Synaptic Activity Cue Cards Flashcards
What are synapses?
The places where neurons connect and communicate with each other, they are how neural impulses get transferred cell to cell.
What are the two types of synapses?
Chemical Synapse and Electrical Synapse.
How does an electrical synapse work?
The transfer of ions through connexon channels in a gap junction
What is different about a electrical synapse from a chemical synapse?
There is direct contact between the presynaptic neuron and the post synaptic neuron, and the electrical synapse does not involve neurotransmitters
How does a chemical synapse work?
Neurotransmitters are getting released into the synaptic cleft where they will go through ion channels at the post synaptic cleft.
What is the major protein connector of the electrical synapse?
Connexon
What are some key characteristics of the electrical synapse
- The narrow gap makes the communication extremely fast.
- Permits easy flow of current
- Ions, ATP molecules can go through it
What are connexons viewed as?
The entire functional unit
What are connexins?
The individual connexon (spans both pre and post synaptic cells)
What is the pore diameter of a connexon?
1.4nM (larger than most channels)
What is the size of an electrical synapse?
About 3.5nM (small for direct transmission)
What are some advantages of a electrical synapse with regards to speed?
Very fast
- It contains a depolarization current with a synaptic delay of 0.1ms
What are some advantages of electrical synapses with regards to flow?
Can have a uni-or bi-directional flow
What does the Uni or Bi directional flow in an electrical synapse do?
It synchronizes activity between neurons
What are some examples of the synchronized activity between neurons as a result of uni or bi-directional flow?
- Regulation of breathing (brain stem)
- Posterior pituitary gland (oxytocin and vasopressin - ADH)
What is the last advantage of an electrical synapse in regards to connections?
It connects neurons and glial cells.
What is an electrical cardio gram?
Traces electrical signalling in the heart.
What is the heart not made up of?
Neurons
What is the cell type in the heart?
It is made up of cardiac muscle cells (myocytes)
What do working myocytes produce in the heart?
Force
What is the electrical signalling in the heart measuring?
Activation, then contraction
What is the SA Node?
Considered the pacemaker of the heart. Its electrical signals normally cause the atria of an adult’s heart to contract at a rate of about 60 to 100 times a minute
What are some characteristics of the chemical synapse?
It is slower, unidirectional and has a wider gap than electrical synapses (40 - 50mM)
What is a chemical synapse dependent on?
Ca2+ neurotransmitter release.
What is the Pre-Synpatic membrane of a chemical synapse?
Active Zones… location of neurotransmitter vesicle collections and internal membrane fusion.. exocytosis
What is the Post-Synaptic Membrane of a Chemical Synapse?
More Density to support synaptic activity.
What is a Ligand Gated Channel?
A ligand (Neurotransmitter) has to bind to it, in order for the channel to open and ions to flow through
- Both a receptor and a channel
What is an example of a Ligand Gated Channel?
The AchR (nicotine-Acetyl choline) receptor
What are G-Protein Coupled Receptors?
- Can activate K+ channels in neurons
- Modulation of action potentials.. the frequency
- Mostly intracellular signalling, metabolism
What is an example of a G-Protein Coupled receptor?
Epinephrine
What are the series of events of G-protein coupled receptors?
Neurotransmitter binds, G protein is activated, G-protein subunits or intracellular messengers modulate channel, Ion flows across membrane, Ion channels open.
What is your ventral horn?
The cell bodies of motor neurons that send axons via the ventral roots of the spinal nerves to terminate on striated muscles
What is a Motor Unit?
One neuron and all the muscles fibres that surround it.
What do somatic motor neurons innervate?
Skeletel muscles
What can one motor neuron innervate?
Many muscle fibres
What is each muscle fibre innervated by?
Only one motor neuron (you can’t have two motor neurons plugged into same muscle fibre)
What is excoystosis?
Moving cellular components from inside of cell to outside
What are the three functions of exocytosis?
1.) Membrane Components
- Adds molecules from vesicle interior (GLUT4)
2.) Recycle Endocytosis products
3.) Secretion (In to out)
- Mucus
- Neurotransmitters
- WBC
What is exocytosis done from?
Secretory Vesicles
What is a Neuromuscular Junction?
The neuromuscular junction (NMJ) is a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/ smooth/ cardiac).
What is the Neuro Muscular Junction a Site for?
It is the site for the transmission of action potential from nerve to the muscle.
What is a patch (voltage) clamp recording?
Can manipulate a solution of Ach concentration and can inject a current
What is a patch (voltage) clamp recording used for?
Examining behaviours of channels
What are the recordings in a Patch (voltage) clamping recording?
I = current
Downward, inward positive current.
What is A Motor end plate?
The specialized postsynaptic region of a muscle cell.
What is the Motor End Plate Potential Proportional To?
Calcium concentration
How many Calcium do you need to release one vesicle?
4 Calciums
What inhibits Ach?
Magnesium
What is the relationship graph between Ca and EPP?
Non Linear
How many vesicles for One Action Potential
About 100 to 300
How many packets of Ach molecules released in one action potential?
5,000 to 10,000
