At the level of the spinal cord at which this axon makes a synapse, a graded potential occurs in the cell membrane of a lower motor neuron. This second motor neuron is responsible for causing muscle fibers to contract.
Monday, May 6, 2024
precentral gyrus of the frontal cortex,
A region of the cortex is specialized for sending signals down to the spinal cord for movement. The upper motor neuron is in this region, called the precentral gyrus of the frontal cortex, which has an axon that extends all the way down the spinal cord.
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?
- sodium ion higher in ECF
- 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.
Hydrophobic
https://biologydictionary.net/hydrophobic/
Hydrophobic Definition
Hydrophobic literally means “the fear of water”. Hydrophobic molecules and surfaces repel water. Hydrophobic liquids, such as oil, will separate from water.
Hydrophobic molecules are usually nonpolar, meaning the atoms that make the molecule do not produce a static electric field.
In polar molecules these opposite regions of electrical energy attract to water molecules. Without opposite electrical charges on the molecules, water cannot form hydrogen bonds with the molecules. The water molecules then form more hydrogen bonds with themselves and the nonpolar molecules clump together.
Hydrophilic – Molecules or substances that are attracted to water.
Hydrophilic – Molecules or substances that are attracted to water.
Polar – Molecules having static electric charges, which can interact with water.
Nonpolar – Molecules that do not have static electric charges, and are much more likely to interact with other nonpolar molecular than with water.
Lipophilic – Substances that are attracted to fat, different than hydrophobic.
Quiz
1. Some amino acids are hydrophobic, and some are hydrophilic. Hydrophobic amino acids tend to cluster together in large proteins. Why is the order of amino acids in a protein important?
A. The order determines the shape of the protein
B. It is not important, as long as all of the amino acids are present
C. Proteins are recognized by sequence of amino acids
Answer to Question #1
2. A substance is created that has very strong electrical dipoles on the molecules, but does not interact with water, due to the strong interaction it has with itself. How would you describe the molecule?
A. Hydrophilic and polar
B. Hydrophobic and nonpolar
C. Hydrophobic and polar
Answer to Question #2
3. Many reptiles, even desert-dwelling reptiles, have hydrophobic scales on the outside of their body. Why would a desert reptile want a hydrophobic covering?
A. To repel harmful sun-rays
B. The barrier also works to stop evaporation
C. To be protected from acid rain
Answer to Question #3
resting membrane potential quizlet practice test
https://quizlet.com/449088392/learn?funnelUUID=4be6fe79-8184-43f7-90ba-e19e526d53ac
In an excitable cell, also permeable to Na+ and Cl-, the electrochemical gradient for Na+ causes it to move___________ the cell.
week one guiding question
Guiding questions for each lecture
You can use these questions to review your lectures and check if you caught everything/understood everything discussed in lecture or your pre-class material.
Lecture 1 guiding questions
At a high level (big picture), can you answer the following?
What makes up the nervous system? (what cells)?
Neuron and glial cell
What are the two major anatomical divisions of the nervous system?
- Central nervous system and
- Peripheral nervous system
What are the divisions of the peripheral nervous system?
Somatic nervous system and Automonic nervous system
⛛under ANS
sympathetic nervous system and parasympathetic nervous system
How do neurons communicate?
Neurons communicate using both electrical and chemical signals. sensory stimuli are converted to electrical signals.
Action potential signals carried along neurons.
synapses are chemical or electrical junctions that allow electrical signals to pass from neurons to other cells.
Can you identify the flow of ions in/out of cells based on concentration gradients?
ions in and out of the cell based on concentration gradients moving from high concentration to low concentration.
Describe the mechanism of the Na+/K+ pump and explain how it contributes to the resting membrane potential of a cell.
Na+/K+ pump help to maintain osmotic equilibrium and membrane potential in cells. The sodium and potassium move against the concentration gradient. Na+/K+ATPase pump maintains the gradient of higher sodium concentration in the extracellularly and higher level of potassium of potassium intracellularly.
What would happen to the resting membrane potential if the Na+/K+ pump was mutated and not working?
Additional information
carrier proteins are typically selective for one or a few substances.
( example Na+ K+)
Carrier proteins can change their shape to move a target molecule from one side of the membrane to the other.
Channel proteins span the membrane and make hydrophilic tunnels across it, allowing their target molecules to pass through by diffusion.
Channel and carrier proteins transport material at different rates.
Subscribe to:
Posts (Atom)