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Home , Body cavity, Efferent arteriole, Excretory system, Urinary system

The rid body of CO2 from energy of cells 4. production and elimination are one of the most liver excretes bile pigments, salts, , some toxins important mechanisms of body 2. elimination of excess nutrients & excess all body systems are directly or indirectly affected by 3. helps to regulate volume & pressure function is directly affected by the volume of fluids eg. composition of blood is determined more by kidney function retained or removed from body: than by diet eg. excessive salts promote retention main function of kidneys is to get rid of metabolic greater volume increases BP wastes eg. dehydration lower volume decreases BP typically referred to as “” excretory wastes = metabolic wastes 4. regulation of & body pH 5. regulates erythropoiesis chemicals & toxins produced by cells during metabolism kidneys produce = erythropoietin that regulates erythropoiesis:

General Functions of Urinary System: hypoxic secretes more erythropoietin excessive O2 inhibits hormone production 1. removal of metabolic wastes & toxins 6. aids in calcium absorption but we have several organs that serve an excretory function other than kidneys: affects the absorption of Calcium from intestine by helping to activate circulating in blood 1. kidneys

2. sweat glands rid body of water, minerals, some nitrogenous wastes (ammonia)

3.

Human & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 1 Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 2

Anatomy of Urinary System extensions of the cortex = renal columns divides the medulla into 6-10 renal Organs: pyramids kidneys – clean and filter blood – tubes that take urine to bladder papilla of each pyramid nestled in cup shaped bladder – stores urine until eliminated calyces – removes urine from body calyces converge to form renal 1. kidneys 2. ureters dorsal body wall the rest of urinary system is “plumbing” retroperitoneal behind parietal funnels urine to paired ureters just above waist tubular extensions of renal pelvis

surrounded by peristalsis moves urine along to bladder

barrier against trauma and spread of 3. bladder infections small, size of walnut when empty

hilum = indentation where vessels and can hold up to 800 ml (24 oz) voluntarily attach up to 2000 ml (60 oz) when obstructed

Frontal Section of Kidney wall consists of 4 layers (same as GI tract) mucosa -innermost layer cortex outer zone of kidney secretes mucous for protection from corrosive effects of urine medulla interior of kidney -fibrous connective tissue

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 3 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 4 muscularis -several layers Histology of Kidney

serosa -visceral peritoneum = functional units of kidneys

involuntary internal & voluntary external each kidney is composed of over 1 million two basic parts:

as bladder expands to hold urine 1. nephric tubule = microscopic, highly convoluted tubule activates stretch receptors in wall that monitor volume 2. associated blood supply

can find various parts of the nephron and its blood supply in the when volume exceeds 200 ml the receptor cortex and medulla of kidney signals enter our conscious perception = desire to urinate Nephric Tubule

4. urethra the nephric tubule is organized into several discrete structures: male: Bowman’s Capsule dual function: cup shaped mouth of nephron usually in cortex rid body of urine release of seminal fluid during orgasm Proximal Convoluted Tubule attached to Bowman’s Capsule female: highly coiled (convoluted) inner surface contains microvilli single function: rids body of urine shorter large loop consisting of: descending limb & ascending limb extends down into medulla more prone to UTI’s

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 5 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 6

Distal Convoluted Tubule branches eventually into appears similar to PCT Afferent Arteriole Collecting Tubule bring blood to individual nephrons many DCT’s drain into one collecting tubule bundles of collecting tubules = pyramids dense bed Pyramids drain into Calyces (sing. = calyx) formed by afferent arteriole inside Bowman’s capsule

Calyces coalesce to form pelvis Bowman’s Capsule + Glomerulus =

Blood Supply blood leaves glomerulus via efferent arteriole [ capillary bed artery] kidneys are highly vascularized Peritubular every minute, 1200 ml/min of blood flows through efferent arteriole divides into another capillary bed kidneys surrounds the rest of the nephric tubule (PCT-LH-DCT-CT) =1/5th of Renal 45 gallons/day; all blood ~60x‘s/day returns blood to vena cava more blood perfuses the kidney per weight than any other

(much more than eg. , , liver, etc)

within the kidney, bloodflow is greatest in the cortex where glomeruli are located; flow decreases with depth in the medulla

Renal Artery

brings blood to kidney

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 7 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 8 Urinary Physiology kidneys can maintain a fairly constant filtration rate changes in arterial pressure from 80 to 180 mmHg produce urine formation in nephrons occurs by: little change in blood flow and filtration rate in glomerulus 1. filtration 2. reabsorption if blood pressure is reduced below this urine 3. secretion formation slows down

1. Filtration filtrate is essentially the same composition as plasma without formed elements or occurs in renal corpuscle: solutes (filtrate) enter Bowmans capsule Glomerulus Bowmans Capsule 2. Tubular Reabsorption water, salts, small molecules and wastes are filtered out of blood urine is not the same composition as this filtrate capillaries of glomerulus: Composition of Plasma, Filtrate & Urine (solids in grams/24hrs; water in liters/24 hrs) Reabsorbed fenestrated capillaries Plasma Filtrate Amount % Urine Proteins 8,000 15 15 100.0% 0 act like sieve Glucose 180 180 180 100.0% 0 molecules less than 10,000MW Salts 1,498 1,498 1,486 99.1% 12 Water 180 180 178 99.2% 1.5 have higher filtration pressure than other 50 50 25 50.0% 25 8 8 7.2 90.0% 0.8 capillaries of body Creatinine 1.5 1.5 0 0.0% 1.8

afferent arteriole is larger than efferent arteriole most of the filtrate is reabsorbed

increases pressure in glomerulus overall, ~99% of glomerular filtrate gets reabsorbed only ~1% of original filtrate actually leaves the pressure ~55mmHg body as urine

(vs 35mmHg in most capillaries) reabsorption is more selective

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 9 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 10

needed nutrients are conserved all small proteins, glucose, amino acids are wastes and toxins are eliminated reabsorbed blood levels of fluids, salts, acidity etc are actively regulated main metabolic wastes removed by kidneys are most water, most salts are reabsorbed “nitrogen wastes”: 1. urea Loop of Henle 2. uric acid 3. creatinine additional Cl+ and Na+ ions are reabsorbed by active transport 1. urea main nitrogen containing waste produced during metabolism under the control of formed in liver as result of breakdown (mineralocorticoids) concentration in urine mainly determined by dietary intake\ secretion controlled by salt 2. uric acid concentrations in tissue fluids end product of nucleic acid metabolism some is also secreted by PCT also affects reabsorption of water 3. creatinine (water follows salt) normal end product of muscle metabolism & Collecting Tubule occurs all along nephric tubule additional water is reabsorbed but different substances are reabsorbed back into blood from different parts of tubule: under control of ADH (antidiuretic hormone)

Proximal Convoluted Tubule No ADH tubules are practically impermeable to water ~80% of materials to be reabsorbed are reabsorbed in PCT with ADH tubules are permeable to water cells lining PCT have microvilli Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 11 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 12 3. Tubular Secretion Urine Analysis

cells of DCT and CT can also actively secrete the kidneys perform their homeostatic functions of some substances controlling the composition of internal fluids of

+ + - body esp K and H HCO3 NH4 some drugs (eg. penecillin) the by-product of these activities is Urine usually urine is slightly acidic urine contains a high concentration of solutes normal diet produces more acid than alkaline waste products in a healthy person, its volume, pH and solute concentration vary with the needs of body

during certain pathologies, the characteristics of urine may change dramatically

an analysis of urine volume, physical and chemical properties can provide valuable information on the internal conditions of the body

Physical Characteristics

eg. Volume

normal = 1000 – 1800ml/day (2-3.5 pints)

influenced by: blood pressure temperature diuretics mental state

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 13 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 14

general health pus from infections eg. Color Chemical Characteristics

normal = yellow-amber (from hemoglobin breakdown) eg. proteins influenced by: ratio of solutes normally too large to filter out presence indicates increased permeability of glomerular >solute conc. = darker yellow to brownish membrane due to: injury

normal urine is slightly acidic: 5.0 - 7.8 normally, all is filtered and all reabsorbed body reabsorbs as much as is needed influenced by: diet when it appears in urine indicates high blood sugar concentrations eg. high protein acidic symptom of mellitis vegetables alkaline metabolic disorders: eg. ketones eg. lungs, kidneys, digestive system, etc produced when excessive quantities of fats are eg. Cells and Castings being catabolized

normally find epithelial cells and some bacterial cells high quantities may be caused by: diabetes Bacteria starvation < 100-1000/ml = contamination by normal flora dieting >100,000/ml = indicates active colonization of urinary too little carbohydrates in diet system

RBC’s & WBC’s presence is almost always pathological inflammation of urinary organs

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 15 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 16 The Aging Urinary System older women become increasingly subject to incontinence kidneys show lots of atrophy in old age esp if pelvic wall muscles have been from ages 25 to 85; number of nephrons weakened by and childbearing declines by 30 – 40% up to 1/3rd of remaining glomeruli become incontinence can also result from senescence of atherosclerotic, bloodless and nonfunctional sympathetic NS kidneys of 90 yr old man are 20 – 40% smaller than those of a 30 yr old and receive only half as much blood proportionately less efficient at clearing wastes while renal function remains adequate there is little reserve capacity reduced renal function is a significant factor in overmedication of the aged drug doses often have to be reduced water balance is more difficult kidneys become less responsive to ADH and sense of thirst is blunted voiding and bladder control become problematic: ~80% of men over 80 are affected by benign prostatic hyperplasia that compresses the urethra reduces force of urine stream makes it harder to empty bladder

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 17 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 18

Disorders of Urinary System form in renal pelvis

Acute or Chronic Renal Failure usually small enough to pass into urine flow (or renal insufficiency) sometimes are up to several centimeters and block pelvis or \ ureter most serious disorder of urinary system leads to destruction of nephrons as pressure builds in kidney nephrons can regenerate and restore kidney function after short- term injuries or individual nephrons can enlarge to a large, jagged stone passing down ureter can stimulate strong compensate contractions that can be excruciatingly painful a person can survive with as little as 1/3rd of one kidney can also damage ureter and cause

when 75% are lost the remaining cannot maintain homeostasis causes: hypercalcemia result is azotemia and acidosis dehydration pH imbalances may also lead to frequent UTI’s enlarged causing urine retention

Cystitis (=bladder infection) (largest stone on record: 3 lbs 16” x14” in )

most are ascending infections move up urethra from outside

especially common in women

if untreated bacteria can spread up ureters to cause pyelitis or infection of pelvis

if infection reaches and nephrons =

kidney infections can also result from invasion by blood borne pathogens (=descending infection)

Kidney Stones =Renal is a hard granule of calcium, phosphate, uric acid and protein Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 19 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 20 Fluid & Balance output is crucial element in control of fluids and electrolytes body is ~2/3rds water (males=63%; women=52%) most important output organ is kidney balance means: input = output major control of urine volume is reabsorption of water Inputs 1. digestive tract: food and drink reabsorption can be controlled to make output match input food ~1200ml/d; beverages ~1000ml/d controlled by two major hormones: 2. metabolism: each cell produces water in catabolism of glucose ADH 250-300ml/d Aldosterone

Outputs additional factors that can affect fluid loss:

1. urine (kidneys) 1. urine volume can also be affected by amount of solutes in urine main loss, ~1500ml/d the more solutes the more urine 2. lungs: water vapor expired with air Diabetes mellitis at rest skin and lungs loose ~900ml/d excess glucose spills over into urine causes excess water to enter nephric tubule by 3. sweat (skin) osmosis results in excessive water loss & dehydration in hot environment with vigorous exercise can lose up to 4L/h 2. hyperventilation 4. (intestines) over extended time can lose significant normally small losses, ~100ml water from lungs

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 21 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 22

may result in dehydration eg. dehydration

3. excessive sweating output > input up to 4L/hour caused by: 4. prolonged vomiting or diarrhea excessive sweating water deprivation Electrolyte Composition of Fluids chronic diarrhea excessive vomiting fluids in the body contain critical electrolytes and other solutes: eg. athletes can lose up to 4l of water/hour but can only safely take in ~2l/hr cations: Na+; Ca++; K+; Mg++ anions: Cl-; CHO3-; HPO4- -; Proteins Blood loses water ECF loses water cells lose These electrolytes function: water

1. essential nutrients or building blocks infants & elderly more likely to suffer dehydration since their kidneys are less able to conserve 2. serve critical role in regulation of various water metabolic pathways treatment: replace water and lost electrolytes 3. affecting membrane potentials of muscle and cells eg. water intoxication

4. control water movement between input > output compartments by affecting osmotic pressures often happens after dehydration 5. help to regulate pH of body fluids water is taken in too quickly without electrolytes Water Balance Disorders input to blood to tissue spaces to cells

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 23 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 24 Acid/Base Balance

can cause as water collects in ISF some of most critical ions in body fluids are H+ (hydrogen) and OH- (hydroxyl) ions causes cells to swell as it moves from tissue spaces into cells the concentrations of these two ions affect the acidity or alkalinity of body fluids especially affects cells sensitive to ion concentrations: muscle and nerve cells acidity/alkalinity is measured on pH scale 1pH unit = 10 fold change in [H+] can result in: pH of 7 is neutral + - heat cramps pH < 7: more H , fewer OH pH > 7: fewer H+, more OH- convulsions confusion large organic molecules, especially proteins, are coma extremely sensitive to changes in pH easily denatured eg. edema =abnormal accumulation of water in ECF since proteins serve a wide variety of roles in the body (enzymes, fibers, carriers, hormones, oxygen transport, caused by: immunity, etc) decreases in plasma proteins due to liver disease variations in pH affect almost every aspect of kidney disease physiology and cell metabolism starvation obstruction of lymphatic vessels even slight changes in pH can be fatal blood = 7.35 – 7.45 increased venous pressure 7 or 7.8 is fatal increased capillary permeability eg. inflammation various acids and bases continually enter and leave sunburn body: in foods and drink gastric secretions bicarbonates from Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 25 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 26

etc pH = 7.41 7.27 acids and bases are also made as a normal part of blood is buffered metabolism: buffers act by combining with strong acids or bases and breakdown of proteins, carbohydrates lipids and nucleic taking them out of solution acids produce acids: amino acids, fatty acids, pyruvic acid, etc “absorbs” the H or OH ions

waste products like CO2 and ammonia are turned into acids in the blood major buffers in body fluids: bicarbonate need some mechanism to neutralize them: phosphate hemoglobin body is protected against large changes in pH in two plasma proteins step process: all buffers have limited capacity

1. buffers – absorb excess hydrogen or hydroxyl ions to buffering alone cannot maintain homeostasis prevent drastic changes in pH indefinitely 2. elimination – acids (or bases) are removed from body by: at some point the acids and bases must actually be + - kidneys - can secrete H and HCO3 removed from the body + lungs – as CO2 is eliminated H are converted to water two main removal systems: skin – can excrete some acids in sweat

Buffers 1. Respiratory Mechanisms 2. Excretory Mechanisms a buffer is a substance that prevents marked changes in pH of a solution when acids or bases are added Respiratory Mechanisms

eg. 1 drop of HCl in pure water plays vital role in removing excess acids pH = 7 3.5 + 1 drop of HCl in plasma with each expiration, CO2 and therefore H are

Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 27 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 28 removed carbonic anhydrase + - may also be caused by strokes, meningitis and CO2 + H2O H2CO3 H + HCO3 brain tumors pH receptors in can increase or decrease respiratory rate based on buildup of acids in blood symptoms: labored acidosis stimulates hyperventilation cyanosis depression of CNS drowsiness, Excretory Mechanisms disorientation

+ - coma death cells of DCT and CT can secrete H & HCO3 can be compensated for by kidneys if blood pH decreases below normal levels tubules will + increase secretion of H b. Metabolic Acidosis accumulation of non-respiratory acids or more efficient mechanism than excessive loss of bases eg. poor kidney function usually urine is slightly acidic prolonged diarrhea normal diet produces more acid than alkaline waste products severe vomiting loss of duodenal fluids diabetes mellitis ketone bodies are acidic Acid/Base Imbalances 2. Alkalosis 1. Acidosis accumulation of excess bases accumulation of excess acids excessive loss of acids excessive loss of bases a. Respiratory Alkalosis a. Respiratory Acidosis caused by hyperventilation hypoventilation; factors that cause buildup of CO2 in blood hyperventilation causes too much CO2 to be ventilated causing an increase in pH generally due to factors that hinder pulmonary ventilation anxiety Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 29 Human Anatomy & Physiology: Urinary System; Ziser Lecture Notes, 2010.5 30

fever, inflammation and severe liver disease some poisonings Summary of Acid-Base Homeostasis hyperventilation sometimes accompanies Acids produced Acids produced Acids in Excessive loss or by Metabolism by respiration foods and drinks gain of acids or bases pulmonary diseases such as asthma, pulmonary edema, and pulmonary embolism maternal hyperventilation often occurs throughout pregnancy possibly caused by effects of hormones on CNS Buffers many underwater swimmers have died when they [bicarbonates; phosphates; proteins] hyperventilated to try to prolong their time Acids and Bases combine with chemical buffers to prevent harmful changes in pH and underwater allow time for lungs and kidneys to remove them symptoms: light headedness agitation tingling dizziness Breathing Rate Tubular Secretion

+ + - stimulated by CO2 & H ions secrete excess H or HCO3 into urine b. Metabolic Alkalosis caused by: gastric drainage (lavage) prolonged vomiting of contents regulates CO2 in plasma regulates pH of blood too many antacids

Acid/Base Homeostasis

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