By C. Ronar. University of Texas of the Permian Basin.
Carnitine acyl transferase I buy super avana 160 mg line, found in the surface of the outer mitochondrial membrane order super avana on line amex, catalyzes the acyl transferase reaction from acylCoA to the carnitine generic 160 mg super avana free shipping. Oxidation of Unsaturated Fatty Acids The oxidation of unsaturated fatty acids requires two additional enzymes called isomerase and reductase. Most naturally occurring unsaturated fatty acids are in cis- configuration, which are not suitable for the action of enoyl-CoA hydratases and hence they must be changed to their trans isomer by an isomerase. The rest of the enzymes are needed for the oxidation in addition to these two for the oxidation are the same. Oxidation of Fatty Acids with Odd Number of Carbons Ruminant animals can oxidize them by B- oxidation producing acetylCoAs until a three carbon propionylCoA residue is left. The acetylCoAs produced are funneled to the Krebs cycle but the propionylCoA produced is converted to succinylCoA by three enzymatic steps. The metabolism of Ketone Bodies When the level of acetyl CoA from β-oxidation increases in excess of that required for entry into the citric acid cycle, It undergoes ketogenesis in the mitochondria of liver (ketone body synthesis). During such conditions, the body totally depends on the metabolism of stored triacylglycerols to fulfill its energy demand. In the synthesis, two molecules of acetyl CoA condense together to form acetoacetyl CoA, a reaction catalyzed by thoilase. The acetoacetate, when its concentration is very high in blood is spontaneously decarboxylated to acetone. See the figure The odor of acetone may be detected in the breath of a person who has a high level of acetoacetate, like diabetic patients. Even tissues like the heart and brain depend mainly on ketone bodies during such conditions to meet their energy demand. Liver does not contain the enzyme required for activation of ketone bodies Aceto acetate is activated by two processes for its utilization. Aceto acetate and β-hydroxy butyrate are the normal substrates for respiration and important sources of energy. Brain switches over to utilization of ketone bodies for energy during starvation and in uncontrolled diabetes. Prolonged starvation, depletion of carbohydrate stores results in increased fatty acid oxidation and ketosis. Similarly in starvation, due to hypoglycemia, there is less insulin, lipolysis increases and ketogenesis increases. Denovo synthesis of fatty acids take place in cytosol of liver, lactating mammary gland, adipose tissue and renal cortex. The formation of malonyl CoA is the committed step in fatty acid synthesis For the synthesis, all the enzymes are required in the form of fatty acid Synthase complex. The formation of malonyl CoA is the committed step in fatty acid synthesis For the synthesis, all the enzymes are required in the form of fatty acid Synthase complex. Biosynthesis of Cholesterol Cholesterol is synthesized in the cell cytosol and endoplasmic reticulum from acetylCoA. Squalene undergoes cyclization, loses three carbon atoms,aquire a double bond,forms cholesterol Regulation of Cholesterol Synthesis: Acetyl CoA is converted to Mevalonate. Catabolism of Cholesterol: Intestinal Bacteria converts cholesterol to coprostanol which is excreted in feces. The patients are treated with chenodeoxycholic acid to solublize the cholesterol or the stones are removed by surgical intervention. It causes obstruction to blood flow, leading coronary heart disease, stroke, myocardial infarction etc. Atherogenesis is the process by which atherosclerotic plaques form, a critical step in the disease, atherosclerosis. Ultimately, this accumulation of cholesterol becomes one of the chief chemical constituents of the atherosclerotic plaque that forms at the site. Glucocerebroside accumulates in liver, spleen, brain and bone marrow, due to the deficiency of glucocerebrosidase. Fatty Liver: Excess accumulation triglycerides in liver causes fatty liver,Liver cirossis and failure of liver function. Causes are: • Elivated levels of free fatty acid in blood • Deficiency of lipotropic factors,which help in the mobilization of fat from liver • Failure in the secretion of lipoproteins from liver • Chronic alcoholism • Prolonged treatment with antibiotics Lipoproteins Plasma lipids contain triacylglycerols, cholesterol and other polar lipids. Based on their density they are classified into four subgroups: 102 Chylomicrons: These are derived from intestinal absorption of triacylglycerols and other lipids and have a very short lifespan. Chylomicrons transport dietary triacylglycerols and cholesterol from the intestine to the liver for metabolism. Membranes give cells their individuality by separating them from their surrounding and they are highly selective and semi permeable containing specific gates, pumps, and channels. Membranes control the flow information between cells and their environment since they contain specific receptor molecules in the form of glycoproteins. Proteins are found submerged in the sea of the lipid bilayers (intrinsic proteins) or loosely bound (extrinsic proteins) and cholesterol is also found intercalated between the lipid bilayers giving the fluidy nature of membranes. Membranes can be regarded as a sea of lipid bilayers and due to the presence of unsaturated fatty acids and cholesterol. This fluidity enables lateral diffusion of molecules such that integral and non-integral proteins span the whole membrane structure. The modern representation of lipids as fluidy and dynamic structures is called the fluid mosaic model. The molecules forming membrane structures do not flip-flop or undergo traverse diffusion and therefore, membranes are asymmetric structurally and functionally. The outer and inner surfaces of all known biological membranes have different components and different enzymatic activities. Cells produce proteins with strikingly different properties and activities by joining the same 20 amino acids in many different combinations and sequences. This indicates that the properties of proteins are determined by the physical and chemical properties of their monomer units, the amino acids. Stereochemistry (Optical activity) Stereochemistry mainly emphasizes the configuration of amino acids at the α carbon atom, having either D or L- isomers. Except for glycine, all amino acids contain at least one asymmetric carbon atom (the α - carbon atom). Common groupings of amino acids are aliphatic, hydroxyl/sulfur, cyclic, aromatic, basic, acidic and acid amides. Structural Classification This classification is based on the side chain radicals (R-groups) as shown in the table 5. Electrochemical classification Amino acids could also be classified based on their acid – base properties Acid amino acids (Negatively charged at pH = 6. Biological or Physiological Classification This classification is based on the functional property of amino acids for the organism. Essential Amino Acids Amino acids which are not synthesized in the body and must be provided in the diet to meet an animal’s metabolic needs are called essential amino acids. About ten of the amino acids are grouped under this category indicating that mammals require about half of the amino acids in their diet for growth and maintenance of normal nitrogen balance.
Blood volume distribution & blood pressure Blood volume is very unevenly distributed through the various vascular segments even though the volume flowing through is relatively constant discount super avana on line. Thick cheap 160 mg super avana fast delivery, elastic arteries and arterioles contain 18% purchase 160 mg super avana free shipping, capillaries hold only 3-4 percent of blood volume, while the heart contains about 7% blood pressure is almost inversely proportional to volume distribution and vascular resistance. There is little change in pressure in large arteries, but resistance increases rapidly in small arteries, causing the pressure to drop to about 70 mm Hg at the beginning of the arterioles. The arterioles have the greatest resistance of the systemic circulation, so that by the time blood reaches the capillaries, pressure has dropped to about 30 mmHg. Direct methods 1 Mercury manometer The principle behind manometry is that the vertical column of manometer fluid exerts a downward Pressure which opposes the blood pressure. When the column reaches a stable height (h), the blood pressure must be equal to the pressure at the bottom of the column, namely ρgh (fluid density ρx force of gravity g x h). Electronic pressure transducer To record the pressure wave form, a fast-responding electronic pressure transducer is needed. The transducer contains a metal diaphragm which deforms slightly when arterial pressure is applied to it via a catheter. The deformation of the diaphragm alters the resistance of a wire Connected to it and the resistance is recorded. Indirect methods Auscultator method (sphygmomanometry) The mercury manometer is used in medical practice throughout the world to measure human blood pressure, by an indirect method called sphygmomanometry. Auscultation of the brachial artery at the antecubital fossa (inner aspect of elbow) with a stethoscope therefore reveals no sound at this stage. As long as this pressure is higher than systolic pressure, the brachial artery remains collapsed and no blood whatsoever flows into the lower artery during any part of the pressure cycle. The transient spurt of blood vibrates the artery wall downstream and creates a dull tapping noise called Korotkoff sound. The jet causes turbulence in the open vessel beyond the cuff, and this sets up vibrations heard through the stethoscope). The sound, this time, has less of the tapping quality but more of a rhythmic harsher quality. Therefore, the sounds suddenly change to a muffled quality and usually disappear entirely. Direct versus indirect methods Several investigators have compared the pressure readings obtained from a cannula inserted into the brachial artery in one arm with the recordings obtained in the other by the auscultatory method. Normal values Many attempts have been made to define normal values for blood pressure but all such efforts have been unsatisfactory. For an adult under certain conditions he would be right, but it is quite wrong to adopt 120/80 mmHg as the normal standard for a resting child, a pregnant woman in midterm or an elderly man. It is not equal to the average of systolic and diastolic pressure because the pressure remains nearer to the diastolic pressure than to the systolic pressure during the greater part of the cardiac cycle. If heart rate increases, the relative amount of time the heart spends in diastole decreases. The increase in pulse pressure is especially striking and iscaused by reduced arterial compliance. Reduced compliance is due to arteriosclerosis (hardeningof the arterioles by fibrosis and calcinosis), and is universal accompaniment to ageing. Conversely, pressure is reduced in the arteries above the heart level and is only 60mmHg or so in human brain during standing. Indirect effect Upon moving from lying to standing, arterial pressure changes at heart level due to changes in cardiac output and peripheral resistance. A transient fall in aortic pressure (which can produce a passing dizziness) is followed by a small but sustained reflex rise. Compared with the relaxed states, while attending a meeting often raise it by 20mmHg. The pressor effect of stress is particularly harmful to patients with ischemic heart disease. Valsalva maneuver: Valsalva maneuver, a forced expiration against a closed or narrowed glottis, causes a complex sequence of pressure changes. Pregnancy: In pregnancy blood pressure gradually falls and reaches a minimum at approximately 6 months. Veins don’t show distensibility are filled; they contain 3- times blood volume than in that of arteries. Veins have more capacity arteries expand and recoil, store pressure during systole of the heart and release it during cardiac diastole -the pressure stores. Capacitance vessels: act as blood reservoirs - veins & venules Regulation of flow through blood vessels Blood vessel caliber, an important factor in the determination of resistance and capacitance, is actively regulated by neural and humoral mechanisms and passively affected by the pressure within it. Vasomotor refers to rhythmic oscillating changes in the caliber of the arterioles, metarterioles, and precapillary sphincters resulting from vasoconstriction or vasodilatation and venomotion. Neural control of vasomotor tone Vasomotor tone is the continuous, low-level activity of vascular smooth muscle fibers that maintain the tension of the vascular walls. It varies in different tissues, and is mainly dependent upon the rate of impulses from the sympathetic nerve fibers to the muscle cells. This tone is higher in skeletal muscles and splanchnic area blood vessels and 193 least in the heart, brain, and kidney. Vasomotor tone is the tension basically to maintain arterial blood pressure; increase in tone increases blood pressure; decrease in tone lowers blood pressure. In order to maintain an adequate coronary and cerebral blood flow while supplying extra blood to the muscles during heavy exercise, blood pressure must be maintained or increased and blood shifted from the splanchnic and renal areas to the active muscles by changes in the resistance of these vascular beds. Sympathetic regulation of vasomotor & venomotor tone Postganglionic sympathetic fibers from the thoracolumbar sympathetic ganglia provide innervation to all blood vessels, though the density of innervations varies in different tissues. Sympathetic fibers innervate smooth muscles in the principal arteries, small arteries, and terminal arterioles in to tissues. Precapillary arterioles and metarterioles in skeletal muscles are also well innervated by sympathetic nerves. Vasoconstriction allows movement of large amount of blood towards the heart in emergencies, such as hemorrhage. Only very few blood vessels are innervated by the parasympathetic, hence this system is less potent. Norepinephrine Stimulation of Alpha Receptors Norepinephrine released from most postganglionic sympathetic fibers reacts with alpha receptors in the skin, Splanchnic area, skeletal muscle, & kidneys to cause a strong vasoconstriction. The blood vessels of the heart and brain lack alpha receptors, consequently nor epinephrine is ineffective in these tissues. Epinephrine stimulation of beta receptors Epinephrine is released into the circulation after sympathetic stimulation of the adrenal medulla and it acts on beta receptors present in the blood vessels of the heart and 194 brain, causing vasodilatation, ensuring that these vital organs are not deprived of blood during stressful situations that induces vasoconstriction elsewhere. Cholinergic sympathetic vasodilation The blood vessels of the skeletal muscles also receive sympathetic cholinergic postganglionic fibers stimulating cholinergic receptors, resulting in vasodilatation, just prior to strenuous exercise, shunting blood to the muscles that will be most active. Parasympathetic regulation of vasomotor activity Postganglionic cholinergic parasympathetic fibers appear to be significant in few tissues; the genital erectile tissues (penis and clitoris) and clitoris glands, such as the salivary glands, where acetylcholine evokes production of vasodilator bradykinin, Local regulation of blood flow The regulation of blood flow thorough the microcirculation is influenced by neural factors as well as some provocative substances that modify vasomotor tone.
Tachycardia and hallucinations (as well as more life-threatening problems) may ensue when such tomatoes are eaten order 160mg super avana otc. Side effects of muscarinic antagonists include constipation purchase super avana 160mg, xerostomia (dry mouth) purchase super avana overnight delivery, hypohidrosis (decreased sweating), mydriasis (dilated pupils), urinary retention, precipitation of glaucoma, decreased lacrimation, tachycardia, and decreased respiratory secretions. Clinically, atropine is used for raising heart rate during situations where vagal activity is pronounced (for example, vasovagal syncope). Its most widespread current use is in preanesthetic preparation of patients; in this situation, atropine reduces respiratory tract secretions and thus facilitates intubation. Because of the importance of this receptor in mediating gastric acid release, M1 antagonists such as pirenzepine help patients with ulcer disease or gastric acid hypersecretion. However, antihistamines and proton pump inhibitors are more useful and more widely used for control of gastric acidity. It is found in the leaves of the tobacco plant (Nicotiana tabacum) in concentrations of 0. At low dosages it stimulates ganglionic nicotinic receptors thus enhancing both sympathetic and parasympathetic neurotransmission. In practice there is stimulation of nicotinic receptors in many other sites especially as nicotine dosages increase. Smoking one cigarette or intravenous administration of 1 mg nicotine will usually raise blood pressure about 10 mm Hg and increase heart rate 15 beats per minute. Higher doses stimulate the heart eliciting the Bezold-Jarisch reflex (bradycardia, hypotension, nausea), and may eventually result in weakness, tremors, and convulsions. A dosage of 60 mg is lethal; there are two lethal doses in one cigar (if it were absorbed rather than smoked). Chronic smoking has effects unrelated to nicotine (or related to nicotine in a still poorly understood way). Smokers have increased metabolic rate that keeps them relatively lean; on discontinuation of smoking the reduction in metabolism usually causes a weight gain. Smokers have an increased risk of cancer (129,000 extra deaths per year), coronary heart disease (170,000 extra deaths per Page 23 Pharmacology 501 January 10 & 12, 2005 David Robertson, M. The st persistence of widespread tobacco use into the 21 century is an incongruity that future historians will probably find tragic and inexplicable. Addiction to nicotine makes it very difficult for regular cigarette users to stop smoking. Since the overwhelming majority of the bad effects of smoking are due to factors other than nicotine itself, nicotine products such as patches (for transdermal nicotine administration), chewing gum, and nasal sprays have been developed to try to administer nicotine without the involvement of tobacco use. Only time will tell to what extent the patches and nasal spray will themselves cause addiction, but experience so far is encouraging. The principal side effects noted have included alterations in taste or smell and increased heart rate. Nicotinic Antagonists (Ganglionic Blockers) The actions of drugs on autonomic ganglia are complex. The effects observed clinically with ganglionic blocking agents are due to blockade of these receptors. Nearly all effects are predictable from the knowledge that ganglionic blockers reduce transmission in all autonomic ganglia, both sympathetic and parasympathetic. In some sites, sympathetic activation seems to predominate over parasympathetic, while in other sites, the opposite is true. Table 3: Mediators and Effects of Ganglionic Blockade on Organ Systems Tissue Predominant System Ganglionic Blockade Effect Arterioles Sympathetic Vasodilation Veins Sympathetic Vasodilation Heart Parasympathetic Tachycardia Iris Parasympathetic Mydriasis Ciliary muscle Parasympathetic Cycloplegia Gastrointestinal tract Parasympathetic Hypomotility Urinary bladder Parasympathetic Urinary retention Salivary glands Parasympathetic Xerostomia Sweat glands Sympathetic cholinergic Anhidrosis F. Cholinesterase Inhibitors The muscarinic and nicotinic agonists mimic acetylcholine effect by stimulating the relevant receptors themselves. This is achieved by cholinesterase inhibitors, which are also called the anticholinesterases. It is used to stimulate motor activity of the small intestine and colon, as in certain types of nonobstructive paralytic ileus. It is useful in treating atony of the detrusor muscle of the urinary bladder, in myasthenia gravis, and sometimes in glaucoma. Like other cholinesterase inhibitors, neostigmine requires an intact postganglionic innervation for full development of its actions. Edrophonium (Tensilon®) is a quaternary amine widely used as a clinical test for myasthenia gravis. Many phosphorothionates, including parathion and malathion undergo enzymatic oxidation that can greatly enhance anticholinesterase activity. Differences in the hydrolytic and oxidative metabolism in different organisms accounts for the remarkable selectivity of malathion. In mammals, the hydrolytic process in the presence of carboxyesterase leads to inactivation. This normally occurs quite rapidly, whereas oxidation leading to activation is slow. In insects, the opposite is usually the case, and those agents are very potent insecticides. Some patients encounter muscarinic side effects due to the inhibition of peripheral cholinesterase by physostigmine. The most common of these side effects are nausea, pallor, sweating and bradycardia. Several centrally acting drugs produce an acute toxic psychosis characterized by confusion and the peripheral signs of cholinergic blockade. These drugs include several plant toxins, antidepressants, H1 receptor antagonists with central effects, and several antiparkinsonian drugs and antipsychotic drugs. Cholinesterase inhibitors that cross the blood-brain barrier are suitable to reverse the central anticholinergic syndrome. Although physostigmine effectively wakes up such patients briefly, it is not certain that its use results in a long-term better prognosis. Two newer agents donepezil (Aricept®) and rivastigmine (Exelon®) have little hepatotoxicity and have replaced tacrine. On the accompanying tables, the effects of intoxication and the therapeutic approach to treatment are outlined. This drug counteracts cholinesterase inhibitor intoxication by reactivating the cholinesterase enzyme. Pralidoxime combines with the anionic site on the enzyme by electrostatic attraction to the quaternary N atom, which orients the nucleophilic oxime group to react with the electrophilic P atom; the oxime-phosphonate is split off, leaving the regenerated enzyme. War Gases Long-acting or "irreversible" cholinesterase inhibitors (organophosphates) are especially used as insecticides. Cholinesterase inhibitors enhance cholinergic transmission at all cholinergic sites, both nicotinic and muscarinic. Sarin which is a war nerve gas is a binary agent composed of two components that are not toxic until mixed. Nerve gases such as the cholinesterase inhibitor, sarin, have been the chemical weapons of choice for over 50 years.
The initial mixing waves are relatively gentle cheap super avana 160 mg line, but these are followed by more intense waves purchase super avana online now, starting at the body of the stomach and increasing in force as they reach the pylorus order super avana amex. It is fair to say that long before your sushi exits through the pyloric sphincter, it bears little resemblance to the sushi you ate. The pylorus, which holds around 30 mL (1 fluid ounce) of chyme, acts as a filter, permitting only liquids and small food particles to pass through the mostly, but not fully, closed pyloric sphincter. In a process called gastric emptying, rhythmic mixing waves force about 3 mL of chyme at a time through the pyloric sphincter and into the duodenum. This prevents additional chyme from being released by the stomach before the duodenum is ready to process it. Chemical Digestion The fundus plays an important role, because it stores both undigested food and gases that are released during the process of chemical digestion. While the food is in the fundus, the digestive activities of salivary amylase continue until the food begins mixing with the acidic chyme. Ultimately, mixing waves incorporate this food with the chyme, the acidity of which inactivates salivary amylase and activates lingual lipase. Lingual lipase then begins breaking down triglycerides into free fatty acids, and mono- and diglycerides. Its numerous digestive functions notwithstanding, there is only one stomach function necessary to life: the production of intrinsic factor. The intestinal absorption of vitamin B12, which is necessary for both the production of mature red blood cells and normal neurological functioning, cannot occur without intrinsic factor. People who undergo total gastrectomy (stomach removal)—for life-threatening stomach cancer, for example—can survive with minimal digestive dysfunction if they receive vitamin B12 injections. The contents of the stomach are completely emptied into the duodenum within 2 to 4 hours after you eat a meal. Since enzymes in the small intestine digest fats slowly, food can stay in the stomach for 6 hours or longer when the duodenum is processing fatty chyme. However, note that this is still a fraction of the 24 to 72 hours that full digestion typically takes from start to finish. In addition, called the small and large bowel, or colloquially the “guts,” they constitute the greatest mass and length of the alimentary canal and, with the exception of ingestion, perform all digestive system functions. The Small Intestine Chyme released from the stomach enters the small intestine, which is the primary digestive organ in the body. Since this makes it about five times longer than the large intestine, you might wonder why it is called “small. As we’ll see shortly, in addition to its length, the folds and projections of the lining of the small 2 intestine work to give it an enormous surface area, which is approximately 200 m , more than 100 times the surface area of your skin. This large surface area is necessary for complex processes of digestion and absorption that occur within it. Just past the pyloric sphincter, it bends posteriorly behind the peritoneum, becoming retroperitoneal, and then makes a C-shaped curve around the head of the pancreas before ascending anteriorly again to return to the peritoneal cavity and join the jejunum. The duodenum can therefore be subdivided into four segments: the superior, descending, horizontal, and ascending duodenum. Located in the duodenal wall, the ampulla marks the transition from the anterior portion of the alimentary canal to the mid-region, and is where the bile duct (through which bile passes from the liver) and the main pancreatic duct (through which pancreatic juice passes from the pancreas) join. This ampulla opens into the duodenum at a tiny volcano-shaped structure called the major duodenal papilla. The hepatopancreatic sphincter (sphincter of Oddi) regulates the flow of both bile and pancreatic juice from the ampulla into the duodenum. Jejunum means “empty” in Latin and supposedly was so named by the ancient Greeks who noticed it was always empty at death. No clear demarcation exists between the jejunum and the final segment of the small intestine, the ileum. The ileum joins the cecum, the first portion of the large intestine, at the ileocecal sphincter (or valve). Parasympathetic nerve fibers from the vagus nerve and sympathetic nerve fibers from the thoracic splanchnic nerve provide extrinsic innervation to the small intestine. Nutrient-rich blood from the small intestine is then carried to the liver via the hepatic portal vein. Histology The wall of the small intestine is composed of the same four layers typically present in the alimentary system. These features, which increase the absorptive surface area of the small intestine more than 600-fold, include circular folds, villi, and microvilli (Figure 23. These adaptations are most abundant in the proximal two-thirds of the small intestine, where the majority of absorption occurs. Beginning near the proximal part of the duodenum and ending near the middle of the ileum, these folds facilitate absorption. Their shape causes the chyme to spiral, rather than move in a straight line, through the small intestine. Spiraling slows the movement of chyme and provides the time needed for nutrients to be fully absorbed. There are about 20 to 40 villi per square millimeter, increasing the surface area of the epithelium tremendously. In addition to muscle and connective tissue to support its structure, each villus contains a capillary bed composed of one arteriole and one venule, as well as a lymphatic capillary called a lacteal. The breakdown products of carbohydrates and proteins (sugars and amino acids) can enter the bloodstream directly, but lipid breakdown products are absorbed by the lacteals and transported to the bloodstream via the lymphatic system. Microvilli As their name suggests, microvilli (singular = microvillus) are much smaller (1 µm) than villi. They are cylindrical apical surface extensions of the plasma membrane of the mucosa’s epithelial cells, and are supported by microfilaments within those cells. Although their small size makes it difficult to see each microvillus, their combined microscopic appearance suggests a mass of bristles, which is termed the brush border. Fixed to the surface of the microvilli membranes are enzymes that finish digesting carbohydrates and proteins. There are an estimated 200 million microvilli per square millimeter of small intestine, greatly expanding the surface area of the plasma membrane and thus greatly enhancing absorption. The submucosa of the duodenum is the only site of the complex mucus-secreting duodenal glands (Brunner’s glands), which produce a bicarbonate-rich alkaline mucus that buffers the acidic chyme as it enters from the stomach. Cells of the Small Intestinal Mucosa Cell Location in the Function type mucosa Epithelium/intestinal Absorptive Digestion and absorption of nutrients in chyme glands Epithelium/intestinal Goblet Secretion of mucus glands Paneth Intestinal glands Secretion of the bactericidal enzyme lysozyme; phagocytosis Intestinal glands of G cells Secretion of the hormone intestinal gastrin duodenum Intestinal glands of Secretion of the hormone cholecystokinin, which stimulates release of I cells duodenum pancreatic juices and bile Secretion of the hormone glucose-dependent insulinotropic peptide, which K cells Intestinal glands stimulates the release of insulin Intestinal glands of Secretion of the hormone motilin, which accelerates gastric emptying, M cells duodenum and stimulates intestinal peristalsis, and stimulates the production of pepsin jejunum S cells Intestinal glands Secretion of the hormone secretin Table 23. Peyer’s patches are most prominent in young people and become less distinct as you age, which coincides with the general activity of our immune system. Epithelial cells continue the digestion and absorption of nutrients and transport these nutrients to the lymphatic and circulatory systems. In the small intestine, the products of food digestion are absorbed by different structures in the villi. Mechanical Digestion in the Small Intestine The movement of intestinal smooth muscles includes both segmentation and a form of peristalsis called migrating motility complexes.