Exam (elaborations)
CMB1004 Excitable Cells Exam Latest Update
- Course
- Institution
CMB1004 Excitable Cells Exam Latest Update ...
[Show more]
Content preview
CMB1004 Excitable Cells ExamLatest Update
What are the four regions of a neurone? - Answer Dendrites
Cell Body
Axon
Axon Terminal
Define an excitable cell - Answer Any cell capable of generating an action potential
Describe how the resting potential is maintained - Answer Cell contains slight -ve
charge (70mv)
Maintained via high permeability of membrane to K+ and active transport of Na+ across
membrane
Define an action potential - Answer A rapid change in membrane potential
What is the equilibrium potential? - Answer The point at which the electrical gradient of
the cell is equal and opposite to the concentration gradient
What is the Nernst equation? - Answer
What occurs at each stage of an action potentials generation? - Answer Depolarisation:
Membrane potential increases from RMP
Repolarisation: Membrane potential decreases following depolarisation
Hyperpolarisation: Membrane potential falls below RMP
Describe the activity of voltage gated ion channels during action potential generation -
Answer 1) Resting state, no gates open
2) Slow rising phase, some Na+ gates open, small amounts of Na+ enters cell
3) Rapid rising phase, all Na+ gates open, some K+ gates open
4) Early repolarisation, all K+ channels open, some Na+ closed
5) Hyperpolarisation, all Na+ closed, some K+ open
Define absolute refractory period - Answer The period immediately following an action
potential generation during which no action potential can be generated regardless of
, stimulus size
Define relative refractory period - Answer The period during hyperpolarisation where an
abnormally large stimulus can generate an action potential
How is the velocity of an action potential increased - Answer Increase the diameter of
the axon
Increase the membrane resistance by insulating with myelin sheath
Define myelination - Answer The process by which axons are insulated with schwann
cell membranes to prevent loss of charge down the axon body
What is saltatory conduction? - Answer Action potentials "jump" between areas of
unmyelinated axons called nodes of Ranvier, increasing transmission of the action
potential
What is an endplate potential? - Answer Depolarisation of the postsynaptic cell to a level
halfway between the equilibrium potential of the two ions (Na+ and K+ typically) involved
Describe the process of signal transmission at the synaptic cleft - Answer 1)
Presynaptic membrane depolarised by action potential, causing Ca2+ gates to open
3) Ca2+ rushes into the axon terminal from outside of the cell
4) Increase in Ca2+ triggers vesicles containing Ach to release them into the synaptic
cleft via exocytosis
5) Ach diffuses across cleft and binds to receptors on the post synaptic membrane,
opening ligand-gated Na+ channels
6) Na+ rushes into the post synaptic cell, K+ rushes out
7) An EPP (Endplate potential) is generated, triggering an action potential
What happens to Ach after binding? - Answer They are broken down by
Acetylecholinesterase
What happens during muscle contraction? - Answer H zone shortens, A band and I band
remain same size as thin filaments slide over thick filaments
Describe the structure of the thick muscle filament - Answer Myosin molecules held
together by M line
Describe the structure of the thin muscle filament - Answer Made of actin, tropomyosin,
myosin
G-actin molecules come together to form F-actin strands which wind together in a
double helix
Tropomyosin winds around double helix
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Flat. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $9.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
80364 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now