Neurons & synapses Flashcards
what is a neuron?
nervecell that carries out nerve impulses?
which part of a neuron is responsible for the transmission?
axons terminals
what is a synapse?
a specialized area of contact between two cells where transmission of information takes place
Synapsis basic structure
- Presynaptic membrane - the membrane portion of the neuron that sends information
- Postsynaptic membrane - the membrane portion of the cells receiving the information
- synaptic cleft - the space between the two membranes
Wich are the types of synapses?
Electrical - the element that the two cells communicate is the propagation of electric current
Chemical - the element that the two cells communicate is a molecule (neurotransmitter)
what are the characteristics of an electrical synapse?
two cells communicate trough the propagation of electrical impulses
There are special junctions between neurons that serve as a bridge between their cytoplasm: gap junctions (3.5nm)
What are the characteristics of a chemical synapse?
- Two cells communicate through a molecule called neurotransmitter.
- There is no communication between the cytoplasm of the two cells
- synaptic cleft (20-40nm)
- more abundant
- unidirectional
- synaptic delay (0.5nm) have to travel and bonds
What are dendrites?
The connections to the synapses of past cells (it receives AP
which are the two types of postsynaptic potentialls and response?
EPSP - excitatory postsynaptic potencial
IPSP - inhibitory postsynaptic potential
Name the Three types of neurons
- multipolar interneurons
- motorneurons
- sensoryneurons
Steps in a chemical synapse
- Diffusion away from the postsynaptic membrane
- degradation (proteolysis neuropeptide)
- reuptake the presynaptic nerve terminal by active transport (non peptide NT)The presynaptic membrane take the neurotransmitter back into the membrane
AP
Resting membrane -70, threshold-55 mv.
1 stimuli
- Depolazition Na+ v.g.c opens entering the cell
3 Repolaryzation na+ channels inactiveded, K+ v.g.c opens Ka+ enters the cell
4 Hypolarization Ka+ channels closes slow - Refactoryperiod K+ channels close slow causes hypolorazition.
Refractory period
5 RESTING MEMBRANE
AP
Resting membrane -70, threshold-55 mv.
1 stimuli
- Depolazition Na+ v.g.c opens entering the cell
3 Repolaryzation na+ channels inactiveded, K+ v.g.c opens Ka+ enters the cell
4 Hypolarization Ka+ channels closes slow - Refactoryperiod K+ channels close slow causes hypolorazition.
Refractory period
5 RESTING MEMBRANE
What is neuromuscular junction?
Is a chemical synapse formed by the contact between a motor neuron and a musclefiber.
the neuromuscular junction makes it possible to transmit the signal that causing the musclefiber to contract
What’s the characteristics of a preganglionoc neuron in Autonomic N.S (sympatich and paradympatethic)?
Cholignergic,myelated, uses ACh
Name two Type of nicotinic receptors
NN Nicotinic receptors 》 present on neurons
NM Nicotinic muscle ,》 present on neuromuscular junction of the muscle cells (skeletonmuscle
Were can NN be found?
Autonomic N.S, ganglia, and C.N.S
How many motor neurons in somatic N.S
One motor neuron to reach the effector area
