Urinary System Lecture Notes Part 2

–Ranges from 1.001 to 1.035 •Is dependent on solute concentration •Ratio of mass of a substance to the mass of an equal volume of distilled water •Distilled water = 1.000 The presence of glucose and ketone bodies in the urine can indicate __________. untreated diabetes mellitus Urine transport, Storage, and Elimination: ● ● ● Ureters Bladder Urethra Ureters •Three layers of ureter wall from inside out –Mucosa - transitional epithelium –Muscularis – smooth muscle sheets •Contracts in response to stretch •Propels urine into bladder –Adventitia – outer fibrous connective tissue Which structure is the muscular tube that delivers urine to t the bladder? Ureter The renal __________ is continuous with the ureter. Pelvis Urine transport, Storage, and Elimination Bladder Urethra Trigone •Muscular tube draining urinary bladder –Smooth triangular area outlined by openings for ureters and urethra •Sphincters •Bladder wall •Involuntary (smooth muscle) at bladder-urethra junction –Mucosa - transitional epithelial mucosa –Internal urethral sphincter –Thick detrusor muscle - three layers of smooth muscle •Contracts to open •Expands and rises superiorly during filling •Voluntary (skeletal) muscle surrounding urethra –External urethral sphincter without significant rise in internal pressure - holds ~ 500 ml The urethra has two only one in women. as it passes through pelvic floor functions in men, but true Micturition •Urination or voiding •Stretch receptors in bladder wall send signals to the micturition center of the Pons •Micturition is a parasympathetic response •Three simultaneous events must occur –Contraction of Bladder muscle by ANS –Opening of internal urethral sphincter by ANS –Opening of external urethral sphincter by somatic nervous system Micturition is __________. Which of the following is NOT a physical characteristic of freshly voided urine in a healthy person? a given volume of urine has a greater specific gravity than the same volume of distilled water clear and pale to deep yellow in color slightly basic in pH slightly aromatic in odor Homeostatic Imbalance Renal calculi Incontinence Urinary retention kidney stones in renal pelvis –Crystallized calcium, magnesium, or uric acid salts usually from weakened pelvic muscles •Large stones block ureter → pressure & pain –Stress incontinence •May be due to chronic bacterial infection, urine retention, ↑Ca2+ in blood, ↑pH of urine •Increased intra-abdominal pressure forces urine through external sphincter –Bladder unable to expel urine –Common after general anesthesia –Hypertrophy of prostate Treatment - catheterization –Overflow incontinence Urine dribbles when bladder overfills Which of the following is NOT one of the most common causes of incontinence in adults? nervous system problems emotional problems a side effect after general anesthesia physical pressure during pregnancy The major calyces are the __________. large branches of the renal pelvis The glomerular (Bowman's) capsule and glomerulus make up the __________. renal corpuscle Which of the following statements about the urinary system is INCORRECT? It carries out the majority of gluconeogenesis in the body. It metabolizes vitamin D to its active form. It produces renin, which helps regulate blood pressure. It produces erythropoietin, which stimulates red blood cell formation. Which of the following substances is the largest component of urine by weight after water? Urea Which of the following is NOT associated with primary nocturnal enuresis? females over the age of 60 years In what part of the nephron is plasma filtered? renal corpuscle the reason glucose is detected in the urine of individuals with uncontrolled diabetes is because __________. the transport maximum for glucose reabsorption has been exceeded Tubular secretion The descending limb of the loop of Henle is relatively impermeable to solutes and freely permeable to water. True Fluid electrolyte and balance Fluid compartments •Water within the body occupies two main fluid compartments •Intracellular fluid (ICF) - about two thirds by volume, contained in cells Inside cell membrane •Extracellular fluid (ECF) - consists of two major subdivisions Outside cell membrane –Plasma - the fluid portion of the blood –Interstitial fluid (IF) - fluid in spaces between cells Plasma and non plasma fluid The largest percentage of body water is located in what compartment? Intracellular fluid (ICF) Most fluid in the body is in the extracellular fluid (ECF) compartment. False Extracellular and intracellular fluids •Water is the universal solvent •Solutes are broadly classified into: –Electrolytes – dissociate into ions in water, minerals in your blood and other body fluids that carry an electric charge O slightly negative, H slightly positive •inorganic salts, all acids and bases, and some proteins •Electrolytes determine the chemical and physical reactions of fluids •Electrolytes have greater osmotic power than nonelectrolytes –Water moves according to osmotic gradients –Nonelectrolytes - examples include glucose, lipids, creatinine, and urea •Each fluid compartment of the body has a distinctive pattern of electrolytes –Extracellular fluids are similar •Sodium is the chief cation(+) •Chloride is the major anion(-) –Intracellular fluids have low sodium and chloride •Potassium is the chief cation •Phosphate is the chief anion The most prevalent electrolyte in the extracellular fluid is __________. Sodium Which condition would cause a drop in pH? Na+ Electrolyte balance in the body usually refers to the balance of __________. Salts The most abundant cation in extracellular fluid is potassium. False Which of the following is NOT an electrolyte? chloride potassium sodium glucose Electrolyte concentration •For single charged ions (e.g. Na+): 1 mEq = 1 mOsm •For bivalent ions (e.g. Ca2+): 1 mEq = 1/2 mOsm •1mEq of either provides same amount of charge Fluid movement among compartments •Compartmental exchange is regulated by osmotic and hydrostatic pressures •Two-way water flow is substantial •Plasma is the only fluid that circulates throughout the body and links external and internal environments •Between plasma and IF across capillary walls –Fluid leaks from arteriole end of capillary, reabsorbed at venule end; lymphatics pick up remaining and return to blood •Between IF and ICF - across cell membrane –Two-way osmotic flow of water –Ions move selectively; nutrients, wastes, gases unidirectional Osmotic and hydrostatic pressures regulate continuous exchange and mixing of fluids ● Water moves freely along osmotic gradients ● All body fluid osmolality almost always equal ● Change in solute concentration of any compartment leads to net water flow ↑ECF osmolality →water leaves cell ↓ ECF osmolality → water enters cell __________ circulates throughout the body and links the internal and external environments. Plasma Osmolality of plasma(blood/extracellular fluid) ↑= if water content goes down or solute content goes up - becomes more concentrated Osmolality ↓= water content goes up or solute concentration goes down - dilute Water balance and ECF Osmolality •To remain properly hydrated, water intake must equal water output •Water intake sources –Ingested fluid (60%) and solid food (30%) –Metabolic water or water of oxidation (10%) •Water output- water coming out –Urine (60%) and feces (4%) –Insensible losses (28%), sweat (8%) •Increases in plasma osmolality (electrolyte concentration) trigger thirst and release of antidiuretic hormone (ADH) A major stimulus for the release of antidiuretic hormone is __________. a rise in plasma osmolality The major source of water loss from the body is __________. Urine Water lost through expired air is referred to as __________. Insensible water loss All of the following would occur if there was an increase in plasma osmolality EXCEPT __________. production of large amounts of urine release of ADH thirst concentrated urine Regulation of water- Homeostasis Water levels changes Intake Output •Hypothalamic Thirst Center – drives water seeking ( thirsty) •Influence and Regulation of ADH –Thirst is quenched as soon as we begin to drink water –Feedback signals that inhibit the thirst centers include: –Water reabsorption in kidney’s collecting ducts is proportional to ADH release –Low ADH levels produce dilute urine and reduced volume of body fluids –High ADH levels produce concentrated urine •Moistening of the mucosa of the mouth and throat –Hypothalamic osmoreceptors trigger or inhibit ADH release •Activation of stomach and intestinal stretch receptors –Factors that specifically trigger ADH release include: prolonged fever; excessive sweating, vomiting, or diarrhea; severe blood loss; and traumatic burns All of the following factors would stimulate the hypothalamic thirst center EXCEPT __________. hypotonic extracellular fluid a decline in blood volume angiotensin II input from baroreceptors ADH acts on the ____________ to ___________ water excretion. Kidneys, decrease Disorders of water balance Dehydration Hypotonic Hydration Increases plasma osmolality Overhydration Edema Decrease in plasma osmolality –Water loss exceeds water intake –Renal Insufficiency or an and the body is in negative fluid extraordinary amount of water balance ingested quickly can lead to cellular overhydration, or –Causes include: hemorrhage, water intoxication severe burns, prolonged –ECF is diluted - sodium content vomiting or diarrhea, profuse sweating, water deprivation, and is normal but excess water is present diuretic abuse –Signs and symptoms: cottonmouth, thirst, dry flushed skin, and oliguria (v. low urine production) –The resulting hyponatremia promotes net osmosis into tissue cells, causing swelling –These events must be quickly reversed to prevent severe –Prolonged dehydration may lead to weight loss, fever, mental metabolic disturbances, particularly in neurons confusion –Other consequences include hypovolemic shock and loss of electrolytes –Treated with hypertonic saline –A typical accumulation of fluid in the interstitial space, leading to tissue swelling (not cell swelling) –Caused by anything that 1. increases flow of fluids out of the bloodstream or 2. hinders their return back to the bloodstream –Factors that accelerate fluid loss include: •Increased blood pressure, capillary permeability •Incompetent venous valves, localized blood vessel blockage •Congestive heart failure, hypertension, high blood volume –Hindered fluid return usually reflects an imbalance in colloid osmotic pressures •Edema - Hindered fluid return –Hypoproteinemia - low levels of plasma proteins •Forces fluids out of capillary beds at the arterial ends •Fluids fail to return at the venous ends •Results from protein malnutrition, liver disease, or glomerulonephritis –Blocked (or surgically removed) lymph vessels: •Cause leaked proteins to accumulate in interstitial fluid •Exert increasing colloid osmotic pressure, which draws fluid from the blood –Interstitial fluid accumulation results in low blood pressure and severely impaired circulation Which of the following is associated with a swelling of cells? Hypotonic hydration The condition in which sodium levels are too low is referred to as __________. hyponatremia Edema is accumulation of fluid in the __________. interstitial space All of the following would cause edema EXCEPT __________. incompetent venous valves hypotension liver disease hypoproteine mia