ap2 final pp

Glomerular filtrate

(similar to plasma, but less protein) collects in capsular space, flows into proximal convoluted tubule. Note the afferent arteriole is larger than the efferent arteriole.

ANP

-Natriuretic peptides Released by heart in response to stretched walls due to increased blood volume or pressure Atrial natriuretic peptide (ANP) is released by atria Trigger dilation of afferent glomerular arterioles and constriction of efferent glomerular arterioles Increase glomerular pressures and increase GFR ANP also decreases sodium reabsorption Net result is increased urine production and decreased blood volume and pressure

1- Glomerular filtration 2-Tubular reabsorption 3-Tubular secretion 4-Water reabsorption

1- Creates a plasma-like filtrate of the blood 2-Removes useful solutes from the filtrate, returns them to the blood 3-Removes additional wastes from the blood, adds them to the filtrate 4-Removes water from the urine and returns it to blood; concentrates urine

Lipid Transport and Use

1- Micelles are absorbed into intestinal mucosa where they are converted into chylomicrons. 2- Intestinal cells secrete chylomi- crons, which are absorbed into lacteals 3- From the lacteals, the chylomicrons proceed within the lymphatic vessels and into the thoracic duct, and from there are distributed throughout the body. 4- Lipoprotein lipase in the capillary endotheliumbreaks down the chylomicrons and releases fatty acids and monoglycerides into the interstitial fluid. 5- Resting skeletal muscles absorb fatty acids and break them down for ATP production or storage as glycogen. Adipocytes absorb fatty acids and use them to synthesize triglycerides for storage.

The Regulation of Digestive Activities

1-Local factors are the primary stimulus for digestion. They coordinate the responses to changes in the pH of the contents of the lumen, physical distor- tion of the wall of the digestive tract, or the presence of chemicals—either specific nutrients or chemical messen- gers released by cells of the mucosa 2- neural control mechanisms The movement of materials along the digestive tract, as well as many secretory functions, is primarily controlled by local factors. Short reflexes are triggered by chemoreceptors or stretch receptors in the walls of the digestive tract; the controlling neurons are located in the myenteric plexus. These reflexes are often called myenteric reflexes. Long reflexes involving interneurons and motor neurons in the CNS provide a higher level of control over digestive and glandular activities generally controlling large-scale peristalsis that moves materials from one region of the digestive tract to another. Long reflexes may involve parasympa- thetic motor fibers in the glossopharyn- geal (IX), vagus (X), or pelvic nerves that synapse in the myenteric plexus.l 3- hormone control mechanism The digestive tract produces numerous hormones that affect almost every aspect of diges- tion, and some of them also affect the activities of other systems. These hormones are peptides produced by entero- endocrine cells, endocrine cells in the epithelium of the digestive tract. We consider these hormones as we proceed down the digestive tract.

countercurrent Multiplier of Nephron Loop

1-More salt is continually added by the PCT. 2-the higher the osmolarity of the ECF, the more water leaves the descending limb by osmosis. 3-The more water that leaves the descending limb, the saltier the fluid is that remains in the tubule. 4-The saltier the fluid in the ascending limb, the more salt the tubule pumps into the ECF. 5- The more salt thatis pumped out of the ascending limb, the saltier the ECF is in the renal medulla.

Large Intestines: Functions and Bacterial Flora

3 parts: cecum, colon, rectum - ends at anusAppendix attached to lower end of cecum Densely populated with lymphocytes- immune function! Large intestine reduces indigestible residue by absorbing water and salts (compaction of waste) Stores feces prior to elimination Eliminates feces by defecation Bacterial flora populate large intestineDigest cellulose and other undigested carbohydrates Body absorbs resulting sugars Help in synthesis of vitamins B and K Vit K required to make clotting factors

Renal Autoregulation

3 special kinds of cells occur in juxtaglomerular apparatus Macula densa: patch of closely spaced epithelial cells of DCT at end of nephron loop on side of tubules facing arterioles Senses variations in NaCl, as an indication of flow and secretes a paracrine factor that stimulates/inhibits JG cells Juxtaglomerular (JG) cells: enlarged smooth muscle cells in afferent arteriole across from macula densa Dilate or constrict arterioles when stimulated by the macula densa Contain granules of renin, secreted in response to drop in BPMesangial cells: in cleft between afferent and efferent arterioles and among capillaries of glomerulus Connected to macula densa and JG cells by gap junctions and communicate via paracrine secretions Connected to foot processes of podocytes Constrict or relax capillaries to regulate flow Renal autoregulation—nephrons adjust own blood flow and GFR without external control, by vasodilating or vasoconstricting the afferent and efferent arterioles and glomerular capillary diameter Enables them to maintain relatively stable GFR despite changes in systemic arterial BP 2 methods of autoregulation: myogenic mechanism tubuloglomerular feedback Myogenic mechanism —based on tendency of smooth muscle to contract when stretched Increased arterial BP stretches afferent arterioleArteriole constrictsPrevents blood flow into glomerulus from changing too much When BP fallsAfferent arteriole relaxesAllows blood flow more easily into glomerulus Filtration remains stable Tubuloglomerular feedback —glomerulus receives feedback on status of downstream tubular fluid (NaCl concentration, which indicates flow rate). adjusts filtration to regulate composition of tubular fluid Regulated by juxtaglomerular apparatus Macula densa detects NaCl content of tubular fluid If NaCl is high, indicates high GFR Can release paracrine to vasoconstrict afferent arteriole to decrease GFR If NaCl is low, indicates low GFR can release paracrine to vasodilate afferent arteriole to increase GFR

Compensation for pH changes

A person cannot live for more than a few hours if blood pH is < 7.0 or > 7.7 Kidney and lungs help regulate pH by altering the amount of H+ that is excreted (as H+ in kidney tubules or CO2 in lungs) Respiratory Compensation - changes in the rate of respiration to stabilize pH if PCO2 increases, pH decreases (acidic) = need to breathe faster if PCO2 decreases, pH increases (basic) = need to breathe slower Renal compensation - changes in the rates of H+ and HCO3-reabsorption and secretion by kidneys to stabilize pH

Disorders of Acid-Base Balance

Acidosis—pH < 7.35 -more common than alkalosis Respiratory Acidosis - When rate of alveolar ventilation fails to keep pace with body's rate of CO2 production- hypercapnia Detected by chemoreceptors, which trigger an increase respiratory rate Caused by Hypoventilation; CNS injuries; emphysema; pneumonia, asthma Metabolic Acidosis - Production of excess acids - overloads bicarb buffering system: Ketoacidosis = starvation; body begins breaking down proteins Lactic acidosis = prolonged strenuous exercise - anaerobic metab. Impaired renal function disrupts removal of H+ or severe bicarbonate loss as in chronic diarrhea (alkaline secretions from pancreas lost) Alkalosis - pH > 7.45 - less common than acidosisRespiratory Alkalosis CO2 eliminated faster than it is produced- hypocapniaHyperventilation causes it - fear, pain, anxiety, fever, stroke usually chemoreceptors correct this before it becomes a serious problem Metabolic alkalosis - Very rareToo many bicarbonate ions present - reduces H+; alkalosis; Overuse of antacids or Repeated vomiting - keep secreting more HCO3- into bloodstream when producing more HCl to replace vomited HCl postprandial alkaline tide - HCl secretions following a meal, increases HCO3- because H+ from H2CO3 goes into stomach and Cl- and HCO3- goes into bloodstream; why you're tired after eating a big meal

Hydrochloric Acid

Activates pepsin, converts pepsinogen to pepsin Breaks up connective tissues and plant cell wallsHelps liquefy food to form chyme Contributes to nonspecific disease resistance by destroying most ingested pathogens Denatures proteins and inactivates enzymes

the DCT and Collecting Duct

Aldosterone—from zona glomerulosa of adrenal cortex Acts on thick segment of nephron loop, DCT, and cortical portion of collecting duct Stimulates reabsorption of Na+ and secretion of K+ Water and Cl− follow Na+, so body retains NaCl and water Helps maintain blood volume and BPUrine volume is reducedUrine has an elevated K+ and reduced Na+ concentration Antidiuretic hormone (ADH) secreted by posterior pituitary In response to dehydration and rising blood osmolarity Action—makes collecting duct more permeable to water by inserting more aquaporins into membrane Water leaves tubular fluid and enters medullary interstitium due to high osmolarity OSMOSIS is a PASSIVE process! No active mechanism Atrial natriuretic peptide (ANP)—secreted by atrial myocardium of heart in response to high BP All actions oppose AII Parathyroid hormone (PTH) secreted from parathyroid glandsinresponsetolowbloodCa2+ (hypocalcemia) to increase Ca2+ reabsorption from DCTStimulates calcitriol synthesis by epithelial cells of PCT DCT reabsorbs Na+, Cl−, and water under hormonal control, especially aldosterone, ADH, and ANP DCT regulates H+ secretion depending on pH of body fluids DCT completes process of determining chemical composition of urine - fine tuning (depends on needs of body, largely reflected in hormone levels) Collecting duct conserves water, maximizes reabsorption PCT reabsorbs 60-70% glomerular filtrate and returns it to peritubular capillaries Much reabsorption by osmosis and cotransport mechanisms linked to active transport of Na+ Nephron loop reabsorbs another 25% filtrateNeed to reabsorb more water (remember you need to reabsorb 99%) Water reabsorbed in the PCT and nephron loop called Obligatory water reabsorption - so will always reabsorb ~85% water, no matter what Facultative water reabsorption - remaining ~15% precisely controlled by aldosterone and ADH and will occur in DCT and collecting duct; depends on needs of body DCT and collecting duct impermeable to water in absence of hormones

The Filtration Membrane

Almost any molecule < 3 nm can pass freely through filtration membrane Water, electrolytes, glucose, fatty acids, amino acids, nitrogenous wastes, and vitamins (note "good stuff" that we'd prefer not to dump into urine) Some substances of low molecular weight are bound to plasma proteins and cannot get through membrane Most calcium, iron, and thyroid hormone Unbound fraction passes freely into filtrate Kidney infections and trauma can damage filtration membrane and allow albumin or blood cells to filter Proteinuria (albuminuria): presence of protein in urine Hematuria: presence of blood in urine Distance runners and swimmers often experience temporary proteinuria or hematuria Prolonged, strenuous exercise greatly reduces profusion of kidney Glomerulus deteriorates under prolonged hypoxia

The Renin-Angiotensin-Aldosterone Mechanism

Angiotensin II Potent vasoconstrictor raising BP throughout body Constricts efferent arteriole raising GFR despite low BP Lowers BP in peritubular capillaries enhancing reabsorption of NaCl and H2O Angiotensin II stimulates adrenal cortex to secretealdosterone promoting Na+ (and H2O) reabsorption in DCT and collecting duct Stimulates posterior pituitary to secrete ADH which promotes water reabsorption by collecting duct Stimulates thirst and H2O intake

Histology

Basic structural plan in order from inner to outer surface Mucosa - mucous membrane inside, near lumen, where food is processed EpitheliumLamina propria Muscularis mucosae Submucosa Muscularis externa Oblique (only for body of stomach - incomplete layer) Inner circular layerOuter longitudinal layer Serosa - serous membrane, outside of tube, facing peritoneal cavity; aka, visceral peritoneum Mucosa - mucous membrane (epithelium + lamina propria); provides protection from chemicals, mechanical stress, and bacteria Epithelium - Stratified squamous from mouth through esophagus, and anal canal Simple columnar in most of digestive tractHas goblet cells (mucous)Has enteroendocrine cells (digestive hormones) Muscularis mucosa - thin layer of muscle that alters shape of lumen, improves contact of food with epithelium For mixing with enzymes and absorption Submucosa - underlying connective tissue Has Submucosal plexus - neurons to control digestive secretions and movement of the muscularis mucosa

The Bicarbonate Buffer System

Bicarbonate buffer system—solution of carbonic acid and bicarbonate ions - requires functional respiratory system and a "bicarb reserve" Reversible reaction important in ECF CO2 + H2O -> H2CO3 -> HCO 3− + H+ Lowers pH (more acidic) by releasing H CO2 + H2O <- H2CO3 <- HCO 3− + H+ Raises pH (more alkaline) by binding H+ Functions best in lungs and kidneys to remove CO2 To lower pH, kidneys secrete less H+ and secrete HCO3− To raise pH, kidneys excrete H+ and lungs excrete CO2

The Pancreas

Both an endocrine and exocrine gland Endocrine portion—islets (1% of pancreas) secrete insulin (beta cells) and glucagon (alpha cells) Exocrine portion (acini)—(99%) secretes pancreatic juice Pancreatic juice: alkaline mixture of water, enzymes, zymogens, sodium bicarbonate, and other electrolytes Acini secrete enzymes and zymogens Ducts secrete bicarbonate Bicarbonate buffers HCl arriving from stomach Neutralizes acidity in duodenum Pancreatic proteases secreted as zymogens:Trypsinogen Converted to trypsin by enterokinase, an enzyme secreted by small intestine Trypsin is autocatalyticChymotrypsinogen: converted to trypsinogen by trypsin Procarboxypeptidase: converted to carboxypeptidase by trypsin Other pancreatic enzymes Pancreatic amylase: digests starch Pancreatic lipase: digests fat Ribonuclease and deoxyribonuclease: digest RNA and DNA respectively

Respiratory Control of pH

CO2 is constantly produced by aerobic metabolismNormally eliminated by lungs at an equivalent rate CO2 + H2O -> H2CO3 -> HCO 3− + H+ Lowers pH by releasing H CO2 + H2O <- H2CO3 <- HCO 3− + H+ Raises pH by binding H Increased CO2 and decreased pH stimulate pulmonary ventilation, while an increased pH inhibits pulmonary ventilation (via peripheral chemoreceptors)

Water Reabsorption by the Collecting Duct

Collecting duct (CD) begins in cortex where it receives tubular fluid from several nephrons As CD passes through medulla, it reabsorbs water and concentrates urine up to four times Medullary part of CD more permeable to water than to NaCl As urine passes through increasingly salty medulla, water leaves by osmosis, concentrating urine

Compensation for Acid-Base Imbalances

Compensated acidosis or alkalosis By kidneys By lungs Uncompensated acidosis or alkalosis pH imbalance that body cannot correct without clinical intervention Respiratory compensation—changes in pulmonary ventilation to correct changes in pH of body fluids by expelling or retaining CO2 Hypercapnia (excess CO2) stimulates pulmonary ventilation eliminating CO2 and allowing pH to rise Hypocapnia (deficiency of CO2) reduces ventilation and allows CO2 to accumulate lowering pH Renal compensation—pH adjustment by changing rate of H+ secretion by renal tubules Slow, but better at restoring fully normal pH than lungs In acidosis, urine pH may fall as low as 4.5 due to excess H+ Renal tubules increase H+ secretion to elevate pH in bloodstream In alkalosis urine pH may rise as high as 8.2 due to excess HCO3− Renal tubules decrease H+ secretion, may secrete bicarbonate ions, to lower pH Most effective at compensating for pH imbalances that last for a few days or longer

Intestinal Motility

Contractions of small intestine have 3 functions Mix chyme with intestinal juice, bile, and pancreatic juiceTo neutralize acid - mostly in duodenumDigest nutrients more effectively - mostly in jejunum Churn chyme and bring it in contact with mucosa for contact digestion and nutrient absorption Move residue toward large intestine Segmentation for #1 and 2 Peristalsis for #3 - when most of the nutrients have been absorbed, start peristaltic waves from duodenum to ileum

Cortical and Juxtamedullary Nephrons

Cortical nephrons 85% of all nephrons Short nephron loops Efferent arterioles branch into peritubular capillaries around PCT and DCT juxtamedullary nephrons 15% of all nephrons Very long nephron loops, maintain osmotic gradient in medulla and help conserve water; concentrates the urine Efferent arterioles branch into vasa recta around long nephron loop

Digestive Function

Digestive system —processes food, extracts nutrients from it, and eliminates the residue Five stages of digestion Ingestion: intake of food Digestion: mechanical and chemical breakdown of food into a form usable by the body Absorption: uptake of nutrient molecules into epithelial cells of digestive tract and then into blood and lymph Compaction: absorbing water and consolidating indigestible residue into feces Defecation: elimination of feces Mechanical digestion —physical breakdown of food into smaller particles by chewing, then mixing and churning in digestive tract Chemical digestion —hydrolysis reactions that break down macromolecules into their monomers Carried out by digestive enzymes produced by salivary glands, stomach, pancreas, and small intestine ResultsPolysaccharides into monosaccharides Proteins into amino acidsFats into monoglycerides and fatty acids Nucleic acids into nucleotides

The Nephron

Each kidney has about 1.2 million nephrons Each composed of two principal partsRenal corpuscle: filters the blood plasmaRenal tubule: long coiled tube that converts the filtrate into urine Nephron's mission - to force fluid and dissolved solutes from plasma into kidney tubules - forming filtrate (10% blood coming into glomerulus gets filtered, 90% passes thru efferent arteriole) Bad stuff (e.g. wastes) remains in renal tubules and ends up in urine Good stuff (e.g., nutrients, electrolytes) must be kept, so its reabsorbed from tubules into bloodstream Bad stuff that didn't get filtered (was in 90% that didn't get filtered) can still end up in urine by being secreted from bloodstream into tubules Push fluid through glomerulus, then selectively exchange substances back with capillary beds that surround nephrons; customize amount of fluid and electrolytes released based on the needs of the body Renal Corpuscle - where filtration occurs - consists of: Glomerulus (fenestrated capillary network) Bowman's capsule (glomerular capsule) Parietal (outer) layer of capsule is simple squamous epithelium Visceral (inner) layer of capsule consists of elaborate cells called podocytes that wrap around the capillaries of the glomerulus - form filtration slits Capsular space separates the two layers of Bowman capsule, collects filtrate made from plasma Renal Tubule - where reabsorption and secretion of tubular fluid occurs Proximal convoluted tubule Nephron loop (loop of Henle) Distal convoluted tubule Collecting ductreceives fluid from many nephrons

Autonomous function of digestive tract

Enteric nervous system - ENS - sensory neurons, motor neurons and interneurons that reside in digestive tissues Can function independent of the CNSHeavily influenced by ANS, especially parasympathetic Concentrated in: submucosal plexus - in submucosa; for secretions and movement of mucosal layer to change lumen shape myenteric plexus - between muscle layers; for mechanical processing and forward movement through tract Enteroendocrine cells - hormone-releasing cells scattered throughout digestive tract

Urine production

Flow of fluid from the point where the glomerular filtrate is formed to the point where urine leaves the body: •glomerular capsule → proximal convoluted tubule → nephron loop →distal convoluted tubule → collecting duct → papillary duct → minor calyx → major calyx → renal pelvis → ureter →urinary bladder → urethra

Functions of the Kidneys

Functions of the Kidneys Elimination of wastesFilters blood plasma; directs waste into urine (filtration or secretion), returns useful substances to blood (reabsorption) Homeostasis Regulate blood volume and pressure by eliminating or conserving water Secretes enzyme, renin, which activates hormonal mechanisms that control blood pressure /electrolyte balance Secretes the hormone, erythropoietin, which stimulates the production of red blood cells Regulate the osmolarity of the body fluids by controlling the relative amounts of water and solutes eliminated; electrolyte reabsorption/secretion Final step in synthesizing hormone, calcitriol, contributes to calcium homeostasis Regulates pH - works with lungs to regulate the PCO2 and acid-base balance of body fluids Conservation of nutrients - glucose reabsorption Detoxification - assists liver

The Stomach

Functions: Storage of ingested food Mechanically breaks down food Begins chemical digestion of protein and fat with acid and enzymes Produces intrinsic factor - required for Vit B12 synthesis, required for erythropoesis Produces chyme: mixture of semidigested food in stomachMost digestion occurs after chyme passes on to small intestineLittle or NO absorption of nutrients in stomach

Regulation of Glomerular Filtration

GFR controlled by adjusting glomerular blood pressure from moment to moment GFR control is achieved by 3 homeostatic mechanisms 1) Renal autoregulation 2) Sympathetic (neural) control 3) Hormonal control

The Gallbladder and Bile

Gallbladder —a pear-shaped sac on underside of liver Serves to store and concentrate bile by a factor of 20 by absorbing water and electrolytes Bile from liver gets to the gallbladder by first filling the bile duct then backing up into the gallbladder through the cystic duct CCK causes contractions of the gall bladder and relaxation of hepatopancreatic sphincter, releasing bile in response to fat in duodenum Bile —yellow-green fluid containing minerals, cholesterol, neutral fats, phospholipids, bile pigments, and bile acids Bilirubin: principal pigment derived from the decomposition of hemoglobin; bilirubin metabolize bilirubin to urobilinogen Responsible for the brown color of feces Bile acids (bile salts): steroids synthesized from cholesterol Emulsifies fats

2 basic types of movements in digestive tract

Gap junctions connect smooth muscles, allow waves of activity to occur in response to stimulation 1. Peristalsis- muscularis externa propels food forward from one region to another with waves of activity that moves a bolus of food along; circular muscles behind the food contract and in front of the food, relax longitudinal muscles ahead of the food contract, which shortens the segment 2. Segmentation - most of small intestine and some of large intestine does this; cycles of contraction and relaxation to churn and mix food up; does NOT propel food along GI tract

Regulation of Gastric Function

Gastric activity is divided into 3 phases Cephalic phase: stomach controlled by brain Thoughts or smell of food increases activity of stomach Gastric phase: stomach controlling itself Presence of food in stomach increases activity of stomach Intestinal phase: stomach controlled by small intestinePresence of food in duodenum decreases activity of stomach Enterogastric reflex - decreased gastric activity due to food in duodenum Nervous and endocrine systems collaborate Increase gastric secretion and motility when food is eatenGastrin - increases gastric motility and secretions when food in stomach CCK and secretin - decrease gastric activity when food in duodenum AND causes relaxation of hepatopancreatic sphincter 1- Cephalic phaseVagus nerve stimulates gastric secretion even before food is swallowed. 2- Gastric phaseFood stretches the stomach and activates myenteric and vagovagal reflexes. These reflexes stimulate gastric secretion. Histamine and gastrin also stimulate acid and enzyme secretion. 3- intestinal phaseIntestinal gastrin briefly stimulates the stomach, but then secretin, CCK, and the enterogastric reflex inhibit gastric secretion and motility while the duodenum processes the chyme already in it. Sympathetic nerve fibers suppress gastric activity, while vagal (parasympathetic) stimulation of the stomach is now inhibited.

Gastric Lipase

Gastric lipase—produced by chief cells Gastric lipase and lingual lipase—minor role in fat digestion Digests 10% to 15% of fats in stomach Remainder of fat is digested in small intestine by pancreatic lipase + bile salts

The Filtration Membrane

Glomerular filtration—special case of capillary fluid exchange process Water and some solutes in blood pass from capillaries of glomerulus into capsular space of nephron Filtration membrane —3 barriers through which fluid passes: 1. Fenestrated endothelium of glomerular capillaries 2. Basement membrane Proteoglycan gel, negative charge 3. Filtration slits Podocyte foot processes wrap around capillaries to form a barrier layer Also negatively charged so are an additional obstacle for large anions Note: blood cells too big to pass through fenestrated capillary pores, and plasma proteins too big and charged to fit through the rest of filtration membrane

Glomerular Filtration Pressure

Glomerular hydrostatic pressure (GHP) Much higher in glomerular capillaries than other capillaries50 mmHg compared to 35 mmHg at arteriole end of systemic capillaries Because afferent arteriole is larger than efferent arteriole Forces fluid from glomerulus into capsular spaceFavors filtration Capsular hydrostatic pressure- CsHP (in capsular space) Unique for glomerular capillaries - due to high filtration rate and continual accumulation of fluid in capsule, en route to PCT 15 mmHg (analogous to IHP for systemic capillaries) Opposes glomerular filtration Net Hydrostatic Pressure = GHP - CsHP = 50-15= 35 mmHg Note: same as arteriole end of systemic capillaries! GFP= Net hydrostatic pressure - net osmotic pressure Colloid osmotic pressure (BCOP) of blood About same as elsewhere: 25 mm Hg Opposes filtration Glomerular filtrate is almost protein-free and has no significant COP Higher filtration pressure of 50 mm Hg, opposed by two opposing pressures of 15 mm Hg and 25 mm Hg Glomerular filtration pressure=net hydrostatic pressure-net osmotic pressure GFP = (GHP - CsHP) - BCOPGFP = (50 - 15) - 25 = 10 mm Hg Glomerular filtration rate (GFR)—amount of filtrate formed per minute by two kidneys combined GFR = NFP x Kf » 125 mL/min. or 180 L/day (male) Net filtration pressure (NFP) Filtration coefficient (Kf) depends on permeability and surface area of filtration barrier Total amount of filtrate produced equals 70 times plasma volume 99% of filtrate is reabsorbed since only 1 to 2 L urine excreted per day Very important to maintain GFR at constant rate to absorb the appropriate levels of water, electrolytes and nutrients, while not accidently absorbing wastes

Renal Physiology

Goal of urine production is to maintain homeostasis By regulating volume and composition of blood Involves excretion of metabolic wastes §Start with Blood Filter through glomerulus to get filtrate (filtration) • Selectivity only based on SIZE of substances Get the "good stuff" out of the tubule - selective for each substance (reabsorption) Dump other wastes from bloodstream into tubule so it enters urine - also selective for substance (secretion)

Circular folds contain:

Goblet cells -mucousAbsorptive cells with brush border enzymes Have capillaries below to absorb nutrients Has lacteal to absorb larger products, like chylomicrons , into the lymphatic vessel

Absorption and Motility

Haustral contractions occur every 30 minutes Is a form of segmentation Distension of a haustrum stimulates it to contract Mass movements occur 1-3 three times a day Is a form of peristalsis Triggered by gastrocolic and ileocolic reflexesFilling of stomach and duodenum stimulates motility of colon Stretching of rectum stimulates defecation reflexes Accounts for urge to defecate that is often felt soon after a meal Large intestine takes about 12 to 24 hours to reduce residue of a meal to feces Does not chemically change residue Reabsorbs water and electrolytes Feces consist of 75% water and 25% solids, of which 30% is bacteria, 30% undigested fiber, 10% to 20% fat, small amount of mucus, and sloughed epithelial cells

Microscopic Anatomy

Hepatocytes - liver cellsHepatic sinusoids: Allows plasma into the space between the hepatocytes and endothelium Blood filtered through the sinusoids comes directly from the stomach and intestines thru hepatic portal vein, and hepatic artery proper Hepatic macrophages (Kupffer cells): phagocytic cells in the sinusoids that remove bacteria and debris from the blood; antigen presenting cells Bile passes into hepatic ducts, then Common bile ductNear duodenum, bile duct joins duct of pancreas, forms expanded chamber: hepatopancreatic (duodenal) ampulla Hepatopancreatic sphincter -Regulates passage of bile and pancreatic juice into duodenum Between meals, sphincter closes and prevents release of bile into the intestines Relaxation triggered by cholecystokinin (CCK) and secretin

Regulation of the Digestive Tract

Hormonal control Chemical messengers secreted into bloodstream; may stimulate distant parts of digestive tract Released into capillaries by enteroendocrine cellsMust enter bloodstream and travel BACK to digestive tract E.g., gastrin, secretin, CCK, etc Paracrine control - local control Chemical messengers that diffuse through tissue fluids to stimulate nearby target cells E.g., histamine and prostaglandins Coordinates digestive response to local stimuli, such as stretch, pH, or the presence of particular nutrients

Control of Water Loss

How concentrated urine becomes depends on body's state of hydration Water diuresis —drinking large volumes of water will produce large volume of hypotonic urine Cortical portion of CD reabsorbs NaCl, but it is impermeable to water Salt removed from urine stays in CDUrine solute concentration may be as low as 50 mOsm/L Diabetes incipitis - lack of ADH - diuresis Producing hypertonic urine Dehydration causes urine to become scanty and more concentrated High blood osmolarity stimulates posterior pituitary to release ADH and then an increase in synthesis of aquaporin channels by renal tubule cells More water is reabsorbed by collecting duct Urine is more concentrated If BP is low in a dehydrated person, GFR will be low Filtrate moves more slowly and more time for reabsorption More salt removed, more water reabsorbed, and less urine produced

Lipids

Hydrophobic quality of lipids makes their digestion and absorption more complicated than carbohydrates and proteins Lingual lipase secreted by the intrinsic salivary glands of the tongue Active in mouth, but more active in stomach along with gastric lipase (secreted by chief cells) 10% to 15% of lipids digested before reaching duodenumPancreatic lipase: in the small intestine; digests most of the fats Fat enters duodenum as large globules exposed to lipase only at their surface Globules broken up (emulsified) into smaller droplets by bile acids Smaller droplets with more exposure to pancreatic lipase Pancreatic lipase breaks triglycerides into monoglycerides and free fatty acids, which form micelles which are absorbed by the intestinal cells Micelles brought into cells and broken down Within the intestinal cell, free fatty acids and monoglycerides are transported to the smooth ER Resynthesized into triglycerides Golgi complex coats these with phospholipids and protein to formchylomicrons Packaged into secretory vesicles that migrate to surface of cell Release their contents into lacteal, so joins lymph, where they travel until they reenter the bloodstream (subclavian vein) Endothelial cells with lipoprotein lipase - breaks down chylomicrons into FFAs and monoglycerides

The Countercurrent Multiplier

Hyperosmotic gradient in medulla allows max water reabsorption Nephron loop acts as countercurrent multiplier - positive feedback Multiplier: recaptures salt and returns it to extracellular fluid of medulla which multiplies salinity in medulla Countercurrent : because of fluid flowing in opposite directions in adjacent tubules of nephron loop Fluid flowing downward in descending limbpermeable to water but not to NaCl, so water leaves tubule but salts don't concentrates tubular fluid to 1,200 mOsm/L at lower end of loo Fluid flowing upward in ascending limb Impermeable to water, but reabsorbs Na+, K+, and Cl− by active transport Adds salt to medulla, decreases osmolarity of tubular fluid as it goes up in the tubule Recycling of urea: papillary duct permeable to ureaUrea contributes to the osmolarity of deep medullary tissue Continually cycled from collecting duct to nephron loop and back

Saliva

Hypotonic solution of ~99% water and following solutes: Salivary amylase: enzyme that begins carbohydrate digestion in mouth Lingual lipase: enzyme activated by stomach acid and digests fat after food is swallowed Mucus: binds and lubricates mass of food and aids in swallowing Lysozyme: enzyme that kills bacteriaImmunoglobulin A (IgA): antibody that inhibits bacterial growthElectrolytes: Na+, K+, Cl−, phosphate, and bicarbonate pH: 6.8 to 7.0

Acids, Bases, and Buffers

Important aspects of homeostasis Metabolism depends on enzymes Enzymes are sensitive to pH Slight deviation from normal pH can: Shut down metabolic pathways Enzymes stop workingAlter structure and function of macromolecules Proteins denatureCell membranes become unstable normal= 7.4 we can tolerate up to 7.35-7.45 = normal pH range of blood and tissue fluid - 7.35 - 6.8 - Acidosis (H2CO3) - 7.45- 8.0 - Alkalosis (HCO3-) past 6.8 and 8.0 = death Challenges to acid-base balance Metabolism constantly produces acid- acidosis more common Lactic acids from anaerobic fermentation (muscles) Phosphoric acid from nucleic acid catabolism Fatty acids and ketones from fat catabolism Carbonic acid from carbon dioxide buffers give or take H+ to resists changes in pH (temporary fix) (happens fast) Buffer —binds H+ and removes it from solution as its concentration rises, or releases H+ into solution as its concentration falls; resists changes in pH - quick, temporary fix for pH problem Restores normal pH in fractions of a second Function as mixtures called buffer systems composed of weak acids and weak bases 3 major chemical buffers: 1. bicarbonate (CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3- ) 2. phosphate - can add or lose H+ (H2PO4 ↔ H+ +HPO4 2-) 3. proteins (hemoglobin) Amount of acid or base neutralized depends on concentration of buffers and pH of working environment * amount of acid or base neutralized depends on concentration of buffers and pH of working environment * how our bodies prevent extreme changes in pH enzymes are activated by pHs (they are sensitive to pH) - metabolism constantly produces acid - acidosis is more common - tissue uses up their O2 producing CO2, H+ and acids

Intrinsic Factor

Intrinsic factor—secreted by parietal cells Essential to absorption of vitamin B12 by small intestine Vitamin B12 is needed to synthesize hemoglobinPrevents pernicious anemia

Renal Control of pH

Kidneys can neutralize more acid or base than either respiratory system or chemical buffers Renal tubules secrete H+ into tubular fluidMost H+ binds to bicarbonate, ammonia, and phosphate buffers Bound and free H+ are excreted in urine (to expel H+ from body) Other buffer systems only reduce H+ concentration by binding it to other chemicals

Urine Formation:

Kidneys convert blood plasma to urine in 3 stages: 1) Glomerular filtration - in renal corpuscle 2) Tubular reabsorption and secretion - in renal tubules 3) Water reabsorption - in collecting/papillary duct Glomerular filtrate—fluid in capsular space, moves into tubule Similar to blood plasma except has less protein Tubular fluid—fluid from PCT through DCT Substances have been removed from tubular fluid (reabsorbed into bloodstream) or added by tubular cells into tubular fluid (secreted from bloodstream) Urine—fluid that enters collecting ductLittle alteration beyond this point except for changes in water content Can become more or less concentrated depending on the blood pressure (reflected by hormone secretion of ADH and aldosterone)

Juxtaglomerular complex

Macula densa • Cells of DCT, near renal corpuscle • Function as chemoreceptors Juxtaglomerular cells • Smooth muscle cells in wall of afferent arteriole • Function as baroreceptors and secrete renin Extraglomerular mesangial cells Located between afferent and efferent arterioles Provide feedback control to regulate arteriole and capillary diameter - secrete local vasodilators and constrictors

Renal Autoregulation

Maintains dynamic equilibrium—GFR fluctuates within narrow limits only BP changes do affect GFR and urine output somewhat Renal autoregulation can't compensate for extreme BP variation, particularly low blood pressures When MAP = 90-160 mm Hg, GFR remains stable If MAP < 70 mm Hg, glomerular filtration and urine output cease Occurs in hypovolemic shock - eg from hemorrhageBody recognizes this as "crisis" and shuts down all extraneous organs

Microscopic Anatomy

Modifications for nutrient digestion and absorption Large internal surface area for digestion and absorption: by great length and 3 types of internal folds of mucosa Circular folds (plicae circulares)—increase surface area by a factor of 2 to 3 Villi—increase surface area by a factor of 10 Microvilli—increase the surface area by a factor of 20 All together increase surface area by ~600-fold Brush border enzymes —embedded in membrane of microvilli Carry out some final stages of enzymatic digestion Not released into lumen; not lost in fluids Contact digestion: chyme must contact brush border for digestion to occur Churning of chyme ensures contact with mucosa

Regulation of the Digestive Tract

Motility and secretion of digestive tract are controlled by neural, hormonal, and paracrine mechanisms Neural controlShort (myenteric) reflexes: LOCAL neural control response to stretch or chemical stimulation acts through myenteric plexus Reflexes bypass the CNS; controlled locally by ENSControls secretions and movement in a particular region of tract Long (vagovagal) reflexes: control via CNSSignals are sent to CNS to provide finer control over digestive functions parasympathetic stimulation of digestive motility and secretion; sympathetic inhibition of motility and secretion

Microscopic Anatomy - gastric glands

Mucous cells—secrete mucusMainly in cardiac and pyloric glands Called mucous neck cells since are concentrated at neck of gland Regenerative (stem) cellsSupply new cells to replace dead cells Parietal cells Secrete hydrochloric acid (HCl), intrinsic factor, and ghrelin (hunger hormone) Chief cellsSecrete gastric lipase and pepsinogen Absent in pyloric and cardiac glands Enteroendocrine cells - G cells, gastrin Secrete hormones that regulate digestion

General Anatomy

Muscularis externa - responsible for mixing, churning and propulsive movement through digestive tract Inner circular layer thickens to form valves (sphincters) that regulate the passage of material through the tract Myenteric plexus - neurons and fibers in between muscle layers to control motility of these muscles; ANS influence:Sympathetic - relaxation of musclesParasympathetic - increased muscle tone and activity Outer longitudinal layer Serosa - serous membrane (visceral peritoneum) covering most of the tract

Anatomy of colon

Muscularis externa of colon is unusual Taenia coli —longitudinal fibers concentrated in three thickened, ribbonlike strips, replaces the usual longitudinal muscle layer Haustra —pouches in the colon caused by the muscle tone of the taeniae coli Internal anal sphincter —smooth muscle of muscularis externa External anal sphincter —skeletal muscle of pelvic diaphragm Intestinal glands - many goblet cells for mucous Lymphatic tissue in submucosa - protection from bacteria

The Small Intestine

Nearly all chemical digestion and nutrient absorption occurs in small intestine, especially the jejenum Receives stomach contents, pancreatic juice, and bile Stomach acid is neutralized hereFats are physically broken up (emulsified) by the bile acids Pepsin is inactivated by increased pHPancreatic enzymes take over job of chemical digestion

Proximal Convoluted Tubule

PCT reabsorbs ~ 65% of glomerular filtrate volume 2/3 of water reabsorption in PCT 99% reabsorption of nutrients here; nutrients removed from tubular fluid and returned to peritubular capillaries Prominent microvilli and lots of mitochondria for active transport Sodium reabsorption is key to everything else Steep concentration gradient that favors its diffusion into epithelial cells Creates osmotic gradient that drives reabsorption of water and other solutes 2 types of transport proteins are responsible for Na+ uptake Cotransport that simultaneously bind Na+ and another solute such as glucose, amino acids, or lactate Na+-H+ countertransport that pulls Na+ into cell while pumping out H+ into tubular fluid

Hydrochloric Acid

Parietal cells produce HCl and contain carbonic anhydrase (CAH) CO2 + H20 -> H2CO3 -> HCO3- +H+ H+ is pumped into gastric gland lumen HCO − exchanged for Cl− (chloride shift) from blood plasma Cl− pumped into lumen of gastric gland to join H+ forming HCl Elevated HCO3 − (bicarbonate ion) in blood causes postprandial alkaline tide increasing blood pH, making you sleepy Gastric juice has a high concentration of hydrochloric acid PH AS LOW AS 0.8

The Nephron Loop (Loop of Henle)

Primary function —generates osmotic gradient in the renal medulla enabling collecting duct to concentrate urine and conserve water Also reabsorbs Na+, K+, and Cl− (in thick ascending limb) and water (in thin descending limb) Electrolyte reabsorption from filtrate Thick ascending segment reabsorbs 25% of Na+, K+, and Cl− Ions leave cells by active transport and diffusion NaCl remains in tissue fluid of renal medulla (peritubular fluid) Water can't follow since thick segment is impermeable Tubular fluid very dilute as it enters DCT (pumped Na, K, Cl out of tubules, but left water in tubule, so decreased osmolarity)

Proteins

Proteases (peptidases)—enzymes that digest proteins Begin their work in the stomach in optimum pH of 1.5 to 3.5 Pepsin digests 10% to 15% of dietary protein into shorter peptides and some free amino acids Pepsin inactivated when it passes into the duodenum and mixes with the alkaline pancreatic juice (pH 8) Pancreatic enzymes trypsin and chymotrypsin take over the process to break polypeptides into even shorter oligopeptides Carboxypeptidase (from pancreas), Aminopeptidase and Dipeptidase (from brush border) break them down into amino acids Transported across intestinal cells and into capillaries, to liver via hepatic portal vein

The Protein Buffer System

Protein buffer system accounts for ~ 75% of all chemical buffering in body fluids Buffering ability due to certain side groups of their amino acid residues Carboxyl (−COOH) side groups release H+ when pH rises Amino (−NH2) side groups bind H+ when pH falls Hemoglobin acts as a buffer this way! (only in RBCs) Other amino acids and plasma proteins buffer this way elsewhere

Contractions of the Small Intestine

Purpose of segmentation is to mix and churn, not to move material along as in peristalsis Peristaltic waves milk chyme toward colon over a period of 2 hours • Ileocecal valve usually closed Food in stomach triggersgastroileal reflex, which relaxes the valve, fills cecum fills with residue til pressure pinches the valve shut

Regulation of Gastric Function

Pyloric sphincter contracts to limit chyme entering duodenum Gives duodenum time to work on chyme Enteroendocrine cells in duodenum secrete glucose- dependent insulinotropic peptide (GIP) - aka, gastric inhibitory peptide Stimulates insulin secretion from beta cells in preparation for processing nutrients about to be absorbed by small intestine

The Liver

Regulates levels of circulating nutrients by selective absorption and secretion and storage After a meal, hepatocytes absorb from blood—glucose, amino acids, iron, vitamins, minerals for metabolism or storage Between meals, hepatocytes break down stored glycogen and release glucose into blood Removes and degradesHormones, toxins, bile pigments, and drugs Synthesis of plasma proteins Secretes into bloodAlbumin, lipoproteins, clotting factors, angiotensinogen, etc. Produces and secretes bile which emulsifies fats

The Nephron - review from 1st lecture

Renal Corpuscle - where filtration occurs - consists of: Glomerulus (fenestrated capillary network) Bowman's capsule (glomerular capsule) Parietal (outer) layer of capsule is simple squamous epithelium Visceral (inner) layer of capsule consists of elaborate cells called podocytes that wrap around the capillaries of the glomerulus - form filtration slits Capsular space separates the two layers of Bowman capsule, collects filtrate made from plasma Renal Tubule - where reabsorption and secretion of tubular fluid occurs Proximal convoluted tubule Nephron loop (loop of Henle) Distal convoluted tubule Collecting ductreceives fluid from many nephrons

Endocrine regulation of GFR

Renin-angiotensin-aldosterone system Three stimuli cause juxtaglomerular cells to release renin: Decrease in blood pressure at glomerulus due to decrease in blood volume, decrease in systemic pressures, or blockage in renal artery or its branches Stimulation of juxtaglomerular cells by sympathetic innervation Decrease in osmotic concentration of tubular fluid at macula densa

Carbohydrates

Salivary amylase stops working in stomach at pH less than 4.5 50% of dietary starch digested before it reaches small intestine Pancreatic amylase works in small intestine- converts starch to disaccharides and trisaccharides within 10 min. Brush border enzymes break these down into monosaccharides, which can be absorbed Transported across intestinal cells into capillaries, then to liver via hepatic portal vein

The Transport Maximum - Tm

Solute reabsorption limited by number of transport proteins in plasma membrane If all transporters are occupied Excess solute appears in urine (glycosuria in diabetics) Transport maximum is the maximum rate of reabsorption, reached when transporters are saturated

Gastric Motility

Stomach shows a rhythm of peristaltic contractions controlled by pacemaker cells in longitudinal layer of muscularis externa Gentle contractions churn and mix food with gastric juice Becomes stronger contraction at pyloric region Mixing waves - churning, not propulsiveChurn food, mix it with gastric juice, and promote its physical breakup and chemical digestionAfter ~30 min., contractions become quite strong Sweeping waves Peristaltic wave passes towards pylorus, it squirts chyme into duodenum Allowing only small amount into duodenum enables duodenum to: Neutralize stomach acidDigest nutrients little by little

Sympathetic Control

Sympathetic nerve fibers richly innervate renal blood vessels Sympathetic nervous system and adrenal epinephrine constrict afferent arterioles in strenuous exercise or acute conditions like circulatory shock (decrease blood pressure and blood volume) Reduces GFR and urine output Redirects blood from kidneys to heart, brain, and skeletal muscles GFR may be as low as a few milliliters per minute Sympathetic activation can override local regulatory mechanisms that act to stabilize GFR

factors controlling glomerular filtration

The glomerular hydrostatic pressure (GHP) is the blood pressure in the glomerular capillaries. This pressure tends to push water and solute molecules out of the plasma and into the filtrate. The GHP, which averages 50 mm Hg, is significantly higher than capillary pressures elsewhere in the systemic circuit, because the efferent arteriole is smaller in diameter than the afferent arteriole The blood colloid osmotic pressure (BCOP) tends to draw water out of the filtrate and into the plasma; it thus opposes filtration. Over the entire length of the glomerular capillary bed, the BCOP averages about 25 mm Hg. The net filtration pressure (NFP) is the net pressure acting across the glomerular capillaries. It represents the sum of the hydrostatic pressures and the colloid osmotic pressures. Under normal circumstances, the net filtration pressure is approximately 10 mm Hg. This is the average pressure forcing water and dissolved substances out of the glomerular capillaries and into the capsular space. Capsular hydrostatic pressure (CsHP) opposes GHP. CsHP, which tends to push water and solutes out of the filtrate and into the plasma, results from the resistance of filtrate already present in the nephron that must be pushed toward the renal pelvis. The difference between GHP and CsHP is the net hydrostatic pressure (NHP). The capsular colloid osmotic pressure is usually zero because few, if any, plasma proteins enter the capsular space.

All of the following statements about the kidney are true, except: a. The renal corpuscle is where filtration occurs. b. The renal pelvis empties into the urethra. c. The adipose capsule cushions, supports and protects the kidneys. d. Approximately 10% of the blood that enters the nephrons is filtered. e. Reabsorption and secretion occur along the renal tubules.

The renal pelvis empties into the urethra.

Different regions of the nephrons show different permeabilities to solutes and water. Which of the following statements about permeabilities is FALSE: a. The thick ascending limb of the loop of Henle is impermeable to water. b. The water permeability of the distal convoluted tubule and the collecting duct is regulated by the presence of ADH; more ADH, more permeable to water. c. The thin, descending limb of the loop of Henle is very permeable to NaCl. (permeable to H2O not Na) d. Aldosterone promotes Na+ reabsorption in the distal convoluted tubule by causing the insertion of more Na+channels and/or pumps. e. The portion of collecting duct deep in the medulla (the papillary ducts) is permeable to urea.

The thin, descending limb of the loop of Henle is very permeable to NaCl. (permeable to H2O not Na)

All of the following are true about juxtamedullary nephrons, except: a. They have long loops of Henle, extending deep into the renal medulla. b. 15% of all nephrons are juxtamedullary. c. They are responsible for making a gradient of hyperosmolarity throughout the medulla. (juxtamedullary nephrons are the ones that undergo the counter current multiplication and they work with the vasorectum for the counter exchanger) d. They make it possible to maximally concentrate urine and reabsorb water. e. They have their renal corpuscles located deep in the renal medulla. (all renal corpuscles are located in the cortex)

They have their renal corpuscles located deep in the renal medulla. (all renal corpuscles are located in the cortex)

Tubular Secretion

Tubular secretion —from capillaries into tubular fluidWaste removal Urea, uric acid, bile acids, ammonia and other drugs Acid-base balance - especially in DCT DCT and collecting duct reabsorb variable amounts of water, salt, calcium - regulated by hormones Aldosterone, atrial natriuretic peptide, ADH, and parathyroid hormone DCT with big role in Acid-base balanceSecretion of H+ and bicarbonate ions help regulate pH of body fluids CO2 in tubular fluid converted into carbonic acid - H+ is usually secreted and bicarbonate is usually reabsorbed Amount of H+ secreted will depend on pH of body fluid Acidosis (pH<7.4) causes increase H+ secreted Alkalosis (pH>7.4) causes decrease in H+ secretion

Gross Anatomy

Two zonesOuter renal cortex - where renal corpuscles are located, where filtration takes place Inner renal medulla - where reabsorption and secretion occurRenal pyramids—where nephron loops and collecting ducts are located,Tip of pyramid is renal papilla, terminal end of collecting duct (papillary duct) passes through here Minor calyx: collects urine from renal papilla of each pyramid;Major calyx: formed by convergence of two or three minor calyces Renal pelvis: formed by convergence of two or three major calyces Ureter: the tube leading from the renal pelvis that drains the urine down to the urinary bladder for storage

Digestion and Absorption

Typical meal consists of protein, carbohydrate, lipids, water, electrolytes and vitamins Need to break it down into absorbable bits Enzymes specific for each class of substratesCarbohydrates break down to monosaccharides Proteins break down to amino acidsLipids break down to fatty acids Nucleic acids to nucleotides

The Countercurrent Exchange System

Vasa recta—capillaries in medulla, branching off efferent arteriole of juxtamedullary nephrons Countercurrent system—formed by blood flowing in opposite directions in adjacent parallel capillaries Exchanger - provides blood supply to medulla, removes some water and and does not remove NaCl and urea from medullary ECF

Absorption

Water - passive flow via osmosis- concentration gradients established to promote water flow (by absorbing nutrients, drawing out water, etc) Ions - mechanisms vary by ion and needs of body for maintenance of homeostasis Vitamins - fat-soluble (ADEK) dissolve in lipids and end up in chylomicrons into lacteals; 9 water soluble vitamins - all easily absorbed except Vit B12, which requires intrinsic factor to bind to it for uptake to occur via active transport

Pepsin

Zymogens—digestive enzymes secreted as inactive proteins Converted to active enzymes by removing some of their amino acids Pepsinogen—zymogen secreted by chief cells HCl removes some of its amino acids and forms pepsin that digests proteins Autocatalytic effect—as some pepsin is formed, it converts more pepsinogen into more pepsin Pepsin digests proteins into shorter peptide chainsProtein digestion is completed in small intestine

carbonic anhydrase

allows CO2 to be converted into H- and HCO3-

which of the following statements is false a. our specific and non specific defenses work together to protect us b. antibodies play a large role in the non specific defenses by recognizing and particular antigens c. our non specific defense do not distinguish between threats d. phagocytic cells engulf pathogens infected and dying cells and debris e. the thymus gland, spleen and lymph nodes are important for specific defenses

antibodies play a large role in the non specific defenses by recognizing and particular antigens

epinephrine and norepinephrine use all of the following mechanisms, except: a. binding cell surface receptors that activate adenylate cyclase b. binding to nuclear receptors to alter gene transcription c. binding to cell surface receptors that cause a decrease in cAMP d. binding to cell surface receptors that use calcium (or calcium bound to calmodulin) as a second messenger

binding to nuclear receptors to alter gene transcription

progesterone

binds to nuclear receptors and alters gene transcription

signaling in the nervous and endocrine systems is similar in all of the following ways except a. both use chemical messengers b. with bind to receptors specific for that chemical messenger c. both are primarily regulated by negative feedback d. both have a similar time delay between release of messenger to actual effect

both have a similar time delay between release of messenger to actual effect

a drug that blocks the effects of insulin would

cause glucose in the urine

Disturbances of Acid-Base Balance

either respiratory - mismatch of CO2 generation and excretion metabolic - generation of acids in body or disruption of HCO3- buffering system Caused by: Any disorder that affects circulating buffers, respiratory function or renal function (emphysema, renal failure) Cardiovascular conditions (heart failure) Conditions affecting CNS (affect control mechanisms and signalling pathways)

all of the following statements are true except a. the cardioacceleratory center uses norepinephrine to increase heart rate b. increased stimulation of the cardio cardioinhibitory center means increased stimulation of the parasympathetic nervous system c. epinephrine is the neurotransmitter that shows the heart rate d. increased stimulation of the vasomotor center causes vasoconstriction which increases blood pressure

epinephrine is the neurotransmitter that shows the heart rate

Glomerular filtration produces a filtrate that: a. has an osmolarity similar to plasma (around 300) b. has a concentration of proteins similar to plasma (plasma has plasma protein filtrate does not) c. only contains waste products to be eliminated in the urine d. both a and b are correct e. both a and c are correct

has an osmolarity similar to plasma (around 300)

negative feedback control of GFR

high GFR -> rapid flow of filtrate in renal tubules -> sensed by macula densa -> paracrine secretion -> constriction of afferent arteriole -> reduced GFR

Which of the following conditions produces a large volume of urine? a. increased angiotensin II (does the opposite of ANP) b. increased ANP c. increased ADH (if it's a large volume of urine it can't be ADH) d. increased aldosterone e. all of the above

increased ANP

a rise in angiotensin 2 levels would result in all of the following except a. elevated blood pressure b. increased sodium retention at the kidneys c. increased urine production d. increased blood volume e. increased water retention

increased urine production

An Overview of the Urinary System.

kidney bean organ, with renal a., v., nerves and ureter entering/exiting at hilus, in center adrenal gland resting on top Organs of the Urinary System Kidneys Produce urine Ureters Transport urine toward the urinary bladder Urinary bladder Temporarily stores urine priorto urination Urethra Conducts urine to exterior; in males, it also transports semen

Kidney position

kidney bean organ, with renal a., v., nerves and ureter entering/exiting at hilus, in center adrenal gland resting on top in retroperitoneal position - between the parietal peritoneum and the body wall held in place there with connective tissue:renal capsule - collagen fiber coating of kidney adipose capsule - fat outside renal capsule renal fascia - dense, fibrous outer layer, with collagen fibers connecting it to the renal capsule, and anchors it to the peritoneum and muscles of body wall important to be held (suspended by renal fascia) in place securely - v. dangerous if not, ureters and renal blood vessels could twist

A glomerular filtration rate that is too high would result in: (would use autoregulation to correct) a. excess reabsorption of sodium and water b. less water and sodium reabsorption c. stimulation of renin release d. stimulate the release of ADH e. all of the above

less water and sodium reabsorption

response to a decrease in the GFR

look at last slide of lecture 9 urinary system part 2

_____ is the movement of water from an area of high water concentration to an area of low water concentration

osmosis

elevated levels of T3 and T4 cause all of the following except: a. increased ATP generation b. negative feedback to the anterior pituitary c. stimulates release of TRH d. negative feedback to the hypothalamus e. inhibition of TSH release

stimulates release of TRH

all of the following hormones bind to cell surface receptors except: a. thyroid hormone b. epinephrine c. lutenizing hormone d. antidiuretic hormone e. CRH

thyroid hormone

the autoregulatory response to low tissue oxygen in a systemic capillary bed is

vasodilation to increase blood flow to that area