3) Structure/Function of Cells in Nervous System Flashcards
What are all the key part of a neuron
axon, myelinated sheath, soma (cell body, dendrites, terminal buttons)
What 3 types of neurons can you get?
Sensory- detects external/internal changes (CNS, PNS, light, sound)
Motor neuron- controls muscle contraction, gland secretion (CNS, PNS)
Interneurons- Found ONLY in the CNS, involved in cognition
The structure of a neuron can be divide into which 3 types
Multipolar neuron- 1 axon, many dendrites attached to soma
Bipolar neuron- 1 axon, 1 dendrite attached to soma
Unipolar neuron- 1 axon attached to soma, on ebranch received sensory info, other sends info TO CNS
What are the 2 key supporting GLIAL cells in the CNS/ Blood-Brain Barrier (BBB) called & their function?
Oligodendrocytes- forms myelin sheath, insulation, lipids
Astrocytes (star cells)- provide physical support to neurons, CNS, nourishment, clean up dead neuron debris, form scar tissue, helps form the BBB
What is the BBB
Semi-permeable barrier separating blood from the circulatory system and CSF in the brain. Prevents blood entering the brain and keeps it safe
What’s the region in the medulla called, where the BBB is weak + what does it allow to enter?
It’s called the Area Postremema. Allows toxins to get in/stimulate the area = body wants to expel the poison from body»_space; this initiates vomiting
Explain the withdrawal reflex process
1) Dendrite detects pain
2) Pains follows up axon
3) muscle withdraws from pain
4) Interneuron in spinal cord excites motor neuron to cause muscle contraction
How does the role of inhibition alter the withdrawal reflex
Follows the same first few steps. But before muscle contraction occurs, another inter neuron inhibits a motor neuron, preventing muscular contraction. (if the person can withstand the heat of a pot for example)
What is a synapse
Location for communication between separate neurons. It is the junction between them (terminal button of one and soma of another)
Why is there a synaptic gap between the 2 neurons
Action Potentials can’t cross the cleft, therefore nerve impulses are carried by neurotransmitter chemicals
Which neuron sends/receives impulses
Pre-synaptic- sends the impulse
Post-synaptic- receives the impulse
Where are neurotransmitter chemicals made and stored?
Made in the pre-synaptic neuron and stored in synpatic vesicles.
How does a post-synaptic neuron receive the neurotransmitter chemical?
It’s membrane has chemical-gated ion channels called neuroreceptors, with specific binding sites for certain neurochems (fitting the binding site like a lock and key)
Explain what an ionotropic receptor of an ion channel allows for
Direct opening of the ion channel on it’s actual binding site
Explain what an indirect opening of an ion channel is
Occurs at a metabotropic receptor, where a transmitter molecule binds to a receptor, which activates an adjacent protein to break away and bind with the ion channel of interest to open it and allows ions through the cell.
(Remember the door bell analogy- you hear it, but someone else opens the door)
Explain reuptake and why it is necessary
Reuptake is the leftover molecules of neurotrans in the cleft that weren’t used in the nerve impulse , get returned back into the terminal buttons of the pre-synaptic neuron
Explain what an EPSP is
Excitatory Post Synaptic Potential-
causes an excitatory depolarisation of the postsynaptic neuron, meaning the nerve impulse is able to continue into the next neuron (threshold is met)
Explain what an IPSP is
Inhibitory Post Synaptic Potential-
counteracts EPSPs on other side of postsynaptic neuron, so APs not triggered in axon for nerve impulse to continue onto next neuron
Describe the nature of the 3 main ion channels and whether they are EPSP or IPSP
Sodium (Na+) = EPSP, influx into cleft causes depolarisation
Potassium (K+)= IPSP (efflux out of cleft causes hyperpolarisation)
Chlorine (Cl-) = IPSP (influx causes hyperpolarisation)
Explain what neuronal integration is
Process of inhibitory and excitatory PSPs summating and controlling the firing rate of a neuron
What happens if there are ONLY EPSPs present and what happens when more IPSPs are introduced
If just EPSPs the excitatory threshold at the axon hillock is met and a neuron fires.
If more IPSPs are present, it is more likely that APs won’t be triggered and the neuron won’t fire
EPSPs always cause what…
IPSPs always cause what…
1) Depolarisation
2) Hyperpolarisation
