Week 2 Flashcards
junction between neurons
- mediates the flow of information
synapse
conducting neuron=
presynaptic
-receiving neuron=
postsynaptic
2 types of synapses:
- electrical synapse
- chemical synapse
which synapse:
- Least common
- Cytoplasm of adjacent cells connected by gap junctions
- Ions flow directly
- Bidirectional
- Fast (allows heart to contract)
- Abundant in embryonic nervous tissue
electrical synapse
which type of synapse
- Releaase of neurotransmitters
- axonalterminal=presynaptic
- receptorregion=postsynaptic
- Neurotransmitter diffuse across synaptic cleft
- One way flow
- Electrical event leads to chemical event
chemical synapse
Flow of info at synapse
- Calcium channels open in the presynaptic neuron and calcium enters the axon terminal
- Neurotransmitter released into synaptic cleft
- Neurotransmitters diffuse bind to postsynaptic receptors; this is reversible because they can bind and unbind
- Ion channels open in the postsynaptic membrane creating a new graded potential
- Excitatory or inhibitory
neurotransmitters move across the synapse via
diffusion
are neurotransimiteres permanent or reversible
reversible, they can bind and unbind
________ is a rate limiting step; neurotransmitters take a bit to release, diffuse, and bind
Synaptic delay
what happens to neurotransmitters
- degraded by enzymes
- reuptake by astrocytes
- diffusion out of synapse
Modification of neurotransmitters:
- agonist = enhances NT effect
* Albuterol asthma inhaler - antagonist = blocks NT action
* Antihistamines block histamine receptor - receptor site can be blocked
* Antipsychotics used to bind to receptor site - time in cleft can be prolonged or lessened
* SSRIs- reuptake inhibitor- stays in the cleft - release blocked or enhanced
* MDMA enhances release of serotonin - synthesis stimulated or inhibited
* Clonidine lowers BP by inhibiting presynaptic NE production
-neurotransmitters generate ________ membrane potentials on postsynaptic membranes
GRADED
- EPSP – excitatory =
depolarizing
- IPSP – inhibitory =
hyperpolarizing
- Summation is important for EPSPs or IPSPs
EPSP
- Sodium channels open for EPSP or IPSP
EPSP
- Reduces AP potential
- Cl- or K+ channels open [Na+ closed]
IPSP
-role of the ________ to ‘inhibit’ unnecessary activity
cerebral cortex
Summation
-add all the EPSPs and IPSPs together
rapid production of EPSPs
- rapid fire from SAME axon terminal
- tons of ESPS all in a row like a machine gun
temporal summation
large number of EPSPs
-impulses arrive from MANY axon terminals
spatial summation
Structural Neurotransmitters:
- acetylcholine [ACh]
- Biogenic amines
- amino acids
- neuropeptides
- novel messgengers
Biogenic amines
- Dopamine- regulates skeletal muscle tone
- Norepinephrine and epinephrine (adrenaline)- both derived from amino acid tyrosine
- Indolamines- serotonin, histamine
- most common= GABA= inhibitory
- glutamate= most common in brain= excitatory
- glucine= inhibitory= found in brain stems and spinal cord
Amino acids
where is glycine found
brain stem an dspinbal cord
3 Novel messengers
- ATP- excitatory in PNS and CNS
- Nitric Oxide- produced on demand- vasodilator
3, Carbon Monoxide
Types of Circuits
- diverging
- converging
- reverberating (oscillating)
- parallel after discharge
- single neuron stimulates many others
- One input, many outputs
- diverging circuits
- many outpours, one input
- one neuron stimulated by many others
converging circuti
- feedback loop
- impulses from distal neurons stimulate proximal neurons repeatedly
- short term memory, sleep wake cycles breathing
reverberating (oscillating) circuti
-single neuron stimulates group of neurons that then stimulate one neuron
parallel after-discharge circuits
left brain logic does what kind of processing
serial
- many pathways and many destination
- right brain
parallel processing
Reflex Arc
- receptor → activated by a stimulus
- sensory neuron → AFFERENT
- interneuron → CNS integration → brain/spinal cord
- motor neuron → EFFERENT
- effector [response] → muscle or gland
