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Animal Physiology 2 > Neuron Structure And Function > Flashcards

Neuron Structure And Function Flashcards

1
Q

What Is A Nervous System?

A

Organization of neurons and support cells for the conduction of electrical and chemical signals for communication within and between cells

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2
Q

Central nervous System

A

Integrating Center
- brain and ganglia

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3
Q

Peripheral Nervous System

A
  • Sensory Receptors eg. mechanoreceptors, photoreceptors
  • Effector Organs eg. muscles, glands
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4
Q

Sponges

A

No nervous system or discrete sense organs
Though, respond to touch (some will close off ostia/osculum)
Respond to excessively high particle concentration
Close off ostia (via epidermal cells);flagellar beating
Class Hexactinellida have a syncytium which can conduct electrical signals along its membrane
Much slower than true neurons
This time-lapse video (one image every 30 seconds) shows a sponge contracting after sediment is added to the water it is filtering. These contractions work like a sneeze, helping remove sediment clogging the sponge’s filtration system.

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5
Q

Centralization and Cephalization

A

the concentration of sense organs, nervous control, etc., at the anterior end of the body (i.e. formation of head and brain), but not radially symmetric animals

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6
Q

Nerve Net

A

All cnidaria
* Diffuse nervous “system” (tissue)
* No nerve bodies (ganglia)
* No central nervous system
No myelin
Bidirectional transmission of (neurochemical) impulses
2 layers: one at base of epidermis and other base of gastrodermis

Nerve Processes Synapse Or Junction With:
1. (Neuro)sensory cells
2. Epitheliomuscular cells
3. Nutritive muscular cells

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7
Q

Nerve

A

Cluster of neuronal axons in the PNS

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8
Q

Ganglia

A

Cluster of neuronal cell bodies that serves specific functions / regions “swellings”

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9
Q

Brain

A

Cluster of nerves that serves the whole organim. May have specialized parts (forebrain, midbrain, and hindbrain)

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10
Q

Ganglionic nervous systems

A

E.g. cockroach * Anterior brain
* Ventral nerve cord
* Chain of ganglia and connectives * Solid
* Ganglia are linked by connectives (neuronal axons in the CNS of invertebrates)

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11
Q

Columnar nervous systems

A

Continuous column of neural tissue * Cell bodies and synaptic area
intermingle
* Dorsal
* Hollow

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12
Q

Preamble to neuron signaling

A
  • Acts quickly, over short distances
  • Electrical and chemical
  • Act only on muscle,glands, or other neurons
  • Finer control (e.g. 100 motor neurons per muscle cell)
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13
Q

Hormonal Signaling

A

slow acting, long lasting
short and long distances
affects many tissues
eg. metabolism, growth control

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14
Q

Dendrites

A

*Bring info to the cell body (receive messages)
*Rough Surface (dendritic spines)
*Usually many dendrites per cell
*No myelin insulation
*Branch near the cell body

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15
Q

Neuron Structure And Function Differ From Other Cells

A

1) Neurons have specialized extensions called dendrites and axons.
2) Neurons communicate with each other, electrochemical
3) Neurons contain some specialized structures (synapses) and chemicals (neurotransmitters)

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16
Q

Axons

A

*Take info away from the cell body (deliver messages)
*Smooth Surface
* 1 axon per cell
*Can be myelinated (not always)
*Myelin = fatty substance that insulates and increases speed of conduction
*Branch further from the cell body
Direction of electrical signal

17
Q

Axon Terminal

A
  • One neuron has multiple terminal branches which end in terminal boutons
  • Forms junctions (synapses) with other cells
  • Presynaptic cell passes information to postsynaptic cell
18
Q

Glia – Supporting Cells

A
  • Glia = Greek “glue”
  • 56:302 Glia:Neurons in C. elegans
  • 1:1 Glia:Neurons in primates
  • 1/10th the size of neurons
  • No electrical conduction
  • No neurotransmitters
  • 4 types (Astrocyte, Schwann, Oligodendrocyte, Microglia)
19
Q

Astrocyte (Astroglia)

A

Star-shaped cells that provide physical and nutritional support for neurons:

1) Provide nourishment to neurons by receiving glucose from capillaries
2) Guide neuronal development
3) Clean up brain debris
4) Regulate neurotransmitters in extracellular space

20
Q

Schwann Cells

A
  • In the PNS: Associated with motor neurons and sensory neurons
  • Wrap around one single neuron at a time
  • Improve conduction speed
  • Associated with regeneration of damaged axon
21
Q

Oligodendrocyte

A
  • Form a myelin sheath for neurons in the CNS
  • Single oligodendrocyte can wrap around several neurons
22
Q

Myelin

A
  • Lipid (fatty) rich substance found around axons
  • Derived from glial cells
  • Acts as an insulator
  • Increases speed of signal
  • Separates by Nodes of Ranvier
  • Demyelination associated with diseases such as Multiple Sclerosis
23
Q

Microglia

A
  • Micro – very small
  • Phagocytosis – clean up debris in the CNS
  • Protect the brain from invading microorganisms * Similar in nature to macrophages
24
Q

What Is Membrane Potential?

A
  • The difference in electric potential between the interior and the exterior of a biological cell
  • Simply – voltage difference
  • This charge differential has the potential
    to “do work”
  • Normally cells are negative relative to the outside
25
Q

Patch Clamping

A
  • Glass micropipette is fused to a tiny region of the membrane.
  • Pipette can function as an electrode to record current changes.
26
Q

The equilibrium potential

A
  • The electrical potential difference across the cell membrane that exactly balances the concentration gradient for an ion
  • Net flow of ions is zero
  • In neurons, the main ion moving is potassium.
  • The equilibrium potential for potassium is -75mV
  • The resting membrane potential is -70mV (other ions contribute)
27
Q

Nernst equation

A

The Nernst equation is used to calculate the equilibrium potential as a function of individual ion concentrations.
- predict individual ion movement

E = RT/zF ln (ion outside cell) / (Ion inside cell)

28
Q

Goldman Equation

A

Is used to calculate membrane potential as a function of all ion concentrations, valences and permeability of ions.

29
Q

Neuron Membrane Potential Is Mainly Controlled By Na + and K +

A

K+ is higher inside the cell
Na + is higher outside the cell
They both want to move down their concentration gradients
K+ channels are open (“leaky”)
Most sodium channels are closed in resting neurons

30
Q

In a resting neuron: Na+/K+ pump

A
  • The Na+/K+ pump compensates for Na+ and K+ leakage - Pumps 3 Na+ back out
  • Pumps 2 K+ back in
  • Net change of -1
  • Electrogenic: unequal ion movement
31
Q

Depolarization

A
  • If Na+ channels open, Na+ moves into the cell
  • The positive charge of Na+ decreases the membrane potential
32
Q

Hyperpolarization

A
  • If K+ channels open, K+ moves out of the cell.
  • The positive charge of K+ increases the magnitude of the membrane potential.

Animal Physiology 2 (17 decks)

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