Chapter 26 and 27 Study Guide

1. What are the 5 main functions of the urinary system?

-removing waste products from bloodstream -storage of urine -excretion of urine -blood volume regulation -regulation of erythrocyte production

b. What wastes are eliminated from Integumentary system

Heat, Water, Salts, Urea

c. Describe specifically how the following acts on the kidneys: antidiuretic hormone

It's a hormone made by the hypothalamus in the brain and stored in the posterior pituitary gland. It tells your kidneys how much water to conserve. ADH constantly regulates and balances the amount of water in your blood.

2. Know the pathway of urine production and excretion (see figure 26-1).

Kidneys-Produce urine Ureters-Transport urine toward the urinary bladder Urinary bladder-Temporarily stores urine prior to urination Urethra-Conducts urine to exterior; in males, it also transports semen

rugae

Many tiny wrinkles, known as rugae, line the inner surface of the urinary bladder and allow it to stretch as it fills with urine..

2. Contrast the ionic composition of extracellular fluids and intracellular fluids (see fig.27-2 in your textbook).

Mg2+ and K+ are found in higher concentrations in the intracellular fluid, whereas Na+ and Cl- are found in higher concentrations in the extracellular fluid.

11. Define transport maximum.

The point at which increases in concentration of a substance do not result in an increase in movement of a substance across a cell membrane. In renal physiology, the concept of transport maximum is often discussed in the context of glucose and PAH.

azotemia

a medical condition characterized by abnormally high levels of nitrogen-containing compounds (such as urea, creatinine, various body waste compounds, and other nitrogen-rich compounds) in the blood.

trigone

a smooth triangular region of the internal urinary bladder formed by the two ureteric orifices and the internal urethral orifice. The area is very sensitive to expansion and once stretched to a certain degree, the urinary bladder signals the brain of its need to empty.

a. Describe specifically how the following acts on the kidneys: Aldosterone

action on sodium reabsorption in the distal nephron of the kidney, which is mediated by the epithelial sodium channel (ENaC).

c. Contrast reabsorption and secretion in the Distal tubule

actively secretes ions, toxins, and drugs, and reabsorbs sodium ions from the tubular fluid.

2. Nucleic Acid metabolism produces what waste product?

ammonia

3. Creatine phosphate catabolism produces what waste product?

creatine

detrusor muscle

remains relaxed to allow the bladder to store urine, and contracts during urination to release urine.

Hypernatremia

signs and symptoms: dehydration, thirst, or fatigue; irritability or restlessness causes: most often occurs in people who don't drink enough water. treatments: drinking more water or IV fluids.

Hypercalcemia

signs and symptoms: increased thirst and urination, belly pain, nausea, bone pain, muscle weakness, confusion, and fatigue. causes: Too much calcium in the blood. treatments: drugs or surgical removal of an overactive gland

Hyperphosphatemia

signs and symptoms: muscle cramps, tetany, and perioral numbness or tingling causes: high phosphate in blood treatments: phosphate binders

Hyponatremia

signs and symptoms: nausea, headache, confusion, and fatigue. causes: low sodium in blood treatments: Limited fluid intake, medications, and hospitalization may be needed.

Hyperkalemia

signs and symptoms: tiredness or weakness, a feeling of numbness or tingling, nausea or vomiting, trouble breathing, chest pain, palpitations or irregular heartbeats. causes: too much potassium in blood treatments: low potassium diet, treatment of insulin and glucose, calcium, bicarbonate, albuterol, epinephrine, etc.

Hypokalemia

signs and symptoms: weakness, fatigue, muscle cramps, pain causes: blood potassium too low treatments: potassium supplements, stop diuretics

Hypomagnesemia

signs and symptoms:Abnormal eye movements, convulsions, fatigue, muscle spasms or cramps, muscle weakness, numbness. causes: low magnesium in blood treatments: magnesium salts

Hypochloremia

signs and symptoms:Dehydration, fluid loss, or high levels of blood sodium may be noted. causes: low chloride ion in blood treatments:Rise in bicarbonate levels to compensate for decreased chloride levels

Hyperchloremia

signs and symptoms:Loss of body fluids from prolonged vomiting, diarrhea, sweating or high fever (dehydration). High levels of blood sodium. Kidney failure, or kidney disorders. Diabetes insipidus or diabetic coma. Drugs such as: androgens, corticosteroids, estrogens, and certain diuretics. causes: high levels of chloride ion in blood treatments: saline solution, potassium supplement

Hypocalcemia

signs and symptoms:Most cases have no symptoms. In severe cases, symptoms include muscle cramps, confusion, and tingling in the lips and fingers. causes: too little calcium in blood treatments: calcium and vitamin D supplements. If there's an underlying condition, that will also need treatment.

Hypophosphatemia

signs and symptoms:Muscle dysfunction and weakness - This occurs in major muscles, but also may manifest as: diplopia, low cardiac output, dysphagia, and respiratory depression due to respiratory muscle weakness. Mental status changes - This may range from irritability to gross confusion, delirium, and coma. causes: low phosphate in blood treatments: magnesium, vitamin d, phosphate supplements

Hypermagnesemia

signs and symptoms:hypotension, respiratory depression, and cardiac arrest causes: high magnesium in blood treatments:IV administration of calcium gluconate and possibly furosemide; hemodialysis can be helpful in severe cases

d. Contrast reabsorption and secretion in the Collecting duct

sodium ion, bicarbonate and urea reabsorption. The collecting system is important in controlling the pH of body fluids through the secretion of hydrogen or bicarbonate ions. If the pH of the peritubular fluid decreases, carrier pro- teins pump hydrogen ions into the tubular fluid and reabsorb bicarbonate ions that help restore normal pH. If the pH of the peritubular fluid rises (a much less common event), the collect- ing system secretes bicarbonate ions and pumps hydrogen ions into the peritubular fluid. The net result is that the body elimi- nates a buffer and gains hydrogen ions that lower the pH.

6. Define and differentiate between: filtration, reabsorption, and secretion.

1. The Glomerulus Filters Water and Other Substances from the Bloodstream 2. The Filtration Membrane Keeps Blood Cells and Large Proteins in the Bloodstream 3. Reabsorption Moves Nutrients and Water Back into the Bloodstream 4. Waste Ions and Hydrogen Ions Secreted from the Blood Complete the Formation of Urine 5. Urine Is 95% Water

10. What are the 5 major functions of the proximal convoluted tubule (PCT)?

1.PCT reabsorbs 2/3 of the filtered Na or (65-80% of Na) and H2O 2.It reabsorbs all of the glucose, and amino acids 3.glucose is reabsorbed via Na-Glu cotransporter 4.It also reabsorbs a fraction of the bicarbonate, potassium, phosphate and calcium 5.It secretes ammonia, which functions as a buffer for secreted H+. It also secretes creatine, which is used to access the function of the kidney.

filtration slits

Blood is filtered through the slit diaphragm (or filtration slit), between the feet or processes of the podocytes. The filtered blood passes out the proximal tubule (B, yellow) on the right.

b.Describe specifically how the following acts on the kidneys: atrial natriuretic peptide

Atrial natriuretic peptide (ANP) is a peptide hormone which reduces an expanded extracellular fluid (ECF) volume by increasing renal sodium excretion. ANP is synthesized, and secreted by cardiac muscle cells in the walls of the atria in the heart.

a. What wastes are eliminated from respiratory system

CO2, Water, Heat

a. Describe the following buffer systems: bicarbonate

Cellular respiration produces carbon dioxide as a waste product. This is immediately converted to bicarbonate ion in the blood. On reaching the lungs it is again converted to and released as carbon dioxide. While in the blood , it neutralises acids released due to other metabolic processes. In the stomach and deudenum it also neutralises gastric acids and stabilises the intra cellular pH of epithelial cells by the secretions of bicarbonate ions into the gastric mucosa.

14. Explain how the nephron acts as a countercurrent exchange system. What important functions does this countercurrent setup allow for? Which nephrons are primarily responsible for this (cortical or juxtamedullary)?

Countercurrent multiplication in the kidneys is the process of using energy to generate an osmotic gradient that enables you to reabsorb water from the tubular fluid and produce concentrated urine. This mechanism prevents you from producing litres and litres of dilute urine every day, and is the reason why you don't need to be continually drinking in order to stay hydrated. Although both cortical and juxtamedullary nephrons regulate the concentrations of solutes and water in the blood, countercurrent multiplication in the loops of Henle of juxtamedullary nephrons is largely responsible for developing the osmotic gradients that are needed to concentrate urine. Fluid leaving the ascending limb of the loop of Henle enters the distal convoluted tubule, where its composition is further adjusted, and then drains into collecting tubules. These tubules empty into collecting ducts that descend back through the medulla, and eventually connect to the ureter, which transports urine to the bladder.

4. Where in the kidney are the nephrons primarily located?

Different sections of nephrons are located in different parts of the kidney: The cortex contains the renal corpuscle, proximal, and distal convoluted tubules. The medulla and medullary rays contain the loops of Henle and collecting ducts.

7. Describe the process of glomerular filtration. Explain why fluid moves out of the capillaries and into the glomerulus. In particular contrast the glomerular capillaries with other capillary beds. What determines what molecules enter the capsular space?

Glomerular filtration is the first step in making urine. It is the process that your kidneys use to filter excess fluid and waste products out of the blood into the urine collecting tubules of the kidney, so they may be eliminated from your body. Fluid moves out of the capillaries into the glomerulus due to capillary hydrostatic pressure. Capillary hydrostatic pressure in intestinal villous capillaries is 15 mm of Hg while it is 55 in glomeruli capillaries. Bowman's capsule (or the Bowman capsule, capsula glomeruli, or glomerular capsule) is a cup-like sack at the beginning of the tubular component of a nephron in the mammalian kidney that performs the first step in the filtration of blood to form urine. A glomerulus is enclosed in the sac. Fluids from blood in the glomerulus are collected in the Bowman's capsule (i.e., glomerular filtrate) and further processed along the nephron to form urine.Any small molecules such as water, glucose, salt (NaCl), amino acids, and urea pass freely into Bowman's space, but cells, platelets and large proteins do not.

c. Sympathetic control

If blood pressure drops too low due to excessive fluid loss, then the sympathetic nervous system will override renal autoregulation. Sympathetic nerves innervate the afferent arteriole, causing smooth muscle contraction. The sequence of events is as follows: loss of ECF volume (due to hemorrhage, diarrhea or dehydration) causes a drop in mean arterial pressure (MAP). Decreased MAP is detected by arterial baroreceptors, which leads to sympathetic nervous system activation, afferent arteriole constriction, and decreased GFR. (Another effect of the sympathetic nervous system is to stimulate renin secretion by the juxtaglomerular cells, activating the renin-angiotensin-aldosterone system (RAAS). The RAAS increases extracellular fluid volume by increasing

internal urethral sphincter

In males and females, both internal and external urethral sphincters function to inhibit the release of urine. In males, the internal sphincter muscle of urethra functions to prevent reflux of seminal fluids into the male bladder during ejaculation.

11. What is meant by "transport maximum"? Describe a circumstance in which an abnormal amount of glucose might be seen in the blood, yet the person is not diseased (in other words....can there be glucose in the urine of a healthy person? Under what circumstances?)

In physiology, transport maximum (alternatively Tm or Tmax) refers to the point at which increases in concentration of a substance do not result in an increase in movement of a substance across a cell membrane. In renal physiology, the concept of transport maximum is often discussed in the context of glucose and PAH. Example: A healthy person eats a bunch of sugar and excretes the excess.

9. Differentiate between the vasa recta and the peritubular capillaries.

Peritubular capillaries are tiny blood vessels that participate in secretion and reabsorption between blood and the inner lumen of the nephron. The vasa recta are the peritubular capillaries that surround the proximal and distal tubules, as well as the loop of Henle, where they are known as vasa recta. The vasa recta, the capillary networks that supply blood to the medulla, are highly permeable to solute and water. As with the loop of Henle, the vasa recta form a parallel set of hairpin loops within the medulla. Not only do the vasa recta bring nutrients and oxygen to the medullary nephron segments but, more importantly, they also remove the water and solute that is continuously added to the medullary interstitium by these nephron segments.

b. Describe the following buffer systems: phosphate

Phosphate buffer system operates in the internal fluids of all cells. It consists of dihydrogen phosphate ions as the hydrogen ion donor ( acid ) and hydrogen phosphate ion as the ion acceptor ( base ) . If additional hydroxide ions enter the cellular fluid, they are neutralised by the dihydrogen phosphate ion. If extra hydrogen ions enter the cellular fluid then they are neutralised by the hydrogen phosphate ion.

c. Describe the following buffer systems: protein

Protein buffer system helps to maintain acidity in and around the cells. Haemoglobin makes an excellent buffer by binding to small amounts of acids in the blood, before they can alter the pH of the blood. Other proteins containing amino acid histidine are also good at buffering.

9. How is GFR regulated?

Renal autoregulation involves feedback mechanisms intrinsic to the kidney that cause either dilation or constriction in the afferent arteriole so as to counteract blood pressure changes and keep a steady GFR. For instance, if the mean arterial pressure increases, renal autoregulation causes the afferent arteriole to constrict, preventing the pressure increase from being transmitted to the glomerular capillaries, and keeping the GFR from increasing.

16. What are the causes of renal insufficiency? How does hemodialysis work?

Renal insufficiency is poor function of the kidneys that may be due to a reduction in blood-flow to the kidneys caused by renal artery disease. Normally, the kidneys regulate body fluid and blood pressure, as well as regulate blood chemistry and remove organic waste. Proper kidney function may be disrupted, however, when the arteries that provide the kidneys with blood become narrowed, a condition called renal artery stenosis. Some patients with renal insufficiency experience no symptoms or only mild symptoms. Others develop dangerously high blood pressure, poor kidney function, or kidney failure that requires dialysis. In hemodialysis, a dialysis machine and a special filter called an artificial kidney, or a dialyzer, are used to clean your blood. To get your blood into the dialyzer, the doctor needs to make an access, or entrance, into your blood vessels. This is done with minor surgery, usually to your arm.

4. Differentiate between respiratory and renal control of blood pH.

Respiratory-As carbon dioxide accumulates in the blood, the pH of the blood decreases (acidity increases). The brain regulates the amount of carbon dioxide that is exhaled by controlling the speed and depth of breathing (ventilation). Renal-The kidneys can regulate reabsorption of carbonic acid in the tubule, increasing or reducing acid secretion. So, urine that is more acidic than normal may mean the body is ridding itself of excess dietary acid and thus making blood pH more alkaline. Ammonia is another way the kidney can regulate pH balance.

5. Differentiate between respiratory and renal compensation of pH imbalances.

Role of the lungs One mechanism the body uses to control blood pH involves the release of carbon dioxide from the lungs. Carbon dioxide, which is mildly acidic, is a waste product of the processing (metabolism) of oxygen (which all cells need) and, as such, is constantly produced by cells. As with all waste products, carbon dioxide gets excreted into the blood. The blood carries carbon dioxide to the lungs, where it is exhaled. As carbon dioxide accumulates in the blood, the pH of the blood decreases (acidity increases). The brain regulates the amount of carbon dioxide that is exhaled by controlling the speed and depth of breathing (ventilation). The amount of carbon dioxide exhaled, and consequently the pH of the blood, increases as breathing becomes faster and deeper. By adjusting the speed and depth of breathing, the brain and lungs are able to regulate the blood pH minute by minute. Role of the kidneys The kidneys are able to affect blood pH by excreting excess acids or bases. The kidneys have some ability to alter the amount of acid or base that is excreted, but because the kidneys make these adjustments more slowly than the lungs do, this compensation generally takes several days.

13. What is a counter current multiplier?

Sodium and chloride ions are actively pumped from the ascending limb of the loop but water is retained, since the ascending limb is impermeable to water. This creates a concentration gradient in the medulla in which the concentration of sodium and chloride is greatest in the region of the bend of the loop. Fluid passing from the loop of Henle to the distal tubule is less concentrated than that entering the loop, but because of the high osmotic pressure in the medulla water diffuses out of the collecting ducts, producing a concentrated urine.

c. What wastes are eliminated from Digestive system

Solid wastes, CO2, Water, Salts, Heat

3. What is the function of the nephron? Differentiate between renal corpuscle and renal tubule. Know the parts of the renal tubule and know the pathway of urine through the nephron.

The nephron is the basic structural and functional unit of the kidney. Its chief function is to regulate the concentration of water and soluble substances like sodium salts by filtering the blood, reabsorbing what is needed and excreting the rest as urine.

6. Contrast cortical nephrons and juxtamedullary nephrons.

The key difference between cortical nephron and juxtamedullary nephron is, the Cortical Nephron does not go deep into the medulla, and their glomerulus is in the cortex while Juxtamedullary Nephron goes deeper into the medulla and their glomerulus lies in the border of cortex and medulla.

a. Describe the myogenic mechanism

The myogenic mechanism is how arteries and arterioles react to an increase or decrease of blood pressure to keep the blood flow within the blood vessel constant.

b. Contrast reabsorption and secretion in the Loop of Henle

The principal function of the loop of Henle appears to be the recovery of water and sodium chloride from the urine.

10. Contrast reabsorption and secretion in the proximal tubule

The proximal tubule regulates the pH of the filtrate by exchanging hydrogen ions in the interstitium for bicarbonate ions in the filtrate; it is also responsible for secreting organic acids, such as creatinine and other bases, into the filtrate.

8. What is glomerular filtration rate (GFR)?

The rate at which plasma is filtered (measured in ml/min). A test used to check how well the kidneys are working. Specifically, it estimates how much blood passes through the glomeruli each minute. Glomeruli are the tiny filters in the kidneys that filter waste from the blood.

d. Renin-angiotensin-aldosterone mechanism

The renin-angiotensin system (RAS) or the renin-angiotensin-aldosterone system (RAAS) is a hormone system that regulates blood pressure and fluid balance. When renal blood flow is reduced, juxtaglomerular cells in the kidneys convert the precursor - prorenin, already present in the blood into renin and secrete it directly into the circulation. Plasma renin then carries out the conversion of angiotensinogen, released by the liver, to angiotensin I.[2] Angiotensin I is subsequently converted to angiotensin II by the angiotensin-converting enzyme (ACE) found in the lungs. Angiotensin II is a potent vasoconstrictive peptide that causes blood vessels to narrow, resulting in increased blood pressure.[3] Angiotensin II also stimulates the secretion of the hormone aldosterone[3] from the adrenal cortex. Aldosterone causes the renal tubules to increase the reabsorption of sodium and water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance). This increases the volume of extracellular fluid in the body, which also increases blood pressure. If the RAS is abnormally active, blood pressure will be too high. There are many drugs that interrupt different steps in this system to lower blood pressure. These drugs are one of the primary ways to control high blood pressure, heart failure, kidney failure, and harmful effects of diabetes.

podocytes

Together with endothelial cells of the glomerular capillary loop and the glomerular basement membrane they form a filtration barrier. Podocytes cooperate with mesangial cells to support the structure and function of the glomerulus.

3. Understand how H+ ions are secreted into the tubular fluid of the renal tubule.

Tubular secretion occurs from the epithelial cells that line the renal tubules and collecting ducts. It is the tubular secretion of H+ and NH4+ from the blood into the tubular fluid (i.e. urine - which is then excreted from the body via the ureter, bladder, and urethra) that helps to keep blood pH at its normal level. The movement of these ions also helps to conserve sodium bicarbonate (NaHCO3).

b. Tubular glomerular feedback

Tubuloglomerular feedback is one of several mechanisms the kidney uses to regulate glomerular filtration rate (GFR). It involves the concept of purinergic signaling, in which an increased distal tubular sodium chloride concentration causes a basolateral release of adenosine from the macula densa cells.

8. What is the relationship between major calyces, minor calyces, and renal pelvis?

Urine formed in the kidney passes through a renal papilla at the apex into the minor calyx; two or three minor calyces converge to form a major calyx, through which urine passes before continuing through the renal pelvis into the ureter.

d. What wastes are eliminated from Urinary system

Wastes containing nitrogen, Water, CO2, Salts, Ions

15. Describe the micturition reflex.

When urination is desired, signals from the brain stimulate the micturition reflex. The brain also decreases action potentials in the somatic motor neurons to relax the external urinary sphincter.

5. Trace the pathway of blood through the kidney.

aorta->renal artery->segmental artery->interlobular artery->arcuate artery->cortical radiate artery->afferent arteriole->glomerulus (capillaries)->efferent arteriole->peritubular capillaries or vasa recta->cortical radiate vein->arcuate vein->interlobular vein->renal vein->inferior vena cava

d. Describe specifically how the following acts on the kidneys: parathyroid hormone

blocks reabsorption of phosphate in the proximal tubule while promoting calcium reabsorption in the ascending loop of Henle, distal tubule, and collecting tubule.

1. Contrast the following concepts: fluid balance, electrolyte balance, acid-base balance.

fluid balance--Cell function depends not only on continuous nutrient supply / waste removal, but also on the physical / chemical homeostasis of surrounding fluids acid-base balance--Acid-base balance is concerned with maintaining a normal hydrogen ion concentration in the body fluids

13. Define incontinence.

lack of voluntary control over urination or defecation.

1. What is buffer? Differentiate between physical and chemical buffers.

lessen or moderate the impact of (something). Chemical buffer: system of one or more compounds that act to resist pH changes when strong acid or base is added Physical buffer: not related to pH

7. Would you expect to find albumin in the filtrate entering the renal tubule?

no, because proteins do not enter the renal tubules

excretion

the process of eliminating or expelling waste matter.

1. Protein catabolism produces what waste product?

toxic ammonium ion (NH4+)