BIOL 1201 Lecture Notes - Lecture 20: Hindbrain, Sensory System, Midbrain

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5 Dec 2015

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Conduct information from receptor to central nervous system: interneuron. Conduct info between sensory and motor neurons: motor. Conduct info from cns to effector cell (muscle, organ, tissue: neuron structure, cell body. Most of organelles, nuclei, er located: dendrites. Part of neuron that receives info from other neurons: axon. Conducts info away from cell body and into output end of neuron: axon hillock. Result of schwann cell growing and wrapping around the cell. Important in terms of aiding in speed of conduction of info along axon: membrane potential, all cells have an electrical gradient or electrical potential across their cell membrane, measured with outside being = 0. Recording electron on the inside: inside is generally -50 to -100 mv (negative relative to the outside) Outside the cell: high [] na, high [] cl- Inside the cell: high [] k, high [] organic molecules (-) K+ diffuse out the cell: more positive molecules outside the cell than inside.

Related Questions

Which of the following statements is TRUE regarding sea anemones?

	None of the answer options is correct.
	Spongesânot sea anemonesâpossess what is considered to be the âsimplestâ nervous system found in animals.
	Because sea anemones are âsimpleâ organisms, these animals only possess motor neurons; sensory neurons or interneurons are never found in sea anemones.
	Although sea anemones possess ânet-likeâ nervous systems, these animals have brains located at their bases (near where they would attach to rocks).
	Although sea anemones lack definitive brains, they do possess ganglia that serve a similar function to the paired ganglia of flatworms.

Some people have low levels of calcium circulating in the blood, a condition known as hypocalcemia. While for many this disorder has little to no effect, for some it can be life-threatening. How could low levels of calcium harm an individual?

	Low levels of calcium would not have any effect on synaptic transmission.
	Low levels of calcium would cause sustained depolarization of the presynaptic cell.
	Low levels of calcium would result in fewer signals sent between the pre- and postsynaptic cell.

Cephalization is: the

	All of these choices are correct.
	development of a brain within the head of an animal.
	concentration of sensory organs within the head end of an animal.
	development of a âhead endâ in an organism.

Which of the following are TRUE about the resting membrane potential? (Select all that apply.)

	It results from voltage-gated sodium channels remaining open for long periods of time.
	It results from K⁺ ions diffusing out of the cell.
	It results from the sodium-potassium pump moving more Na⁺ ions out of the cell than K⁺ ions into the cell.

Afferent and efferent neurons differ in:

	their size.
	the directionality of the information they send.
	their pattern of myelination.

A neuron that responds to the environment is a(n):

	interneuron.
	homeostatic neuron.
	motor neuron.
	sensory neuron.

Which of the following is NOT the role of an interneuron?

	stimulating a muscle to contract
	conveying information from the internal environment of an animal
	relaying information from sensory to motor neurons
	maintaining homeostasis

Where are postsynaptic cell receptor proteins synthesized?

	the Golgi apparatus
	the lysosome
	the cytoplasm
	the rough endoplasmic reticulum

Inhibition of the flexor muscle during the knee-extension reflex is an example of:

	homeostasis.
	reciprocal inhibition.
	negative feedback.
	All of these choices are correct.

10.

What type of cells produce myelin for sensory neurons?

	pyramidal neurons
	glial cells
	melanocytes
	astrocytes

Nerve cells that conduct messages are called (1) ____. (2) _____ cells, which support and nurture the activities of neurons, make up less than half the volume of the nervous system. (3) _______ neurons respond to specific kinds of environmental stimuli, (4) ______ connect different neurons in the spinal cord and brain, and (5) ______ neurons are linked with muscles or glands. All neurons have a (6) _______ ________ that contains the nucleus and the metabolic means to carry out protein synthesis. (7) _______ are short, slender extensions of the (6), and together these two neuronal parts are the neuronsâ âinput zoneâ for receiving (8) _____. The (9) _____ is a single long, cylindrical extension away form the (10) ______; in motor neurons, the (11) ______ has finely branched (12) ________ that terminate on muscle or gland cells and are âoutput zones,â where messages are sent on to other cells. A neuron at rest establishes unequal electric charges across its plasma membrane, and a(n) (13) ____ ____ is maintained. Another name for (13) is the (14) _____ _____ _____; it represents an ability for the membrane to be disturbed. Weak disturbances of the neuronal membrane might set off only slight changes across a small patch, but strong disturbances can cause a(n) (15) _______ ______, which is an abrupt, short-lived reversal in the polarity of charge across the plasma membrane of the neuron. For a fraction of a second, the cytoplasmic side of a bit of membrane becomes positive with respect to the outside. The (16) ______ that travels along the neural membrane is nothing more than short-lived changes in the membrane potential. A. Neurons H. Sensory B. Motor I. Endings C. Interneurons J. Disturbance D. Cell body K. Signals (stimuli) E. Axon L. Voltage differential F. Dendrites M. Resting membrane potential G. Neuroglial N. Action potential

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Santiago Ramon y Cajalâs theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohmâs law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

BIOL 1201 Lecture Notes - Lecture 20: Hindbrain, Sensory System, Midbrain

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