question: Why does body shakes at the end of urinating?
comment: That involuntary shiver is called a “Frisson”. It is caused either by the sensation of the drop in temperature as the warm pee leaves your body or by a confusion between signals in the autonomic nervous system (ANS).
passages: Section::::Anatomy and physiology.:Physiology.:Voluntary control.
  
  The mechanism by which voluntary urination is initiated remains unsettled. One possibility is that the voluntary relaxation of the muscles of the pelvic floor causes a sufficient downward tug on the detrusor muscle to initiate its contraction. Another possibility is the excitation or disinhibition of neurons in the pontine micturition center, which causes concurrent contraction of the bladder and relaxation of the sphincter.
   When human and mouse spermatozoa are exposed to a fluid flow, roughly one half of them (i.e., both capacitated and noncapacitated spermatozoa) reorient and swim against the current. The flow, which is prolactin-triggered oviductal fluid secretion, is generated in female mice within 4 h of sexual stimulation and coitus. Thus, rheotaxis orients spermatozoa towards the fertilization site. It was proposed that capacitated spermatozoa might detach from the oviductal surface faster than non-capacitated spermatozoa, enabling them to swim into the main current. To understand the mechanism of sperm turning in rheotaxis, quantitative analysis of human sperm flagellar behavior during rheotaxis turning was carried out. The results revealed, both at the single cell and population levels, that there is no significant difference in flagellar beating between rheotaxis turning spermatozoa and free-swimming spermatozoa. This finding taken together with the constant internal Ca signal, measured during rheotaxis turning, demonstrated that, in contrast to the active process of chemotaxis and thermotaxis, human sperm rheotaxis is a passive process and no flow sensing is involved.
   The 13th coil carries the Laconic inscription:
   The flanking leucine-zipper layers act as a water-tight seal to shield the ionic interactions from the surrounding solvent. Exposure of the "zero ionic layer" to the water solvent by breaking the flanking leucine zipper leads to instability of the SNARE complex and is the putative mechanism by which formula_1-SNAP and NSF recycle the SNARE complexes after the completion of synaptic vesicle exocytosis.
  
  Section::::Mechanism of membrane fusion.
  
  Section::::Mechanism of membrane fusion.:Assembly.
   The psoas lies postero-lateral to the lumbar sympathetic ganglia, and the needle tip will often pass through the psoas major for a lumbar sympathetic block.
  
  Section::::Clinical significance.
  
  Tightness of the psoas can result in spasms or lower back pain by compressing the lumbar discs. A hypertonic and inflamed psoas can lead to irritation and entrapment of the ilioinguinal and the iliohypogastric nerves, resulting in a sensation of heat or water running down the front of the thigh.
   As it functions to innervate the external urethral sphincter it is responsible for the tone of the sphincter mediated via acetylcholine release. This means that during periods of increased acetylcholine release the skeletal muscle in the external urethral sphincter contracts, causing urinary retention. Whereas in periods of decreased acetylcholine release the skeletal muscle in the external urethral sphincter relaxes, allowing voiding of the bladder to occur. (Clarification: Unlike the internal sphincter muscle, the external sphincter is made of skeletal muscle, therefore it is under voluntary control of the somatic nervous system.)
  
  Section::::Clinical significance.
  
  Section::::Clinical significance.:Anesthesia.
   As various drugs and other factors act on the resting potential and bring it closer to the threshold potential, an action potential is more easily and rapidly obtained. Likewise, when the sodium channels are in a state of greater activation, then the influx of sodium ions that allows the membrane to reach threshold potential occurs more readily. In both instances, the excitability of the myocardium is increased.
  
  Section::::Drugs, ions and conditions.
  
  Section::::Drugs, ions and conditions.:Increasing bathmotropy.
   Section::::Function.:Kairomones.
   Section::::Bayliss effect.:Proposed mechanism.:Unstable Membrane Potentials.
  
  Many cells have resting membrane potentials that are unstable. It is usually due to ion channels in the cell membrane that spontaneously open and close (e.g. If channels in cardiac pacemaker cells). When the membrane potential reaches depolarization threshold an action potential (AP) is fired, excitation-contraction coupling initiates and the myocyte contracts.
  
  Section::::Bayliss effect.:Proposed mechanism.:Slow wave potentials.
   Medullary ischemic reflex
  
  The medullary ischemic reflex is a big response to a drop in blood pressure in the brain particularly in the medulla, where the lack of oxygen due to decreased perfusion triggers an autonomic response from the cardiac and vasomotor centers. The cardiac and vasomotor centers respond to the decrease in blood pressure with sympathetic outflow to the heart and blood vessels. This outflow causes increased heart rate and force of contraction, as well as bodywide vasoconstriction. Together these responses increase blood pressure and perfusion rate to the brain, ending the feedback loop.
   Section::::Anatomy and physiology.:Disorders.:Experimentally induced disorders.:Deafferentation.
  
  When the sacral dorsal roots are cut in experimental animals or interrupted by diseases of the dorsal roots such as tabes dorsalis in humans, all reflex contractions of the bladder are abolished. The bladder becomes distended, thin-walled, and hypotonic, but there are some contractions because of the intrinsic response of the smooth muscle to stretch.
  
  Section::::Anatomy and physiology.:Disorders.:Experimentally induced disorders.:Denervation.
   When the mind is agitated due to our interactions with the world at large, the physical body also follows in its wake. These agitations cause violent fluctuations in the flow of prana in the nadis.
  
  Section::::Pranayama.
   Although the cause of the periodicity in flow is not known for certain, the most accepted theory (first postulated in the early 18th century) is that as groundwater flows continuously into a cavern, it fills a narrow tube that leads upwards from near the base of the cavern, then downwards to the spring. As the water level reaches the high point of the tube, it creates a siphon effect, sucking water out of the chamber. Eventually air rushes into the tube and breaks the siphon, stopping the flow if there is no other source feeding the spring, or reducing the flow if there is a continuous flow from another non-siphon source.
   Many neurotoxins directly affect SNARE complexes. Such toxins as the botulinum and tetanus toxins work by targeting the SNARE components. These toxins prevent proper vesicle recycling and result in poor muscle control, spasms, paralysis, and even death.
  
  Section::::Toxins.:Botulinum neurotoxin.
   There are several mechanisms directly linked to the terminal cisternae which facilitate Excitation-Contraction coupling. When Excitation of the membrane arrives at the T-tubule nearest the muscle fiber, a Dihydropyridine (DHP) channel is activated. This is similar to a voltage gated calcium channel, but is not actually an ionotropic channel. Instead, it serves to activate Ryanodine, which will let calcium ions pass into the sarcoplasmic reticulum, and triggers calcium release to the muscle fiber itself.
   The sarcoplasmic reticulum, a specialized type of smooth endoplasmic reticulum, forms a network around each myofibril of the muscle fiber. This network is composed of groupings of two dilated end-sacs called terminal cisternae, and a single transverse tubule, or T tubule, which bores through the cell and emerge on the other side; together these three components form the triads that exist within the network of the sarcoplasmic reticulum, in which each T tubule has two terminal cisternae on each side of it. The sarcoplasmic reticulum serves as reservoir for calcium ions, so when an action potential spreads over the T tubule, it signals the sarcoplasmic reticulum to release calcium ions from the gated membrane channels to stimulate a muscle contraction.
   The B-side on the 7" was "That's What You Get (For Being Polite)".
  
  Section::::Live performances.
   BULLET::::- Phase 1: Sodium channels close; this stops depolarization. Potassium channels open, leading to an outward current of K out of the cells.
  
  BULLET::::- Phase 2: Potassium channels remain open (outward current of K), and calcium channels now also open (inward current of Ca), resulting in a plateau state.
   BULLET::::- Hydrogen ions are formed from the dissociation of carbonic acid. Water is a very minor source of hydrogen ions in comparison to carbonic acid. Carbonic acid is formed from carbon dioxide and water by carbonic anhydrase.
  
  BULLET::::- The bicarbonate ion (HCO) is exchanged for a chloride ion (Cl) on the basal side of the cell and the bicarbonate diffuses into the venous blood, leading to an alkaline tide phenomenon.
  
  BULLET::::- Potassium (K) and chloride (Cl) ions diffuse into the canaliculi.
   Tubular secretion occurs at PCT and DCT; for example, at proximal convoluted tubule, potassium is secreted by means of sodium-potassium pump, hydrogen ion is secreted by means of active transport and co-transport, i.e. antiporter, and ammonia diffuses into renal tubule.
  
  Section::::Other functions.
  
  Section::::Other functions.:Hormone secretion.
   Section::::Acellular casts.:Crystal casts.
  
  Though crystallized urinary solutes, such as oxalates, urates, or sulfonamides, may become enmeshed within a ketanaline cast during its formation, the clinical significance of this occurrence is not felt to be great.
  
  Section::::Cellular casts.
  
  Section::::Cellular casts.:Red blood cell casts.
   Section::::History and further developments.
  
  It was common practice for blacksmiths to hammer peen the concave side of leaf springs, which enhanced their life, although the exact mechanism was unknown. The maximum tensile stresses are located on the surface of the concave portion of leaf springs; the peening effectively offset the maximum tensile stresses, also located on the surface, when the compressive stresses were induced by peening with a ball peen hammer.
   However, in some Southeastern European areas such as Bulgaria and southern Albania, it is used for the opposite purpose, to indicate affirmation, meaning "yes". In those regions, nodding in fact means "no" as well, the complete reverse of most other places in the world.
  
  Section::::Origin.
   Section::::Mechanisms.
  
  Section::::Mechanisms.:Pilus structure.
  
  The type IV pilus complex consists of both the pilus itself and the machinery required for its construction and motor activity. The pilus filament is largely composed of the PilA protein, with more uncommon minor pilins at the tip. These are thought to play a role in initiation of pilus construction. Under normal conditions, the pilin subunits are arranged as a helix with five subunits in each turn, but pili under tension are able to stretch and rearrange their subunits into a second configuration with around subunits per turn.
   Section::::History.
  