Nervous System Flashcards
Specialized cells responsible for conduction nerve impulses
neuron
List ways in which neurons communicate .
- Physical Communcation (via ion exchange and generation of AP)
- Chemical Communcation (neurotransmitter)
List the major components of a Neuron.
- Dendrites (receives signal AP)
- Soma (Cell body, location of nucelus and mitochondria)
- Axon Hillock (cell body transition to axon, transmission of AP to axon)
- Axon (Long appendage down which AP travel)
- Synaptic bouton (Nerve Terminal)
- releases neurotransmitters into synaptic cleft to allow for transmission of signal to next neuron
List two important structures found on axon that assist in saltatory conduction.
- Myelin Sheath
- Nodes of Ranvier
What is the purpose of the myelin sheath and and nodes of Ranvier?
- Myelin Sheath
- Insulation: Prevent signal lost or crossing signals
- Increase AP across axon
- Nodes of Ranvier
- Regions in which AP “jump” along axon, speeding up conduction.
What are the major components of the synapse?
- Synaptic Bouton (Pre-synaptic cell)
- Synaptic Cleft
- Membrane of Post-synaptic cell
Creates myelin for CNS.
Oligodendrrocytes
Creates myelin for PNS.
Schwann Cells
Ganglia
Cluster of neuronal cell bodies if PNS.
Nuclei
Cluster of neuronal cell bodies if CNS.
Types of information a neuron can carry.
- Sensory (Sensory neurons)
- Motor (Motor Neurons)
- Both (Interneurons)
(Nerve tracts, bundle of individual axons, carry only one type)
Cells within nervous syste that support neurons.
Glial Cells
List three types of Glial Cells.
- Astrocytes
- Microglia
- Empendymal Cells
Glial cells that form blood brain barrier (controlling transmission of solutes from blood to nervous system)
astrocytes
Glial cells that that lines ventricles and secrete CSF.
Ependymal Cells
Glial cells that are phagocytes and are responsible for breaking down pathogens and waste in CNS.
Microglia
Resting membrane potential
-70 mV
What two things maintains resting membrane potential?
- Selective permeability of specific ions (Na/K)
- Na+/K+ ATPase Pump
How many sodium and potassium ions are pumped out/in respectively by Na+/K+ ATPase pump.
3 sodium out, 2 potassium in (reason for why cells have a higher negative charge when compared to extracellular fluid)
Incoming signals can be either ________ or ________. What does this mean?
- Inhibitory
- Depolarize neuron - contribute to AP
- Excitatory
- Hyperpolarize neuron - Makes it harder for AP to occur
Types of summation that refers to addition of multiple signals of a single neuron add up over a period of time to produce/inhibit and AP in the next neuron.
Temporal Summuation
Types of summation that refers to addition of multiple signals of all surrounding neurons near are summed at a given moment in time to produce AP in next neuron.
Spatial summation
Describe the different events prior, during, and after an AP.
- Neurotransmitted bind to receptors on post-synaptic cell
- Conformation changes occur in receptors that eventually open up channels for which sodium can flow in (working down its electrochemical gradient)
- Threshold is reach: -55 mV.
- Sodium Voltage gated channels open up and Na+ continues to flood in.
- Peak of AP is at +35 mV
- At this point, Na+ voltage gated channels imactivate and K+ voltage gated channels open up (working down electrochemical gradient)
- K+ Floods out of cell, causing hyperpolarization
- K+ voltage gated channels close
- Refractory Period begins where Na+/K+ leak channels as well as Na+/K+ ATPase pump works together to allow membrane to return to resting membrane potential
Absolute vs. Relative Refractory Period
- Absolute
- No matter how strong incoming impulses are, neuron is unable to fire an AP during this time.
- Relative
- Cell requires larger than normal stimulus to fire AP
Are AP unidirectional or multidirectional?
Unidirectional
They propagate along an axon, jumping from node to node. Because previous node is now in refractory period, it will be unable have a simultaneous AP traveling in the opposite direction.
Explain the events that occur at the Synapse (includes nerve terminal, synaptic cleft, and post-synaptic membrane).
- Once AP has reached nerve terminal, Ca+ voltage gated channels open and Ca+ floods into terminal
- Results in the release of neurotransmitters sitting in nerve terminal (via exocytosis)
- Neurotransmitters travel through synaptic cleft
- Once they reach post-synaptic membrane, they bind to receptors on membrane that will change comformation to allow Na+ to flow in.
What are the two major receptors on post-synaptic membrane.
- Ligand Gated ion channels
- G-Protein Coupled Receptors
List the ways in which neurotransmitters can be cleared from synaptic cleft?
- Enzymatically broken down
- Absorbed back into pre-synaptic cell via reuptake carriers
- Diffusion out of synaptic cleft
Removes acetylcholine from post-synaptic cleft.
Acetyl-cholinesterase
Which is an efferent neuron and which is a afferent neuron?
- Sensory
- Motor
- Sensory: afferent
- Motor: Efferent
Myelinated axons that lie deeper in the brain.
White matter
Unmyelinated axons and dendrites on the outer portion of the brain.
Grey Matter
Two division of PNS. (often act in opposition to one another)
- Parasympathetic/Autonomic Nervous System
- Sympathetic/Somatic Nervous System
Explain important details about autonomic nervous system.
- Rest and Digest
- Includes:
- Resting and Sleeping states
- Decreasing HR
- Constricting Bronchioles
- Increasing Peristalisis and Excocrine Secretions
- Includes:
- Main Role: Conserving energy
- Two neurons that work to transmit signals
- Pre-Ganglionic and Post-Ganglionic
- Cell body of preganglionic neuron is in CNS.
- Pre-ganglionic neuron travels to PNS, where it meets with cell body of post-ganglionic nerve and transmits signal to target tissue
- Pre-Ganglionic and Post-Ganglionic
Explain important details about Parasympathetic nervous system.
- Fight or Flight
- Increase HR
- Redistribution of blood to Periphery
- Increase glucose concentration (for ATP production)
- Relaxes bronchi
- Decrease activity of digestive organs
- Dialation is important
- Epinephrine is release into the blood
- Has one neuron that goes directly from spinal cord to muscle
How interneurons in the spinal cord relay information to the source of the stimulus while simultaneously routing information to brain. (2 types)
Reflex Arc
Describe the Monosynaptic Reflex Arc
Sensory neuron that synapses with and fires directly onto motor neuron.
Describe the Polsynaptic Reflex Arc
Sensory neuron fires onto a motor neuron as well as other interneurons that fire onto other motor neurons.
Describe the muscle-stretch reflex.
- Only occurs on side of the body
- Stimulus: Afferent neuron (Somatosensory Neuron)
- Excites motor neuron on the spinal cord that sends a stimulus back, causing the knee to contract
- Excites other inhibitory inteneurons (connected to other motor neurons) that will cause the muscles in the back of the thigh to relax. If there is no inhibitory interneuron, the leg would not become straight because the hamstring would not relax.
- Response: Efferent Neuron (Motor Neuron)
- Together these neurons synapse
- This is an example of reciprocal inhibition.
