Importance of equatorial region Action potential are generated from this equatorial region by stretching. Muscle spindle receptors lie parallel to the extra fusal fibers. Functionally these receptors are connected to the origin and insertion of the tendon i.e. lengthening of the whole muscle will stretch the equatorial region. Contraction of polar ends also generate action […]
Myotatic reflex or Knee jerk reflex Myotatic reflex is a sudden stretch of a muscle causes its reflex contraction. Commonly known as “KNEE-JERK” reflex. It forms the basis of the maintanence of “Muscletone” Receptor organ concerned with this reflex is Muscle –spindle organ. These receptors are encapsulated in the belly of skeletal muscle. CNS receives sensation from these
Nystagmus Nystagmus is the movement of the eye in relation to the movement in the head of the animal. It consists of rhythmic movements of the eyes in a dorsoventral, lateromedial, or oblique directions. It is characterized by the slow movement of the eye in one direction and then quick return to its original starting
Physiology of Vestibular apparatus The vestibular apparatus located in internal ear that detects sensation related to equilibrium (linear acceleration of head). Popularly known as OTOLITHIC organ. It consist of bony labyrinth (semicircular canal with utricule and saccule) and membranous labryinth. This is the functional part of the vestibular apparatus and is composed of cochlear duct,
Postural Reflexes Postural Reflexes is also known as postural reactions. It is defined as the position or arrangement of the body and its limbs. It is controlled by the activity of the skeletal muscles of the neck and limbs. Control of posture involves mechanisms that alter the excitable activity of α-motor neurons of the spinal
Properties of polysynaptic arcs Series synaptic reflex arcs Several simple reflex arcs are united in series to give a chain of reflex arcs, e.g. flexor and extensor responses related to muscle tone. Convergent effector reflex arcs Two or more afferent neurons are in synaptic relation with only one efferent neuron. Hence, stimulation of many receptors
Properties of reflex arc One way conduction (Bell and Magendie law) The dorsal root fibres of the spinal cord are afferent (sensory), while the ventral root fibres are efferent (motor). The sensory impulses are centripetal (towards the CNS) and motor impulses are centrifugal (away from the CNS). Slow speed of conduction Slow build up of EPSP
Classification of reflex arc Components of reflex arc The neural circuit for reflex is referred to as reflex arc. Five components commonly make up a reflex arc. They are the receptor organ, sensory (afferent) neurons, interneurons in spinal cord or brain, motor neurons (efferent) and an effector organ (muscle or glands). Classification of reflex arcs
Reflexes A reflex is a specific, stereotyped, involuntary response to peripheral stimulation. The spinal cord is a reflex neural system and its activity is modified by influences transmitted from the brain via descending fiber system. The regulating system of the brain are informed of the reflex activity initiated within the spinal cord and is able
Spinal animal and Thalamic animal Spinal animal Spinal animal is prepared either transecting at the spinomedullary junction or by ligating both carotid arteries and the mid-vertebral artery to arrest the brain activities. Frog’s head behind the tympanic membrane is transected to separate spinal cord from the brain. Transection is to be done below the foramen magnum.
