Nervous tissue

Question 1

Information processing

Answer 1

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

Question 2

Coordination and control

Answer 2

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

Question 3

Two main components of nervous tissue

Answer 3

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

Question 4

Various glia types

Answer 4

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

Question 5

Astrocytes

Answer 5

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

Question 6

Oligodendrocytes

Answer 6

myelination greatly increases the conduction speed of action potentials

Question 7

Microglia

Answer 7

immune cells in the CNS that protect against pathogens

Question 8

Schwann cells

Answer 8

myelinate axons in the PNS

Question 9

Ependymal cells

Answer 9

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

Question 10

Dendrites

Answer 10

•receive messages from other neuronsat specialised junctions called synapses

Question 11

Axon hillock

Answer 11

• serves as junction between cell body and axon

* integrates signals from multiple synapses

Question 12

Axon

Answer 12

•propagate integrated signal to axon terminals

Question 13

Axon terminals

Answer 13

• Synapse on other neurons, muscles, or target organs

* Chemicals released, signals communicated to cells of target tissue

Question 14

Nodes of Ranvier

Answer 14

Sites where signal is recharged

Question 15

Ion channel

Answer 15

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

Question 16

Membrane potential

Answer 16

difference in electrical potential across membrane

Question 17

Resting potential

Answer 17

membrane potential of inactive cells

Question 18

Negative potential

Answer 18

more sodium ions outside cell than potassium ions inside the cell

Question 19

Potassium ions

Answer 19

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

Question 20

Sodium-potassium

Answer 20

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

Question 21

Action potentials

Answer 21

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

Question 22

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

Answer 22

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

Question 23

Action potential travels down the axon

Answer 23

as the membrane of the axon depolarizes and repolarizes

Question 24

Action potential: Myelin

Answer 24

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

Question 25

Action potential: Nodes of Ranvier

Answer 25

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

Question 26

Sporadic amyotrophic lateral sclerosis(sALS)

Answer 26

•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