Answer Depolarization is increment of positive charges on the cell membrane caused by drawing in the cations like Na+ or Ca+, while repolarizationis the process of increasing negative charge on the cell membrane by transferring out K+ cations or drawing in Cl – anions.Answer 2. a. Cerebellum: Cerebellum is primarily related to the motor activities of the humans and animals. Patients with damage in cerebellum can generate motor activity, but these activities are uncoordinated, erratic, and very poorly organized. Of late, this brain structure is also believed to help in language, imagery, attention, etc. and critical in learning processes.b. Hypothalamus: The functions involve control of the endocrine system. It is also related to food intake and fear processing. It characterizes several sexual features since it can regulate a number of sex-related hormones.c. Cerebrum: Olfaction (which is related to the system of smelling), sensory processing and movement are the prime functions. It also helps in the language and communicatory processes along with the development of learning skills. d. Corpus Callosum: It is a large white matter portion of the brain that connects the right and left hemispheres of the cerebrum and helps in communication between the two. Several axonal projections originate form this structure. Corpus callosum can be held responsible as functional in regulating body balance since defects in this structure result in diseases like epilepsy, dyslexia, etc.e. Pons: Thisstructure built of white matter has tracts that carry signals from thecerebral regiondown to the medulla and cerebellum. It also consists of the tracts carrying sensory signals to thalamus. Defects in pons functions cause lack of body balance, difficulty in walking, swallowing, speaking, and feeling touch.Answer 3.a. Neurolemmais the most exterior nucleated covering of the neural cytoplasm which surrounds the neuronal axons in Schwann cells. It provides covering to the nerve fibers in PNS (Peripheral Nervous System).b. Dendrites help in the integration ofsynaptic inputsand in determination of the level to whichelectrical impulses or action potentialsare generated by neuron. Dendrites also help in releasing neurotransmitters and support the generation of action potentials.c. Axon terminals are the sites through which action potentials are carried to the adjacent neurons. The nervous conduction provided by axon terminals help in preventing schizophrenia, epilepsy, memory and learning disorders, etc.d. The main function of the axon hillock involves summation of IPSP (Inhibitory Postsynaptic Potentials) and EPSP (Excitatory Postsynaptic Potentials) to calculate whether the threshold for triggering an action potential has been crossed or not. In the case the threshold is crossed, the action potential can be propagated to the rest of the axon or to the dendrites by back-propagation mechanism.Answer 5.Spinal nerve plexus are a combination of fascicles of fibers emanating from neighboring spinal nerves. They form a connective network for conduction of impulses.For the example of a specific location of spinal nerve plexus, the cervical plexus (one of the spinal nerve plexuses) can be examined which is located from the C1 up to the C4 cervical segments of neck.Answer 6.Neuroglial cells do not conduct nervous impulses but provide a nervous support system to the nerve tissues. For example, astrocytes are the neuroglial cells which are located in the capillaries of the brain. They form the barrier of blood-brain separation and control the conduction of different substances between the two.Answer 8.Response of human body to an external, unbalanced stimulus to restore homeostasis is called reflex. according to a components based definition, reflex or more precisely, reflex arc consists of the following:1. Receptor (at the terminal part of sensory neuron)2. Afferent neuron (conducts the impulse to CNS (Central Nervous System))3. Synapsis/synapses (impulse integration and coordination inside the CNS)4. Efferent neuron (Conducting impulse from CNS to effector)5. Effector (a gland or muscle that responds to the stimulus)EC – 1Parasympathetic divisionEC – 2γ-aminobutyric acid