Nervous System Review Questions

A type of brain trauma likely to result in a long term coma is:

...

Motor functions of the extensor muscles of the arm, forearm, and fingers would be affected by damage to which one of these nerves?

...

What is a reflex arc? Name its minimum components.

1) Receptor: Site of the stimulus action 2) Sensory Neuron: Transmits afferent impulses to the central nervous system 3) Integration Center: In simple reflex arcs, may be a single synapse between a sensory neuron and a motor neuron (monosynaptic reflex). More complex reflex arcs involve multiple synapses with chains of interneurons (polysynaptic reflex). The integration center is always within the central nervous system. 4) Motor Neuron: Conducts efferent impulses from the integration center to an efferent organ. 5) Effector: Muscle fiber or gland cell that responds to the efferent impulses (by contracting or secreting)

1.Astrocytes 2.Oligodendrocyte 3.Ependymal 4.Satellite

1. ½ of neural tissue,Provide a barrier between neurons and blood supply,and control their exchanges for protection. 2.have flat extensions that wrap around the nerve fibers (extensions) producing the fatty insulating 3.line the cavities of the brain and spinal cord. 4.protective, cushioning cells in the PNS.

How many pairs of spinal nerves are there?

31 pairs.

Briefly explain how nerve impulses are initiated and transmitted, and why conduction at synapses always happens

A threshold stimulus causes a reversal in membrane permeability that allows Na+ to enter the neuron through Na+ voltage-gated channels. This causes local depolarization and generates the action potential, which is then self-propagating. This event is quickly followed by a second permeability change that restricts Na+ entry, but allows K+ to leave the neuron, causing repolarization or resumption of the polarized state. One-way conduction occurs at synapses because axons (not dendrites) release the neurotransmitter.

Histological examination of a slice of neural tissue reveals a bundle of nerve fibers held together by cells whose multiple processes wrap around the several fibers and form a myelin sheath. The specimen is likely to be:

A tract.

Where might gray matter nucleus be located?

Alongside the vertebral column. Within the brain. Within the spinal cord.

33. The sympathetic and parasympathetic fibers serve the same organs. How can their opposing effects be explained?

Although both the sympathetic and parasympathetic preganglionic fibers release acetylcholine, their postganglionic fibers (in close contact with the effector organs) release different neurotransmitters. The sympathetic fibers release norepinephrine and the parasympathetic fibers release acetylcholine. These different neurotransmitters produce opposing effects in the effector organs.

Discuss how the brain is protected by bone, membranes, fluid, and capillaries.

Bone: Enclosed by the skull. Membranes: The meningeal membranes—dura mater, arachnoid mater, and pia mater—enclose the brain within the skull and provide a passage for the circulation of CSF and its return to the blood. Fluid: Cerebrospinal fluid (CSF) cushions the brain from physical trauma. Capillaries: The capillaries of the brain are permeable only to glucose, a few amino acids, and respiratory gases. Hence, they protect the brain from possibly harmful substances in the blood.

The spinal cord feature associated with the leash of nerves supplying the upper limbs is the:

Brachial plexus and cervical enlargement.

List the structures of the CNS and PNS

CNS- the brain and spinal cord PNS-nerves connecting the brain and spinal cord

Name the four major nerve plexus formed by the ventral rami and the body region served by each.

Cervical, Brachial, Lumbar, Sacral

29. What region of the body is served by the dorsal rami of the spinal nerves? the ventral rami?

Dorsal rami: Posterior body trunk. Ventral rami: Limbs and anterior, lateral body trunk.

The pineal gland is located in the

Epithalamus.

What is gray matter? White matter? How does the arrangement of gray and white matter differ in the cerebral hemispheres and the spinal cord?

Gray matter is neural tissue composed primarily of nerve cell bodies and unmyelinated fibers. White matter is composed primarily of myelinated fibers. In the cerebral hemispheres, most of the gray matter is outermost (superficial), and the white matter is deep. In the spinal cord, the white matter is superficially located and the gray matter is internal or deep.

Which of the following is true of the autonomic, but not the somatic, nervous system?

Has motor neurons located in ganglia.

What are the two main functions of the spinal cord?

It connects a large part of the peripheral nervous system to the brain. Acts as a minor coordinating center responsible for some simple reflexes like the withdrawal reflex.

Glial cells present in large numbers in areas of bacterial infection in the brain are most likely be:

Microglia.

What does myelinating the axon do to the impulse?

Myelinated axons, provide sort of a "boost" to increase the speed of the transmission across long axons.

What are the two great controlling systems of the body?

Nervous system and endocrine system.

Two major cell groups make up the nervous system- neurons and connective tissue cells such as astrocytes and Schwann cells. Which are "nervous" cells? Why? What are the major functions of the other cell group?

Neurons are the "nervous cells." They exhibit irritability and conductivity. The major functions of the neuroglia are protection, support, myelination, and a nutritive/metabolic function relative to the neurons. Schwann cells are myelinating cells in the peripheral nervous system.

How does the autonomic nervous system differ from the somatic nervous system?

The autonomic nervous system has a chain of two motor neurons (rather than one) extending from the CNS and is controlled involuntarily (rather than voluntarily). The ANS has different effector organs (cardiac muscle, smooth muscle, and glands), and it can release both acetylcholine (parasympathetic nervous system) and norepinephrine (sympathetic nervous system). This system has cell bodies of motor neurons inside and outside the CNS. Also, the two divisions of the ANS have antagonist actions to each other.

An example of integration by the nervous system is:

The decision to go back for an umbrella.

One neuron transmits a nerve impulse at 40 meters per second; another conducts at the rate of 1 meter per second. Which neuron has a myelinated axon?

The fibers that conducts at 40M/sec.

Give the basis for the functional classification of neurons.

The functional classification of neurons is based on the general direction of the impulse. Impulses traveling from sensory receptors to the CNS are afferent (sensory) neurons. Impulses traveling from the CNS to effector organs travel along efferent (motor) neurons. Neurons that are in the CNS and connect afferent and efferent pathways are called interneurons or association neurons.

Except for the vagus nerves, what general area of the body do the cranial nerves serve?

The head and neck region.

32. What is the difference in function of the sympathetic and parasympathetic divisions of the autonomic nervous system (a) in general and (b) as specifically relates to the operation of the cardiovascular and digestive systems?

The parasympathetic division of the ANS is the "housekeeping system." It acts to conserve body energy and to keep the body running at minimum levels of energy use during nonemergency periods. Its effect is seen primarily in the normal operation of the digestive system and the urinary system. The sympathetic division is the "fight-or-flight" system; it acts during periods of short-term stress to increase heart rate and blood pressure to increase oxygen levels in the body, as well as increasing blood glucose levels, and to shunt blood to necessary organs. Generally, sympathetic activity inhibits digestive system functioning. The parasympathetic system has the opposite effect.

Other than serving as a conduction pathway, what is a major function of the pons? Why is the medulla the most vital part of the brain?

The pons also has important nuclei that participate in the control of respiratory rhythm. The medulla is vital because it contains the major respiratory centers, the vasomotor center (which controls blood vessel diameter, hence blood pressure), and the cardiac centers. Without breathing and heart activity, life stops.

Explain both the structural and functional classifications of the nervous system. In your explanation, include the subdivisions of each.

The structural classification includes all the nervous system organs. The major subdivisions are the central nervous system which includes the brain and spinal cord, and the peripheral nervous system which is mainly nerves. The functional classification divides the peripheral nervous system into afferent (sensory) and efferent (motor) branches. The motor division is further divided into the somatic and autonomic branches.

22. What is the function of the thalamus? The hypothalamus?

The thalamus is a relay station for sensory impulses ascending to the cerebral cortex for interpretation; as impulses pass through the thalamus.

Name four types of cutaneous sensory receptors. Which of the receptor types is most numerous? Why?

Touch, pressure, heat, & pain

Cranial nerves that have some function in vision include the:

Trochlear.

How many pairs of cranial nerves are there? Which are purely sensory? Which activates the chewing muscles? Which helps regulate heart rate and activity of the digestive tract?

Twelve pairs. Purely sensory: Olfactory (I), optic (II), and vestibulocochlear (VIII). Activates the chewing muscles: trigeminal (V). Regulates heartbeat, etc.: Vagus (X).

Which contains only motor fibers?

Ventral root.