1. APs and Synaptic Transmission

Question 1

What is sensory biology?

Answer 1

The study of how organisms perceive and respond to sensory information.

Question 2

How does a cell detect and transmit sensory information?

Answer 2

Through processes like reception, transduction, and encoding of sensory information.

Question 3

What is the difference between sensation and perception?

Answer 3

Sensation refers to the detection of sensory stimuli, while perception involves the interpretation of sensory stimuli.

Question 4

What types of sensory systems will be covered?

Answer 4

Vision, olfaction, taste, touch, hearing, pain.

Question 5

Mechanotransduction

Answer 5

Process by which cells convert mechanical stimuli into electrical signals.

Question 6

Role of sensory neurons

Answer 6

Respond to specific classes of stimuli and transmit signals to other neurons. They can be excited or inhibited.

Question 7

Structure of a typical neuron

Answer 7

Axons, dendrites, soma, axon hillock, and growth cones.

Question 8

Explain the concept of depolarization and hyperpolarization in sensory neurons

Answer 8

Depolarization makes the neuron more positive than its resting potential, increasing the likelihood of synaptic vesicle release. Hyperpolarization makes the neuron more negative than its resting potential, inhibiting signal transmission.

Question 9

How do neurons communicate primarily?

Answer 9

Neurons communicate primarily through the release of synaptic vesicles.

Question 10

What is the “law of specific nerve energies”?

Answer 10

States that the nature of perception is defined by the pathway over which sensory information is carried. Each sensory pathway conveys a specific type of information.

Proposed by Johannes Peter Muller, 1835

Question 11

What are the four pieces of basic information that all sensory systems must encode?

Answer 11

Modality, location, intensity, and duration or timing.

Question 12

How is sensory information processed in relay centers?

Answer 12

Sensory information is processed by higher-order neurons acting together. It undergoes filtering, processing, and integration, ultimately leading to perception.

Question 13

Explain the basis for APs

Answer 13

APs are based on changes in membrane potential, specifically depolarization and hyperpolarization.

Question 14

What is the role of Na+/K+ ATPase in neuronal signaling?

Answer 14

Na+/K+ ATPase actively pumps sodium ions out of the cell and potassium ions into the cell, establishing essential ionic gradients for neuronal signaling and cellular homeostasis.

Question 15

What is the role of ion channels in initiating APs?

Answer 15

Ion channels are essential for the rapid changes in membrane potential that lead to APs.

Question 16

Explain the role of ion gradients in establishing a resting potential

Answer 16

Ion gradients are critical for maintaining the slightly negative resting potential of neurons.

Question 17

What happens at the steady state in terms of ion currents?

Answer 17

The net inward current equals the net outward current, primarily driven by potassium ions.

Question 18

What are the key ions involved in establishing the resting potential of a neuron?

Answer 18

Na+ and K+

Question 19

What role do Na⁺ and K⁺ ions play in AP generation?

Answer 19

Na+ ions contribute to depolarization during AP initiation, while K+ ions play a role in repolarization and hyperpolarization.

Question 20

How does the concept of synaptic vesicle release relate to neuronal communication?

Answer 20

Neurons primarily communicate through the release of synaptic vesicles, which contain neurotransmitters for signal transmission.

Question 21

Explain the importance of selective ion channels in neuronal signaling

Answer 21

Allow specific ions to pass through the cell membrane, enabling changes in membrane potential essential for AP generation.

Question 22

Why is it essential for sensory neurons to be excited or inhibited?

Answer 22

Both excitation and inhibition are used to control the flow of sensory information and modulate responses to different stimuli.

Question 23

What is the function of a growth cone in a neuron?

Answer 23

Facilitates the extension and guidance of an axon.

Question 24

What is the role of delayed electrical signals in sensory transmission?

Answer 24

Convey ‘sense’ energies to the brain.
-Delayed electrical signals convey sensory information from peripheral receptors to the central nervous system, allowing the brain to process and perceive external stimuli.
-The time delay is essential for sensory perception. (we live in the past!**)

Question 25

What does the Quantum Hypothesis propose about synaptic transmission?

Answer 25

Suggests that nt release at synapses occurs in discrete units or “quanta,” implying that synaptic transmission is not continuous but involves quantal release.

Question 26

What did Fatt and Katz discover in their postsynaptic muscle recordings in 1952?

Answer 26

Fatt and Katz’s recordings revealed that at certain synapses, nt release is exceptionally reliable and never fails, highlighting the reliability of synaptic transmission.

Question 27

What did Del Castillo and Katz demonstrate about synaptic release in 1954?

Answer 27

Demonstrated that synaptic release is both probabilistic and quantal, meaning that nt release is not guaranteed and occurs in discrete, quantal units.

Question 28

What are the key steps in synaptic transmission?

Answer 28

Bringing the presynaptic neuron to threshold to the activation of postsynaptic receptors, including AP generation and nt release.

Question 29

What are the three primary steps involved in the synaptic vesicle cycle?

Answer 29

1. Docking and priming
2. Release (exocytosis)
3. Retrieval (endocytosis) of synaptic vesicles

Question 30

How does Synaptotagmin I (Syt1) function in synaptic transmission?

Answer 30

Functions as the Ca2+ sensor in synaptic transmission.
-Detects the increase in Ca2+ levels within the presynaptic neuron’s terminal.
-Leads to its insertion into transmembrane structures.
-This insertion causes the vesicle and plasma membranes to fuse and results in the exocytosis of nts.

Question 31

What impact does the KO Syt1 have on synaptic transmission?

Answer 31

Abolishes fast synchronous release, while having no effect on slow asynchronous responses.