BCMB 230 1st Edition Lecture 24 Outline of Last Lecture I.Plasma pH RegulationII.Reabsorption and SecretionIII.Bicarbonate Handling-pH in the KidneyIV.Digestive SystemOutline of Current Lecture I.AbsorptionII.Lymphatic SystemIII.Control of Digestive SystemIV.Functions of LiverV.Endocrine SystemCurrent LectureI. AbsorptionAbsorption: moving digested material from lumen (cavity space of digestive organs) into blood-Most absorption occurs in the small intestine. -Water absorption happens in the stomach.Maintain high glucose levels in plasma. The body wants to absorb the maximum amount, so it requires secondary active transport with Na+.-Amino acids do the same thing. Also need secondary active transportFructose-not present in the plasma in very high levels; use facilitated diffusionFatty acids/monoglyceridesCan get a micelle-droplet of fatty acid because of amphipathic nature-emulsion droplets and fat droplets-membrane is permeable to fat so no transporters are needed-within epithelial cell of intestines, synthesize triglycerides within the endoplasmic reticulum to get them out of the intestine-don’t want buildup, so need to move them out of the cells into the rest of the body-moved out of the cell by exocytosis-now have a chylomicronMain transport system to get it from interstitial fluid to adipose cells under skin somewhereII. Lymphatic SystemThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.-has a series of vessels like capillaries and veins of circulatory system-lymph capillaries-small, thin walled, very permeable, have pores that are valved that allow material to move into but not out of them-lymphatic vessels-much like veinsIn digestive system, these lymphatic capillaries have a special name: lactealsHave to make and break down fat several times to transport them because we don’t have a transporter for itIII. Control of Digestive System-movement-controlled by smooth muscle, can be regulated -secretion-regulate through sympathetic nervous system-digestion-control to an extent, by controlling muscles and glands; but if there is too much food we can’t not digest it; try to maximize this-absorption-can’t regulate intake of nutrients and calories; try to maximize thisTwo nervous systems that work in the digestive systemHave nerves in the wall-called plexus-collectively call this network of nerves as the enteric nervous systemHave both long and short neural reflexes3 different ways to control:Long neural reflexShort neural reflexHormones-come from GI tract-four main ones: gastrin, CCK, secretin, and GIPGastrin is from the stomach (gastric hormone), other three come from small intestine (intestinalhormone)Gastric hormone-stimulate stomachIntestinal hormones-inhibit stomach, promote things important for intestine; particularly secretion of various enzymes into small intestineControl of HCl Secretion During a Meal-separate through stimuli-cephalic phase (head)-senses, thought of food-start to control secretion and movement-results in increase of HCl secretion-stimuli come from stomach-gastric phase-distension, increase in peptides, decrease in H+ concentration-results in increase of HCl secretion-stimuli come from intestine-intestinal phase-distension, increase in H+ concentration, increase in osmolarity-results in decrease of HCl secretionCommon bile duct and pancreatic duct share the same opening; sphincter of Oddi controls this-can control secretion of bile salts and bicarbonate, and pancreatic enzymes-done by one of the intestinal hormonesIV. Functions of the Liver-important in digestion; provide bile salts that helps with fat absorption-important in blood clotting; provide proteins-important in osmotic balance; provides albumin-steroid hormones come primarily from two glands: from gonads (ovaries or testes, testosterone, estrogen) or adrenal cortex (also have steroids, aldoseterone, cortisone, cortisol, etc)-in females, testosterone from adrenal cortex is important in sex drive of females, imbalance can cause a woman to develop manly characteristics (estrogen levels are falling)-hormones tend to be bound to protein, not soluble in water-liver also involved in immune system-makes proteins involved with immune systemMajor symptoms of liver damage-jaundice -if the whites of the eyes are white, it is just dietary; if the whites of the eyes are yellow, check for liver functionV. Endocrine SystemIf there is an issue/disease in the endocrine system, can cause problems of secretion (at gland itself) or can have problems at the target cell which is a problem in responsiveness-with secretion, there can be too little which is a hyposecretion or too much which is a hypersecretion-take blood sample to determine which one-different categories in both of these depending on where the issue is-some glands are controlled by hormones, these hormones are called tropic hormones; mostly coming from anterior pituitary which is controlled by hormones from the hypothalamus;anterior pituitary controls parts of adrenal cortex, the gonads, thyroidSecretion can be primary, secondary, or tertiary—not with responsivenessPrimary is a defect in the gland that produces the hormoneHormone levels appropriateResponse reduced-hyporesponsivenessResponse