An 11-year-old male was having difficulty reading the graphs that his teacher was showing at the front of classroom. His teacher recommended he be seen by an ophthalmologist. Not only was he asked to look at a Snellen letter chart for visual acuity but he was also asked to identify numbers in an Ishihara chart. He responded that he merely saw a bunch of dots. Abnormal color vision is 20 times more  common in men than women because most cases are caused by an abnormal

#Question id: 11204

#Unit 7. System Physiology – Animal

Why do Na+ ions enter the cell when voltage-gated Na+ channels are opened in neurons?

#Question id: 11205

#Unit 7. System Physiology – Animal

What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?

#Question id: 11206

#Unit 7. System Physiology – Animal

Tetrodotoxin blocks voltage-gated sodium channels, and ouabain blocks sodium-potassium pumps. If you added both tetrodotoxin and ouabain to a solution containing neural tissue, what responses would you expect?

#Question id: 11207

#Unit 7. System Physiology – Animal

In multiple sclerosis, the myelin sheaths around the axons of the brain and spinal cord are damaged and demyelination results. How does this disease manifest at the level of the action potential?

 I) Action potentials move in the opposite direction on the axon.

 II) Action potentials move more slowly along the axon.

 III) No action potentials are transmitted.

#Question id: 11208

#Unit 7. System Physiology – Animal

Neurotransmitters are released from axon terminals via ________.

#Question id: 11209

#Unit 7. System Physiology – Animal

Acetylcholine released into the junction between a motor neuron and a skeletal muscle binds to a sodium/potassium channel and opens it. This is an example of ________.