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Pituitary Pars Intermedia Dysfunction
Pituitary pars intermedia dysfunction (PPID), or equine Cushing's disease, is an endocrine disease affecting the pituitary gland of horses. It is most commonly seen in older animals, and is classically associated with the formation of a long, wavy coat (hirsutism) and chronic laminitis. Pathophysiology Unlike the human and canine forms of Cushing's disease, which most commonly affect the ''pars distalis'' region of the pituitary gland, equine Cushing's disease is a result of hyperplasia or adenoma formation in the pars intermedia. This adenoma then secretes excessive amounts of normal products, leading to clinical signs. Dopaminergic control of the pars intermedia The pituitary gland consists of three parts: the ''pars nervosa'', the ''pars intermedia'', and the ''pars distalis''. The most critical structure to PPID, the ''pars intermedia'', is regulated by the hypothalamus. The neurons of the hypothalamus innervate cells known as melanotropes within the ''pars intermedia'', rele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pituitary Gland
The pituitary gland or hypophysis is an endocrine gland in vertebrates. In humans, the pituitary gland is located at the base of the human brain, brain, protruding off the bottom of the hypothalamus. The pituitary gland and the hypothalamus control much of the body's endocrine system. It is seated in part of the sella turcica a fossa (anatomy), depression in the sphenoid bone, known as the hypophyseal fossa. The human pituitary gland is ovoid, oval shaped, about 1 cm in diameter, in weight on average, and about the size of a kidney bean. Digital version. There are two main lobes of the pituitary, an anterior pituitary, anterior lobe, and a posterior pituitary, posterior lobe joined and separated by a small intermediate lobe. The anterior lobe (adenohypophysis) is the glandular part that produces and secretes several hormones. The posterior lobe (neurohypophysis) secretes neurohypophysial hormones produced in the hypothalamus. Both lobes have different origins and they are both co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrenal Cortex
The adrenal cortex is the outer region and also the largest part of the adrenal gland. It is divided into three separate zones: zona glomerulosa, zona fasciculata and zona reticularis. Each zone is responsible for producing specific hormones. It is also a secondary site of androgen synthesis. Layers The adrenal cortex comprises three main zones, or layers that are regulated by distinct hormones as noted below. This ''anatomic zonation'' can be appreciated at the microscopic level, where each zone can be recognized and distinguished from one another based on structural and anatomic characteristics. Zona glomerulosa The outermost layer, the zona glomerulosa is the main site for the production of aldosterone, a mineralocorticoid. The synthesis and secretion of aldosterone are mainly regulated by the renin–angiotensin–aldosterone system. The zona glomerulosa cells express a specific enzyme aldosterone synthase (also known as CYP11B2). Aldosterone is largely responsible ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dexamethasone Suppression Test
The dexamethasone suppression test (DST) is used to assess adrenal gland function by measuring how cortisol levels change in response to oral doses or an injection of dexamethasone. It is typically used to diagnose Cushing's syndrome. The DST was historically used for diagnosing depression, but by 1988 it was considered to be "at best, severely limited in its clinical ability" for this purpose. Physiology Dexamethasone is an exogenous steroid that provides negative feedback to the pituitary gland to suppress the secretion of adrenocorticotropic hormone (ACTH). Specifically, dexamethasone binds to glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ... receptors in the anterior pituitary gland, which lie outside the blood–brain barrier, resulting in regulatory mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyrotropin Releasing Hormone
Thyrotropin-releasing hormone (TRH) is a hypophysiotropic hormone produced by neurons in the hypothalamus that stimulates the release of thyroid-stimulating hormone (TSH) as well as prolactin from the anterior pituitary. TRH has been used clinically in diagnosis of hyperthyroidism, and for the treatment of spinocerebellar degeneration and disturbance of consciousness in humans. Its pharmaceutical form is called protirelin (INN) (). Physiology Synthesis and release TRH is synthesized within parvocellular neurons of the paraventricular nucleus of the hypothalamus. It is translated as a 242-amino acid precursor polypeptide that contains 6 copies of the sequence -Gln-His-Pro-Gly-, with both ends of the sequence flanked by Lys-Arg or Arg-Arg sequences. To produce the mature form, a series of enzymes are required. First, a protease cleaves to the C-terminal side of the flanking Lys-Arg or Arg-Arg. Second, a carboxypeptidase removes the Lys/Arg residues leaving Gly as the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Equine Metabolic Syndrome
Equine metabolic syndrome (EMS) is an endocrinopathy affecting horses and ponies. It is of primary concern due to its link to obesity, insulin dysregulation, and subsequent laminitis. There are some similarities in clinical signs between EMS and pituitary pars intermedia dysfunction, also known as PPID or Cushing's disease, and some equines may develop both, but they are not the same condition, having different causes and different treatment. Pathogenesis The cells of adipose (fat) tissue synthesize hormones known as adipokines. In humans, dysfunction of adipose tissue, even in cases without obesity, has been associated with the development of insulin resistance, hypertension, systemic inflammation, and increased risk of blood clots (thrombosis). The inflammation produced by these hormones are thought to inflame adipose tissue, leading to the production of more adipokines and perpetuation of the cycle, and a constant low-level, pro-inflammatory state. Although it is suspected th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Narcolepsy
Narcolepsy is a chronic neurological disorder that impairs the ability to regulate sleep–wake cycles, and specifically impacts REM (rapid eye movement) sleep. The symptoms of narcolepsy include excessive daytime sleepiness (EDS), sleep-related hallucinations, sleep paralysis, disturbed nocturnal sleep (DNS), and cataplexy. People with narcolepsy typically have poor quality of sleep. There are two recognized forms of narcolepsy, narcolepsy type 1 and type 2. Narcolepsy type 1 (NT1) can be clinically characterized by symptoms of EDS and cataplexy, and/or will have cerebrospinal fluid (CSF) orexin levels of less than 110 pg/ml. Cataplexy are transient episodes of aberrant tone, most typically loss of tone, that can be associated with strong emotion. In pediatric-onset narcolepsy, active motor phenomena are not uncommon. Cataplexy may be mistaken for syncope, tics, or seizures. Narcolepsy type 2 (NT2) does not have features of cataplexy, and CSF orexin levels are normal. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyphagia
Polyphagia, or hyperphagia, is an abnormally strong, wikt:incessant, incessant sensation of Hunger (physiology), hunger or desire to eat often leading to overeating. In contrast to an increase in appetite following exercise, polyphagia does not subside after eating and often leads to rapid intake of excessive quantities of food. Polyphagia is not a disorder by itself; rather, it is a symptom indicating an underlying medical condition. It is frequently a result of abnormal blood glucose levels (both hyperglycemia and hypoglycemia), and, along with polydipsia and polyuria, it is one of the "3 Ps" commonly associated with uncontrolled diabetes mellitus. Etymology The word ''polyphagia'' () uses classical compound, combining forms of ''wikt:poly-#Prefix, poly-'' + ''wikt:-phagia#Suffix, -phagia'', from the Greek words πολύς (polys), "very much" or "many", and φᾰ́γω (phago), "eating" or "devouring". Underlying conditions and possible causes Polyphagia is one of the most ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anhydrosis
Hypohidrosis is a medical condition in which a person exhibits diminished sweating in response to appropriate stimuli. In contrast with hyperhidrosis, which is a socially troubling yet often benign condition, the consequences of untreated hypohidrosis include hyperthermia, heat stroke and death. An extreme case of hypohidrosis in which there is a complete absence of sweating and the skin is dry is termed anhidrosis. The condition is also known as adiaphoresis, ischidrosis, oligidria, oligohidrosis and sweating deficiency. Causes The causes are the following: Diagnosis Sweat is readily visualized by a topical indicator such as iodinated starch ( Minor test) or sodium alizarin sulphonate, both of which undergo a dramatic colour change when moistened by sweat. A thermoregulatory sweat test can evaluate the body’s response to a thermal stimulus by inducing sweating through a hot box (also called a ''hot room''), a thermal blanket, or physical exercise. Failure of the topical indic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperhidrosis
Hyperhidrosis is a medical condition in which a person exhibits excessive perspiration, sweating, more than is required for the Thermoregulation, regulation of body temperature. Although it is primarily a physical burden, hyperhidrosis can deteriorate the quality of life of the people who are affected, frequently leading to psychological, physical, and social consequences. Hyperhidrosis can lead to difficulties in professional fields, with more than 80% of patients experiencing moderate to severe emotional effects from the disease. This excess of sweat happens even if the person is not engaging in tasks that require muscular effort, and it does not depend on the exposure to heat. Common places to sweat can include underarms, face, neck, back, groin, feet, and hands. It has been called by some researchers 'the silent handicap'. Both ''diaphoresis'' and ''hidrosis'' can mean either ''perspiration'' (in which word sense, sense they are synonymous with ''sweating'') or ''excessive per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polyuria
Polyuria () is excessive or an abnormally large production or Frequent urination, passage of urine (greater than 2.5 L or 3 L over 24 hours in adults). Increased production and passage of urine may also be termed as diuresis. Polyuria often appears in conjunction with polydipsia (increased thirst), though it is possible to have one without the other, and the latter may be a cause or an effect. Primary polydipsia may lead to polyuria. Polyuria is usually viewed as a symptom or Medical sign, sign of another Disease, disorder (not a disease by itself), but it can be classed as a disorder, at least when its underlying causes are not clear. Causes The most common cause of polyuria in both adults and children is uncontrolled diabetes mellitus, which causes osmotic diuresis; when glucose levels are so high that glycosuria, glucose is excreted in the urine. Water follows the glucose concentration passively, leading to abnormally high urine output. In the absence of diabetes mellitus, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polydipsia
Polydipsia is excessive thirst or excess drinking.Porth, C. M. (1990). ''Pathophysiology: Concepts of altered health states''. Philadelphia: J.B. Lippincott Company. The word derives , which is derived . Polydipsia is a nonspecific symptom in various medical disorders. It also occurs as an abnormal behaviour in some non-human animals, such as in birds. Causes Diabetes Polydipsia can be characteristic of diabetes mellitus, often as an initial symptom. It is observed in cases of poorly controlled diabetes, which is sometimes the result of low patient adherence to anti-diabetic medication. Diabetes insipidus ("tasteless" diabetes, as opposed to diabetes mellitus) can also cause polydipsia. Other physiological causes It can also be caused by a change in the osmolality of the extracellular fluids of the body, hypokalemia, decreased blood volume (as occurs during major hemorrhage), and other conditions that create a water deficit. This is usually a result of osmotic diuresis. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laminitis
Laminitis is a disease of the feet of ungulates, found mostly in horses and cattle involving inflammation of the laminae. Clinical signs include foot tenderness progressing to inability to walk, increased digital pulses, and increased temperature in the hooves. Severe cases with outwardly visible clinical signs are known by the colloquial term ''#Rotation, sinking, and founder, founder'', and progression of the disease will lead to perforation of the coffin bone through the sole of the hoof or being unable to stand up, requiring Animal euthanasia, euthanasia. Laminae The bones of the hoof are suspended within the Anatomical terms of location#Other directional terms, axial hooves of ungulates by layers of modified skin cells, known as laminae or lamellae, which suspend the bony column from the hoof wall, contributing to shock absorption during locomotion. In horses, there are about 550–600 pairs of primary epidermis (zoology), epidermal laminae, each with 150–200 secondary la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
