Biology

Nervous System and Neurons

1,164 Questions

The nervous system and neurons section covers the structural and functional aspects of the human nervous system. Topics include nerve fibers, the myelin sheath, and sympathetic nervous system functions. This material is crucial for general science preparation in various competitive exams.

Neuron structureMyelin sheath productionSympathetic nervous systemCranial and spinal nervesParasympathetic functions

Nervous System and Neurons Questions

Multiple choice

An inhibitory neurotransmitter decreases the electrochemical activity of neurons. Among the following, ___________ is a chief inhibitory neurotransmitter in mammals.

  1. gadopentetic acid

  2. galantamine

  3. galactose

  4. γ-aminobutyric acid
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

γ-Aminobutyric acid is the chief inhibitory neurotransmitter in the mammalian central nervous system. It plays a role in regulating neuronal excitability throughout the nervous system.

Multiple choice

Myelin sheath is the insulating envelope surrounding the nerve fibre and facilitates the transmission of nerve impulses. Which of the following amino acids helps in the maintenance of the myelin sheaths?

  1. Cysteine

  2. Histidine

  3. Glutamine

  4. Glutathione
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Histidine is known to be vital in the maintenance of the myelin sheaths surrounding nerves, particularly the auditory nerve and is used to treat some forms of hearing disability.

Multiple choice

Blocking of acetylcholine receptors at the postsynaptic neuromuscular junction by circulating antibodies causes

  1. myasthenia gravis

  2. polymyalgia rheumatica

  3. microscopic polyangiitis

  4. Behcet's syndrome
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Myasthenia gravis or muscle weakness is caused by circulating antibodies that block acetylcholine receptors at the postsynaptic neuromuscular junction. It inhibits the excitatory effects of neurotransmitter acetylcholine on nicotinic receptors at neuromuscular junctions.

Multiple choice

Which of the following statements regarding the coordination of activities in sponges is INCORRECT?

  1. Glass sponges rapidly transmit electrical impulses through all parts of the syncytium.

  2. Myocytes are thought to be responsible for transmitting signals between different parts of the body.

  3. Adult sponges are well equipped with neurons.

  4. Some species can contract the osculum independently of the rest of the body.

  5. Sponges may also contract in order to reduce the area that is vulnerable to attack by predators.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Adult sponges lack neurons or any other kind of nervous tissue. However most species have the ability to perform movements that are coordinated all over their bodies, mainly contractions of the pinacocytes, squeezing the water channels and thus expelling excess sediment and other substances that may cause blockages.

Multiple choice

Adrenaline directly affects the

  1. islet of langerhans

  2. sinoatrial node

  3. oxyntic cells of stomach

  4. dorsal root ganglia of spinal cord
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Adrenaline (epinephrine) directly stimulates the sinoatrial (SA) node, increasing heart rate and cardiac output. It binds to beta-1 adrenergic receptors on SA node cells, enhancing the rate of depolarization and firing frequency.

Multiple choice

The diameter of axon is regulated by ____________________________.

  1. endoneurium

  2. epineurium

  3. perineurium

  4. neurolemma

  5. neurofibrils
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Neurofilaments are the intermediate filaments found in neurons. They are a major component of the neuronal cytoskeleton, and are believed to function primarily to provide structural support for the axon and to regulate axon diameter. Neurofilaments are composed of polypeptide chains or subunits which belong to the same protein family.

Multiple choice

Which among the following nerves innervate(s) the human penis?

  1. Sacral spinal nerve

  2. Genitofemoral nerve

  3. Sacral nerves 2, 3 and 4

  4. Sciatic nerve

  5. Labialscrotal nerve
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Innervation of the penis comes from the pudendal nerve which is made up of the 2nd, 3rd and 4th sacral nerves. The penile nerve (also known as the dorsal nerve of the penis) is the deepest branch of the pudendal nerve.

Multiple choice

There are twelve pairs of cranial nerves in human beings. Ten of the twelve cranial nerves originate in which part of the human brain?

  1. Hypothalamus

  2. Pituitary gland

  3. Brainstem

  4. Pineal gland

  5. Thalamus
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The brainstem includes the midbrain, pons and medulla. It acts as a relay center connecting the cerebrum and cerebellum to the spinal cord. It performs many automatic functions such as breathing, heart rate, body temperature, wake and sleep cycles, digestion, sneezing, coughing, vomiting, and swallowing. Ten of the twelve cranial nerves originate in the brainstem.

Multiple choice

Which among the following statements regarding the innervation of the human heart is FALSE?

  1. Preganglionic sympathetic fibres ascend from the upper five thoracic segments of the spinal cord.

  2. The effect of autonomic nervous system on coronary artery and blood flow is reciprocatory.

  3. Postganglionic fibres descend to the heart and form two plexuses.

  4. During rest, the vagal tone is recessive.

  5. Afferent fibres carrying pain sensation run to the spinal cord.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

During rest, the vagal tone is the dominant. There is continuous parasympathetic activity that has a negative chronotropic character.