Types of visions in animals Monocular or periscopic Laterally placed eyes (frog and reptiles) viewing the object independently due to wide visual angle between optic axis and mid line of the eye. Binocular vision Anterio laterally placed eyes (primates, carnivores, birds), both the eyes view the same object simultaneously, overlap of field of vision due […]

Visual pathway in animals Hyperpolarization of rods and cones alter the activity of bipolar cells. Impulse frequency of ganglion cells too get altered. Horizontal cells influence Bipolar cells, Amacrine cells influence ganglion cells to detect contrast and contour. Axons of ganglion cells project as OPTIC NERVE to the lateral geniculate nucleus of THALAMUS (visual relay

Mechanism of photoreception As the light strikes the photoreceptors, transformation of photo pigment occurs with the resultant HYPERPOLARIZATION of receptor cells. During darkness, the Na+ channel are opened / remain open on rod and cone cell membrane. Na+ leak into rods and lower the membrane potential. As light strikes the rods retinal is released from rhodopsin and

Photo transduction The light falls on the retina by the adjusting the refractive media of the eye. As the light falls on the retina, the rods and cones absorb energy and convert it into electrical signal. The rods and cones are located at the back of the retina synapse with bipolar cells which in turn

Physiological anatomy of eye SCLERA Covering of the eye – Protective in function, Tough in nature. CORNEA (stratified squamous) Transparent Structure, anterior modification of sclera. CHOROID Vascular and Pigmented area of sclera in its posterior part. RETINA Innerside of choroid, has PHOTORECEPTORS. DARK PIGMENT Animal with day light vision, to absorb light which has to

Enteric Nervous System Innervations are from sympathetic and parasympathetic divisions of ANS, which control on intramural plexus (myenteric/auerbach plexus and meissner’s plexus). Intramural plexus made up of 108 neurons which is almost equal to number of neurons in spinal cord. Sympathetic division made of thoracolumbar outflow has got preganglionic cholinergic nerve fibres. They end upon coeliac

Reflex activities of Autonomic Nervous System Autonomic reflexes These reflexes arc, similar to somatic reflex arc have Sensory part Motor part. Visceral sensory fibers enter the dorsal horn of spinal cord, branching into spinal sensory column. They employ interneurons. Interneurons transmit impulses to the preganglionic neurons in the spinal cord or to the brain stem.

Functions of sympathetic and parasympathetic divisions Effector organ Sympathetic Receptor Parasympathetic Heart S A node Increased in heart rate        b1   Decrease in heart rate  Atria Increase contractility and conduction velocity b1 ¯ contractility &­ conduction velocity AV node and Conduction system ­ conduction velocity b1 ¯ conduction velocity Ventricles contractility & conduction velocity b2 — ArteriolesCoronary, skeletal, Pulmonary, renal,

Physiology of Parasympathetic nervous system The parasympathetic nervous system is composed mainly of the cranial and sacral spinal nerves. The preganglionic neurons, arising from either the brain or sacral spinal cord, synapse with just a few postganglionic neurons which are located in or near the effector organ (muscle or gland). The parasympathetic nervous system is responsible for the body’s rest and

Physiology of Sympathetic nervous system Cell bodies of preganlionic sympathetic fibers are located on the intermedia lateral column of thoracic & upper lumbar spinal cord Fibers from these nucleus emerge out through respective spinal nerves from ventral root of the spinal cord. Short fibres of pre ganglionic system synapse with autonomic ganglia. Sympathetic trunk Sympathetic