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39 Cards in this Set
- Front
- Back
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distance btw cells? and what does it contain
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20-40 A. filled with ECF
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what is a gap junction made of?
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connexons. 4-6 connexins (protein) form each connecxon
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how large is a gap junction
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15 A in diameter
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where are gap junctions normally found? what types of cells
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cardiac and smooth m
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characteristics of ephaptic connction
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allows for coord contractions
cells are elec coupled and behave as single unit "single unit muscle" (syncitium) |
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which is more common elec or chem connections
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chem connections
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neuron anatomy
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cell body: soma
dendrite: up to 1 mm long axon: up to 1 m axon hillock |
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other names of axon hillck
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initial segment, trigger zone, summing pt
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where are N. synthesized and packaged
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cell body
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how large is a synaptic gap/cleft
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200 A wide, 2 membranes thick
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how long does it take for N to cross the cleft
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0.3 - 0.5 usec. FAST!
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how long do channels in postsynaptic cell stay open
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10-20 msec
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how long is a synaptic delay
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0.5-1 msec
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how long does diffusion take
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1 usec
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what are the types of N in PNS
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acetylcholine (ACH)
norepinephrin |
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what typs of N are in CNS
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glutamate: excite
glycine: in GABA: In Serotonin histamine dopamine others |
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whats the mV of an EPSP or IPSP? how fast?
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0.5 mV
10-20 msec. both of these are graded postynaptic potentials |
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how long can an AP last
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1 msec
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what happens in a temporal summation
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have to be sent fast. it means summing the EPSP or IPSP from one presynaptic N over time
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what happens in spatical summation
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EPSP and IPSP are sumed. the closer 2 elec ptoentials are the easer and more likely it is to sum them together. spatical summation depends on proximtiy fo elec potentials
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in a presynaptic site of NMJ, how many ACH molecules are in vesicle
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10,000
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what inhibits a postsynaptic site
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Mg
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how large is EPP depolarization
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50 mV
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what alters ACH release
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black widow spider: increas ACH release
clostridium botulinum: decreases release |
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what blocks ACH receptor sites
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curare: reversible receptor
myasthenia gravis: antibodies against ACH receptor sites |
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what inhibits ACH esterase
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organophosphates (pesticices, nerve gas)
neostigmine: inhibits ACH estrase |
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whatis normal level of Ca concentration intracellular?
when depolarized? |
10^-7 M
10 ^5 M |
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2 reasons for presence of SR
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1. muscle diameter is so large take 1 sec for Ca to diffuse across. so SR speeds up contraction.
2. coord contractions |
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smooth muscle vs. skeletal m
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shorter fibers and no bands
slower contraction thick, thin, intermediate fila no sarcomeres dense bodies (no Z-line) greater shortening no t-tubeules, very little SR Tm but no Tn |
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what is volition
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you want to do something, so your brain sends out a signal to your body to accomplish teh action.
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2 reasons whyou can't send Ap down both diractions of same axon
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1. refactory period
2. synapses only send info in one direaction, N stored in terinal end of axon |
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2 purposes for receptors
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1. to detect sensory stimuli
2. transduction |
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transduction is what
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translating the stimuli inot an electical signal (depol, hyper)
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what are the 6 types of receptors in the body
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1 mechanoreceptors
2 chemoreceptors 3. osmoreceptors 4. thermoreceptors 5. photoreceptors 6. Nociceptors |
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example of mechanoreceptro
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hari cell by bending the haris one way or another. conductance of Na is increased or decreased. bending the haris loosens mem and channels upon. "receptor potential"
proprioception, hearing, balance, BP, stretch, |
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what is a receptor potential
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it's a graded potential
usually a depolarization size of graded pot. is proportional to strength of stimulus. |
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adequate stimulus
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this is the stim that the receptor is designed for. Ex; eye = light
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what are teh 4 types of receptions the brain needs in order to fully interpret a stiumulus
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1. modality
2. quality 3. intensity 4. location |
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cell conduction mechanism in vision and hearing.
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vision: decrease Na
hearing: increase in K (conductance) |
