Nerves Flashcards by Hassan Sadiq

What are the divisions of the nervous system

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What are the different parts of the brain

(12 cranial)

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What are the different parts of the spinal cord

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Describe the structure of the spinal cord

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What is the general structure of a neuron

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What are the different types of neurons

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What is the distribution of nerves In the spine

Roots: EITHER sensory OR motor
Spinal nerves: sensory AND motor
Rami: sensory AND motor

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What is the morphology of neurons

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What is glia

Non-neuronal cells of brain and nervous system

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What are the different types of glia

CNS
Peripheral NS (PNS)

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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

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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

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Describe the resting membrane potential

Inside of cell negative relative to outside (potential difference)
Most neurons at -70mV

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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

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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

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What is the conc. of K+, Na+, Cl-

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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