Lecture 1 Question Review

What are three physical characteristics that distinguish axons from dendrites?

1. Axons usually branch at right angles, while dendrites branch at a variety of angles. 2. Axons can extend over a meter long while dendrites rarely are longer than 2 mm. 3. Dendrites taper in width, while axons are usually uniform. **The cell body usually gives rise to one axon, while many dendrites typically extend from the soma.

State whether each of the following statements is true or false. If false, change the statement to make it true. 1. Spines are usually found on axonal branches. 2. Spines are presynaptic sites. 3. Protein synthesis primarily occurs on the rough ER in the soma and axons. 4. Kinesin is the motor protein that transports vesicles to the soma. 5. Myelin is produced by astrocytes in the peripheral nervous system.

1. F -- dendritic branches. 2. F -- postsynaptic sites. 3. F -- soma and dendrites. 4. F -- dynein. 5. F -- Schwann cells.

Colchicine is a drug that causes microtubules to break apart or depolymerize. What effect would this drug have on anterograde transport? What would happen in the axon terminal?

Anterograde transport would not be able to occur, because it is dependent on kinesis 'walking' along the microtubules. The axon terminal would probably degenerate, as it needs organelles, proteins, and materials from the soma to function (can't get those if axoplasmic transport breaks down). **If the colchicine doesn't kill the cell, then materials would just accumulate on the side of the axon closest to the soma.

What did Golgi and Cajal disagree about?

Camillo Golgi -- reticular theory (the brain is an exception to cell theory, the brain is continuous; the neurons communicate by continuity). Santiago Ramón y Cajal -- neuron doctrine (see above).

Knowledge of genes uniquely expressed in a particular category of neurons can be used to understand how those neurons function. Give one example of how you could use genetic information to classify a neuron.

Genes help determine which neurons will be specific to a certain neurotransmitter, and neurons can be classified by neurotransmitter.

What is myelin and what does it do? Which cells provide myelin to the central nervous system?

Myelin insulates a neuron to a) keep the current from leaking out and to b) speed up the action potential. Oligodendrocytes provide myelin in the CNS (Schwann cells in the PNS).

What are the main types of glial cells, and what is the main function of each? Glia outnumber neurons in the brain, yet neurons are the predominant focus of neuroscience textbooks. Why?

Neurons are focused on because they are the ones that actually send all the signals in the brain. Oligodendrocytes (CNS; Schwann cells in PNS): provide myelin. Astrocytes: regulate extracellular environments. Microglia: clean up debris, function as phagocytes/immune cells in brain.

Name the three main parts of the brainstem.

Pons, medulla, midbrain.

State the neuron doctrine in a single sentence. To whom is this insight credited?

Santiago Ramón y Cajal -- the neuron is the basic unit of the cell; communicate with each other via signals.

Is the myelin sheath of somatosensory neurons axons (axons from cells in the dorsal root ganglia) provided by Schwann cells or oligodendrocytes? Why?

Schwann cells, because they lie in the peripheral nervous system.

Imagine that you are a neurosurgeon, about to remove a tumor lodged deep inside the brain. The top of the skull has been removed. What now lies between you and the brain? Which layer(s) must be cut before you reach the CSF?

The brain has three layers between the brain tissue and skull 1. Dura mater (top most): tough, water-proof cap; keeps CSF in. 2. Arachnoid membrane: attaches to dura and pia mater to form subarachnoid space; stores CSF. 3. Pia mater (closest to brain tissue): closely adhering to brain, like plastic wrap; keeps extracellular fluid in brain.

Are the dorsal root ganglia in the central or peripheral nervous system?

The dorsal root ganglia are in the PNS, as they lie outside the spinal cord.

Which parts of a neuron are shown by a Golgi stain and are not shown by a Nissl stain?

The whole neuron is shown is shown by the Golgi stain. Because so few neurons are shown in the Golgi stain, you can see individual neurons and synapses. The Nissl stain shows the soma primarily, as it stains ribosomes/acids (DNA and RNA).

What in the brain do you find the CSF (cerebrospinal fluid)? Name the parts of the CNS it will pass through in its voyage from brain to blood. What is the function of the CSF?

Ventricles, subarachnoid space. Protects brain via buoyancy; helps clear the brain of waste products from metabolism. CSF exits the ventricular system via the subarachnoid space. It is then absorbed into the blood by the blood vessels (called arachnoid villi).

Microtubules are used for a. axoplasmic transport b. protein synthesis c. synaptic transmission d. action potential propagation

a. axoplasmic transport

Which of the following is not an established role for glial cells? a. Sending action potentials to assist neural computation b. Maintaining the ionic environment surrounding nerve cells c. Increase the speed of propagation of neural impulses d. Assisting synaptic transmission via neurotransmitter uptake e. Helping clean up the extracellular environment after trauma or injury

a. sending action potentials to assist neural computation

In which lobe is the hippocampus (a structure involved heavily in memory) located? a. temporal b. parietal c. occipital d. frontal

a. temporal

The Diencephalon includes the: a. thalamus b. tectum c. lateral ventricles d. fourth ventricle e. a and d

a. thalamus

The scientist who shared the Nobel Prize with Camillo Golgi for his anatomical studies of the CNS was a. Allesandro Volta. b. Luigi Galvani. c. Santiago Ramón y Cajal. d. Louis Pasteur e. Thomas Hodgkin

c. Santiago Ramón y Cajal

Synaptic potentials vary proportionally to the _______ of the stimulus. a. size b. duration c. size and duration d. no relationship

c. size and duration

Which of the following is not part of the brain? a. Diencephalon b. Cerebellum c. Cerebral hemispheres d. Spinal cord e. Brainstem

d. spinal cord

The region near the junction of the neuronal cell body (soma) and an axon that has a high concentration of voltage-gated channels is called a. the presynaptic density b. the synaptic bulb c. a node of Ranvier d. a vesicle e. none of the above

e. none of the above (axon hillock)

Among the following structures, state those which are unique to neurons and the ones that are not: nucleus, mitochondria, rough ER, synaptic vesicle, and Golgi apparatus.

not unique: nucleus, mitochondria, rough ER, Golgi apparatus unique: synaptic vesicle