2715187
Description
Flashcards by Kyra Bingham, updated more than 1 year ago
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Created by Kyra Bingham
almost 9 years ago
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| Question | Answer |
| List the major subdivisions of the human nervous system. | - Central and Peripheral Nervous Systems - Somatic and Autonomic Nervous Systems - Afferent and Efferent Divisions |
| What two organs make up the central nervous system? | Brain and spinal cord (and nerves) |
| Contrast the somatic nervous system with the autonomic nervous system. | |
| What are the five main types of glia? | 1. Astrocytes 2. Microglia 3. Ependymal cells 4. Oligodendrocytes 5. Schwann cells (PNS) |
| Describe the myelin sheath found on some nerve fibres. | - Formed by oligodendrocytes in CNS and Schwann cells in PNS - Made up of myelin, a fatty substance - Nodes of Ranvier are the gaps between adjacent Schwann cells - Increases conduction speed of nerves |
| What is a neurilemma? | The part of the Schwann cell where the nucleus and cytoplasm are pushed to the perimeter of the cell. Oligodendrocytes in the CNS do not have neurilemma. |
| Describe the three different forms of Schwann cells. | - Unmyelinated nerve fibres - Myelinated nerve fibres - Satellite cells |
| What is the difference between an axon and a dendrite? | Dendrite - Input and output zone - Receives and conducts electrical or chemical signals Axon - Conduction zone - Sometimes myelinated - Conducts AP (electrical signals) |
| What are three structural categories of neurons? | (Pseudo)Unipolar Bipolar Multipolar |
| What are the three main functional categories of neurons? | Afferent Efferent Interneurons |
| What are the essential components of a reflex arc? | - Receptor - Afferent neuron - CNS (Interneuron) - Efferent neuron - Effector |
| What are the three layers of connective tissues that hold the fibres of a nerve together? | - Endoneurium (around axon) - Perineurium (around fascicle) - Epineurium (around nerve) |
| What is the difference between a nerve and a tract? | - Nerves are bundles of nerve fibres in the PNS. They have the three layers of connective tissue covering them. - Tracts are bundles of nerve fibres in the CNS. They do not have a connective tissue covering |
| How does white matter differ from grey matter? | White matter - Composed of myelinated tracts and nerves Grey matter - Composed of unmyelinated tracts and nerves - Small, distinct regions usually called nuclei (CNS) or ganglia (PNS) |
| Under what circumstances can a nerve fibre be repaired? | - Damage is not extensive - Cell body and neurilemma are intact - Scarring has not occurred |
| What mechanisms are involved in producing the resting membrane potential? | - Gated protein channels - Sodium ions - Potassium ions - Sodium-potassium pumps |
| In a resting neuron, what positive ion is most abundant inside the plasma membrane? | Potassium ions |
| How does depolarisation of a membrane differ from hyperpolarisation? | Depolarisation - Reduction of membrane potential - Membrane potential value moves toward zero - Excitatory Hyperpolarisation - Increase of membrane potential - Membrane potential value moves away from zero - Inhibitory |
| List the events that lead to the initiation of an action potential. | 1. Stimulus-gated sodium channels open. Membrane depolarises. 2. As threshold potential is reached, voltage-gated sodium channels open. 3. Membrane depolarises further. 4. AP magnitude peaks at +30mV when voltage-gated sodium channels close. 5. Voltage-gated potassium channels open. Repolarisation begins. 6. Brief period of hyperpolarisation, then RMP restored by sodium-potassium pump and ion channels returning to resting state. |
| What is meant by the term threshold potential? | The potential (voltage) that needs to be reached in order for voltage-gated sodium channels to open, and therefore conduct the AP. |
| How does impulse conduction in an unmyelinated fibre differ from impulse conduction in a myelinated fibre? | Myelinated fibres conduct AP faster than unmyelinated fibres. |
| What are the three structural components of a synapse? | 1. Synaptic knob (presynaptic neuron) 2. Synaptic cleft 3. Plasma membrane of postsynaptic neuron |
| List the steps of synaptic transmission. | 1. AP reaches synaptic knob, calcium ion channels open. 2. Calcium ions trigger neurotransmitter release across synaptic cleft. 3. Neurotransmitters bind to receptors on postsynaptic membrane, causing certain ion channels to open. 4. If the excitatory postsynaptic potential (EPSP) reaches threshold potential, AP is initiated. |
| What is an EPSP? What is an IPSP? | EPSP - Excitatory Postsynaptic Potential - Excitatory neurotransmitters cause sodium and potassium ion channels to open - Temporary depolarisation IPSP - Inhibitory Postsynaptic Potential - Inhibitory neurotransmitters cause cause potassium and/or chloride ion channels ot open - Temporary hyperpolaristion |
| How does temporal summation differ from spatial summation? | Temporal summation - High frequency of APs in presynaptic neuron causes postsynaptic potentials to overlap and add together Spatial summation - When multiple presynaptic neurons provide input that add together |
| How do excitatory neurotransmitters differ from inhibitory neurotransmitters? | Excitatory neurotransmitters - Increase probability that target cell will fire an AP Inhibitory neurotransmitters - Decrease probability that target cell will fire an AP |
| What are the four chemical classes of neurotransmitters? | Class I Acetylcholine Class II Amines Class III Amino acids Class IV Other small molecules |
| What are neuromodulators? | A co-transmitter that regulates or modulates the effects of the neurotransmitter(s) released with it |
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