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Flashcards in Nervous tissue Deck (26)
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1

Information processing

•sensory neurons-sensory input (external or internal cues)
•interneurons-integration of signals
•motor neurons-motor output

2

Coordination and control

•mainly nervous (nerve impulses) & endocrine (~hormones) systems

3

Two main components of nervous tissue

1. neurons (nerve cells)
•generate electrical signals (conducted nerve impulses / action potentials)
2. glia
•mainly support neuronal function

4

Various glia types

1. Astrocytes
2. Oligodendrocytes
3. Microglia
4. Schwann cells
5. Ependymal cells

5

Astrocytes

information transfer, regulate extracellular ion concentrations, promote blood flow to neurons, help form the blood-brain barrier, and act as stem cells to replenish certain neurons

6

Oligodendrocytes

myelination greatly increases the conduction speed of action potentials

7

Microglia

immune cells in the CNS that protect against pathogens

8

Schwann cells

myelinate axons in the PNS

9

Ependymal cells

line the ventricles of the brain, promote circulation of the cerebrospinal

10

Dendrites

•receive messages from other neuronsat specialised junctions called synapses

11

Axon hillock

•serves as junction between cell body and axon
•integrates signals from multiple synapses

12

Axon

•propagate integrated signal to axon terminals

13

Axon terminals

•Synapse on other neurons, muscles, or target organs
•Chemicals released, signals communicated to cells of target tissue

14

Nodes of Ranvier

Sites where signal is recharged

15

Ion channel

a protein complex penetrates a cell membrane, allow specific ions through membrane

16

Membrane potential

difference in electrical potential across membrane

17

Resting potential

membrane potential of inactive cells

18

Negative potential

more sodium ions outside cell than potassium ions inside the cell

19

Potassium ions

diffuse out at a much faster rate than sodium ions diffuse into the cell because more potassium leakage channels than sodium

20

Sodium-potassium

pumps move two potassium ions inside the cell as three sodium ions are pumped out to maintain the negatively-charged membrane inside the cell; this helps maintain the resting potential

21

Action potentials

forms when a stimulus causes the cell membrane to depolarize, causing all sodium ion channels to open

22

potassium ion channels are opened and sodium ion channels are closed:

cell membrane becomes hyperpolarized as potassium ions leave the cell; the cell cannot fire during this refractory period

23

Action potential travels down the axon

as the membrane of the axon depolarizes and repolarizes

24

Action potential: Myelin

insulates the axon to prevent leakage of the current as it travels down the axon

25

Action potential: Nodes of Ranvier

contain sodium and potassium ion channels, allowing the action potential to travel quickly down the axon by jumping from one node to the next.

26

Sporadic amyotrophic lateral sclerosis(sALS)

•Progressive neuro degenerative disease that affect nerve cells in brain and spinal cord
•“Sporadic”-> cause of disease unknown
•Motor neurons die -> ability of brain to initiate and control muscle movement lost
•Microscopic changes include:
1. neuronal and axon loss
2. loss of myelinated axons in lateral and anterior columns of spinal cord and decrease in size of anterior horn of spinal cord