the nervous system, function to transmit information |
| Neuroglia | cells that support neurons, maintain function of neurons; greatly outnumber neurons |
| Most neurons have (4 marks) | cell body, dendrites, axon, axon terminals |
| Axon hillock | is the trigger zone where axon meets cell body |
| Dendrites | receive information |
| axon | electrical signal propagated here |
| axon terminal | passes signal on |
| Classifying Neurons: Structural classification | based on the number of processes (axon or dendrites) that extend from the cell body such as mutipolar, biopolar, unipolar neuron (one process b/t axon terminal and cell body) |
| Classifying Neurons: Functional classification: Sensory neuron | also called afferent neurons; convey action potentials (APs) into the central nervous system (brain+spinal cord); for example: detecting things such as touch through sensory neurons of the finger to CNS |
| Classifying Neurons: Functional classification: Motor neuron | also called efferent neurons; convey APs away from CNS to the periphery of the body; for example: motor neurons tell the muscle to contract |
| Classifying Neurons: Functional classification: Interneurons | mainly in CNS, b/t sensory and motor neurons |
| Graded potentials | used for short distance only; are initiated in dendrites and cell body of the neuron |
| Action potentials | allow for long-distance communication, propagated along the axon |
| Ways to maintain resting membrane potential; how much mV for it? | -70mV, which is maintian by 1) Na+/K+ ATPase - pumps out 3 Na+ for every 2K+ pump in ; 2) Leakage channels - randomly open or closed - K+ leaks out of cell |
| When ion channels are open, they allow sepcific ions to move across the plasma membrane, down their electrochemical gradient. What is electrochemical gradient? | ions move from areas of high conecentration to areas of low concentration = chemical gradient; cation move to a negative charged area, anion to positively charged = electrical gradient |
| Electrical signals for 3 types of gated channels: Ligand-gated | channels respond to a neurotransmitter which is chemical stimulus, typically concentrated in synapse |
| Electrical signals for 3 types of gated channels: Voltage-gated | respond to changes in membrane potential, typically found along axon: the sodium and potassium voltage-gated channels of nerve and muscle. the voltage-gated calcium channels that play a role in neurotransmitter release in pre-synaptic nerve endings. |
| Electrical signals for 3 types of gated channels: Mechanically-gated | respond to mechanical deformation, found in sensory cell such as skin |
| Depolarizing graded potential | stimulus that causes the cell to be less negatively charged |
| Hyperpolarizing graded potential | stimulus that causes the cell to be more negatively charged |
| Graded potentials can be added together - the net result is a larger or smaller graded potential, where is it located? | axon hillock : trigger zone - receive from dendrites and then cell body and add them all up |
| Action potential (AP) | is a signal which travels the length of the neuron; if a neuron receives a threshold stimulus = min depolarization (-55mV), an AP is produced an spread down the axon to the axon terminals; if stimulus is < threshold, no AP occurs |
Created by:
sharonlisw
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