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Biology > Neural signaling > Flashcards

Neural signaling Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Describe chain of events when stimulus starts in PNC

A
  1. Stimulus
  2. Receptor
  3. Sensory neurone
  4. Relay neurone
  5. Motor neurone
  6. Effector
  7. Response
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2
Q

Describe chain of events when stimulus starts in CNC

A
  1. Stimulus
  2. Sensory receptor
    Through sensory neurone
  3. Impulse
    Through relay neurone
  4. Motor neurone
  5. Effective receptor
    Through motor neuron
  6. Effective movement response
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3
Q

Definition of neurones

A

Specialized cells that transmit electrical impulses within the nervous system

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4
Q

Impulse

A

ions moving in and out of cell, changing its voltage

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5
Q

Describe the states of the neurone

A
  1. Resting potential: 3 Na+ out, 2 K+ in (causes concentration gradient). -70 millivolts
  2. Depolarization: Na+ in, makes inside of cell more positive
  3. Repolarization: K+ out, makes inside of cell negative again bur order is wrong
  4. Refractory period: Na+ out, K+ in
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6
Q

What is myelin

A

Mixture of protein and phospholipids produced by schwann cells. It wraps around the axon, leaving only the nodes of Ranvier exposed.
Electrical signal can be sent around at much greater speed because of saltatory conduction.

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7
Q

Describe pathway of signal from one neurone to the next

A
  1. Action potential arrives to end of presynaptic neurone. Trigger the opening of voltage-gated calcium ion channels.
  2. Calcium ion channel proteins open. Ca+ ions diffuse in.
  3. Ca+ forces vesicles full of neurotransmitters to fuse with membrane.
  4. Neurotransmitters diffuse across synaptic cleft, bind with receptor molecules on postsynaptic membrane.
  5. Receptor proteins open, sodium ions diffuse through.
  6. Postsynaptic membrane is depolarised. Action potential generated again, travels down axon.
  7. Neurotransmitters broken down
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8
Q

What is acetylcholine

A

Neurotransmittor which activates muscle contractions, awakening, and attention.

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9
Q

Function and adaptations of motor neurones

A

Carry impulses from CNS to effectors.
Large body that lies within CNS.
Nucleus in cell body.
Many, highly-branched dendrites that extend from cell body to provide large SA for axon terminals of adjacent neurones.

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10
Q

Function and adaptations of relay neurones

A

Intermediate: connect sensory and motor neurones. Found within CNS.
Short, highly-branched axons and dendrites.
No myelin sheath.

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11
Q

Function and adaptations of sensory neurones

A

Carry impulses from receptors to CNS.
Cell body that branches off in middle of the cell.
Single, long dendron that carries impulses to cell body and a single, long axon that carries impulses away from cell body.

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12
Q

Squid vs human neurones

A

Squids: gaint axons, unmyelinated. Up to 1mm wide.
Humans: myelinated (except for relay neurones) and from 4 to 100 um wide.

  • Wider diameter means faster conduction.
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13
Q

Describe the steps of an action potential change

A
  1. Voltage-gated sodium ion channels open
  2. Sodium ions diffuse into the cell through facilitated diffusion
  3. Depolarization (more positive than negative)
  4. Voltage-gated sodium ion channels close, voltage-gated potassium ions open
  5. Potassium ions diffuse out of the cell through facilitated diffusion
  6. Repolarization
  7. Sodium potassium pump reestablishes the resting potential by actively pumping Na+ out, K+ in (ATP involved)
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14
Q

What is an action potential

A

The changes in voltage across membrane: wave of positive voltage

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15
Q

Self-propagating

A

Deporalization in one part causes depolarization in the next part

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16
Q

What is one way to speed up reactions in neurones?

A

Increasing diameter OR myelinating

17
Q

Explain acetylcholine as an example for neural signalling.

A

Acetylcholine causes muscle movement and contraction. It travels as the neurotransmitter and when signal is no longer needed, enzyme acetylcholinesterase breaks it down into acetyl and choline. Choline is reabsorbed by postsynaptic neuron to make more acetylcholine.

18
Q

Local current

A

The movement of sodium ions between polarised and depolarised regions

19
Q

How do we measure local current?

A

Using an oscilliscope measures electrical potential, using electrodes to measure voltage in our membrane

20
Q

Exogeneous chemicals

A

Block binding or promote it

21
Q

What is an example of an exogenous chemical in insects and what happens with it

A

Neonicotinoids (insecticides/pesticides) block normal synaptic transmission. They bind to the acetylcholine receptors, blocking real acetylcholine from binding. Acetylcholinesterase doesn’t recognize it, so it is not destroyed. Neonicotinoids remain there, blocking normal synaptic transmission. If insect cannot get acetylcholine to bind, it will cause paralysis and eventually death.

22
Q

What is an example of an exogenous chemical in humans and what happens with it

A

Cocaine promotes synaptic transmission. It blocks the reuptake of dopamine into the synaptic neurones, meaning that the action potential keeps on being relayed which eventually causes an overstimulation and blocks off other important messages (like danger!)

23
Q

What is an inhibitory neurotransmitter

A

A transmitter which makes the membrane even more negative, making it harder for nerve impulses to be sent. Example = gaba

24
Q

Summation

A

When multiple releases of an excitatory neurotransmitter are needed to cause an action potential in the postsynaptic neurone.
Action potential will only ensue if:
* Neurotransmitters from several neurones
* Several neurotransmitters from one neurone

25
Q

Conflicting information?

A

The excitatory neurotransmitters must outnumber the inhibitory neurotransmitters in order to reach threshold potential

26
Q

Calcium 2+ ions in skeletal muscle

A
  1. It is released from the muscle in nervous stimulation
  2. It binds to the troponin
  3. The troponin and tropomyosin move away from and uncover the binding sites
  4. Allows myosin to bind to actin
  5. Sarcomere shortens

Biology (11 decks)

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