BIO288 Introductory Physiology Past Paper 05/02/2024 PDF

BIO288: Introductory Physiology (05/02/2024) Announcements Exam #3: ○ Grades posted yesterday ○ Retake grades posted today ○ Answer key will be posted at the same time ○ Exams will be distributed today Homework #9: ○ Will be available today (05/02/2024) at 5:00 pm ○ Due Monday (05/06/2024) 11:59 pm...

BIO288: Introductory Physiology (05/02/2024) Announcements Exam #3: ○ Grades posted yesterday ○ Retake grades posted today ○ Answer key will be posted at the same time ○ Exams will be distributed today Homework #9: ○ Will be available today (05/02/2024) at 5:00 pm ○ Due Monday (05/06/2024) 11:59 pm Quiz #5: ○ Will be available today (05/02/2024) at 5:00 pm ○ Due friday (05/03/2024) at 11:59 pm Course Surveys ○ Upon 90% completion = 2 extra credit points will be given to the class Review There are 5 stages of digestion: ○ Ingestion: taking food into gastrointestinal GI tract ○ Digestion: physiological processes by which ingested food is turned into component molecules ○ Absorption: moving component molecules from the intestinal lumen to the cells ○ Assimilation: converting food molecules into cell components ○ Elimination: excretion of undigested/unused food 1/13 Lecture Notes The liver ○ Physiology: Metabolic regulation Hematological regulation Bile production The liver has an artery leading to it because it needs its own blood supply to acquire the nutrients and oxygen it needs to complete necessary functions. ○ Regulatory function: Composition of circulating blood Nutrients metabolism Nutrient storage (such as storing iron when not ingesting enough of it) Waste product removal Drug inactivation ○ How does the liver play into transporting nutrients to blood? Step 1: products of digestion are absorbed into the capillaries within the villi of the small intestines Step 2: the digested food molecules then travel through the hepatic portal veins to the liver Step 3: the liver monitors the blood components (metabolize products, store nutrients, detoxification) Step 4: hepatic veins (they lead back to the heart) deliver blood to the circulatory system 2/13 URINARY SYSTEM To be in balance means what comes into the body must eventually be used or excreted to maintain homeostasis. ○ Balance Solutes and water enter and exit plasma at the same rate Quantity stays the same Input + production = utilization + output ○ Positive balance: Solute or water water enters plasma faster than it exits Quantity increases Input + production > utilization + output ○ Negative balance: Solutes or water are exiting plasma faster than it enters Quantity decreases Input + production < utilization + output Factors affecting plasma composition ○ Kidneys normally regulate solute and water content which determines volume ○ Composition is also affected by exchange between different compartments of the body: Cells (can be outputs or inputs) Connective tissue Gastrointestinal tract Sweating Hemorrhage (blood loss) Respiration 3/13 iClicker #1: Knowledge: Which of the following equations correctly illustrates the concept of balance? a) Input + utilization = product + output b) output + production = utilization + output c) Input + output = utilization + production d) Input + production = utilization + output Reason: Input is a form of ingestion and digestion is an additive factor. Utilization and output describe what is being removed. iClicker #2: Knowledge: A substance is in negative balance when a) It enters plasma at the same rate it exits plasma (balanced) b) It enters plasma at a greater rate than it exits plasma (positive balance) c) It exits plasma at a greater rate than it enters plasma d) Its usage by cells is decreased (positive balance) e) Its production by cells is increased (positive balance) Reason: If it is exiting faster than it is entering, then it is describing a negative balance. Five homeostatic functions of the urinary system: ○ Regulates blood volume and blood pressure (by altering blood volume, blood pressure is altered in a directly proportional manner) By adjusting volume of water lost in urine Releasing erythropoietin (hormone necessary for RBC creation) ○ Regulates plasma ion concentration Controls amounts of sodium, potassium, and chloride ions (by controlling quantities lost in urine) Balancing calcium ion levels (through synthesis of calcitriol) ○ Helps stabilize Blood pH 4/13 by eliminating hydrogen ions (making blood more basic) and bicarbonate ions in urine ○ Conserves valuable nutrients (such as glucose) By preventing excretion of nutrients while excreting organic waste products ○ Assists liver in detoxifying poisons Structures of the urinary system ○ Kidneys: form urine ○ Ureters: two of them - transport urine from kidneys to bladder ○ Bladder: stores urine to avoid constant urination ○ Urethra: excretes urine from bladder to outside of the body ○ Adrenal glands: on top of the kidneys - they play a pivotal role in regulating kidney function as well as secreting hormones such as epinephrine. Major regions of the kidney ○ Renal cortex Outside component Superficial portion of the kidney in contact with renal capsule ○ Renal medulla Center area of the kidney Using the loop of Henle, it produces an osmotic gradient that allows us to create urine with higher concentration compared to the extracellular fluid which allows us to remove waste products without losing water Contains renal pyramids (6-18 distinct triangular structures) Renal columns Bands of cortical tissue separate adjacent renal pyramids Extend into medulla ○ Renal lobe 5/13 Multiple lobes inside the kidney Composes the nephrons which produce the urine, contains the renal medulla where we have the osmotic gradient, and contains blood vessels. Includes renal pyramids, overlying area of renal cortex, and adjacent tissues of renal columns Produces urine Other regions of the kidney that constitute a transportation pathway and DO NOT produce or modify urine ○ Renal papilla Ducts discharge urine into minor calyx, a cup-shaped drain ○ Major calyx Formed by four or five minor calyces ○ Renal pelvis Large funnel shaped chamber Fills most of the renal sinus Connected to ureter which drains the kidney ○ Hilum Point of entry for renal artery and renal nerves Point of exit for renal vein and ureter Urine flow: glomerulus → tubules → calyx → pelvis → ureter 6/13 iClicker #3: Knowledge: Which of the following is NOT one of the functions of the urinary system? a) Regulation of plasma ionic composition and pH b) Regulation of plasma volume and blood pressure c) Regulation of plasma protein concentration d) Regulation of plasma osmolarity Reason: the nephrons and the kidneys do not regulate protein composition because the proteins should not be filtered into the nephrons. The kidneys are not monitoring plasma protein concentration. Vocabulary for renal processes: ○ Primary urine: is the urine that leaves the glomerulus (component of the nephron) and it is what is being modified while moving through the nephron ○ Definitive urine: is the urine that leaves the nephron, goes through the collecting duct, through the calyxes, and into the bladder. ○ Nephron: the functional unit of the renal process where modifications are underwent - it is the functional unit of the renal process Anatomy of the nephron ○ Renal corpuscle: Glomerulus: capillary network for filtration Glomerular capsule (Bowman’s capsule): receives the filtrate and manages inflow to renal tubules leading to the start of primary urine. ○ Renal tubules: Long tubular passageway 7/13 Begins at renal corpuscle Reabsorb what we want to keep and pick up necessary components to maintain blood pH such as bicarbonate and H+ ions. We also secrete things we do not need into the renal tubules. End of renal tubule: definitive urine 2 types of nephrons: (distinguished by location) ○ Type 1: Cortical Short loop of Henle Majority of nephrons are cortical nephrons 80-85% Can produce concentrated urine ○ Type 2: juxtamedullary Long loop of Henle - descend deep into the medulla (inner part of the kidney) Responsible for the medullary osmotic gradient 15-20% of nephrons Can produce highly concentrated neuron (due to concentration gradient ) The renal corpuscle ○ Bowman’s capsule + glomerulus = renal corpuscle ○ The bowman’s capsule is made of podocytes (epithelial cells) ○ Podocytes interdigitate with capillary wall, forming myriad slits ○ Thus, the barrier between blood and the capsule is highly porous but not to WBC, RBC, albumin, and other components we do not want to be moved to the filtrate. ○ Note that Glomerular capillaries and glomerulus are the same 8/13 There are three layers between plasma in lumen of capillary and filtrate in bowman’s capsule: ○ Capillary endothelial cells ○ Basement membrane ○ Endothelial cells (podocytes) The renal tubule: ○ The flow of primary urine through the renal tubule ○ As the primary urine is formed, it flows from the capsule to the proximal convoluted tubule. This process is unregulated which means it happens constantly (not modified by hormones or neuronal signals) ○ The primary urine then moves to the proximal straight tubule where it is regulated ○ The proximal tubule then empties into the loop of Henle ○ The primary urine finally flows into the distal convoluted tubule and continues to the connecting tubule and down the collecting duct where it is the definitive urine. 3 sections of the loop of Henle: ○ Descending limb ○ Thin ascending limb ○ Thick ascending limb iClicker #4: Knowledge: What is the functional unit of the kidneys? a) The nephron b) The renal pelvis c) The cortex d) The medulla 9/13 Reason: The nephron is where urine is produced. It is where the primitive urine is produced and upon secretion and absorption we get definitive urine. 4 basic renal exchange processes: ○ Glomerular filtration: from glomerulus to bowman’s capsule ○ Reabsorption: from tubules to peritubular capillaries ○ Secretion: from peritubular capillaries to tubules ○ Excretion: (not in kidneys) from tubules to the outside of the body Glomerular filtration: ○ The filtration membrane is composed of: Fenestrated capillary epithelium (having many pores) Basement membrane Capsule podocyte layer ○ Blood arrives via the afferent arteriole and exits via the efferent arterioles. The efferent arteriole has a smaller diameter than afferent arteriole to allow manipulation of blood pressure in glomerulus which is completely independent of pressure inside the rest of the body. This pressure gradient allows movement into the bowman’s capsule. Driving forces (starling forces) of glomerular filtration which is the movement of water and ions from blood to bowman’s capsule: ○ Glomerular capillary hydrostatic pressure (PGC): pressure of blood and fluid pushing against walls of capillary (more volume → higher pressure) 60 mmHg High due to resistance of efferent arterioles ○ Bowman’s capsule oncotic pressure (ΠBC): Similar to osmotic pressure but it describes the pressure formed by plasma proteins which do not move across to the bowman's capsule. 0 mmHg null due to lack of proteins inside the bowman’s capsule ○ Bowman’s capsule hydrostatic pressure (PBC): 10/13 Fluid pushing on walls inside the bowman’s capsule Will be lower than that of glomerular capillary because of the large area of the bowman’s capsule and the fluid is not being restricted from leaving (volume moving away and going down renal tubules) 15 mmHg due to large volume of filtrate in closed space but not high compared to those found in capillaries ○ Glomerular oncotic pressure (ΠGC): High due to high plasma protein concentration 29 mmHg Glomerular Filtration Pressure = (PGC + ΠBC) - (PBC + ΠGC) = (60 mmHg + 0 mmHg) - (15 mmHg + 29 mmHg) = 16 mmHg Net Result ○ Pressure forces water and some solutes into the Bowman’s capsule ○ However, blood cells and large proteins CANNOT cross the filtration membrane ○ Glomerular filtration rate DOES NOT VARY with circulatory system blood pressure. ○ Pressure inside the glomerulus is controlled via: Intrinsic control: kidney adjusts constriction and dilation of arterioles Extrinsic control: neural and hormonal adjustment of arteriole diameter Questions: How are poisons released through the urine? ○ Substances that are already metabolized by the liver are then excreted in the urine. The blood and the nephrons are closely tied together so you can secrete them and urinate them. Is our urine water and waste and does it contain bilirubin? 11/13 ○ Water, other waste products, urea (nitrogen waste), ions, and bilirubin via urobilinogen (which gives urine its yellow color). How does the water come into the kidneys? ○ Water comes into the kidneys through the blood. The Kidney regulates water in plasma inside blood vessels. Do the blood vessels come from the gut to the kidney? ○ Your gut vessels go to the liver then back to the heart. Blood is coming from the heart through the renal artery to be processed then goes back out through the renal vein. The kidneys monitor blood and water already in the circulatory system while the liver monitors that coming from the GI tract. If both nephron types produce concentrated urine, why do we have two types? ○ Because if we only have cortical nephrons, no significant osmotic gradient will be created, and if just juxtamedullary nephrons, it would be energetically inefficient and costly. Are the structures in the nephron all smooth muscle? ○ No it is connective tissue - think about capillaries. Is reabsorption in the tubules unregulated? ○ Reabsorption in the proximal tubule is unregulated but in the distal convoluted tubule, connecting tubule, and collecting duct we have regulated absorption. Are kidney stones and bladder stones a result of faulty urinary tract systems not breaking down ions? 12/13 ○ Mainly, it is calcium that becomes a problem because it forms into stone-like structures and remember this is not happening in the nephron only but also in minor calyx and other structures. How are we able to survive with one kidney? ○ Your kidney can ramp up the processes. With one single kidney, you have an issue detoxifying substances and a longer time to filter, but it is still possible. 13/13