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45 Cards in this Set
- Front
- Back
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Nerve |
Many neurons bundled together |
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Neurons |
One nerve cell |
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3 types of neurons |
Sensory- long dendrite, short axon. Carry info from sensory receptor cells to CNS Motor- short dendrite, long axon. Carry info from CNS to effector Interneuron- short dendrite, short or long axon. Carry info within CNS |
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Dendrites |
Receive nerve impulse from postsynaptic bulbs and carries nerve impulse to the cell body |
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Axon |
Conducts nerve impulse from cell body to terminal branches |
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Schwann cells |
Type of support cell that wraps around long processes of neurons Form myelin sheath |
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Myelin sheath |
Inner sheath formed by Schwann cells around long processes Helps speed up nerve conduction |
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Neurilemma |
Outer sheath Helps with nerve regeneration |
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Nodes of ranvier |
Gaps in myelin sheath between Schwann cells Allow for Saltatory conduction (fast nerve impulse conduction) |
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Saltatory conduction |
Very fast nerve impulse conduction where the impulse jumps from node to node |
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CNS vs PNS |
CNS- nerves in spinal chord and brain PNS- peripheral nervous system, all nerves not in brain or spinal chord |
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Branches of PNS |
Somatic (voluntary) autonomic (involuntary): parasympathetic (calm/normal) and sympathetic (fight or flight) |
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What is an action potential |
Nerve impulse, an electrochemical change between inside and outside of membrane |
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Path of action potential |
Dendrites , through cell body and along axon towards axon bulb Moves in wave like motion |
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Start of action potential |
Stimuli causes movement of Na+ and K+ across membrane |
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Membrane characteristics contributing to action potential |
Na/K- pump work continuously to slowly restore Na to outside of membrane and K to inside Na and K gates- open for short time, molecules move quickly |
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4 steps of action potential |
Resting potential, depolarization, repolarization and refractory period |
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Resting potential |
Neuron CAN accept a stimuli -65mV Both Na and K gates closed More Na outside, more K inside |
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Depolarization |
Neuron CANT accept stimuli -65mV becomes +40mV Na gates open, k gates closed Na moves to inside, no K movement |
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Repolarization |
+40mV becomes -65mV Na gates closed, K gates open No Na movement, k moves outside |
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Refractory period |
Stays at -65mV Both gates closed More Na inside and K outside, pump must reverse |
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Synapse |
Space between presynaptic and postsynaptic membrane |
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Neuron to neuron transmission |
- Ap is received at axon bulb, Na gates open and Ca also enters axon bulb from synapse by active transport - Ca++ binds with contractile proteins causing them to shorten, causes synaptic vesicles to be pulled up to membrane - vesicles open at membrane, releases neurotransmitters (proteins) into synapse - neurotransmitters diffuse across synapseand bind to receptor sites on postsynaptic membrane Depending on number of excitatory neurotransmitters, inhibitory transmitters, and presence of drugs, ap may or may not develop on second neuron |
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Norepinephrine |
Excitatory neurotransmitter Decreases the permeability of postsynaptic membrane causing Na gates to open Increases chance of ap occurring on neuron 2 |
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Acetylcholine |
Inhibitory neurotransmitter Increase permeability of postsynaptic membrane, causing K gates to open Decreases chance of ap occurring on neuron 2 |
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How and why are neurotransmitters broken down after being released in synapse |
So they don’t interfere with future ap or cause 2nd neuron to fire an ap at random Monoamine oxidase breaks down norepinephrine Acetylcholinesterase breaks down acetylcholine |
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Autonomic branch of PNS |
One set of sensory neurons and 2 sets of motor neurons taking ap out Results in swelling of mixed nerve where cells bodies of second motor meet. Swelling called ganglion. It’s location separates parasympathetic branch and sympathetic branch |
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Parasympathetic vs sympathetic branches of autonomic branch |
Parasympathetic: relaxed state, acetylcholine, spinal nerves enter spine at cranial-sacral region, long pre-ganglionic fibers, short post-ganglionic fibers Sympathetic: fight or fight, norepinephrine, spinal nerves enter at thoracic-lumbar region, short pre-ganglionic fibres , long post-ganglionic fibers |
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What happens when sympathetic branch fires |
Increased heart rate, blood pressure, respiration, ATP production Increases blood flow to skeletal muscles, decreases to digestive organs Muscles tense Senses heightened |
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Reflex arc |
Part of somatic branch Allows faster response to dangerous situation by bypassing brain |
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Hypothalamus |
Control centre where nervous system and endocrine system meet Receives neurotransmitters from brain then takes one of two pathways 1) releases hormones into blood, stimulates anterior pituitary to produce and release own hormones into blood 2) uses nerve to stimulate posterior pituitary to release hormones already produced in hypothalamus |
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Cerebrum function |
Interprets touch, vision, emotions etc |
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Thalamus function |
Relay motor and sensory signals to cerebral cortex |
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Copus callosum |
Bridge between left and right side of brain |
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Cerebellum function |
Regulates motor movements |
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Grey vs white matter in brain |
Gray: location of all synapses, contains cell bodies, dendrites , axon terminals White: non-functional, acorns connecting different parts of gray matter |
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When will an ap fire in neuron 2 |
If sum of all excitatory and inhibitory responses is above the threshold of -50mV |
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Spatial summation |
Multiple neuron 1 releases neurotransmitters into one neuron 2 |
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Temporal summation |
One neuron 1 releases neurotransmitters repeatedly onto neuron 2 |
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All or none law |
The neuron either fires at maximum intensity or not at all Not followed by a nerve, only individual neurons |
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Mixed nerves |
Dendrites of sensory neurons and axons of motor neurons |
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Cranial nerves |
Enter CNS at brain sensory, motor, or mixed nerves found here |
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Spinal nerves |
Enter CNS at spinal cord Mixed nerves only |
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Sensory nerves vs motor nerves |
Sensory- dendrites of sensory neurons Motor- axons of motor neurons |
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Somatic branch of PNS |
Have one set of sensory neurons bringing ap into spinal cord and one set of motor neurons taking ap out |
