The pancreas is an organ of the digestive system and endocrine system of vertebrates. In humans, it is located in the abdomen behind the stomach and functions as a gland. The pancreas is a mixed or heterocrine gland, i.e., it has both an endocrine and a digestive exocrine function. 99% of the pancreas is exocrine and 1% is endocrine. As an endocrine gland, it functions mostly to regulate blood sugar levels, secreting the hormones insulin, glucagon, somatostatin and pancreatic polypeptide. As a part of the digestive system, it functions as an exocrine gland secreting pancreatic juice into the duodenum through the pancreatic duct. This juice contains bicarbonate, which neutralizes acid entering the duodenum from the stomach; and digestive enzymes, which break down carbohydrates, proteins and fats in food entering the duodenum from the stomach.
Bile, or gall, is a yellow-green fluid produced by the liver of most vertebrates that aids the digestion of lipids in the small intestine. In humans, bile is primarily composed of water, produced continuously by the liver, and stored and concentrated in the gallbladder. After a human eats, this stored bile is discharged into the first section of the small intestine.
Peristalsis is a type of intestinal motility, characterized by radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an anterograde direction. Peristalsis is progression of coordinated contraction of involuntary circular muscles, which is preceded by a simultaneous contraction of the longitudinal muscle and relaxation of the circular muscle in the lining of the gut.
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.
The control of ventilation is the physiological mechanisms involved in the control of breathing, which is the movement of air into and out of the lungs. Ventilation facilitates respiration. Respiration refers to the utilization of oxygen and balancing of carbon dioxide by the body as a whole, or by individual cells in cellular respiration.
The dorsal column–medial lemniscus pathway (DCML) (also known as the posterior column-medial lemniscus pathway is the major sensory pathway of the central nervous system that conveys sensations of fine touch, vibration, two-point discrimination, and proprioception from the skin and joints. It transmits this information to the somatosensory cortex of the postcentral gyrus in the parietal lobe of the brain. The pathway receives information from sensory receptors throughout the body, and carries this in the gracile fasciculus and the cuneate fasciculus, tracts that make up the white matter dorsal columns of the spinal cord. At the level of the medulla oblongata, the fibers of the tracts decussate and are continued in the medial lemniscus, on to the thalamus and relayed from there through the internal capsule and transmitted to the somatosensory cortex. The name dorsal-column medial lemniscus comes from the two structures that carry the sensory information: the dorsal columns of the spinal cord, and the medial lemniscus in the brainstem.
Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function, fluid balance, oxygen delivery, acid–base balance and much more. Electrolyte imbalances can develop by consuming too little or too much electrolyte as well as excreting too little or too much electrolyte. Examples of electrolytes include calcium, chloride, magnesium, phosphate, potassium, and sodium.
The crossed extensor reflex or crossed extensor response or crossed extension reflex is a reflex in which the contralateral limb compensates for loss of support when the ipsilateral limb withdraws from painful stimulus in a withdrawal reflex. During a withdrawal reflex, the flexors in the withdrawing limb contract and the extensors relax, while in the other limb, the opposite occurs as part of the crossed extensor reflex. To provide a more clear explanation, this opposite occurrence means one limb with perform flexion at the hip and knee with the extensors relaxed, while the other limb will perform extension at the hip and knee while flexors are relaxed. Besides shifting the body weight to the other side, the reflex pathway is also associated with leg coordination when walking by flexing muscle on one side, while extending muscle on the other side. This crossed extensor response is properly part of the withdrawal reflex.
The median eminence is generally defined as the portion of the ventral hypothalamus from which the portal vessels arise. The median eminence is a small swelling on the tuber cinereum, posterior to and on top of the pituitary stalk; it lies in the area roughly bounded on its posterolateral region by the cerebral peduncles, and on its anterolateral region by the optic chiasm.
The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease. Decreased blood pressure decreases baroreflex activation and causes heart rate to increase and to restore blood pressure levels. Their function is to sense pressure changes by responding to change in the tension of the arterial wall. The baroreflex can begin to act in less than the duration of a cardiac cycle and thus baroreflex adjustments are key factors in dealing with postural hypotension, the tendency for blood pressure to decrease on standing due to gravity.
In renal physiology, renal blood flow (RBF) is the volume of blood delivered to the kidneys per unit time. In humans, the kidneys together receive roughly 20 - 25% of cardiac output, amounting to 1.2 - 1.3 L/min in a healthy adult. It passes about 94% to the cortex. RBF is closely related to renal plasma flow (RPF), which is the volume of blood plasma delivered to the kidneys per unit time.
Effective renal plasma flow (eRPF) is a measure used in renal physiology to calculate renal plasma flow (RPF) and hence estimate renal function.
In endocrinology, permissiveness is a biochemical phenomenon in which the presence of one hormone is required in order for another hormone to exert its full effects on a target cell. Hormones can interact in permissive, synergistic, or antagonistic ways. The chemical classes of hormones include amines, polypeptides, glycoproteins and steroids. Permissive hormones act as precursors to active hormones and may be classified as either prohormones or prehormones. It stimulate the formation of receptors of that hormone.
The muscles of respiration are the muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. The elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities.
William Francis Ganong Jr. was an American physiologist at the University of California, San Francisco (UCSF), and was one of the first scientists to trace how the brain controls important internal functions of the body.
Cystometry, also known as flow cystometry, is a clinical diagnostic procedure used to evaluate bladder function. Specifically, it measures contractile force of the bladder when voiding. The resulting chart generated from cystometric analysis is known as a cystometrogram (CMG), which plots intravesical pressure against the volume of fluid in the bladder.
The Golgi tendon reflex (also called inverse stretch reflex, autogenic inhibition, tendon reflex) is an inhibitory effect on the muscle resulting from the muscle tension stimulating Golgi tendon organs (GTO) of the muscle, and hence it is self-induced. The reflex arc is a negative feedback mechanism preventing too much tension on the muscle and tendon. When the tension is extreme, the inhibition can be so great it overcomes the excitatory effects on the muscle's alpha motoneurons causing the muscle to suddenly relax. This reflex is also called the inverse myotatic reflex, because it is the inverse of the stretch reflex.
The Golgi tendon organ (GTO) is a proprioceptor – a type of sensory receptor that senses changes in muscle tension. It lies at the interface between a muscle and its tendon known as the musculotendinous junction also known as the myotendinous junction. It provides the sensory component of the Golgi tendon reflex.
Jason X.-J. Yuan is an American physician scientist whose research interests center on pulmonary vascular pathobiology and pulmonary hypertension. His current research is primarily focused on the pathogenic mechanisms of pulmonary vascular diseases and right heart failure.
Kim Elaine Barrett is a research physiologist, specialising in digestive disorders such as inflammatory bowel disease. She was Distinguished Professor of Medicine and Dean of the Graduate Division at University of California, San Diego before moving to her current position as Vice Dean for Research and Distinguished Professor of Physiology and Membrane Biology in the School of Medicine at University of California, Davis in 2021. She is the Editor-in-Chief of The Journal of Physiology, and is a Past-President of the American Physiological Society.
