Submucosal

FIGURE 5.18 Vasculature structure along a portion of bronchia muscle. Airway epithelia are not shown in this figure but lie between the submucosal venules and the airway lumen. Modified from Deffe-bach et al. ... 

Airway surfaces, like skin, are continually exposed to the ambient environment. In contrast to skin submucosal vessels, however, w hich shed excess heat by vasodilating when heated and conserve heat by vasoconstricting when chilled, it is unclear how the airway vasculature responds to temperature extremes. Inspiring cold air poses two challenges to conducting airway tissues the risk of tissue injury should inadequate heat reach the airway surface and excessive body heat loss due to increasing the radial temperature gradient. Vasodilation would protect airway tissue but increase heat loss, while vasoconstriction would produce the opposite effect. 

Nasal vasculature may offer some insight into this question, though research to date has been equivocal. Nasal turbinate vessels can be classified as either capacitance vessels or resistive vessels. Capacitance vessels appear to vasodilate in response to infection while resistance vessels appear to respond to cold stimuli by vasoconstriction. Buccal vascular structures also respond to thermal stimuli but appear to respond principally to cutaneous stimuli. How pharyngeal and tracheobronchial submucosal vessels react to thermal stimuli is not known, though cold-induced asthma is believed to result from broncho-spasms caused by susceptible bronchial smooth muscle responding to exposure to cold dry air.- This asthmatic response suggests an inadequate vascular response to surface cooling. 

Airway surface liquid (ASL) A mixture of periciliary fluid and submucosal... 

The pattern of inflammation in UC is continuous and confluent throughout the affected areas of the GI tract. The inflammation is also superficial and does not typically extend below the submucosal layer of the GI tract (Fig. 16-2). Ulceration or erosion of the GI mucosa may be present and varies with disease severity. The formation of crypt abscesses within the mucosal layers of the GI tract is characteristic of UC and may help to distinguish it from CD. Severe inflammation may also result in areas of hypertrophied GI mucosa, which may manifest as pseudopolyps within the colon.12 The inflammatory response may progress in severity, leading to mucosal friability and significant GI bleeding. 

Zhao X, Deak E, Soderberg K, et al. Vaginal submucosal dendritic cells, but not Langerhans cells, induce protective Thl responses to herpes simplex virus-2. J Exp Med 2003 197(2) 153-162. 

The plicae circulares, or circular folds, form internal rings around the circumference of the small intestine that are found along the length of the small intestine. They are formed from inward foldings of the mucosal and submucosal layers of the intestinal wall. The plicae circulares are particularly well developed in the duodenum and jejunum and increase the absorptive surface area of the mucosa about threefold. Each plica is covered with millions of smaller projections of mucosa referred to as villi. Two types of epithelial cells cover the villi ... 

HIV is present in peripheral blood mononuclear cells, the major source of transmitted virus. Titers, however, are quite low, about 10,000 infectious doses per ml of blood, so that the blood is less infectious than in hepatitis B virus infections. The amount present tends to fall after seroconversion and rises again during development of AIDS-related complex and AIDS. Smaller amounts of virus are also present in semen and saliva, and probably even smaller amounts in colostrum, the human cervix, and tears. Infection is reported in CD4 positive submucosal cells in the rectum and large bowel and could be a route of entry in homosexuals. 

Figure 7.2 Mucosal-to-submucosal (m-s) Tapp values of atenolol and caffeine obtained in freshly isolated porcine buccal mucosa from ten animals (average SEM).

Figure 7.5 Mucosal-to-submucosal (m-s), Tapp values across human buccal culture of midazolam (CYP3A4 substrate), bufuralol (CYP2D6 substrate), tolbutamide (CYP2C9 substrate), and the nonmetabolized, high-permeability control compound caffeine (average SEM, N = 1 — 3 replicates). (Asterisk) in the presence of CYP inhibitors (CYP3A4-ketoconazole CYP2D6-quinidine CYP2C9-suphaphenazole). In all treatments integrity of the culture was verified by permeation of Lucifer yellow (< 2.0 x 10-6 cm/s). Results from internal study by Absorption Systems Company.

Chronic inflammatory response is one of the hallmarks of allergic diseases. Over the course of pollen season, there might be even a tenfold increase in numbers of nasal epithelial submucosal mast cells. Histamine released from these cells might not only induce acute allergic symptoms but also be crucial for sustaining this response into a chronic phase, as increasing evidence suggests that it influences several immune/inftammatory and effector functions (table 2) [2]. 

The cholinoceptor antagonist pi-renzepine, unlike atropine, prefers cho-linoceptors of the Mi type, does not penetrate into the OIS, and thus produces fewer atropine-like side effects (p. 104). The cholinoceptors on parietal cells probably belong to the M3 subtype. Hence, pirenzepine may act by blocking Ml receptors on ECL cells or submucosal neurons. 

Rats treated with 200 mg/kg/day by gavage for 4, 5, or 6 weeks showed early treatment-related changes in the lungs (significant increases in serum angiotensin) and possible preneoplastic changes in the forestomach, characterized by epithelial hyperplasia, hyperkeratosis, subepithelial and submucosal inflammation, and edema. ... 

Other adverse reactions include nausea diarrhea pyrexia dermatitis exfoliative dermatitis urticaria alopecia sore mouth mouth ulcers fever abdominal cramping leukopenia red-orange urine priapism (causal relationship not established) paralytic ileus and intestinal obstruction from submucosal or intramural hemorrhage. 

The innervation of the gastrointestinal tract is complex. The myenteric and submucosal plexuses contain many interneurons. These possess a number of neurotransmitters and neuromodulators, including several peptides, such as enkephalins, substance P, and vasoactive intestinal peptide. Reflex activity within the plexuses regulates peristalsis and secretion locally. The effects of sympathetic and parasympathetic nerve stimulation are superimposed on this local neural regulation. 

The myenteric and submucosal plexuses contain ganglion cells giving rise to excitatory cholinergic fibers that directly innervate the smooth muscle and gland... 

Both the parasympathetic and sympathetic nervous systems provide extrinsic gastrointestinal innervation. Parasympathetic stimulation increases muscle contraction of the gut, while sympathetic stimulation inhibits contractions. Stimulation of either a- or 13-adrenoceptors will result in inhibition of contractions. The intramural nervous system consists of a myenteric (Auerbach s) plexus between the circular and longitudinal muscle areas and a submucosal (Meissner s) plexus between the muscularis mucosa and the circular muscle layers. These two plexuses contain stimulatory cholinergic neurons. 

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