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75-409: Blinking is a bodily function; it is a semi-autonomic rapid closing of the eyelid . A single blink is determined by the forceful closing of the eyelid or inactivation of the levator palpebrae superioris and the activation of the palpebral portion of the orbicularis oculi , not the full open and close. It is an essential function of the eye that helps spread tears across and remove irritants from

150-484: A brownish green colour that ranges anywhere from dark to light. During mating seasons , the males will also develop brightly coloured spots in order to attract females, which can be red, green or blue. Unlike other fish, the mudskipper's eyes protrude from the top of its flat head. Their most noticeable feature however is their side pectoral fins that are located more forward and under their elongated body. These fins are jointed and function similarly to limbs , which allow

225-413: A computer screen, it can be an indication of computer vision syndrome . Computer vision syndrome can be prevented by taking regular breaks, focusing on objects far from the screen, having a well-lit workplace, or using a blink reminder application. Studies suggest that adults can learn to maintain a healthy blinking rate while reading or looking at a computer screen using biofeedback . Eye blinking can be

300-746: A criterion for diagnosing medical conditions. For example, excessive blinking may help to indicate the onset of Tourette syndrome , strokes or disorders of the nervous system . A reduced rate of blinking is associated with Parkinson's disease . Autonomic nervous system The autonomic nervous system is regulated by integrated reflexes through the brainstem to the spinal cord and organs . Autonomic functions include control of respiration , cardiac regulation (the cardiac control center), vasomotor activity (the vasomotor center ), and certain reflex actions such as coughing , sneezing , swallowing and vomiting . Those are then subdivided into other areas and are also linked to autonomic subsystems and

375-509: A critical role in the formation of enteric ganglia derived from cells known as vagal neural crest. In mice, targeted disruption of the RET gene results in renal agenesis and the absence of enteric ganglia, while in humans, mutations in the RET gene are associated with megacolon. Similarly, Kit, another receptor with tyrosine kinase activity, is implicated in Cajal interstitial cell formation, influencing

450-481: A membrane called the dermal cup rises to cover them. Although other fully aquatic goby species do not have the ability to blink, mudskippers did not evolve different muscles or glands to blink with; their blinking is accomplished with the same muscles in a different configuration. Rather than having specialized glands to produce eye lubricant, the fluid film on their cornea is likely composed of mucus secreted by their skin and water from their environment, possibly stored in

525-485: A physiological response and the other inhibits it. An older simplification of the sympathetic and parasympathetic nervous systems as "excitatory" and "inhibitory" was overturned due to the many exceptions found. A more modern characterization is that the sympathetic nervous system is a "quick response mobilizing system" and the parasympathetic is a "more slowly activated dampening system", but even this has exceptions, such as in sexual arousal and orgasm , wherein both play

600-499: A role. There are inhibitory and excitatory synapses between neurons . A third subsystem of neurons has been named as non-noradrenergic, non-cholinergic transmitters (because they use nitric oxide as a neurotransmitter ) and are integral in autonomic function, in particular in the gut and the lungs . Although the ANS is also known as the visceral nervous system and although most of its fibers carry non-somatic information to

675-593: A seated position. It is important to note that the data supporting increased parasympathetic activity in the supine position was derived from an experiment involving participants between the ages of 25 and 30 who were considered healthy and sedentary. Caffeine may influence autonomic activity differently for individuals who are more active or elderly. Mudskipper Apocryptes Apocryptodon Boleophthalmus Oxuderces Parapocryptes Periophthalmodon Periophthalmus Pseudapocryptes Scartelaos Zappa Mudskippers are any of

750-573: A significant amount more sleep than adults do and, as discussed earlier, fatigued eyes blink more. However, throughout childhood the blink rate increases, and by adolescence, it is usually equivalent to that of adults. There have been mixed results when studying gender-dependent differences in blinking rates, with results varying from the women's rate nearly doubling the men's to no significant difference between them. In addition, women using oral contraceptives blink 32% more often than other women on average for unknown reasons. Generally, between each blink

825-487: A single long, slender process. The rich structural diversity of enteric neurons highlights the complexity and adaptability of the ENS in orchestrating a wide array of gastrointestinal functions, reflecting its status as a dynamic and sophisticated component of the nervous system. The visceral sensory system - technically not a part of the autonomic nervous system - is composed of primary neurons located in cranial sensory ganglia:

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900-519: Is a conscious blink, with the use of all 3 divisions of the orbicularis oculi muscle. Infants do not blink at the same rate of adults; in fact, infants only blink at an average rate of one or two times in a minute. The reason for this difference is unknown, but it is suggested that infants do not require the same amount of eye lubrication that adults do because their eyelid opening is smaller in relation to adults. Additionally, infants do not produce tears during their first month of life. Infants also get

975-432: Is an interval of 2–10 seconds; actual rates vary by individual, averaging around 17 blinks per minute in a laboratory setting. However, when the eyes are focused on an object for an extended period of time, such as when reading, the rate of blinking decreases to about 4 to 5 times per minute. This is the major reason that eyes dry out and become fatigued when reading. When the eyes dry out or become fatigued due to reading on

1050-415: Is associated with increased capillary density in their skin. This mode of breathing, similar to that employed by amphibians , is known as cutaneous respiration . Another important adaptation that aids breathing while out of water is their enlarged gill chambers, where they retain a bubble of air. These chambers close tightly when the fish is above water, due to a ventromedial valve of the gill slit, keeping

1125-408: Is better termed complementary in nature rather than antagonistic. For an analogy, one may think of the sympathetic division as the accelerator and the parasympathetic division as the brake. The sympathetic division typically functions in actions requiring quick responses. The parasympathetic division functions with actions that do not require immediate reaction. The sympathetic system is often considered

1200-462: Is by far the most diverse and widespread genus of mudskipper. Eighteen species have been described . Periophthalmus argentilineatus is one of the most widespread and well-known species. It can be found in mangrove ecosystems and mudflats of East Africa and Madagascar east through the Sundarbans of Bengal , Southeast Asia to Northern Australia , southeast China , Taiwan , and

1275-520: Is common with the rest of the Oxudercinae gobies) with one section inserting on the dorsal rays and the other section inserting on the ventral rays. Mudskippers have the ability to breathe through their skin and the lining of their mouth (the mucosa ) and throat (the pharynx ); this is only possible when the mudskippers are wet, limiting them to humid habitats and requiring that they keep themselves moist. The ability to breathe through their skin

1350-461: Is coordinated with the inferior rectus to pull down the lower lid when one looks down. The correlation between human eyelid blink behavior and psychological stress was also demonstrated by means of a laboratory study. Lying may affect the rate of blinking. Blinking is used for communication in humans, some primates, in human interactions with cats, and by female concave-eared torrent frogs to initiate mating with males. Though one may think that

1425-440: Is critical for regulating the local and systemic immune-inflammatory responses and may influence acute stroke outcomes. Therapeutic approaches modulating the activation of the ANS or the immune-inflammatory response could promote neurologic recovery after stroke. The specialised system of the autonomic nervous system was recognised by Galen . In 1665, Thomas Willis used the terminology, and in 1900, John Newport Langley used

1500-404: Is determined by the "blinking center", but it can also be affected by external stimulus. Some animals, such as tortoises and hamsters , blink their eyes independently of each other. Humans use winking , the blinking of only one eye, as a form of body language . Blinking provides moisture to the eye by irrigation using tears and a lubricant the eyes secrete. The eyelid provides suction across

1575-412: Is likely due to caffeine's ability to increase sympathetic nerve outflow. Furthermore, this study found that recovery after intense exercise was slower when caffeine was consumed prior to exercise. This finding is indicative of caffeine's tendency to inhibit parasympathetic activity in non-habitual consumers. The caffeine-stimulated increase in nerve activity is likely to evoke other physiological effects as

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1650-407: Is possible that other bioactive ingredients in decaffeinated espresso may also contribute to the inhibition of parasympathetic activity in habitual caffeine consumers. Caffeine is capable of increasing work capacity while individuals perform strenuous tasks. In one study, caffeine provoked a greater maximum heart rate while a strenuous task was being performed compared to a placebo . This tendency

1725-601: Is reduced dopamine availability such as Parkinson's disease have reduced eye blink rate, while conditions in which it is raised such as schizophrenia have an increased rate. Blink rate is associated with dopamine-related executive function and creativity. Blinking is present in all major tetrapod crown groups . The soft tissues involved in blinking have not been preserved in the fossil record, but study of mudskippers (a group of amphibious fish species that evolved blinking independently from other tetrapod species, but for similar purposes), suggest that blinking (which involves

1800-518: Is sent through the oculomotor nerve . The duration of a blink is on average 100–150 milliseconds according to UCL researcher and between 100 and 400 ms according to the Harvard Database of Useful Biological Numbers. Closures in excess of 1000 ms were defined as microsleeps . Greater activation of dopaminergic pathways dopamine production in the striatum is associated with a higher rate of spontaneous eye blinking. Conditions in which there

1875-420: Is sometimes classified within the family Gobiidae ( gobies ). Recent molecular studies do not support this classification, as oxudercine gobies appear to be paraphyletic relative to amblyopine gobies (Gobiidae: Amblyopinae ), thus being included in a distinct " Periophthalmus lineage", together with amblyopines. Mudskippers can be defined as oxudercine gobies that are "fully terrestrial for some portion of

1950-624: The Ryukyus , to Samoa and Tonga Islands. It grows to a length of about 9.5 cm and is a carnivorous opportunist feeder. It feeds on small prey such as small crabs and other arthropods . However, a recent molecular study suggests that P. argentilineatus is in fact a complex of species, with at least three separate lineages, one in East Africa, and two in the Indo-Malayan region. Another species, Periophthalmus barbarus ,

2025-510: The brainstem (cranial nerves III, VII, IX, X) or the sacral spinal cord (S2, S3, S4). These are the preganglionic neurons, which synapse with postganglionic neurons in these locations: these ganglia provide the postganglionic neurons from which innervations of target organs follows. Examples are: Development of the Enteric Nervous System: The intricate process of enteric nervous system (ENS) development begins with

2100-438: The cornea or objects that appear rapidly in front of the eye. A reflex blink is not necessarily a conscious blink either; however it does happen faster than a spontaneous blink. Reflex blink may occur in response to tactile stimuli (e.g., corneal , eyelash , skin of eyelid , contact with eyebrow ), optical stimuli (e.g. dazzle reflex , or menace reflex ) or auditory stimuli (e.g., menace reflex ). A voluntary blink

2175-457: The geniculate , petrosal and nodose ganglia , appended respectively to cranial nerves VII, IX and X. These sensory neurons monitor the levels of carbon dioxide , oxygen and sugar in the blood, arterial pressure and the chemical composition of the stomach and gut content. They also convey the sense of taste and smell, which, unlike most functions of the ANS, is a conscious perception. Blood oxygen and carbon dioxide are in fact directly sensed by

2250-400: The peripheral nervous system . The hypothalamus , just above the brain stem , acts as an integrator for autonomic functions, receiving autonomic regulatory input from the limbic system . Although conflicting reports about its subdivisions exist in the literature, the autonomic nervous system has historically been considered a purely motor system, and has been divided into three branches:

2325-428: The spinal cord in the thoracic and lumbar areas, terminating around L2-3. The parasympathetic division has craniosacral "outflow", meaning that the neurons begin at the cranial nerves (specifically the oculomotor nerve , facial nerve , glossopharyngeal nerve and vagus nerve ) and sacral (S2-S4) spinal cord. The autonomic nervous system is unique in that it requires a sequential two-neuron efferent pathway;

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2400-473: The sympathetic nervous system , the parasympathetic nervous system , and the enteric nervous system . Some textbooks do not include the enteric nervous system as part of this system. The sympathetic nervous system is often considered the " fight or flight " system, while the parasympathetic nervous system is often considered the "rest and digest" or "feed and breed" system. In many cases, both of these systems have "opposite" actions where one system activates

2475-409: The " fight or flight " system, while the parasympathetic system is often considered the "rest and digest" or "feed and breed" system. However, many instances of sympathetic and parasympathetic activity cannot be ascribed to "fight" or "rest" situations. For example, standing up from a reclining or sitting position would entail an unsustainable drop in blood pressure if not for a compensatory increase in

2550-401: The 23 extant species of amphibious fish from the subfamily Oxudercinae of the goby family Oxudercidae . They are known for their unusual body shapes, preferences for semiaquatic habitats, limited terrestrial locomotion and jumping , and the ability to survive prolonged periods of time both in and out of water. Mudskippers can grow up to 30 cm (12 in) long, and most are

2625-479: The CNS, many authors still consider it only connected with the motor side. Most autonomous functions are involuntary but they can often work in conjunction with the somatic nervous system which provides voluntary control. The autonomic nervous system has been classically divided into the sympathetic nervous system and parasympathetic nervous system only (i.e., exclusively motor). The sympathetic division emerges from

2700-403: The ENS earned recognition for its autonomy in the early 1900s. Boasting approximately 100 million neurons, a quantity comparable to the spinal cord, the ENS is often described as a "brain of its own." This description is rooted in the ENS's ability to communicate independently with the central nervous system through parasympathetic and sympathetic neurons. At the core of this intricate structure are

2775-468: The Human Body". Its functions include: At the effector organs, sympathetic ganglionic neurons release noradrenaline (norepinephrine), along with other cotransmitters such as ATP , to act on adrenergic receptors , with the exception of the sweat glands and the adrenal medulla: A full table is found at Table of neurotransmitter actions in the ANS . Recent studies indicate that ANS activation

2850-426: The area postrema, that detects toxins in the blood and the cerebrospinal fluid and is essential for chemically induced vomiting or conditional taste aversion (the memory that ensures that an animal that has been poisoned by a food never touches it again). All this visceral sensory information constantly and unconsciously modulates the activity of the motor neurons of the ANS. Autonomic nerves travel to organs throughout

2925-484: The arterial sympathetic tonus. Another example is the constant, second-to-second, modulation of heart rate by sympathetic and parasympathetic influences, as a function of the respiratory cycles. In general, these two systems should be seen as permanently modulating vital functions, in a usually antagonistic fashion, to achieve homeostasis . Higher organisms maintain their integrity via homeostasis which relies on negative feedback regulation which, in turn, typically depends on

3000-439: The autonomic nervous system. Some typical actions of the sympathetic and parasympathetic nervous systems are listed below. Promotes a fight-or-flight response , corresponds with arousal and energy generation, and inhibits digestion The pattern of innervation of the sweat gland —namely, the postganglionic sympathetic nerve fibers—allows clinicians and researchers to use sudomotor function testing to assess dysfunction of

3075-524: The autonomic nervous systems, through electrochemical skin conductance . The parasympathetic nervous system has been said to promote a "rest and digest" response, promotes calming of the nerves return to regular function, and enhancing digestion. Functions of nerves within the parasympathetic nervous system include: The enteric nervous system is the intrinsic nervous system of the gastrointestinal system . It has been described as "the Second Brain of

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3150-542: The body attempts to maintain homeostasis . The effects of caffeine on parasympathetic activity may vary depending on the position of the individual when autonomic responses are measured. One study found that the seated position inhibited autonomic activity after caffeine consumption (75 mg); however, parasympathetic activity increased in the supine position. This finding may explain why some habitual caffeine consumers (75 mg or less) do not experience short-term effects of caffeine if their routine requires many hours in

3225-399: The body wall. This unusual morphology creates a pectoral fin with two fin segments (the radials and the rays) and two movable hinge joints: a 'shoulder' joint where the cleithrum meets the radials and an 'intra-fin' joint where the radials meet the rays. In addition, ... the abductor superficialis muscle of the pectoral fin is divided into two sections (rather than being a single muscle, as

3300-450: The body. Most organs receive parasympathetic supply by the vagus nerve and sympathetic supply by splanchnic nerves . The sensory part of the latter reaches the spinal column at certain spinal segments . Pain in any internal organ is perceived as referred pain , more specifically as pain from the dermatome corresponding to the spinal segment. Motor neurons of the autonomic nervous system are found in "autonomic ganglia". Those of

3375-415: The carotid body, a small collection of chemosensors at the bifurcation of the carotid artery, innervated by the petrosal (IXth) ganglion. Primary sensory neurons project (synapse) onto "second order" visceral sensory neurons located in the medulla oblongata, forming the nucleus of the solitary tract (nTS), that integrates all visceral information. The nTS also receives input from a nearby chemosensory center,

3450-552: The daily cycle" (character 24 in Murdy, 1989 ). This would define the species of the genera Boleophthalmus , Periophthalmodon , Periophthalmus , and Scartelaos as "mudskippers". However, field observations of Zappa confluentus suggest that this monotypic genus should be included in the definition. Mudskippers typically live in burrows in intertidal habitats , and exhibit unique adaptations to this environment that are not found in most intertidal fishes , which typically survive

3525-443: The eye at faster and more dangerous speeds in air than in water. Additionally, when at their fully aquatic juvenile stage of development, their eyes are not in the positioning with which they blink, but as adults, their eyes elevate to a position that can blink, which they do when they are not submerged or bump into a surface, suggesting blinking emerged as an adaptation to terrestrial life as opposed to aquatic life. Early tetrapods in

3600-440: The eye from the tear duct to the entire eyeball to keep it from drying out. Blinking also protects the eye from irritants. Eyelashes are hairs which grow from the edges of the upper and lower eyelids that create a line of defense against dust and other elements to the eye. The eyelashes catch most of these irritants before they reach the eyeball. There are multiple muscles that control reflexes of blinking. The main muscles, in

3675-415: The eye retracting in mudskippers) may have arose in response to selective pressures upon species shifting from aquatic to terrestrial habitats. For example, compared to an aquatic environment, in a terrestrial environment, the corneal cells must be kept moist such that vital substances like oxygen can more easily diffuse into them, detritus may adhere to the eye in dry conditions, and objects may move towards

3750-441: The gills moist, and allowing them to function while exposed to air. Gill filaments are stiff and do not coalesce when out of water. The different species have adapted to various diets on the mudflats. Boleophthalmus boddarti is detritivorous , while others will eat small crabs, insects, snails and even other mudskippers. Digging deep burrows in soft sediments allows the fish to thermoregulate , avoid marine predators during

3825-435: The high tide when the fish and burrow are submerged, and lay their eggs. When the burrow is submerged, several mudskipper species maintain an air pocket inside it, which allows them to breathe in conditions of very low oxygen concentration. To reduce toxic ammonia production, mudskippers can suppress amino acid breakdown when exposed to air. Another method they use involves the partial breakdown of amino acids leading to

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3900-555: The infraorbital space behind the dermal cup membrane. Mudskippers likely evolved blinking in response to conditions of terrestrial life, such as to keep their eyes wet out of water (they blink more frequently in high evaporation conditions and only when colliding with things in water) and to clean and protect the eye from debris, which may adhere to the eye or approach at a faster, more dangerous speed when in air versus when in water. Their eyes are not elevated when they are still juveniles, which are fully aquatic. The genus Periophthalmus

3975-482: The intestine, adding another layer of sophistication to the functional dynamics of the ENS. The varied morphological shapes of enteric neurons further contribute to the structural diversity of the ENS, with neurons capable of exhibiting up to eight different morphologies. These neurons are primarily categorized into type I and type II, where type II neurons are multipolar with numerous long, smooth processes, and type I neurons feature numerous club-shaped processes along with

4050-605: The lining of their mouth and throat, allowing them to stay out of water for long periods of time. It has been discovered that they spend up to three quarters of their life on land. They are found in tropical , subtropical , and temperate regions, including the Indo - Pacific and the Atlantic coast of Africa. Compared with fully aquatic gobies, these specialised fish present a range of anatomical and ethological adaptations that allow them to move effectively on land as well as in

4125-424: The male has completed digging his burrow he will resurface and will begin attempting to attract a female through assorted yet typical displays. These displays consist of body undulations, different postures and energetic movements. Once the female has made her choice she will then proceed to follow the male into the burrow where she will lay hundreds of eggs and allow them to be fertilized. After fertilization occurs,

4200-478: The migration of cells from the vagal section of the neural crest. These cells embark on a journey from the cranial region to populate the entire gastrointestinal tract. Concurrently, the sacral section of the neural crest provides an additional layer of complexity by contributing input to the hindgut ganglia. Throughout this developmental journey, numerous receptors exhibiting tyrosine kinase activity, such as Ret and Kit, play indispensable roles. Ret, for instance, plays

4275-435: The mudskipper to crawl from place to place. Although having the typical body form of any other gobiid fish, these front fins allow the mudskipper to actively "skip" across muddy surfaces (hence the common name ) and even climb low-hanging tree branches and scrubs . Mudskippers have also been found to be able to leap distances of up to 61 centimetres (24 in) by laterally flexing and pushing with their tails. Oxudercinae

4350-452: The myenteric plexus (Auerbach's) and the submucous plexus (Meissner's), two main plexuses formed by the grouping of nerve-cell bodies into tiny ganglia connected by bundles of nerve processes. The myenteric plexus extends the full length of the gut, situated between the circular and longitudinal muscle layers. Beyond its primary motor and secretomotor functions, the myenteric plexus exhibits projections to submucosal ganglia and enteric ganglia in

4425-473: The overall complexity of the ENS structure. In this intricate landscape, glial cells emerge as key players, outnumbering enteric neurons and covering the majority of the surface of enteric neuronal-cell bodies with laminar extensions. Resembling the astrocytes of the central nervous system, enteric glial cells respond to cytokines by expressing MHC class II antigens and generating interleukins. This underlines their pivotal role in modulating inflammatory responses in

4500-438: The pancreas and gallbladder, showcasing the interconnectivity within the ENS. Additionally, the myenteric plexus plays a unique role in innervating motor end plates with the inhibitory neurotransmitter nitric oxide in the striated-muscle segment of the esophagus, a feature exclusive to this organ. Meanwhile, the submucous plexus, most developed in the small intestine, occupies a crucial position in secretory regulation. Positioned in

4575-418: The parasympathetic branch are located close to the target organ whilst the ganglia of the sympathetic branch are located close to the spinal cord. The sympathetic ganglia here, are found in two chains: the pre-vertebral and pre-aortic chains. The activity of autonomic ganglionic neurons is modulated by "preganglionic neurons" located in the central nervous system. Preganglionic sympathetic neurons are located in

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4650-432: The period of cohabitation between the male and female is rather short. Eventually, the female will leave and it is the male that ends up guarding the egg filled burrow from hungry predators. Mudskippers are amphibious. When leaving the water and moving into a more dry environment on land, they are still able to breathe using water that is trapped inside their large gill chambers. They are also able to absorb oxygen from

4725-493: The preganglionic neuron must first synapse onto a postganglionic neuron before innervating the target organ. The preganglionic, or first, neuron will begin at the "outflow" and will synapse at the postganglionic, or second, neuron's cell body. The postganglionic neuron will then synapse at the target organ. The sympathetic nervous system consists of cells with bodies in the lateral grey column from T1 to L2/3. These cell bodies are "GVE" (general visceral efferent) neurons and are

4800-480: The preganglionic neurons. There are several locations upon which preganglionic neurons can synapse for their postganglionic neurons: These ganglia provide the postganglionic neurons from which innervation of target organs follows. Examples of splanchnic (visceral) nerves are: These all contain afferent (sensory) nerves as well, known as GVA (general visceral afferent) neurons . The parasympathetic nervous system consists of cells with bodies in one of two locations:

4875-422: The production of alanine, which also reduces ammonia production. Mudskippers can reduce the membrane permeability of their skin and acidify the water in their burrows to reduce levels of ammonia from the environment. Mudskippers evolved the ability to blink independently from terrestrial tetrapods . Their eyes are located high on their head compared to other gobies, and they blink by lowering their eyes as

4950-556: The retreat of the tide by hiding under wet seaweed or in tide pools . These burrows are most often characterised by their smooth and vaulted ceilings. The way the males dig these burrows has been found to be directly linked to their ability to survive submerged in almost anoxic water. It has also been found to play a crucial role in the development of the eggs within the burrow. Mudskippers are quite active when out of water, feeding and interacting with one another, for example, to defend their territories and court potential partners. Once

5025-417: The spinal cord, at the thorax and upper lumbar levels. Preganglionic parasympathetic neurons are found in the medulla oblongata where they form visceral motor nuclei; the dorsal motor nucleus of the vagus nerve; the nucleus ambiguus, the salivatory nuclei , and in the sacral region of the spinal cord. Sympathetic and parasympathetic divisions typically function in opposition to each other. But this opposition

5100-475: The spontaneous, rhythmic, electrical excitatory activity known as slow waves in the gastrointestinal tract. Understanding the molecular intricacies of these receptors provides crucial insights into the delicate orchestration of ENS development. Structure of the Enteric Nervous System: The structural complexity of the enteric nervous system (ENS) is a fascinating aspect of its functional significance. Originally perceived as postganglionic parasympathetic neurons,

5175-441: The stimulus triggering blinking is dry or irritated eyes, it is most likely that it is controlled by a "blinking center" of the globus pallidus of the lenticular nucleus —a body of nerve cells between the base and outer surface of the brain. Nevertheless, external stimuli can contribute. The orbicularis oculi is a facial muscle; therefore its actions are translated by the facial nerve root. The levator palpebrae superioris' action

5250-408: The submucosa between the circular muscle layer and the muscularis mucosa, the submucous plexus's neurons innervate intestinal endocrine cells, submucosal blood arteries, and the muscularis mucosa, emphasizing its multifaceted role in gastrointestinal function. Furthermore, ganglionated plexuses in the pancreatic, cystic duct, common bile duct, and gallbladder, resembling submucous plexuses, contribute to

5325-491: The surface of the cornea and conjunctiva . Blinking may have other functions since it occurs more often than necessary just to keep the eye lubricated. Researchers think blinking may help with disengagement of attention; following blink onset, cortical activity decreases in the dorsal network and increases in the default-mode network, associated with internal processing. Blink speed can be affected by elements such as fatigue, eye injury, medication, and disease. The blinking rate

5400-597: The term, defining the two divisions as the sympathetic and parasympathetic nervous systems. Caffeine is a bioactive ingredient found in commonly consumed beverages such as coffee, tea, and sodas. Short-term physiological effects of caffeine include increased blood pressure and sympathetic nerve outflow. Habitual consumption of caffeine may inhibit physiological short-term effects. Consumption of caffeinated espresso increases parasympathetic activity in habitual caffeine consumers; however, decaffeinated espresso inhibits parasympathetic activity in habitual caffeine consumers. It

5475-561: The transition to land, which would later yield all non-mudskipper blinking species, possessed similar characteristics regarding eye positioning that suggest blinking arose in response to aerial vision and terrestrial lifestyle. There are three types of blinking. Spontaneous blinking is done without external stimuli and internal effort. This type of blinking is conducted in the pre-motor brain stem and happens without conscious effort, like breathing and digestion . A reflex blink occurs in response to an external stimulus, such as contact with

5550-566: The upper eyelid, that control the opening and closing are the orbicularis oculi and levator palpebrae superioris muscle . The orbicularis oculi closes the eye, while the contraction of the levator palpebrae muscle opens the eye. The Müller's muscle, or the superior tarsal muscle , in the upper eyelid and the inferior palpebral muscle in the lower 3 eyelid are responsible for widening the eyes. These muscles are not only imperative in blinking, but they are also important in many other functions such as squinting and winking. The inferior palpebral muscle

5625-420: The water. As their name implies, these fish use their fins to move around in a series of skips. Although mudskippers' fins do not have a joint homologous to the elbow, the joint between the radials and the fin rays serves a functionally analogous role. The mudskipper pectoral fin differs from most actinopterygian fishes in that the radials of the mudskipper pectoral fin are elongated and protrude from

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