GIMcCoy

State whether each pair's secretion is serous or mixed (serous/mucous). Parotid 20% serous Submandibular 70% mostly mucous Sublingual 5% mostly mucous

lubrication, taste, teeth cleaning, neutralizes reflux

starch digestion

Sucrose = glucose + fructose; maltose = glucose + glucose; trehalose = glucose + glucose (but different bond than for maltose); and lactose = glucose + galactose

Amylase comes from saliva and the pancreas. Glucoamylase, sucrose, isomaltase, lactase, and trehalase all come from the brush border of enterocytes

Hydrolysis is the splitting (lysis) of a covalent bond (between two carbons or a carbon and a nitrogen, for example) by adding the components of a water moleculeH attaches to one atom from the broken bond and OH attaches to the other atom.

Glucose and galactose: secondary active transport with sodium and facilitated diffusion in small intestine. Fructose: Facilitated diffusion only; small intestine

Locations are stomach, pancreas, and small intestineEnzymes are pepsin (released as precursor pepsinogen) and peptidases (such as trypsin, chymotrypsin, elastase, and carboxypeptidases A and B)

Amino acids are absorbed as peptides, dipeptides, and tripeptides by enterocytes in the duodenum and jejunum via specialized membrane transporters

When a particular amino acid transporter is defective or missing in the enterocyte membrane, severe deficiency of that amino acid results in the body due to lack of absorption, along with clinical symptomsBottom line: Each transporter type is crucial.

Emulsification and then breakdown of triglycerides into fatty acids and glycerol

Bile contains bile acids, phospholipids, cholesterol, and bile pigments (which are the produces of hemoglobin breakdown)The purpose of bile acids is emulsification of lipids prior to lipid digestion.

Some of the colorless bile pigment urobilinogen is reabsorbed from the gut, instead of excreted in fecesIt is then filtered by the kidneys, and turns to yellow urobilin when exposed to air. In addition, some urobilinogen is converted to urobilin in the intestines, then reabsorbed and filtered by the kidney.

Monoglycerides and free fatty acids can be absorbed by enterocytes, then they are reassembled into triglycerides, packaged in chylomicrons and exocytosed to the lacteal, a part of the lymphatic system

A lacteal absorbs chylomicrons into the lymphatic systemA chylomicron is composed of cholesterol, triglycerides, phospholipids, and apolipoproteins. Chylomicrons are too big to be absorbed by a capillary, but they will fit through the slits in lacteal vessels and can enter the circulation via the thoracic duct into the left brachiocephalic vein.

Fat soluble: A, D, E, K. Water soluble: Bs, C The fat-soluble ones can be components of micelles

Water is absorbed passively in two ways: via tight junctions between enterocytes, and also through special channels called aquaporins in enterocyte membranes8.8 L/day

Na+: active, jejunum to colon Cl-: passive, jejunum to colon K+: passive, jejunum and ileum HCO3-: passive, jejunum

Iron must be in the ferrous (+2) state before absorption into enterocytes of the duodenum and jejunumIt is then reduced to its elemental state, Fe, and bound to the protein ferritin before leaving the enterocyte and entering the blood. In the blood, it is transferred to the protein transferrin and travels to the liver, then bone marrow.

Ca+2 ions enter the microvilli of enterocytes through calcium channels, then bind to the protein calmodulin, get passed off to calbindin, packaged in vesicles, then pumped out of the cell by a Ca-ATPase protein transporterVitamin D facilitates this process by inducing the synthesis of three of the vital proteins: the transporter, calbindin, and the calcium channel.

Mineralocorticoids (especially aldosterone): favor Na+ absorption Glucocorticoids (especially cortisol): favor ions and water absorption Catecholamines: favor NaCl absorption Somatostatin: favor ions and water absorption

Parasympathetic stimulation, via acetylcholine favors digestion and movement, so absorption is DECREASED, but secretion is INCREASED. Sympathetic stimulation via norepinephrine favors slowing down and absorption(So consider absorption an anti-digestion activity, because it occurs when digestion is complete.)

Mast cells, phagocytes, lymphocytes, basophils, neutrophils

Metabolizes food (transformation), holds vitamins and iron (storage), makes key proteins (synthesis), makes bile (synthesis), removes aged RBCs (catabolism), detoxes harmful substances (catabolism), digests bacteria from GI tract (catabolism)

An acinus is a liver unit where the center is the portal triad, not the central canalHepatocytes can be divided into three zones, based on how close to the portal triad they are, which is where the most oxygenated blood is located.

Zone 1 favors oxygen-requiring reactions: oxidative metabolism, gluconeogenesis, and ureagenesis Zone 3 favors reactions that don't require much, if any oxygen: glycolysis and lipogenesis

Sinusoidal endothelial cells are capillary boundaries Hepatocytes transform, synthesize, and break down substances(See question 74.) Kupffer cells are macrophages that phagocytize bacteria, virus particles, and old RBCs Stellate (Ito) cells store fat and vitamin A

Lactic acid, amino acids, glycerol

Anaerobic respiration in muscle results in lactic acid productionLactic acid then travels in the blood to the liver, where it is converted back to glucose and then stored as glycogen or released back into the blood, perhaps to travel back to the muscle and again be involved in anaerobic respiration.

Lipoprotein: a complex composed of various apolipoproteins Chylomicrons and lipoproteins are the means by which insoluble lipids can be transported in watery blood plasma Chylomicrons, VLDL, IPL, and LDL are all spherical, phospholipid-lined fat transportersThe non-denser ones have MORE cholesterol and the dense ones have LESS cholesterol. So, in order of their cholesterol content (from most to least) they are Chylomicron > VLDL > LDL > HDL.

Chylomicrons are absorbed from the gut via lacteals and get into the bloodstream via the lymphatic ductThey travel to the liver and are converted to the denser, smaller VLDLs. An enzyme in the wall of blood vessels (lipoprotein lipase) then breaks down VLDL, so that the triglycerides are released and what is left is LDL. LDL then takes cholesterol to all the organs of the body, because it is a component of all cell membranes and also used to make steroid hormones. HDLs remove cholesterol from peripheral tissue and transport it to the liver again. Cholesterol can be converted to bile acids and excreted in feces.

Transamination (conversion to the aa glutamate) Deamination and conversion to glucose or cell respiration intermediates like pyruvate or acetyl CoA Deamination and conversion to urea

Blood leaving the pancreas contains insulin and glucagon, which will affect the liver's sugar metabolism to influence plasma glucose concentration

Norepinephrine decreases blood flow to the liver through vessel constriction and also stimulates expulsion of blood from the liver and into the systemic circulationThat helps raise blood pressure that is low due to hypovolemia.

The liver's production of the plasma protein albumin gives the blood enough osmotic pressure to draw tissue fluid back into circulationWhen the liver is compromised and cannot make enough albumin, abdominal swelling occurs, because fluid that seeps out of capillaries cannot be recovered efficiently.

Heme produced in a phagocyte is converted to biliverdin, and then to bilirubinBilirubin travels in blood, bound to albumin. Hepatocytes take up this bilirubin and conjugate it and excrete it in bile. Conjugated bilirubin can then be converted to urobilinogen and stercobilin in the intestines. These products can either be excreted in feces, or the urobilinogen can be filtered by the kidney and converted to urobilin before excretion in urine. Further, as stated in the answer to question 63, some urobilinogen is converted to urobilin in the intestines, before reabsorption and filtration by the kidneys.

The liver adds an OH- group to carbon #25 of the vitamin D precursor molecule

When the flow of bile from the liver to the small intestine is blocked, it backs up in the liver, bloodstream, and body tissues, and the bilirubin it contains then colors the skin and sclera

The chemical reactions of metabolism always produce some waste heat

T3 (triiodothyronine) Stimulates Na+/K+ ATPase and oxygen consumption

Brown fat varies in appearance from regular adipose, because although it has obvious storage spaces for lipid (as regular adipose does), it is also richly vascular and innervated for sympathetic stimulationIn adults it can be found mainly in the lower neck and supraclavicular region. It looks brown, because it contains a lot of mitochondria, which have heme-containing cytochromes. (Each heme has 4 Fe atoms, and Fe is brown.) The triglycerides present are the source of energy for the proton gradient in the electron transport system.

Thermogenin stimulates mitochondria to allow protons to run along the electron transport system gradient in the cristae without ATP being formed in the processSo the energy that is released is not being stored, but takes the form of waste heat instead.

The posterior hypothalamus

In the skin. There are two kinds, warm and cold.

Radiation is the movement of heat energy through space via infrared waves in the electromagnetic spectrum Convection is the movement of heat energy in currents through fluid, like air or water Conduction is heat movement through direct contact of a heat-containing object with a cooler one Evaporation of water from skin is cooling, because conversion of water from liquid to gas requires a relatively high amount of heat energy (26 kJ/mL).

Bacteria or viruses (as well as the host's leukocytes stimulated by these pathogens) release pyrogensPyrogens travel in blood to the hypothalamus, where they stimulate the hypothalamus to reset its temperature set point via interleukin 1. The hypothalamus is stimulated to break down membrane phospholipids to arachidonic acid and ultimately to prostaglandins. Prostaglandin E2 signals skeletal muscle to shiver and increase tone, as well as prevention of heat loss via vasoconstriction. No prostaglandins, no fever.

In both cases the victim feels hot and weak and may faintHowever, in heat exhaustion body temperature is normal or even a bit low, and skin is moist and clammy. Pupils are dilated from sympathetic stimulation by norepinephrine. Dehydration from profuse sweating leads to low blood pressure. In heat stroke, heat damage to tissue has already occurred. CNS damage may lead to constricted pupils and a very high body temperature. GI symptoms may include massive ulceration, hemorrhages and engorged intestinal vessels. Also the skin is hot and dry, sweating stops, and shock may occur.

Certain inhalation anesthetics can provoke a reaction in some people that have a particular autosomal dominant geneThe result is massive head production in skeletal muscles, due to a suddenly elevated metabolic rate. The heart races, blood pressure rises, and muscles become rigid. Treatment is ice and intravenous dantrolene, a muscle relaxant.

difficulty swallowing

LES does relax (open) properly

LES doesn't stay contracted (closed) properly

Intraesophageal pressure is equal in intrathoracic pressure, which is lower than atmospheric pressure on average, due to inspiration

UES keeps air out of esophagus. LES keeps acid out of esophagus.

Likenesses: Both have actin and myosinBoth use sliding action of actin and myosin against each other for shortening. Differences: Smooth muscle is smaller than skeletal, does not have striations, has a much higher ratio of actin to myosin, has intermediate filaments that anchor contractile ones, is organized into bundles, and is unitary (gap junctions allow cytoplasm exchange from cell to cell)

Phasic: contract periodically and relax in between contractions Tonic: usually in a state of contraction (tone) without regular relaxation (as sphincters)

Not action potentials, but oscillating depolarization and repolarizations of membrane potential; 3-12/min is average, but they're faster in the small intestine and slower in colon; originate in myenteric plexus, specifically in the interstitial cells of Cajal thereThe Cajal cells start the depolarizations like pacemaker cells in the heart, and the electrical changes spread to other cells.

A slow wave is like an EPSP, but it isn't enough stimulation on its own to cause an action potentialWhen a slow wave is combined with the acetylcholine from vagal stimulation, the additive effects may be enough to result in action potential and muscle contraction.

there is no submucosal plexus in the stomach.

Emptying speeded by: upper stomach not very distended, stronger peristalsis in the lower stomach, relaxation of the pyloric sphincter, less rhythmic segmentation in the duodenum (meaning it's emptying)

Emptying slowed by: upper stomach distended due to fullness, weak peristalsis in lower stomach, contraction of pyloric sphincter, active rhythmic segmentation in the duodenum (meaning it's still full), fat and/or acid in the duodenum

Isotonic liquids, hypertonic liquids, carbohydrates, protein, fat

Purposes are digestion and absorption;

12/min

Peristalsis is coordinated, wave-like contraction of smooth muscle that propels solids or liquids through the gutSensory neurons in the gut mucosa stimulate interneurons of the enteric nervous system. One interneuron can connect with two motor neurons in the myenteric plexus of the smooth muscle layer. The motor neuron at the oral end will respond by releasing a stimulatory neurotransmitter like acetylcholine or substance P to affect nearby smooth muscle fibers, which results in smooth muscle contraction. The motor neuron at the aboral (caudad) end of the interneuron will respond to interneuron stimulation by releasing an inhibitory neurotransmitter like NO or VIP, which relaxes smooth muscle. So food moves from the oral end to the aboral end of the gut tube.

Small intestine relaxes when over extended

Smooth muscle contractions in the stomach stimulate the ileum's smooth muscle

Stomach stretching leads to smooth muscle contractions in the large intestine and increases the frequency of mass movements

Migrating myoelectric complexes are waves of activity that sweep through the intestines in a regular cycle during the fasting state (stomach growling); they occur in the stomach and small intestines for several minutes every 90 minutes or soMMCs help keep indigestible substances moving, as well as keep bacteria from moving up from the large intestine to the small intestine.

Motilin is made by M cells of Peyer's patches in the duodenum and jejunumMotilin stimulates MMCs. Erythromycin is a motilin agonist, which can lead to increased gut movement.

The vagus nerve innervates the ascending and transverse colon, while the rest of the colon is innervated by pelvic nerves from the sacral spinal cordIt absorbs all the fluid it receives from the ileum (which is 0.5 to 1.5 L), except for about 50-100 mL/day.

Rectum distends with waste to at least 25% full, internal anal sphincter relaxes, abdominal pressure rises due to forced inspiration and contraction of the respiratory and abdominal muscles, smooth muscle in the rectum and anal canal contracts, external sphincter voluntarily relaxes

Water (75%), bacteria, fiber, and inorganic matter are the main componentsStercobilin and urobilin, which are products of bilirubin metabolism due to RBC breakdown, color feces brown.

Each are examples of reverse peristalsis, but vomiting expels stomach and perhaps duodenum contents from the body, regurgitation brings the material only up to the mouth, and retching only gets it into the esophagus, because the UES doesn't open

Reverse peristaltic waves are initiated, the pyloric sphincter relaxes, person inspires, glottis closes, abdominal muscles contract, LES relaxes, food comes up, UES relaxes, food is expelled

Vomiting is controlled in the vomiting center of the brain's medullaChemoreceptors in the fourth ventricle of the brain may be stimulated and send a stimulatory message to the medulla.

Hypochloremic alkalosis due to stomach acid loss, dehydration due to liquid loss, kidney compensation with Na+ reabsorption from aldosterone production, bicarb follows the Na+, so the alkalosis is perpetuated, hypokalemia due to shift of K+ (from plasma into cells) for H+ as stomach scrambles to make more acid to replace what's been lost

Lubrication for taste and swallowing. Protection against bacteria and acid erosion. Digestion of starch and perhaps lipid. When the hormone aldosterone (from the adrenal glands) is present, flow is lower, and the reabsorption of NaCl is greater than that of K+ and bicarbIn the absence of aldosterone, flow rates are higher and saliva composition is similar to plasma, because there isn't time to modify it before it's released.

Parasympathetic innervation is via cranial nerves VII and IX, affecting muscarinic receptors by the neurotransmitter acetylcholineSympathetic innervation is via spinal nerves T1-T3, affecting beta-adrenergic receptors by the neurotransmitter norepinephrine. Acetylcholine leads to a watery, enzyme-rich saliva, while norepinephrine favors a thicker, glycoprotein-rich mucous.

Parietal cells are found in the body of the stomach and secrete HCl and intrinsic factor. Chief cells are found in the body of the stomach and secrete pepsinogen. G cells are found in the antrum of the stomach and secrete gastrin. Mucous cells are found in the antrum of the stomach and secrete mostly mucous (and also some pepsinogen).

Intrinsic factor combines with cobalamin (vitamin B12) to make it possible for cobalamin to be absorbed via special receptors on the brush border of enterocytes in the ileum

Carbon dioxide from cell respiration combines with water in the presence of carbonic anhydrase to make carbonic acid, which ionizes. The bicarb goes to the blood, while H+ is secreted into the stomach lumen with Cl-An ATPase pump is required for this secretion, and this pump is inhibited by stomach acid-reducing drugs like omeprazole. As stomach acid is produced in response to a meal, bicarb exchanges with Cl- in the blood, creating the alkaline tideEventually, this bicarb will be secreted back into the GI tract in pancreatic secretions.

HCl secretion is increased by acetylcholine, histamine and gastrin, while it is decreased by atropine, cimetidine (Tagamet), somatostatin, and prostaglandins (like misoprostol or Cytotec)

Both work by attaching to a cell membrane receptor which affects a nearby G protein to stimulate production of a second messengerThe second messenger for acetylcholine is IP3/Ca++ (inositol triphosphate and calcium ions), while the second messenger for histamine is cAMP.

Cephalic, Gastric, Intestinal

The taste or smell of food alerts the medulla oblongata to stimulate the stomach via acetylcholine from the vagus nerve to make gastrin, 30% of stomach secretions resulting

The distension of the stomach from food alerts the medulla oblongata to stimulate the stomach via acetylcholine from the vagus nerve to make gastrin, 60% of stomach secretions resulting

The presence of acid foods or lips in the duodenum alerts the medulla oblongata to stimulate the stomach via acetylcholine from the vagus nerve to make gastrin, 10% of stomach secretions resulting

Stomach acid (aggressive), Hpylori infection (aggressive), NSAIDs (aggressive), nicotine from cigarettes (aggressive), alcohol (aggressive), impaired blood flow due to ischemia or shock (impaired defense), delayed gastric emptying (impaired defense), duodenal gastric reflux (impaired defense)

Acinar cells make digestive enzymes.Ductal cells make bicarb

Amino acids and fatty acids stimulate duodenal I cells to produce CCK, which stimulates acinar cells to make enzymesH+ stimulate duodenal S cells to make secretin, which stimulates ductal cells to release bicarb.

Potentiation requires that stimuli act on different membrane receptors and trigger different cellular mechanisms for the stimulation of secretionCCK, secretin, and acetylcholine all work together to maximize the stimulation on an acinar cell to produce enzymes.

Due to malfunction of a chloride pump, sticky mucous builds up on the outside of pancreatic exocrine cells, so enzymes cannot be released as they should, digestion does not occur properly, and food cannot be absorbed in the small intestine

the chemical breakdown of food molecules into pieces small enough to enter enterocytes

the movement of digested food, water, or electrolytes from the gut lumen, past the enterocytes and into the bloodstream

Glucose, galactose, or fructose

starch and glycogen are both glucose polymers