When we migrate from dark to light, we fail to see for sometime but after a time visibility becomes normal. It is an example of 
It takes some time for rhodopsin to split into scotopsin and retinal (bleaching) and release of transmitter passing nerve impulse via bipolar and ganglion cells to the optic nerves. This is a case of adaptation. It differs from accommodation which is a reflex mechanism by which the focus of the eye change to make the images of distant and near objects sharp on the retina.
What is intensity of sound in normal conversation? 
The word noise is taken from the latin word nausea and is defined as unwanted or unpleasant sound that causes discomfort.
Neuroglia consist of cells found in the
Neuroglia are non-nervous cells present- along with and in between the neurons in central nervous system, ganglia and retina. They have roles like myelin formation, transport of materials to neurons, maintenance of ionic balance and phagocytosis.
Suspensory ligament is part of 
Stretching and relaxation of suspensory ligament changes the focal length of lens for accommodation.
In vertebrates, simple reflex action is 
A reflex action is a nerve mediated spontaneous, automatic and involuntary response to a stimulus acting through specific receptors without consulting the will of the animal.
Anesthetics reduce pain by blocking the transmission of nerve impulses. The kind of chemicals working as anesthetics are those that block 
In this manner, they block transmission of nerve impulse.
In the chemistry of vision in mammals, the photosensitive substance is called 
Rhodopsin is a biological pigment present in the rod of the retina and it is light sensitive protein belongs to GPCR family proteins. Rhodopsin is extremely sensitive to light, and when exposed to light it undergoes into immediate photobleaching and gives vision in low-light conditions.
The Nissl’s granules of nerve cells are made up of [1997, 03]
Prominent granules (Nissl’s granules) observed in the cytoplasm of the cyton are believed to be made of ribosomes.
A Nissl body (or Nissl granule or tigroid body) is a large granular body found in nerve cells. It was named after Franz Nissl, German neurologist (1860-1919). Nissl bodies can be demonstrated by selective staining, which was developed by Nissl and the stain used was an aniline stain to label extranuclear RNA granules.These granules are rough endoplasmic reticulum (with ribosomes) and are the site of protein synthesis.Nissl bodies show changes under various physiological conditions and in pathological conditions they may dissolve and disappear (karyolysis).
Cornea transplantation is outstandingly successful because 
Cornea transplants are easy, since there are no blood vessels involved.
In humans, visceral organs are innervated by
The activities of all visceral organs are coordinated through the regulation of their smooth muscles and glands by the nerve fibres of the sympathetic and parasympathetic nervous system. These constitute the autonomic nervous system which carry out functions that are not under the control of our will.
The sympathetic nerves in mammals arise from
In mammals, the sympathetic nerves arise from thoraco-lumbar nerves (autonomic nervous system).
Respiratory centre is situated in 
Respiratory centre is situated bilaterally in medulla oblongata, while breathing is controlled by pneumotaxic and apneustic centres in pons varolii. Impulse for voluntary forced breathing starts in cerebral hemisphere.
CNS is mostly made of
Light rays entering the eye is controlled by 
The iris is the ring of pigmented tissue surrounding the pupil that varies in color. The iris opens and closes to control the amount of light entering the eye through the pupil. The pupil is the opening in the center of the iris where light enters the eye. When looking at the eye, the pupil appears black.
Retina is most sensitive at 
Fovea centralis is the most sensitive part of retina (in fact most sensitive part of the eye). This is the area of most acute vision. Actually it is a small depression present in mammals (not in frog) at macula lutea or yellow spot.
Function of iris is to 
Iris controls the size of pupil by contracting or relaxing of its circular muscles. It controls the amount of light entering in eye.
Iris is part of 
Iris consists of two layers, outer thickened layer is continuation with choroid and inner simple cuboidal epithelium layer continued from retina.
Afferent nerve fibres carry impulses from 
Afferent nerve fibres – sensory nerve fibres which carry senses from receptors to brain or spinal cord (CNS).
Efferent nerve fibres – motor nerve fibres carry orders or responses from CNS to effectors (muscles and glands).
Third ventricle of brain is also known as 
It is the cavity of diancephelone which is connected ahead with the lateral ventricles or paracoel of cerebral hemisphere by foramen of Monro & behind with the iter (the duct of
midbrain). The ventral wall of diocoel in known as hypothalamus.
One function of parasympathetic nervous system is 
Sympathetic system prepares the body for stress or emergency conditions while parasympathetic system is associated with the period of rest. So when one faces the stress or emergency conditions sympathetic system enlarges the pupil to allow more light in the eye while during rest parasympathetic nervous system constricts the pupil to its normal condition.
Which of the following cranial nerves can regulate heart beat? 
Xth pair of cranial nerves (vagus nerves) has a motor branch called cardiac nerve which innervate cardiac muscles.
Sensitive pigmented layer of eye is 
Retina consists of a pigmented layer and a nervous tissue layer, first there is the photoreceptor layer containing photosensitive cells, the rods and cones, Rod cells are sensitive towards light and are used for vision in dim light, having no ability to detect colour, whereas cones are used for bright light vision with the ability to make coloured images of the object. Next is the intermediate layer containing short sensory bipolar neurons. Bipolar cells inturn synapse with the retinal ganglion cells, whose axons bundle together as the optic nerve.
Acute vision is present in 
Vulture, some other birds and man have acute vision
Vagus nerve is
Vagus nerve is 10th pair of nerves arising from medulla oblongata of brain. These are mixed nerves i.e. having both sensory as well as motor nerve fibres.
Light rays entering the eye is controlled by
Pupil is the opening which controls the amount of light entering in eye. When light intensity is high, it decreases in size and when light intensity is low it dilates to allow more light in the eye to make eye enable to see the object.