Nokea
The diameter of a motor nerve fibre is
- A. 1-2 micrometre
- B. 3-5 micrometre
- C. 5-12 micrometre
- D. 12-20 micrometre
Correct Answer: D
Rationale: Motor nerve fibers, such as alpha motor neurons, typically have a diameter of 12-20 micrometers. Larger diameters allow for faster conduction of action potentials.
You may also like to solve these questions
When the individual is be unable to recognise everyday objects and name them correctly, this is known as
- A. Prosopagnosia
- B. Anomia
- C. Agnosia
- D. Aphosonomia
Correct Answer: C
Rationale: Agnosia is a neurological condition characterized by the inability to recognize or identify objects, people, sounds, or shapes, despite having intact sensory abilities. This condition arises from damage to specific areas of the brain responsible for processing sensory information. Agnosia can manifest in various forms, such as visual agnosia (inability to recognize objects) or auditory agnosia (inability to recognize sounds).
As the potassium ions move out of the axon, the oscilloscope records a ________.
- A. depolarization
- B. repolarization
- C. equalizing of negative and positive ions
- D. shutdown of the membrane pumps
Correct Answer: B
Rationale: As potassium ions move out of the axon during repolarization, the oscilloscope records a return of the membrane potential to its negative resting state. This phase of the action potential is called repolarization and is essential for resetting the neuron so it can fire another action potential. Repolarization ensures that the neuron is ready to transmit subsequent nerve impulses.
The elevated ridges of tissue on the surface of the cerebral hemispheres are known as ______ while the shallow grooves are termed ______.
- A. sulci; gyri
- B. gyri; sulci
- C. ganglia; gyri
- D. tracts; ganglia
Correct Answer: B
Rationale: The elevated ridges on the cerebral hemispheres are called gyri, and the shallow grooves are called sulci. Ganglia, tracts, receptors, and effectors are unrelated to these structures. Thus, B is the correct answer.
What role, if any, do Hox genes play in specification of neuronal fate?
- A. Different Hox genes are activated along the dorso-ventral axis by the gradient of Shh.
- B. Different combinations of Hox genes specify the identities of neurons along the antero-posterior axis
- C. Hox genes determine the identity of the segments along the axis of the vertebrate spinal cord
- D. Hox genes determine the different subtypes of neurons that form along the dorso-ventral axis.
Correct Answer: B
Rationale: Hox genes are crucial for specifying neuronal identity along the antero-posterior axis. Different combinations of Hox genes are expressed in distinct regions of the developing nervous system, providing positional information that guides the differentiation of neurons into specific subtypes. This ensures the proper organization and function of the spinal cord and brain.
The intracranial pressure is decreased by:
- A. intravenous mannitol
- B. placing the patient in a head-up position
- C. hyperventilation
- D. all above
Correct Answer: D
Rationale: Intracranial pressure (ICP) can be reduced by intravenous mannitol (an osmotic diuretic), placing the patient in a head-up position (to improve venous drainage), and hyperventilation (which reduces CO2 levels and causes cerebral vasoconstriction). All these methods are clinically used to manage elevated ICP.