An age-related condition when the eye's lens doesn't change shape as easily as it once did [Presbyopia] is usually caused by:
1. decreasing the flexibility of the lens
2. an eyeball that is slightly too short
3. an eyeball that is slightly too long
4. a cornea with asymmetric curvature

Protein synthesis in neuron is carried out directly by:

The most common neurotransmitter in the body is:

1. serotonin

2. GABA

3. acetylcholine

4. adrenaline

An opioid peptide produced in the brain, especially in the pituitary gland, that blocks the sensation of pain is:

1. substance P

2. beta-endorphin

3. nicotine

4. neuropeptide

The type of neuron seen in the retina of human eye are:

1. bipolar

2. unipolar

3. multipolar

4. sensory

The peripheral nervous system in humans PNS consists of cranial nerves and:

1. spinal cord

2. sensory nerves

3. the brain

4. spinal nerves

Blood brain barrier formation is the function of:

1. microglia

2. Schwann cell

3. astrocyte

4. oligodendrocytes

The neuron in humans with many nerve fibers arising from its cell body and that carries impulses to the effectors would be called as:

The regulation of the composition of cerebrospinal fluid is the function of:

1. astrocytes

2. oligodendrocytes

3. microglia

4. ependyma

All the following statements regarding nerve impulse conduction are correct except:
1. Myelinated neurons have a higher conduction velocity than unmyelinated neurons.
2. Nerve impulses occur in an all-or-none manner.
3. The neuron cannot be stimulated during the depolarization phase.
4. The strength of impulses carried along a single nerve fiber can vary with the strength of their stimulus.