Nervous System Part 2 Flashcards
What do axon terminals contain?
- synaptic vesicles filled with NT
- mitochondria
- active zone: specialized proteins that control exocytosis of vesicles, voltage gated ion channels
How do synaptic vesicles get released into the synapse?
The membrane depolarize and ALOT of Ca2+ goes into the cell, and then interacts with proteins to trigger the vescicles to fuse with active site plasma membrane
How does the axon terminal make new synaptic vescicles?
It has proteins inside it that can generate
How is acetylcholine re-uptaken into the axon terminal? What is another way that it can be recycled?
- Broken apart by AChE and returned into the axon terminal
- transporter proteins or astrocytes
How does cocaine affect the dopamine transporter protein?
It is an inhibitor
How do SSRI’s work?
They block the function of the transporter protein for a related NT — serotonin—
What is an excitatory post synaptic potential? What is an inhibitory post-synaptic potential?
Excitatory: make a neuron more likely to fire an AP (an EPSP depolarizes the membrane and is usually generated by the opening of channels that are permeable to Na+)
Inhibitory: make a neuron less likely to fire an AP (an IPSP is generated by the opening of channels that are permeable to K+, or channels permeable to Cl- and often hyperpolarizes)
What is an agonist?
A drug that mimics the action of an endogenous NT
What is an antagonist?
The drug that blocks the activation of an NT receptor (the NT can’t bind so cellular activity is blocked)
Is alcohol an agonist or an antagonist? What about caffiene?
Both are antagonists
What is the effect on a graded potential when SSRI’s cause serotonin to stay in the cleft for a long time?
- the graded potential increases because there is more serotonin taken up into the cell
What is graded potential summation?
Two ESPs can add together and create a larger depolarization, or an IPSP can subtract from EPSPs and move the potential further from the threshold
What is spatial summation?
Overlap of two graded potentials generated by two different presynaptic neurons
What is temporal summation?
The overlap of 2 graded potentials generated by 2 APs of the same presynaptic neuron at different times
What are metabotrophic receptors?
Receptors that signal through G proteins
What is convergence, divergence and parallel processing?
Convergence: 1 post synaptic neuron receives many inputs
Divergence: 1 pre synaptic neuron shares its outputs with more than one neuron
Parallel processing: many post synaptic neurons receive and pass on the same information to different places
What is serial processing, recurrence and recurrent inhibition?
- sequential post synaptic neurons receive and filter the information at each stage
- postsynaptic neuron synapses back on the presynaptic partner
- the recurrence is blocked by an inhibitor
What are the steps of a spinal reflex?
- Stimulation of a receptor
- Activation of sensory neuron
- Information processing in the CNS
- Activation of motor neuron
- Response of peripheral effector
What are the steps of a stretch reflex?
- begins at the muscle spindle (intrafusal muscle fibres)
1. Tapping the tendon stretches the muscle
2. Stretch activates mechanoreceptor channels in the sensory neuron GP, then AP
3. Sensory neuron synapses directly on the muscle’s alpha motor neurons, triggering EPSPs
4. Action potentials cause the extrafusal muscle fibres to contract, causing a movement
How are stretch reflexes enhanced?
Divergence: stretch receptor sensory neuron activates interneurons and the muscle’s motor neuron
What are the steps of the withdrawal reflex?
- Free nerve endings within the epidermis/dermis detect potential damage
- Sensory neuron synapses on the interneurons
- Synapses lead to sending signals to the brain, contracting the agonist muscle and relaxing the antagonist muscle
What are the steps of the crossed extensor reflex?
- Sensory neuron sends signal to spinal cord and synapses on interneuron
- Sends signal to brain, and diverges to send signals to both legs
- Ipsilateral side: flexors contract to lift the foot
- Contralateral side: extensors contract so it can support the weight of the body
What do the somatic and visceral nervous systems control
Somatic: skeletal muscle
Visceral: everything that’s not skeletal muscle
What are the three layers of the meninges?
- Dura mater: dense irregular connective tissue associated with periosteum
- Arachnoid mater: elastic connective tissue with extensive trabeculae, and a simple squamous epithelium
- Pia mater: areolar connective tissue and simple squamous epithelium
What is the structure of the BBB?
Endothelial cells in CNS capillaries are connected by tight junctions, limiting the movement of water and hydrophilic molecules
How is cerebral spinal fluid circulated? How is it reabsorbed into the circulatory system?
- circulates from ventricles to the subarachnoid space, pumped through CNS tissue
- CSF is absorbed back into the circulatory system via arachnoid granulations that penetrate through dura into sinuses
What is the glymphatic system?
Astrocytes that push CSF through the CNS tissue and filter wastes. Especially active during sleep
What is white matter made of? What is grey matter made of?
White: myelinated axons (white because myelin contains fat)
Gray: glia, neuronal cell bodies, dendrites and axon terminals
What does S, L, Th and C stand for in the dorsal column?
Sacral, lumbar, thoracic and cervical
What are the three divisions of the telencephalon?
Limbic system, basal ganglia, cerebral cortex
What are the primary sensory cortices? What are primary motor cortices?
Sensory: first cortical region to receive sensory information (from the thalamus)
Cortical: last cortical region to process motor information, and projects directly to the spinal cord
What does the accurate fasciculus do?
Connects an auditory association area involved in comprehending language to a promoter area involved in speech productions (Broca’s to Wernicke’s)
What is the longitudinal fasciculi?
Tracts of white matter that connect frontal lobe to other parts of the forebrain
What does the corpus callosum do?
Enables coordination of movement between the hemispheres
What are the four different types of brain waves in an EEG?
Alpha, beta, theta and delta
What causes a seizure?
Often a piece of scar tissue sets off neuronal activity— lots of graded potentials firing action potentials
- become too synchronized
How is the resting potential of any cell created and maintained?
K+-ATPase pumps Na+ out and K+ in, setting up a K+ gradient. The K+ leaks out of the membrane through the K+ leak channel. There are a large number of negatively charged proteins in the cytoplasm that cannot leak out. When the K+ leaks out there is a separation of charge that causes the inside to be negative (due to the proteins) with respect to the outside
