Neural Control and Coordination Test - 2

GABA or gamma-aminobutyric acid is a principal inhibitory neurotransmitter. It is involved in the reduction of neural excitability in the mammalian CNS.
So, the correct answer is 'Inhibitory neurohormone'.

Nissl bodies found in the cell body of the neurons are the granules of rough endoplasmic reticulum (RER) with rosettes of free ribosomes.The main function of Nissl bodies within neurons is to aid in the production and dispersal of chemical substances such as proteins and peptides. 
So, the correct answer is option B.

Neurotransmitters are the chemicals that transmit the nerve impulse across the synapse. They are stored in synaptic vesicles of axon terminal and are released into the synaptic cleft. Acetylcholine is the neurotransmitter secreted by both pre- and post-ganglionic parasympathetic cholinergic neurons. The enzyme cholinesterase inactivates excess acetylcholine into its chemical components acetic acid and choline. Thus, the correct answer is option B.

The node of Ranvier is a periodic gap in the insulating sheath on the axon of certain neurons that serves to facilitate the rapid conduction of nerve impulses. These interruptions in the myelin covering were first discovered in 1878 by French histologist and pathologist Louis Antoine Ranvier, who describes the nodes as constrictions. They are present in myelinated nerves.

The sensory (afferent) division carries sensory signals by way of afferent nerve fibers from receptors in the central nervous system (CNS). It can be further subdivided into somatic and visceral divisions. The somatic sensory division carries signals from receptors in the skin, muscles, bones and joints.

Saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of nerve impulses.

Neurotransmitters are chemical substances, which cause postsynaptic changes in the receiving neuron. It is contained within the synaptic vesicles. Common neurotransmitters include, acetylcholine, dopamine, norepinephrine (noradrenaline), and serotonin. So, the correct answer is option D.

A Nissl body, also known as Nissl or tigroid substance is a large granular body found in neurons. These granules are rough endoplasmic reticulum (RER) with rosettes of free ribosomes and are the sites of protein synthesis.
Hence, the correct answer is Option A.

Muscle spindles are sensitive to changes in velocity and are innervated by type 1anerve fibers. These afferent nerve fibersconduct the impulse directly to the spinal cord, where they are immediately conducted via interneurons to alpha motor neurons, which stimulate musclecontraction.

Neurons (nerve cells) have three parts that carry out the functions of communication and integration: dendrites, axons, and axon terminals. They have a fourth part the cell body or soma, which carries out the basic life processes of neurons. The figure at the right shows a "typical" neuron.

Neurons that receive information from our sensory organs (e.g. eye, skin) and transmit this input to the central nervous system are called afferent neurons. Neurons that send impulses from the central nervous system to your limbs and organs are called efferent neurons.

Saltatory conduction is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.
Propagation of an action potential in a myelinated nerve involves the opening and closing of ion channels exclusively at the Nodes of Ranvier. This saltatory conduction accelerates the rate at which an action potential travels down an axon.

Action potentials are generated by special types of voltage-gated ion channels in a cell's plasma membrane. When the channels open (in response to depolarization in transmembrane voltage), they allow an inward flow of sodium ions, which changes the electrochemical gradient, which in turn produces a further rise in the membrane potential. This then causes more channels to open, producing a greater electric current across the cell membrane. The process proceeds until all of the available ion channels are open, resulting in a large upswing in the membrane potential. The rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state.

Brain cells remain in the beginning stage of interphase of cell reproduction for their life, and never divide, and instead develop by forming new synapses with other neurons. They lack cellular machinery for cell division. So, the correct answer is option A. 

Neurons are the structural and functional unit of the nervous system. Each neuron consists of dendrites, axon, and soma. Dendrites are the small extension of nerve cells that receive signals from sensory receptors or other neurons. The long extension of the cell body of the nerve cell is called as axon that serves to conduct the nerve impulse away from the cell body. Cyton /soma is the metabolic center of the nerve cell where the metabolic contents are manufactured. It is not involved in nerve impulse conduction. A nephron is the anatomical and functional unit of kidney and thus is the part of the excretory system. Thus, the correct answer is option A.

Nerve impulses are conducted with great velocity. In mammalian nerve, the speed of conduction may be as high as 100 meters per second.

Synapse, also called neuronal junction, the site of transmission of electric nerve impulses between two nerve cells (neurons) or between a neuron and a gland or muscle cell (effector). A synaptic connection between a neuron and a muscle cell is called a neuromuscular junction

The rate of impulse conduction in a nerve depends on the diameter of a fibre and the presence or absence of myelin. 

Neurons with myelin conduct impulse much faster than those without myelin. Schwann cells (or oligodendrocytes) are located at regular intervals along the axons. Between areas of myelin are non-myelinated areas present, called as the nodes of Ranvier. Because fat (myelin) acts as an insulator, membrane coated with myelin does not conduct an impulse. So, in a myelinated neuron, action potentials only occur along the nodes and, therefore, impulses jump over the areas of myelin, going from node to node in a process called as saltatory conduction.

The central role of enzymes as biological catalysts. A fundamental task of proteins is to act as enzymes- catalysts that increase the rate of virtually all the chemical reactions within cells. Although RNAs are capable of catalyzing some reactions, most biological reactions are catalyzed by proteins.
Cholinesterases are enzymes that are involved in helping the nervous system to function properly, cholinesterase test measure the activity of these enzymes.
Acetylcholinesterase is involved in transmission of nerve impulses by breaking down acetylcholine, a chemical that helps to transmit signals across nerve endings.

Both endocrine and nervous system are the integrative system in the body. 
The nervous system has three overlapping functions. These functions are based on the sensory input, integration and motor output. The nervous system is a highly integrated system, the control center of which is the brain.
Endocrine system has organs such as Thyroid, Pituitary glands that secrete hormones which regulate body functions. Hence, option D is correct.

Refractory period is the time during which another stimulus given to the neuron (no matter how strong) will not lead to a second action potential. Thus, because Na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials. The absolute refractory period takes about 1-2 ms.

Neurilemma (also known as neurolemma, sheath of Schwann, or Schwann's sheath) is the outermost nucleated cytoplasmic layer of Schwann cells (also called neurilemmocytes) that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.

An axon is also known as a nerve fiber. It is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body. The function of the axon is to transmit information to different neurons, muscles and glands.

Refrectory period because Na+ Chanel is not active this time.And depolarize stimuli and not new lead action potential during this time and refectory period is 1-2 ms.

The body's various functions and processes are controlled by nervous system and endocrine system. But the nervous system plays a primary role in regulating the activities of organs of bodies and to act on the stimulus from outside also. The coordination of different parts of central nervous system and peripheral nervous system together regulate all voluntary as well as involuntary functions.

Acetylcholine is synthesized from acetyl coenzyme A and choline by the enzyme choline acetyltransferase. In the nervous system, this enzyme is thought to exist primarily in the nerve terminal cytoplasm. Coenzyme A is synthesized in mitochondria and accesses choline acetyltransferase following transport across the mitochondrial membrane into the cytoplasm. In addition to its synthesis in the liver, choline employed in acetylcholine production is derived from dietary sources. 

One hundred years ago, in 1897, Charles Sherrington adopted the name synapse. 

Motoneurons or multipolar neurons carry signals from the CNS to the muscles and glands. These neurons have many processes originating from the cell body. Multipolar cells are the most numerous type. These have been further sub-categorized into Golgi type II cells, that are small neurons, usually interneurons, and Golgi type I cells that are large multipolar neurons.

The outer membrane has positive charge and inner membrane is negative. This is how the membranes of axon generally is. That is why the condition is known as resting potential. On stimulation by impulses, the membrane permeability changes resulting in negative outside and positive inside, that's action potential. 
Hence, the correct answer is Option B.

Increased axon diameter in axons leads to increase action potential velocity. As there is an increase in diameter of a fibre, its internal resistance decreases. The internal resistance decreases faster relative to the membrane resistance - therefore the distance the membrane potential can travel is increased by an increased diameter. So, the correct answer is option B.