Nerves Flashcards
What are the divisions of the nervous system
What are the different parts of the brain
(12 cranial)
What are the different parts of the spinal cord
Describe the structure of the spinal cord
What is the general structure of a neuron
What are the different types of neurons
What is the distribution of nerves In the spine
Roots: EITHER sensory OR motor
Spinal nerves: sensory AND motor
Rami: sensory AND motor
What is the morphology of neurons
What is glia
Non-neuronal cells of brain and nervous system
What are the different types of glia
CNS
Peripheral NS (PNS)
Describe the glia of the CNS
Astrocytes - Maintain external environment for neurons
Surround blood vessels and form blood brain barrier
Ependymal - Produce cerebrospinal fluid
Microglia - Macrophages of the CNS, remove infection
Oligodendrocytes - Form myelin sheaths in the CNS
What are the different types of membrane potentials
Action potentials
Transmit signals over long distances
Graded potentials
Decide when action potential should be fired
Resting membrane potentials
Keeps cell ready to respond
Describe the resting membrane potential
Inside of cell negative relative to outside (potential difference)
Most neurons at -70mV
How is a resting membrane potential created
Dominated by permeability of resting membrane to K+
K+ continually leaks out channels down conc. gradient, established by Na+/K+ pump
Reason resting membrane potential is close to K+ equilibrium potential
Close because some other leaky channels
How is the size of membrane potential determained
Size of initial concentration gradient
Small conc.gradient
= small resting membrane potential
Large conc. gradient
= large resting membrane potential
Need lots of K+ to leak out to reach equilibrium
What is the conc. of K+, Na+, Cl-
What is a graded potential
Membrane potential that determines when action potential is fired
What are the different types of graded potentials
Generator potentials - sensory receptors
Postsynaptic potentials - synapses
End plate potentials - At neuromuscular junction
Pacemaker potentials - In pacemaker tissues
What size response to graded potentials give
Size proportional to size of stimuli
What are the properties of a graded potential
Decremental, get smaller as they move along membrane
Depolarising or hyperpolarising
Summate (add together)
Explain how EPSPs are generated
Opening Na+/K+ channels or closing leaky K+ channels to depolarise membrane
Explain how IPSP are generated
Opening Cl- channels or opening K+ channels, hyperpolarising
What is the role of synaptic integration in neuronal function
Summation of synaptic inputs to decide if initial segment will reach threshold
Axo-dendritic, Axo-somatic, Axo-axonic synapses
How is an action potential generated
Voltage-gated Na+ channels mediate depolarising
Voltage-gated K+ channels mediate repolarising and hyperpolarising
What are the different properties of action potentials
Threshold value
‘All or nothing’
Self propagating
Refractory period
Travel slowly
Encoded stimulus intensity varies in firing frequency not amplitude
Describe the action of different channels during action potential
How does myelination increase the speed of action potentials
Increased membrane resistance (less current leaks out membrane)
Decreased membrane capacitance (less current wasted charging membrane)
What are the consequences of demyelinating diseases
Attack myelin sheath
Decreased membrane resistance (more current leaks out membrane)
Increased membrane capacitance (more current wasted charging membrane)
Conduction fails
What are the different types of nerve fibres
What is the function of nodes of Ranvier
Action potential jumps from one node to the next, saltatory conduction
What is the neuromuscular junction
Synapse between motor neuron and skeletal muscle
First step in triggering muscle contraction is to evoke action potential in skeletal muscle membrane (the sarcolemma)
What is the structure of the neuromuscular junction
Presynaptic terminal filled with vesicles containing acetylcholine (ACh)
Synaptic cleft
Postsynaptic end plate of the skeletal muscle fibre
What is the process of neuromuscular transmission Slide 1
What is the process of neuromuscular transmission Slide 2
What is the process of neuromuscular transmission Slide 3
What are the key characteristics of the neuromuscular junction
Ligand-gated Na+/K+ channels evoke end plate potential
Very large graded potential, always big enough to reach threshold
No synaptic integration
Post-junctional folds increase number of voltage-gated Na+ channels close to where it is evoked
What are the different classes of neurotransmitters
Amines
Amino acids
Peptides
Purines
Gases
What are the different postsynaptical potentials
Fast EPSPs (ionotropic)
Slow EPSPs (metabotropic)
Fast IPSPs (ionotropic)
Slow IPSPs (metabotropic)
What are the different pathways in transmission
Monosynaptic reflex - Afferent (sensory) synapses directly to efferent (motor)
Polysynaptic reflex - Afferent synapses to interneurons, interneurons synapses to efferent
Describe inhibitory reflex pathways
Introduces inhibitory neurotransmitters
Describe the ultrastructure of synapses between neurons
What is synapse plasticity
Changes in strength of synapses
Can be activity-dependent
Different synaptic plasticity:
Long-term potentiation/depression
