Draw labelled diagrams of the following:
$(a)$ Neuron
$(b)$ Brain
$(c)$ Eye
$(d)$ Ear

(N/A) The diagrams for the requested structures are as follows:
$(a)$ Neuron: $A$ nerve cell consists of a cell body (cyton) with dendrites,a nucleus,Nissl's granules,an axon,myelin sheath,nodes of Ranvier,and synaptic knobs.
$(b)$ Brain: The human brain is divided into the forebrain (cerebrum,thalamus,hypothalamus),midbrain,and hindbrain (pons,cerebellum,medulla),connected to the spinal cord.
$(c)$ Eye: The human eye structure includes the cornea,aqueous chamber,lens,iris,ciliary body,retina,choroid,sclera,fovea,blind spot,and optic nerve.
$(d)$ Ear: The human ear consists of the pinna,external auditory canal,tympanic membrane,middle ear ossicles (malleus,incus,stapes),oval window,cochlea,cochlear nerve,and Eustachian tube.