Neural Control and Coordination Test - 64

The principal method by which sound frequencies are discriminated from one another is based on the place of maximum stimulation of the nerve fibres from the organ of Corti lying on the basilar membrane. High frequency resonance of the basilar membrane occurs near the base, where the sound waves enter the cochlea through the oval window. But low frequency resonance occurs near the helicotrema, mainly because of the less stiff fibres. 

• Cell bodies of preganglionic neurons of parasympathetic division are located in the brain and in the sacral region of the spinal cord. 
  
  
• So, the parasympathetic division is called as craniosacral division.
   
  Hence, Option C is correct.

• The dendrites accept signals generated by other neurons. These signals may be excitatory or inhibitory. All signals present at the dendrites of a neuron are combined and the result will determine whether or not that neuron will fire. If a neuron fires, an electrical impulse is generated. 
• An axon, or nerve fibre, is a long slender projection of a nerve cell or neuron, that conducts electrical impulses away from the neuron's cell body or soma. 
• Axon terminals have knob-like swellings at the very end called synaptic knobs. The function of a synaptic knob is to change the action potential that is carried by axons into a chemical message. 

• Hair cells (sense cells) are the sound receptors of the auditory system. 
• In mammals, the auditory hair cells are located within the organ of Corti on a thin basilar membrane in the cochlea of the inner ear. 
• Cochlea produces nerve impulses in response to the sound vibration.
• The vestibular labyrinth of mammals comprises the utricle (utriculus), the saccule (sacculus), and the semicircular canals (ductus semicirculares), which are filled with a fluid, the endolymph.
  
• Semicircular canals are three tiny, fluid-filled tubes in the inner ear that help you keep your balance along with sacculus & utriculus.
  

• The eustachian tube is a canal, which connects the middle ear to the nasopharynx, which consists of the upper throat and the back of the nasal cavity. 
• It regulates the pressure within the middle ear, equalizing it with the air pressure outside the body.
• So, the correct answer is option D.

A medullated nerve fiber is also called as myelinated nerve fiber. The nerve fibers, which are covered by the myelin sheath are called as medullated nerve fibers. Myelin sheath is derived from Schwann cells. Myelin sheath is made up of alternate concentric layers of lipids and proteins. Myelinated nerve fiber also shows the presence of neurolemma. It covers the nerve fiber.

So, the correct answer is 'Both A and B'

Synaptic delay is the time necessary for the conduction of a signal across a synapse. It is the interval between the arrival of a nerve impulse at the ending of a presynaptic fibre and the start of the postsynaptic potential. 

• Ependyma is the thin epithelium-like lining of the ventricular system of the brain and the central canal of the spinal cord. 
• Ependyma is one of the four types of neuroglia in the central nervous system and is involved in the production of cerebrospinal fluid.

Thus, the correct answer is (C), 'Ependymal cells'.

Split-brain operation is also known as corpus callosotomy, a surgical technique used for alleviating epileptic seizures. This procedure involves cutting the corpus callosum, the main bond between the left and right hemispheres of the brain. So, the correct answer is option B.

Cartilage is devoid of blood supply. The nutrients diffuse through a dense connective tissue surrounding the cartilage (called the perichondrium) and into the core of the cartilage. Due to the lack of blood vessels, cartilage grows and repairs more slowly than other tissues. The cornea also has no blood supply; it gets oxygen directly through the air. Oxygen first dissolves in the tears and then diffuses throughout the cornea to keep it oxygenated.