A&P II Urinary System Study Guide PDF

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A&P II Exam 5 Study Guide Dr. Jackson Hannah Klonowski | December 10 2019

Renal & Urinary System Anatomy & Physiology - CH 26 (all sections) I. Overview of the Urinary System A. What are the anatomical components of the urinary system? a. Kidneys: produce urine b. Ureters: transport urine towards bladder, smooth muscle initiates peristaltic contractions, transitional epithelium lined, outer layer of connective tissue c. Urinary Bladder: temporarily stores urine, transitional epithelium (stretch & recoil), detrusor muscle d. Urethra: transports urine to exterior, longer in men, layer of smooth muscle and stratified squamous epithelial lining / mucosal cells B. Major Functions→ a. Excretion: removal of organic wastes from body fluids b. Elimination: discharge of aqueous waste into the environment c. Osmoregulation: homeostatic control of: fluids, buffering systems & electrolytes, acids / bases d. Conservation: of valuable nutrients (glucose, aa’s, urea) - during starvation deamination of aa’s for use in cellular respiration e. Regulation of blood volume (directly) & BP (indirectly) f. Regulation of blood & urine pH II. A.

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Renal Anatomy & Physiology Where are the kidneys located/positioned? How are they oriented within this space? a. the kidneys sit posterior OUTSIDE the peritoneal cavity b. right kidney is slightly inferior to the left c. supportive tissues: renal fascia, perirenal fat, fibrous capsule What are the structural (anatomical and histological) features of the kidneys? a. renal cortex b. renal medulla c. renal pyramids d. renal columns e. fibrous capsule f. renal papillae g. renal pelvis h. minor calyx i. major calyx How does blood flow into/out of the kidney (to the level covered in lecture)? a. renal artery→ afferent arterioles→ glomerulus→ efferent arterioles→ peritubular capillaries→ venules→ renal vein What are the two types of nephrons and where are they located? a. Cortical nephrons: located in the cortex towards the outside layer of kidney

b. Juxtamedullary nephrons: located inferior to cortical nephrons deeper into the medulla, intertwines with the vasa recta blood supply E. What is the structure of each of the following parts of the nephron and collecting duct system? How does each of these parts of the nephron function? a. Renal Corpuscle = Bowman’s Capsule + Capsular Space + Glomerulus: thin squamous cells, production of filtrate i. macula densa: ii. juxtamedullary cells: iii. podocytes: on the visceral layer of the capsule, iv. mesangial cells: b. Proximal Collecting Tubule (PCT): cuboidal cells with microvilli, reabsorption of water, ions and organic nutrients, approx. 50-70% of filtrate is reabsorbed here, osmotic concentration = 300mOsm c. Thin Descending Loop: simple squamous cells, reabsorption of water / permeable to water, impermeable to urea d. Thick Ascending Loop: cuboidal cells, reabsorption of sodium and chloride, net movement of sodium and chloride into peritubular fluid e. Distal Convoluted Tubule (DCT): cuboidal cells with few microvilli, secretion of ions, acids, drugs & toxins, hormonal control of reabsorption, impermeable to urea f. Collecting Ducts (CD): simple cuboidal cells, variable reabsorption of water, secretion of sodium, potassium, bicarbonate, and hydrogen ions, impermeable to urea, highest concentration of 1200mOsm g. Papillary Duct: simple columnar cells, delivery of urine into renal calyx, permeable to urea h. Peritubular Capillaries: blood supply to the PCT and DCT i. Vasa Recta: blood supply to juxtamedullary nephrons, comes from the efferent arteriole F. What is the path of flow of the urine filtrate in the kidneys from the point of filtration to the point of being eliminated through the ureters? a. PCT→ thin descending loop→ thick ascending loop→ DCT→ collecting ducts→ papillary duct→ minor calyx→ major calyx→ renal pelvis→ ureters→ bladder→ urethra III. Diuresis A. Physiology of the Glomerulus a. How are Bowman’s capsule and the Glomerulus structured in order to perform filtration of the blood plasma? What processes lead to the formation of urine at the glomerulus? b. What factors influence glomerular filtration pressure and the rate of urine filtrate formation? i. changes in pressure in the glomerular capsule ii. blood-colloid osmotic pressure (BCOP): iii. glomerular hydrostatic pressure (GHP): iv. capsular hydrostatic pressure (CHP): v. net filtration pressure = GHP-BCOP-CHP

c. What is the role of Autoregulation of GFR? i. metabolic theory: humoral autoregulation of blood flow; vasodilation of vessels in response to metabolic stimuli / increased metabolism (exercise) = increased blood flow 1. low oxygen levels (hypoxia) or high carbon dioxide levels (hypercapnia) 2. release of histamines 3. elevated localized body temperature 4. alterations of local blood pH ii. myogenic theory: humoral autoregulation of blood flow; detects changes in BP 1. decreased GFR = dilation of afferent arterioles to increased glomerular BP, constriction of efferent arterioles & contraction of mesangial cells d. What is the role of neural regulation of GFR by the SNS/PNS? i. sympathetic nervous system compensates for decreased BP by vasoconstriction of afferent arterioles and dilation of efferent arterioles to lower GFR ii. no parasympathetic role e. What is the role of Hormonal regulation of GFR? i. erythropoietin (EPO): secreted by interstitial fibroblasts in the kidney in response to hypoxia; increases RBC production to increase BV and peripheral BP, directly increases BCOP ii. atrial natriuretic peptide (ANP): secretes by heart atrial cells, blocks angiotensin II production, direct control of lowering BV to homeostasis iii. brain natriuretic peptide (BNP): secreted by brain smooth muscle to increase water excretion in urine and increases sodium loss, direct control of lowering BV back to homeostasis iv. renin-angiotensin II system: juxtaglomerular cells secrete renin in response to low fluid flow detected by the macula densa, 1. renin + angiotensinogen→ angiotensin I 2. angiotensin I + angiotensin converting enzyme (ACE) → angiotensin II 3. angiotensin II stimulates adrenal cortex to release aldosterone and constricts efferent arterioles increasing BP 4. aldosterone stimulates sodium uptake and thirst response f. How does Glomerulonephritis and Acute Renal Failure relate to damage to the glomerular filtration system? B. Physiology of the Nephron a. What are the cellular transport mechanisms (types and functions) found along each segment of the nephron? i. sodium-potassium pumps ii. co-transporters b. What is the role of countercurrent multiplication to create and maintain the renal pyramid concentration gradient? i. countercurrent multiplication: process of creating a concentration gradient

in juxtamedullary nephrons to create the most concentrated urine possible, reabsorption of water form tubular fluid C. Physiology of the DCT & Collecting Duct a. How do hormones regulate the volume, concentration, pH of the urine output by the DCT/CD? b. What are the basic characteristics of a normal urine sample? i. pH of 6.0 ii. 700-2000 mL a day iii. specific gravity of 1.03-1.3 iv. nitrogenous waste includes urea, uric acid, creatine and small amounts of ammonia c. What would be abnormal test results from a urinalysis and what might these results indicate pathophysiologically? i. protein = pregnancy, other disease ii. glucose = diabetes mellitus iii. polyuria (high volume of dilute urine) = diabetes insipidus iv. cloudy texture = infection v. severe dehydration can indicate acute renal failure IX. Micturition A. How is the micturition reflex regulated by the autonomic nervous system (SNS and PNS)? a. stretch receptors in the bladder signal to sensory nerves in the pelvis that tell parasympathetic system to stimulate detrusor muscle contraction b. CNS reflex can override the urge to urinate until the individual can voluntarily relax the external sphincter B. How is this influenced by conscious voluntary control? C. What happens when a person loses voluntary control of micturition? (aka urinary incontinence) D. What is the role of the internal and external sphincters in this process? a. internal sphincter is under involuntary control but remains closed to prevent leakage of urine b. external sphincter is skeletal muscle and voluntarily controlled

Fluid, Electrolyte, & Acid-Base Balance - CH 27 I. Fluids & Electrolytes A. What is meant by the terms fluid balance, electrolyte balance, and acid–base balance? How are these important for maintaining homeostasis? a. Fluid compositions of human body→ i. Adult males: 60% water (33% intracellular fluid, 27% extracellular fluids), 40% solids ii. Adult females: 50% water (27% intracellular fluid, 23% extracellular fluids), 50% solids iii. Intracellular fluid (ICF): rich in potassium and magnesium

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Extracellular fluid (ECF): plasma + interstitial fluid, rich in sodium and chloride How are fluid and electrolyte levels regulated? a. ADH antidiuretic hormone: released by the posterior pituitary, conserves water by reabsorbing it into circulation and preventing dehydration and decreasing urine volume i. caffeine and alcohol suppress ADH in the kidneys causing more frequent urination How does fluid move within the ECF, between the ECF and the ICF, and between the ECF and the environment? a. Isotonic solutions: no osmotic flow, ECF = ICF, RBCs appear normal b. Hypotonic solutions: osmotic flow of water into cells, low solute concentration in ECF, RBCs appear bulging c. Hypertonic solutions: osmotic flow of water out of cells, high solute concentration in ECF, RBCs appear shriveled What buffering systems are in place to maintain the pH balance of the ICF and ECF? a. carbonic acid-bicarbonate buffer system: weak acid or bases captures the free ions to prevent a significant change in pH b. phosphate buffer system: most predominant buffer system, when weak acids come into contact with strong bases, the weak acid reverts back to the base to form water c. ammonia buffer system: release of hydrogen ion from ammonia breaks it down into urea which is secreted into the tubular fluid for urine removal, ammonia is a result of amino acid breakdown How do the kidneys compensate for changes in pH balance? a. acidosis: results from the addition of hydrogen, kidney response is to secrete more H, conserve bicarbonate and remove carbon dioxide from urine b. alkalosis: results from the removal of hydrogen, kidney response is conservation of H and secretion of bicarbonate...