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[[File:Patellar-knee-reflex.png|thumb|right|400px|Patellar Reflex]]

[[File:Patellar-knee-reflex.png|thumb|right|400px|Patellar Reflex]]

==Introduction==

==Introduction==

A reflex arc represents a mechanism by which a physiological function is automatically managed or regulated. Reflex arcs can be found throughout the body, ranging from [[Muscles_-_Anatomy_%26_Physiology#Skeletal_Muscle|skeletal muscles]] to [[Muscles_-_Anatomy_%26_Physiology#Smooth_Muscle|smooth muscle]] in glands. Reflex arcs are initiated via the excitation or stimulation of specific sensory cells that are directly connected to motor neurons thus enabling [[Spinal_Cord_-_Anatomy_%26_Physiology#Upper_and_Lower_Motor_Neurons|motor nerve]] impulses to be automatically passed on to that particular muscle or gland. Therefore a basic reflex arc consists of sensory cells and their associated nerve fibers, motor nerve fibres and the ultimate muscle or gland. Some reflex arcs can include a coordination centre within the spinal cord or brain prior to stimulation of the motor nerve. Reflex arcs can involve a single or mutliple segments up and down the body, although reflex arcs do not require brain input in order to function. However, the brain can act to modulate reflexes. The brain obtains its afferent information via the [[Macroscopic Anatomy of the CNS#1. Ascending Pathways|ascending sensory tracts]] of the spinal cord. The [[Macroscopic Anatomy of the CNS#2. Descending Pathways|descending tracts]] originate from the brain to allow responses to be modulated. These tracts constitute the white matter of the spinal cord.

A reflex arc represents a mechanism by which a physiological function is automatically managed or regulated. Reflex arcs can be found throughout the body, ranging from [[Muscles_-_Anatomy_%26_Physiology#Skeletal_Muscle|skeletal muscles]] to [[Muscles_-_Anatomy_%26_Physiology#Smooth_Muscle|smooth muscle]] in glands. Reflex arcs are initiated via the excitation or stimulation of specific sensory cells that are directly connected to motor neurons thus enabling [[Spinal_Cord_-_Anatomy_%26_Physiology#Upper_and_Lower_Motor_Neurons|motor nerve]] impulses to be automatically passed on to that particular muscle or gland. Therefore a basic reflex arc consists of sensory cells and their associated nerve fibers, motor nerve fibres and the ultimate muscle or gland. Some reflex arcs can include a coordination centre within the spinal cord or brain prior to stimulation of the motor nerve. Reflex arcs can involve a single or mutliple segments up and down the body, although reflex arcs do not require brain input in order to function. However, the brain can act to modulate reflexes. The brain obtains its afferent information via the ascending sensory tracts of the spinal cord. The descending tracts originate from the brain to allow responses to be modulated. These tracts constitute the white matter of the spinal cord.

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A number of different sensory inputs are utilised by reflex arcs, including; skin receptors, muscle spindles, the retina, the [[Ear_-_Anatomy_%26_Physiology#Inner_Ear|Organ of Corti]] and the olfactory mucosa. These sensory aspects of reflex arcs feed into two main types of reflex systems in the body; '''Autonomic''' reflexes and '''Somatic''' reflexes.  

A number of different sensory inputs are utilised by reflex arcs, including; skin receptors, muscle spindles, the retina, the [[Ear_-_Anatomy_%26_Physiology#Inner_Ear|Organ of Corti]] and the olfactory mucosa. These sensory aspects of reflex arcs feed into two main types of reflex systems in the body; '''Autonomic''' reflexes and '''Somatic''' reflexes.

 

==Autonomic Reflexes==

==Autonomic Reflexes==

Autonomic reflexes control and regulate smooth muscle cells, cardiac muscle cells and glands. In general these reflexes contain the same basic components as somatic reflexes but a key difference is that autonomic reflexes have the ability to both stimulate or inhibit the smooth muscle/gland.

Autonomic reflexes control and regulate smooth muscle cells, cardiac muscle cells and glands. In general these reflexes contain the same basic components as somatic reflexes but a key difference is that autonomic reflexes have the ability to both stimulate or inhibit the smooth muscle/gland.