Guiding question week 2

 Guiding Questions:

The resting membrane potential

 Describe the mechanism of the Na+/K+ pump and explain how it contributes to the resting membrane potential of a cell.

• 3 sodium ion bind to the Na+/K+
• ATP is hydrolyzed providing energy to change the formation
• the pump release the na outside the cell 
• two potassium ion K+ from ECF bind to the pump 
• ATP hydrolyzed restoring the pump original formation 
• the pump release the K+ inside the cell 
  
  
  

What would happen to the resting membrane potential if the Na+/K+ pump was mutated and not working?

• Loss of ion gradients , normal concentration of Na+ and K+ would be discrupted. 
• increase intracellular sodium
• decrease intracellular potassium 
• altered resting membrane potential
• hyperpolarization or depolarization

Describe several ways that intracellular fluid (ICF) differs from extracellular fluid (ECF). What ions are higher in the ICF vs ECF?

1. sodium ion higher in ECF
2. Potassium ion higer in ICF 

• ICF is the liquid inside cells, while ECF includes plasma, IF, and CSF.
• The composition of ICF and ECF differs in terms of ion concentrations, proteins, and pH.
• ICF and ECF play distinct roles in maintaining cellular function and overall body homeostasis.

Describe what a concentration gradient is and how it leads to diffusion and the establishment of a dynamic equilibrium.

 Na+/K+ Pumps help maintain osmotic equilibrium and membrane potential. Sodium and potassium ion move against concentration gradients. The sodium and potassium ion move from high concentration to low concentration. The sodium and potassium pump maintain the concentration gradient high sodium in ECF and high potassium in ICF .

 Can you identify the flow of ions in/out of cells based on concentration gradients?

Na+/K+ pump move the ion sodium in side the cell against concentration gradient from high concentration to low concentration. The pump help to maintain  the resting membrane potatial by keeping the intracellular Na+ level low . 

ECF sodium level 145 

ICF sodium level 

Describe the mechanism of Na+ and K+ leak channels. How do they contribute to the resting membrane potential of a cell? How do they contribute to membrane permeability?

What is the resting membrane potential? What voltage value is it typically for most cells in your body?

 

Altering the resting membrane potential

If the concentration gradient of K+ decreases across the cell membrane, what happens to the membrane potential?

If the cell all the sudden became permeable (think gated membrane channels opening) to K+, what would happen to membrane potential? What about Ca2+? Na+?

What is hyperpolarization vs depolarization of the membrane potential? What ion channels should be opened to cause either?

Graded Potentials

Draw and describe the structure of a neuron.

Identify each of the following structures on your drawing and describe their structures: dendrites, dendritic spines, cell body, axon, axon hillock, collateral, axon terminal, synapse, postsynaptic cell

Where are the sensory receptors located on a neuron? From where on the neuron are neurotransmitters released?

Where do graded potentials occur?

What type of stimuli causes a graded potential? How does the strength of the stimulus affect the amplitude of the graded potential?

As a graded potential travels through the cell body, they lose amplitude. Explain why. ***more on this next week

What is an EPSP? What is an IPSP? What ion channels contribute to each? Are each caused by depolarizations or hyperpolarizations?

How does an EPSP contribute to triggering an action potential? What about an IPSP?

Action Potentials***

Differentiate between graded potentials and action potentials.

Where in the neuron do action potentials occur?

How does the strength of the stimulus effect the amplitude of the action potential? Why are they all-or-none?

***more on this next week

Explain how ion permeability changes during the rising phase and falling phase of an action potential.

What is the stimulus for opening EACH of the channels used during an action potential?

What is the order of stimulus, opening and closing of all of these channels?

How is the resting membrane potential reestablished after an action potential?

Hint, we did this for our in-class activity! Can you visualize what’s happening with each of the channels?

Voltage gated Na+ channels in the axon contain two gates. What are they? How are they triggered?

What are the absolute and relative refractory periods?

How does the inactivation gate on the Na+ channel cause the absolute refractory period?

What causes the relative refractory period?

***I will update after lecture to see how much of APs we get through.