Mini 2 - Digestive + Renal Flashcards
Which digestive hormones/substances stimulate the PLC pathway?
ACh (M3), Serotonin (5HT), CCK (CCK1).
Does the gallbladder have all the layers of the gut tube>
Not submucosa.
What is special about PAH?
Totally secreted - C=RPF = 600mL/min
Where is the macula densa?
Thick ascending loop of Henle.
What is alkaptinuria?
Deficiency of homogentisate oxidase. Homogentisate accumulates, black pigment deposits in cartilage, arthritis in elderly.
What are the functions of Vitamin E (Tocopherol)? What is the active form?
alpha-tocopherol is the most active. Works as an antioxidant, scavenges free radicals.
How much energy is obtained from carbs?
4kcal/g
Does the small intestine have a muscularis mucosa?
Yes.
What percent of daily calories should be gotten from simple sugars and disaccharides?
<10%
What are the fat-soluble vitamins?
A (Retinol), D (Cholecalciferol), E (Tocopherol), K (Quinone).
In Farber disease, what enzyme is defective and what accumulates?
Defective - ceraminidase Accumulates - ceramides in joints, CNS, liver, heart, kidney
What do Intercalate cells reabsorb and secrete?
Reabsorb potassium (but can secrete) and chloride paracellularly. Secrete H+.
In the filtration apparatus, what do the glomerulus capillary endothelium and the basement membrane do?
Capillary endothelium prevents cell penetration (pores 50-100nm), basement membrane prevents penetration of plasma proteins.
Where is enteropeptidase made and as what zymogen? What does it target?
Made in the duodenal and jejunal brush border cells as proenteropeptidase. Targets a residue of 4XAsp Lys, hydrolysis occurs on the Lys c-term.
What is in the esophageal submucosa?
Esophageal glands that secrete mucus.
Desctibe the submucosa of the stomach.
No glands, large blood vessels, Meissner’s plexus.
What tissue besides epithelium is in the kidney?
LCT renal intetstitium.
Describe tubuloglomerular feedback.
More fluid means more sodium coming in with the macula densa NCCK. This activates the Na+/K+ pump. More ATP is produced (and adenosine), binding to the P2X (and A1) receptor on smooth muscle calcium channel, causing vasoconstriction. Ca2+ also enters granular cells, decreasing renin release.
What are the functions of Vitamin B6 (Pyridoxine)? What is the active form?
Found as pyridoxine (plants), pyridoxal, and pyridoxamine (ianimal products). Active form is pyridoxal phosphate (PLP). PLP it the cofactor for many enzymes - e.g. decarboxylation, transamination, deamination, condensation. In high doses can be used to treat carpal tunnel.
What are the types of papillae and which have taste buds?
Filiform (most abundant), Fungiform (taste buds on dorsal surface, less keratin), Circumvallate (generally nonkeratinized, 250 taste buds/papilla facing laterally), Foliate (rudimentary in human).
What class of drug is Omeprazole and how is it administered?
PPI, oral. Given as acid-resistant enteric coated formulation.
What is WIlson’s disease?
What are the levels of Cu and ceruloplasmin, and how do you treat it?
An autosomal recessive mutation in ATP7B which encodes a Cu@+ ATPase that transports copper into the ER/golgi. Copper accumulates in the liver and brain leading to dementia, movement disorders, Kayser-Fleisher rings. Will result in high blood copper, low blood ceruloplasmin. Treat with penicillamine (Cu chelator).
How does somatostatin affect the GI system?
It inhibits parietal cells, inhibits ECL cells, inhibits G cells. Decreases acid.
Describe a Vitamin D (Cholecalciferol) deficiency.
Rickets (lack of bone mineralization) if in a child, but in adults it is osteomalacia (demineralization).
Where is dipeptidase made and as what zymogen? What does it target?
Made in SI enterocytes, acts in and on brush border. Has no zymogen. Targets dipeptides.
What enzymes make a type A blood antigen and which make type B?
A = N acetylgalactosamine B = galactose trasferase Added onto terminal galactose.
What is lined by urothelium?
Calyces, ureter, bladder, urethra.
How much H+ is excreted via the two methods of H+ excretion?
40mmol with each but ammonia can increase to as much as 500mmol.
Describe a Vitamin B9 (Folate) deficiency.
Common in pregnant women and alcoholics. Causes megaloblastic anemia - can leadt to neural tube abnormalities in the fetus.
What enzyme in the GI besides trypsin can autocatalyze in acidic conditions? And where is it activated?
Pepsin. In the stomach (the rest of the enzymes are cleaved in the SI).
Where in the lower intestinal tract is crypt cell bicarbonate secretion highest?
Proximal colon.
Of the water-soluble vitamins, which areconsidered energy-releasing?
B1 (Thiamine), B2 (Riboflavin), B3 (Niacin), B5 (Pantothenic acid), B7 (Biotin).
What enzyme do you use in beta oxidation is there is an even double bond?
2,4 dienoyl CoA isomerase. Uses NADPH.
What is normal RPF?
600mL/min.
How are branched chain amino acids metabolized?
Transaminated to alpha-ketoacids and then and then dealt with by branched chain alpha keto acid dehydrogenase. Val and Ile completion goes through propionylCoA, Leu goes through a purely ketogenic degradation.
How do bacteria aid in digesting lipids?
It makes SCFAs that the colon can absorb via secondary active transport. Byproducts can be gas, pain, etc.
What is homocystinuria? How do you treat it?
Deficiency of cystathione synthase (B6). Osteoporosis, ectopia lentis, thromboembolism (arterian and venous), mild mental deficiency, psychiatric problems. Give B6, maybe B9/B12, restrict methionine, give betaine to stimulate homocystine-to-methionine converstion.
What are the food sources of Vitamin E (Tocopherol)?
Vegetable oil, oil seeds, wheat germ.
Describe the muscularis externa of the large intestine.
The outer longitudinal layer is formed into 3 longitudinal strips - teniae coli.
Describe a Vitamin A (Retinol) deficiency.
Common in developing countries. Night lindness, eventual loss of retinal cells, xeropthalmia.
What controls the ileocecal sphincter?
The SNS, vagus, ENS. Ileal distension/irritation leads to relaxation, cecal distension/irritation leads to contraction.
What is special about inulin?
Ms = Mr = 0 C=GFR = 120mL/min
What class of drug is misoprostol and how is it administered?
Mucosal protective agent, oral, vaginal, rectal.
How are bile acids and salts reabsorbed?
Through enterohepatic circulation, reabsorbed in the terminal ileum. Primary and secondary bile acids passively diffuse in. Na+ dependent carrier mediated secondary active transport beings in primary bile salts only.
Describe glycerophospholipids and name the 4 relevant ones.
Glycerol backbone, 2FAs (middle one usually unsaturated) attached through ester bonds. Phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol.
What is clearance?
The volume of plasma cleared of a substance per unit of time.
What is metoclopramide used to treat?
Diabetic gastroparesis, good for advancement of nasoenteric feeding tube, can do GERD but is not preferred - may be given with a PPI in patients with reractory heartburn or regurgitation.
What substances stimulate the lower esophageal sphincter?
Between swallows - vagal excitatory fibers (ACh, SP). During swallow - vagal inhibitory fibers (VIP, NO).
What is the effect of dietary cholesterol on serum cholesterol?
Currently we think none.
What is kwashiorkor?
A diet inadequate in protein (high carb subsistence diet) resulting in a pot belly, fatty liver, hypoalbuminemia, edema.
How do omeprazole and esomeprazole work?
They are proton pump inhibitors on the apical parietal cell H+/K+ ATPase. They covalently, irreversibly bind.
What does Adipose Triglyceride Lipase (ATGL) have a preference for?
End FA.
What is Menkes Disease?
X-linked recessive mutation in ATP7A gene, wwhich encodes an intestinal Cu2+ translocase. Cupper accumulates in the small intestine and kidneys, lowly in the brain. Results in kinky hair, seizures, unstable body temperature. Will result in low blood copper and ceruloplasmin. Poor prognosis, usualy death by 3 years of age, give copper supplements.
What are the food sources of Vitamin B1 (Thiamine)?
Most foods, yeast, lean pork, legume seeds.
What cells are in the crypts of the large intestine epithelia?
The lower 2/3 entirely goblet cells. Has EECs, SCs too.
What is the net H+ from metabolism that isn’t balanced out by OH-?
80mmol.
What enzymes break down lipids?
Lingual (~pH 5) and gastric lipases (pH 3-6) - 10% digestion in the stomach. Pancreatic lipase in the duodenum (uses colipase and cholesterol esterase and PLA). Colipase attaches to a TG on the surface of an emulsion droplet, and serves as an anchor for lipase which hydrolyzes the ester bonds.
What class of drug is magnesium hydroxide and how is it administered?
Antacid, oral. Also considered an osmotic laxative.
What are some adverse effects of aluminum hydroxide?
Constipation.
What sizes and charges of molecules are filtered better or worse?
under 18A are freely, >42A not filtered. If between 18 and 42 then positively charged are filtered more and negatively charged are filtered less. If smaller than 18A, negatively charged are filtered more, positively charged are filtered less.
What triggers renin release?
Decreaed renal perfusion or hyponatremia.
How much energy is obtained from alcohol?
7kcal/g
How is CPSI regulated?
N- acetylglutamate is an allosteric activator, arginine regulates its synthesis.
What is special about kidney circulation?
Has two capillary beds, an afferent arteriole -> CN (glomerulus) -> efferent arteriole -> CN -> venule. The second capillary network is either peritubular capillaries or vasa recta.
How does metoclopramide work?
A dopamine D2 receptor antagonist. It enhances gastric emptying, speeds up digestion, antinausea and antiemetic action.
Where is secretin made?
By S cells mainly in the duodenum (some in the jejunum).
In Sandhoff disease, what enzyme is defective and what accumulates?
Defective - Hex A and B (A has alpha and beta subunits, B is beta homodimer). Accumulates - GM2 and globosides.
What are the functions of VItamin B1 (Thiamine)? And what’s its active form?
Thiamine pyrophosphate. It is a cofactor in several metabolic enzymes carrying out aldehyde transfer or oxidative decarboxylation. E.g. PDH, alpha KG dehydrogenase, transketolase (in HMP, assayed by erythrocyte transketolase reaction).
What are the three types of intestinal segmentation movements?
Regularly spaces, isolated, irregularly spaced.
How does an increase in total resistance in kidney circulation affect filtration/reabsorption?
Increased reabsorption.
What is molybdenum needed for? Where is it found?
Nitrogenases and oxidizing proteins. Found in legumes, grains, nuts.
What is the normal plasma pH?
7.37-7.45.
What is special about the appendix?
It has the most lymphatic nodules per unit area of any GI organ.
What is GIP’s target?
Pancreatic beta cells (potentiates insulin secretion), parietal cells, G cells (inhibit gastric secretion and motility).
What is the relationship between urine flow rate and potassium excretion?
Proportional.
How do parasympathetic and sympathetic stimulation affect the medullary salivatory nucleus?
PNS increases flow and stimulates watery parotid secretions. SNS reduces flow (still flow though) and stimulates thicker, enzyme rich submucosal secretions. Both have both, neither have neither.
How is Tay-Sachs inherited and what are the symptoms?
Autosomal recessive. Classic version is infantile onset (3-6mo), death by 3 years. Growth retardation, dysphagia, seizures, decreaed mental skills and muscle tone, deafness, blindness, paralysis, cherry red spot in the macula surrouned by grey-white.
In which parts of the small intestine is folate/B9 absorbed?
Duodenum.
What’s the gallbladder muscularis externa like?
Muscle fibers oriented in all directions to facilitate emptying.
What is methylmalonc acidemia? How do you treat it?
Deficiency of methylmalonyl CoA mutase (needs B12). Causes acidosis, ketosis in acute attacks. Treat with adenosyl-cobalamin or dietary protein restriction, avoidance of stress, avoidance of fasting and low-carb diets.
What are the food sources of Vitamin B6 (Pyridoxine)?
Liver, fish, whole grains, nuts, egg yolk.
Describe vomiting/emesis.
Peristalsis suppressed, powerful abdominal muscle contraction creating strong pressure gradient, stomach, LEX, esophagus relax. Sometimes there is antiperistalsis/retroperistalsis.
How is the carnithine shuttle regulated?
Malonyl CoA inhibits CPTI.
What does fluoride do? What can deficiency cause?
It helps form hard bones and teeth. fluoroapatite is harder than hydroxyapatite. Deficiency can cause tooth decay.
What are the three ketone bodies?
Acetoacetate, 3-hydroxybutyrate, acetone/
What is the specific target of salivary alpha amylase?
alpha 1->4 glycosidic linkages in starch. Produce is maltose and smaller starches.
What percent of the diet should be fat?
25-35%.
Describe a deficiency in Vitamin B1 (Thiamine).
Can occur if polished rice is the primary diet. Can cause Beriberi - mild has GI complaints, weakness, burning feet sensation. Severe has peripheral neuropathy, mental abnormality, ataxia. Dry beriberi means there are neurological deficits, wet beriberi means there is edema due to cardiac dysfunction. Can also cause Wernicke-Korsakoff syndrome (common in alcoholics). Acute has Wernicke encephalopahty (mental deramgement, ataxia, eye paralysis), chronic has Korsakoff psychosis (severe debilitating anterograde amnsia, frontal lobe damage). Mamillary bodies disappear.
What is the amino acid you want for the urea cycle?
Glutamate.
How does K+ secretion change as you move down the colon?
Decreases. Passive secretion paracellular and greatest in distal colon. Active secretion transcellular and greatest in proximal colon.
What is the main signal of motilin?
Not very well understood, lack of nutrients.
What is the effect of calcitriol on the kidney?
Increases calcium reabsorption in the DCT.
What does phospholipase C do?
Cleaves the headgroup in a glycerophospholipid between glycerol and the phosphate.
How is the venous blood relatively in respiratory acidosis compared to the arterial?
Increased PCO2, increased bicarbonate concentration, lowered pH.
How many tongue muscles are there - how are they aligned and with what nerve are they controlled?
3, orthogonally, CN XII.
How is bicarbonate concentration affected by an increase of CO2 in and not in the presence of additional buffer?
An increase in CO2 barely affects the bicarbonate concentration, but having other buffers present will cause it to increase because it will reduce the H+.
What separates the anterior/oral and posterior/pharyngeal surfaces of the tongue?
The sulcus terminalis. (Foramen cecum at its apex is the origin of the thyroid gland).
What is non-ketotic hyperglycinemia? How do you treat it?
Lack of glycine cleavage enzyme. Give NMDA receptor blockers or Benzoic aid.
What’s the gallbladder mucosa like?
Simple columnar, lamina propria, no muscularis mucosa.
What are the essential amino acids?
Ones that must be obtained from the diet. Val, Ile, Leu, His, Lys, Met, Thr, Phe, Trp, .
Describe a Vitamin D (Cholecalciferol) toxicity.
Toxic in very high doses. Is stored in body fat. Loss of appetite, nausea, thirst, stupor, hypercalcemia.
List the crypt cell channels.
How do lipolytic digestion products (FAs) enter enterocytes? Where do they go?
Through FAT or just through diffusion. They reform as triglycerides and go to golgi, released as chylomicrons that go into lymph.
How is ADH stimulated to be released.
Osmoreceptors (neurons) in the Nucleus Paraventricularis and Nucleus Supraopticus in the hypothalamus cause ADH to be released from the posterior pituitary (neurohypophysis). Baroreceptors also input to these neurons (low BP).
How is the recommended daily intake determined for vitamins/minerals?
Such that 98% of people won’t show signs of a deficiency.
Describe triglyceride synthesis.
A G3P backbone (made from DHAP or glycerol in the liver) is taken. A FA Coa is added (usually unsaturated at the middle position) and then the phosphate is removed to add the third fatty acid.
What is the mucosa like in the cardia of the stomach and what cell types are there?
No goblet cells, glands are as big as the pits, long, branched, coiled. Mucus secreting cells, SCs, EECs, few parietal cells.
Describe Vitmain B6 toxicity.
Toxic in high doses (400X RDA, 500mg/day), can have neuro symptoms. But in less high doses (100mg.day_ can be used to treat carpal tunnel.
How is acetoacetate ketone body generated?
Ac CoA is made into acetoAcCoA, which is then made into HMG COA with HMG CoA Synthase. Then HMG CoA Lyase catalyzes it into AcCoA and acetoacetate.
What does the liver do?
Makes and secretes bile acids and pigments, excretes heavy metals, cholesterol, bile pigments, drugs and hormones, detoxifies, has hematopoietic functions in fetal life, some defense (Kupffer cells), activates Vitamin D.
How are bile salts moved into the lumen from the hepatocytes?
Transporter Z ATPase moves the ones conjugated to taurine/glycine, Transporter Y ATPase moves the ones conjugated to sulfate/glucuronate.
What kind of muscle is in the esophageal muscularis externa?
Starts out skeletal, then mixed, then just smooth.
How are proteins usually absorbed in the GI tract?
As mono/dipeptides.
How is phosphatidylserine synthesized?
From phosphatidylethanolamine in the liver using phosphatidylethanolamine serine transferase. PS can also be decarboxylated to PE which can then be methylated to PC.
What is an adverse effect of bismuth subsalicylate?
Black stool.
What receptors do parietal cells have?
CCK, M3, H2 (histamine).
Where is triglyceride synthesis carried out?
In the liver, and a little in the muscle and adipose.
Describe the classic hepatic lobule.
Central vein in the center, hexagonal. Emphasizes the endocrine function of the hepatocyty.
What is the contraction pattern of the gut wall from the stomach down (besides the sphincters).
Phasic. A slow wave - phasically changing membrane potential. A spike (AP) is a consequence of the slow wave reaching the threshold.
How does ADH work?
It binds, stimulates a Gs mechanism, causes aquaporins to be moved to the luminal membrane.
What is the contraction pattern of the esophagus and bladder?
Normally relaxed, tightens for short bursts - opposite of sphincters.
Describe the structure of a hepatocyte.
Can be binucleated, are cube-like with 6 major surfaces (2 sinusoidal and 4 lateral). Sinusoidal domains covered in microvilli that project into the space of Disse. The lateral domains form the bile canaliculi.
Where besides the GI are there lipases?
Muscle and adipose have it in their capillary lumen.
Describe the muscularis externa of the small intestine.
Has Myenteric Plexus between the two layers.
What are the functions of Vitamin B7 (Biotin)?
Prosthetic group for many ATP-dependent carboxylases, typically covalently bound.
What is propionic acidemia? How do you treat it?
Deficiency of propionyl carboxylase (needs B9). Comes with recurrent metabolic acidosis, neurologic complications. Treat with dietary restriction.
What are hepatic sinusoids?
Specialized capillaries that carry blood through the parenchyma; have sinusoidal endothelium, Ito cells (fat storing in space of Disse, store vit A, secrete lipid collagen), and Kupffer cells (macrophaces, APCs).
In which parts of the small intestine is calcium absorbed?
The whole thing.
What can Histidine be metabolized into?
Histidase can remove NH3 to make FIGlu, which can be converted to glutamate. FIGlu accumulates after an oral histidine load if there is a B9 deficiency.
Where is the ENaC found and what is it?
Epithelial sodium channel. Found in the distal colon.
What is normal renal blood flow?
1100mL/min (25% of CO)
Which side of the cell does minor hormone guanylin come from?
The apical side.
What is salivary ductal processing?
Na+ and Cl- reabsorbed from primary saliva.
Describe the regulation of Acetyl CoA carboxylase.
Activated by citrate and in dephosphorylation. Downregulated by accumulation of LCFAs and AMP kinases.
What does ALT do?
Transfers a nitrogen from Ala to alpha-ketoglutarate, making a glutamate.
What is phenylketonuria? How do you treat it?
Autosomal recessive phenylalanine hydroxylase deficiency. Excess Phe causes mental retardation, light skin and hair, eczema, ‘mousy’ odor of infant. Tyrosine is now an essential amino acid. Treat by limiting Phe in diet, especially in pregnancy.
What does the Meissner’s/Submucosal Plexus control?
GI secretions.
What is the glycocalyx?
Outer carb coating on membranes, made from glycolipids. It is dark staining on EM.
What is a chylomicron remnant?
A chylomicron that has been depleted of triglyceride. It goes to the liver, fatty acids are repackaged back into VLDLs.
What sets the pace for slow waves? What are the paces n the different organs?
Insterstitial cells of Cajal (ICCs) in the stomach and within the walls of the SI and LI. Stomach - 3-4/min Duodenum - 10-12/min Colon - 3-7/min
What is saliva like at high and low flows?
Very hypotonic at the slowest flow (highest K+). At fastest flow, elevated bicarbonate and NaCl (inefficient reabsorption). Less hypotonic.
What sort of tissue is the kidney primarily made of?
Epithelium.
What is cystathionuria?
A deficiency in cystathionase, no clinical symptoms. Cystathione accumulates.
Where is carbohydrate breakdown done
In the duodenum and jejunum.
How much linoleic acid is needed in the daily diet?
12g or 17g
What are the two important primary bile acids to know?
Cholic acid/cholate and chenodeoxycholic acid.
What is the end result of beta oxidation of an odd chain fatty acid and how do you deal with it?
Propionyl CoA. Propionyl CoA carboxylase (B7 cofactor) uses ATP to turn it into methylmalonyl CoA which is processed by methylmalonyl CoA mutase (B12 cofactor) into succinyl CoA.
How does reduction in ECV affect calcium reabsorption?
Increases it.
What are the cells of the thin Loop of Henle like?
Simple squamous.
What are the types of cells in the distal tubule and collecting duct?
Principal cells and intercalated cells (both cuboidal). Principal is more abundant, have numerous basal infoldings, distinct lateral margins, few microvilli. Intercalated cells are far fewer and actively secrete H+.
What’s the difference between amylose and amylopectin?
Amylose is linear and digested slower, amylopectin is branched and digested faster.
How are urea cycle deficiencies treated?
Avoid protein, fasting, low carbs, stress, replace amino acids with their alpha ketoacids. In the case of an arginosuccinate lyase deficiency, just give arginine (it can be excreted).
What are the 5 patterns of digestion/absorption?
- monomer, no digestion needed 2. digestion in lumen into monomers 3. digestion in lumen into oligomers, further digestion at brush border into monomers 4. dimers and trimers absorbed into enterocyte, digested into monomers inside cells 5. digested into monomers in lumen, absorbed into enterocytes, repackaged into larger molecules before exiting enterocytes
Is the stuff coming out of pancreatic ducts acidic or basic?
Basic.
What are the functions of Vitamin B3 (Niacin)?
Converted to NADH and NADP - coenzymes for numerous reactions and also redox carriers. Can also be used to treat hyperlipidemia.
What is an adverse effect of lubiprostone?
Nausea.
What is a sphingolipid?
Ceramide (sphingosine + FA) + headgroup.
What are EECs alternate names? What do they look like in histological staining?
APUDs (Amine precursor uptake and decarboxylation), Gastro/entero endocrine cells. G cells (gastrin), D cells (somatostatin), EC cells (serotonin).
If the Sphincter of Oddi is closed, where does bile back up into?
The gallbladder.
What does the macula densa do?
Senses sodium concentration in the urine (or lowered blood volume), and signals juxtaglomerular cells.
Describe the effect of vagal neurons on gastric acid secretion.
Increases - stimulate parietal cells, ECL cells, G cells, inhibit D cells.
What are bile canaliculi? Where do they drain into?
Small, tubular, PM-bound enlargements in the EC space between two adjacent hepatocytes, sealed by zonula occludens. They drain into the canals of Hering (short simple epithelia), which drain into bile ducts.
What are the portions of the collecting duct?
Collecting tubule, cortical collecting duct, medullary collecting duct, papillary ducts/ducts of Bellini (end at renal papilla).
What is secretin’s signal?
pH under 4.5 in the duodenal lumen - minorly in the jejunal lumen.
What are the functions of Vitamin D (Cholecalciferol)? What is its active form?
Active form is calciferol. Maintains plasma calcium concentration - increases intestinal absorption, mininmizes kidney loss through resorption.
What is a glycemic load?
How much a typical serving of a food raises blood [glucose].
What is the headgroup on sphingomyelin?
Choline.
What is iodine needed for? What can deficiency cause?
Thyroid hormone - goiter.
How do blood and bile flow through the hepatocyte?
Blood goes into the center through the periphery, bile goes outward.
How does acidosis affect potassium and calcium?
Decreases calcium reabsorption, increases potassium reabsorption.
What are the sources of dietary fiber?
Bran, navy beans, shredded wheat, cranberry beans, lentils, peas.
What increases CFTR activity?
ACh (M3 ENS receptors), VIP, prostaglandins, histamine, (AC action), serotonin (5HT, PLC), anything that increases guanylyl cyclase.
Describe Hormone sensitvive Lipase (HSL).
Has a preference for the middle position FA. Epinephrine (cAMP) stimulates its activity by the kinase action, insulin activates phosphatase.
How does bicarbonate secretion change as you move down the colon?
Decreases (highest in proximal colon).
When sphingomyelin is made from phosphatidylcholine, what is the other product?
DAG.
What can Serine be metabolized into?
3PG (from which it originates), pyruvate, Glycine.
What class of drug is lactulose and how is it administered?
Osmotic laxative, oral and rectal.
What does warfarin do?
Blocks Vitamin K epoxide reductase, which regenerates Vitamin K.
What does fatty acid synthesis require and where is it done?
Requires ATP and reducing equivalents NADPH. It takes place in the cytosol.
Is salive hypo, iso, or hypertonic to plasma?
Hypotonic. Watery, contains ions.
How does calcium leave the cell?
Basolaterally - via a calcium/hydrogen exchanger (primary active transport) or a Na+/Ca++ antiport using the sodium potassium pump.
What is the medullary ray?
Straight tubes (straight prox and distal tubules and also collecting duct) going to and from medulla.
How does alanine contribute to the urea cycle?
In the liver amines are sent to glutamate (generating pyruvate).
What is marasmus?
Calorie intake is relatively less than protein intake (weaning to low calorie foods) resulting in emaciation, anemia, low subcutaneous fat, weakness.
What are the food sources of Vitamin K (Quinone)?
Cabbage, spinach, kale, egg yolk, liver, is also synthesized by gut flora.
What is the effect of ADH on tubule fluid osmolarity?
Tubular fluid is hypoosmolar as it reaches the late distal tubule, if ADH is present water will be reabsorbed to equalize osmolarity.
In Tay-Sach’s disease, what enzyme is defective and what accumulates?
Defective - Hexasominisade A Accumulates - GM2 ganglioside
What is the mucosa like in the fundus/body of the stomach and what cell types are there?
Shallow puts and deep glands (straight). Neck of glands has mucus cells, SCs, lots of parietal cells. Base of glands has few parietal cells, chief cells, mucus cells, EECs.
What is MSUD?
Maple syrup urine disease, accumulation of branched chain amino acids and their alpha ketoacids.
What do Chief cells produce and what are their alternate names? In what part of the glands are they? What do they look like in histological staining?
Peptic/Zymogenic cells. They produce pepsinogen and a weak lipase. Lower 1/3 of gland. Basophilic, granules are visible, triangular in shape, smaller than parietal cells.
How is calcium kept in the cell before being moved across the basolateral membrane? How does it come into the cell?
Held in place with calbindin. It can come in paracellularly or transcellularly.
What are the two essential fatty acids?
Linoleic acid (C 18:2 cis 9,12) - omega 6. Linelenic acid (C 18:3 cis 9,12,15) - omega 3
How does increased efferent arteriolar resistance affect GFR and RPF?
Increases glomerular capillary pressure, increasing filtration but decreases RPF. So GFR effect unclear.
What is the contraction pattern of blood vessels/airways?
Normally partially contracted, has tone/
Where is K+ absorption in the GI tract?
In the distal colon only. Exchanged with hydrogen at surface epithelial cells.
What class of drug is bismuth subsalicylate and how is it administered?
A musosal protective agent, oral.
How is clearance calculated?
Urine flow X urine concentration / Arterial plasma (must make sure plasma concentration is constant) mL/min units.
How is calcium reabsorbed in the kidney?
In the proximal tubule and the thick ascending loop of henle, there is an apical calcium channel, and a basolateral Ca++/3Na+ exchanger and a Ca++/2H+ ATPase.
How do you calculate amount filtered?
GFR X Pa
What is a phosphate buffer good for?
In ECF, bad in erythrocytes.
What does phospholipase A do?
Cleaves FAs from glycerol (A2 can release arachidonic acid from PI or PE).
What is the primary function of the large intestine?
Resorbtion of water and salts.
What is acrodermatitis enteropathica?
A defect in zinc absorption. Results in inflammation with pimples, diarrhea, abnormal nails. Congenital form is chromosome 8 SLC39A mutation.
What are osmotic laxatives good for?
Clearing for imaging procedures.
What epithelium lines the stomach?
Simple columnar.
What is manganese needed for?
Many enzymes - ATPases, arginase, pyruvate carboxylase, peptidases, etc. Important in healthy bones and cartilage, metabolism and reproductive functions.
How are protein/peptide hormones metabolized?
Quickly - act fast and are secreted quickly, fast on and fast off.
Which vitamins can have toxicity?
A (Retinal), D (Cholecalciferol), K (Quinone), B3 (Niacin), B6 (Pyridoxine).
List the parietal cell channels.
What are the adverse effects of mineral oil?
Impaired absorption of fat-soluble vitamins, pneumonitis upon aspiration.
How does increased afferent arteriolar resistance affect GFR and RPF?
Decreases both. Decreased filtration.
How is Metachromatic Leukodystrophy (MLD) inherited and what are the symptoms?
Autosomal recessive. Difficulty walking, muscle wasting, blindness, convulsions, dysphagia, paralysis, dementia (infantile or juvenile), psychiatric disorder (in adults).
When in the esophagus is it adventitia and when is it serosa?
Adventitia in the thorax, serosa in the abdomen.
What are globosides?
Ceramides with more than one sugar in a linear linkage.
How many grams of protein generate how much urea?
3g protein to 1g urea.
Is the muscle sensitive to glucagon?
No.
How does sucralfate work and what is it best used to treat?
It is negatively charged and binds to positively charged proteins on ulcerated tissue. It is best as a short term therapy for duodenal ulcers, also reduces incidence of upper GI bleeding in critically ill patients.
How much water and salts reabsorption is done in which parts of the kidney tubular system?
2/3 in proximal tubule, 1/3 in distal.
What is a normal standard bicarbonate?
24
Describe the hepatic acinus.
Blood from each acinus supports two or more classic lobules. It emphasizes the different oxygen and nutrient contents of blood. The closer to the central vein the lower the oxygen content - periportal, mid-zonal, centrilobular spaces.
What are the food sources of Vitamin D (Cholecalciferol)?
Fatty fish, liver, egg yolk, milk (if fortified). Gotten from diet as ergocalciferol, can be made in the skin.
What are plasmalogens?
Similar to phospholipids except the end FA group has an ether linkage and a double bond rather than an ester linkage.
How much energy is obtained from protein?
4kcal/g
Describe the functions of Vitamin B5 (Pantothenate).
Part of CoA, coenzyme in FA synthetase.
What is Olestra?
An 8 FA indigestible disaccharide.
What are some adverse effects of Cimetidine?
Inhibits several enzymes of the hepatic cyt p450 metabolism pathways. Inhibits binding of DHT to androgen receptors and inhibits estradiol metabolism - gynecomastia, loss of libido, impotence.
Where are aminopeptidases made and as what zymogen? What does it target?
Made in IC compartments and have no zymogen. A brush border enzyme. Target is amino terminal peptide bonds.
Desribe fatty acid synthesis.
Acetyl CoA is turned into Malonyl CoA using Acetyl CoA carboylase. Then the FAS enzyme cysteine site is primed with a starter chain, and the malonyl CoA is added to the ACP on the pantethiene arm of the enzyme. A condensation reaction adds the starter chain to the malonyl CoA (one CO2 lost). THen there is a reduction with ketoreductase, a dehydration, and a reduction with enoyl reductase (each reduction is at the cost of an NADPH). The new chain is translocated to the enzyme Cys-SH and everything is repeated until there is a saturated 16 carbon palmitate.
How does bile go from the canaliculi?
Interlobular ducts, septal ducts, lobar ducts, R&L hepatic ducts.
What are the trace elements?
Fe, Zn, Cu, Mn.
How frequently does the proximal colon do mass peristalsis?
1-3x a day. May move the contents 20cm or more.
Are all size fatty acids made into chylomicrons?
No, just ones 14-18 carbons. Small and medium FAs just go to the liver.
