Membrane Potential Flashcards
What are the 3 types of Cell Signalling?
Endocrine
Paracrine
Autocrine
What is Endocrine signalling?
Endocrine signals target distant cells. Endocrine cells produce hormones that travel through the blood to reach all parts of the body
What is Paracrine signalling?
Paracrine signals target cells in the vicinity of the emitting cell. Neurotransmitters represent an example
What is Autocrine signalling?
Autocrine signals are produced by the target cell, are secreted, and affect the target cell itself via receptors. An example of this are immune cells.
What is the resting potential voltage of a Nerve Cell?
-70 mv
What is the resting potential voltage for a smooth muscle cell?
-40 mv
What is the resting potential voltage for a skeletal muscle cell?
-90 mv
What is the Nernest equation used for?
Calculating how much of an ion is present at a given time.
What is present inside the cell in greater amounts during resting potential, potassium or Sodium?
Potassium
What are the two gradients at play regarding resting potential?
Concentration gradient
Electro-chemical gradient
During an action potential, what comes in and what goes out of the cell?
Potassium out and sodium in
What are the 4 phases of action potential?
Polarized
Depolarised
Repolarized
Hypopolarized
What is polarized?
Negative inside the cell but positive outside
What is depolarised?
The cell becomes positive inside the cell and negative outside
What is repolarised?
When the positive cell returns to negative inside and positive outside
What is Hyperpolarization?
When the cell becomes too negative and needs to restablise
What is the Absolute Refactory Period?
the period immediately following the firing of a nerve fiber when it cannot be stimulated no matter how great a stimulus is applied
When does the Relative Refactory period occur?
During hyperpolarization until the cell stabilizes to resting potential
What direction does a signal travel?
Only forward - because behind the cell is in hyperpolarization
Explain what Continuous propagation is and give a cell that you would find it in?
This is when an impulse continually moves forward as in slowly taking little steps walking forward - unmyelinated neurons
Explain what Salutatory propagation is and give a cell that you would find it in?
This is when an impulse takes leaps forward, jumping node to node, which is the only location that depolarization occurs. Myelinated neurons
