Bronchiole smooth muscle

Nicotinic Muscarinic Autonomic ganglia All parasympathetic effector cells Visceral and bronchiole smooth muscle Cardiac muscle Exocrine glands (salivary, intestinal, lacrimal] Sweat glands Mediate transmission to postganglionic neuron Contraction (generally] Decreased heart rate Increased secretion Increased secretion... 

Beta-2 Bronchiole smooth muscle Some arterioles (skeletal muscle, liver] Gastrointestinal smooth muscle Skeletal muscle and liver cells Uterus Gallbladder Relaxation (bronchodilation] Vasodilation Decreased motility Increased cellular metabolism Relaxation Relaxation... 

Beta-2 Receptors. Beta-2 receptors are found primarily on the smooth muscle of certain vasculatures, the bronchioles, the gallbladder, and the uterus.9 Their presence in bronchiole smooth muscle is especially important in the pharmacologic management of respiratory conditions such as asthma (see Chapter 26). These receptors are also responsible for mediating changes in the metabolism of skeletal muscle and liver cells. Beta-2 receptors are also located on the heart, although the predominant effects on cardiac tissue seem to be mediated through the beta-1 subtype. 

When nonselective beta blockers are used, some antagonism of beta-2 receptors also occurs.2,31 The antagonism of beta-2 receptors on bronchiole smooth muscle often leads to some degree of bronchoconstric-tion and an increase in airway resistance. Although this event is usually not a problem in individuals with normal pulmonary function, patients with respiratory problems such as asthma, bronchitis, and emphysema may be adversely affected by nonselective beta antagonists. In these patients, one of the beta-1-selective drugs should be administered. 

Respiratory smooth-muscle cells contain the beta-2 subtype of adrenergic receptors.76 (See Chapter 18 for a discussion of adrenergic receptor classifications.) Stimulation of these beta-2 receptors results in relaxation of bronchiole smooth muscle. Lienee, drugs that stimulate these beta-2 adrenergic receptors (i.e., beta-adrenergic agonists) produce bronchodilation and can be used to prevent or inhibit airway obstruction in bronchospastic diseases.22,99... 

Sinoatrial node Atrial contractility Bronchiole smooth muscle Gastrointestinal tract Smooth muscle Secretions Sphincters... 

It is a powerful antagonist of histamine, antagonizing its effect on smooth muscle of the bronchioles, bladder and partially the intestines and preventing the dilation of capillaries. Promethazine is used in the treatment of allergic reactions. 

P-Adrenoceptors have been subdivided into P - and P2-adrenoceptors. A third subset called nontypical P-adrenoceptors or P -adrenoceptors have been described but are stiU the subject of debate. In terms of the interactions with various subsets of P-adrenoceptors, some antagonists are nonselective in that they antagonize the effects of activation of both P - and P2-adrenoceptors, whereas others are selective for either P - or P2-adrenoceptors. P - and P2-adrenoceptors coexist in almost all organs but generally, one type predominates. The focus herein is on the clinically relevant P -adrenoceptor-mediated effects on heart and on P2-adrenoceptor-mediated effects on smooth muscles of blood vessels and bronchioles, the insulin-secreting tissue of the pancreas, and skeletal muscle glycogenolysis for side effects profile (36). 

Bronchial smooth muscle tone. Changes in bronchial smooth muscle tone are particularly important in the bronchioles compared to the bronchi. Recall that the walls of the bronchioles consist almost entirely of smooth muscle. Contraction and relaxation of this muscle has a marked effect on the internal radius of the airway. An increase in bronchial smooth muscle tone, or bron-choconstriction, narrows the lumen of the airway and increases resistance to... 

Pharmacology These agents are used to produce bronchodilation. They relieve reversible bronchospasm by relaxing the smooth muscles of the bronchioles in conditions associated with asthma, bronchitis, emphysema, or bronchiectasis. Bronchodilation may additionally facilitate expectoration. 

Although anticholinesterase agents can be used in the treatment of atony of the bladder and adynamic ileus, they are contraindicated in cases of mechanical obstruction of the intestine or urinary tract. Caution should also be used in giving these drugs to a patient with bronchial asthma or other respiratory disorders, since they will further constrict the smooth muscle of the bronchioles and stimulate respiratory secretions. 

In the lungs, NO affects not only blood vessels but also the bronchi and bronchioles as well. In newborns with defective gas exchange, NO inhalation decreases pulmonary arterial blood pressure, enabling more blood to be oxygenated. In adults with obstructive lung diseases, NO inhalation seems to relax airway smooth muscle, thus acting as a bronchodilator. 

Atropine relaxes the smooth muscles of bronchi and bronchioles which results in widening of the airways. It is effective in relieving bronchospasm produced by cholinergic agents. 

Stratified squamous to mucociliated epithelium with olfactory cells Mucociliated epithelium (ciliated, mucous cells, basal cells) smooth muscle cells fibroblasts neuroendocrine cells immune cells Mucociliated epithelium with Clara cells in distal bronchioles and alveolar ducts... 

It contains prunasin, which, when broken down in the body, quells spasms in the smooth muscles that line the bronchioles. Wild cherry syrup is effective in treating coughs, bronchitis, whooping cough, and other lung problems. 

Functional smooth muscle by 8-10 weeks, to respiratory bronchioles by 26 weeks... 

Bronchiole Mucosa, smooth muscle, adventitia Distributes air... 

Answer By mimicking the actions of epinephrine on smooth muscle, albuterol raises [cAMP], leading to relaxation and enlargement (dilation) of the bronchi and bronchioles. Because /3-adrenergic receptors also control many other processes, drugs that act as /3-adrenergic... 

Therapeutic uses Caffeine and its derivatives relax the smooth muscles of the bronchioles. Previously the main-stay of asthma therapy, theophylline has been largely replaced with p-agonists and corticosteroids (see p. 220). 

Systemic absorption may occur when eye drops containing beta-blockers are administered. Beta-receptors are found in heart muscle (predominantly beta-1) and the smooth muscle of the blood vessels and bronchioles (mainly beta-2). Selective beta-blockers (atenolol, bisoprolol, metoprolol, nebivolol, acebutolol) primarily (but not exclusively) antagonize beta-1 receptors, while the non-selective drugs (carvedilol, celiprolol, esmolol, labetalol, nadolol, oxprenolol, pindolol, propanolol, sotalol, timolol) block both beta-1 and beta-2 receptors,... 

Smooth muscle fibers of the bronchioles and ureters are contracted by these drugs, and the ureters may show increased peristaltic activity. 

In addition to the more or less standard actions of anticholinergic compounds due to their ability to interfere with the actions of acetylcholine on muscarinic receptors (resulting in acceleration of the heart relaxation of smooth muscles in bronchi and bronchioles, intestinal tract, urinary tract, iris and ciliary body of the eye, bile ducts and gall bladder, and some cutaneous blood vessels and decrease or abolition of secretion by glands of the gascrolncesclnal tract and skin), these substances may have pronounced effects on the central nervous system, as has been mentioned earlier. A large amount of research with experimental animals has been directed toward elucidation of the basic mechanisms Involved in these actions. 

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