Presentation on theme: "The Urinary Tract Consists of four main parts paired kidneys & ureters, a single bladder & urethra The urinary tract is a pathway for the elimination of."— Presentation transcript:
1The Urinary TractConsists of four main parts paired kidneys & ureters, a single bladder & urethraThe urinary tract is a pathway for the elimination of metabolic by-products and toxic and other non-essential molecules all dissolved in a small amount of water (urine)
2Kidney Structure & Function Excretion: removal of metabolic by-products, toxic molecules & other non-essential moleculesConservation of water, as necessaryMaintenance of acid-base balance in the blood
3The Ureters & Kidney Stones The ureters carry the urine formed in the kidneys to the bladderUreters are fibromuscular tubes, lined by transitional epithelium.Their narrow structure makes them prone to being obstructed by mineralized concentrations (“stones”) from the kidneys.If the stones are too large to pass naturally, they can be crushed using shockwave therapy.
4Urinary Bladder & Urethra The urinary bladder is also a fibromuscular structure and the mucosa is lined with transitional epitheliumThe bladder can hold as little as 50mL of urine or up to mL without injuryAs it distends, it rises into the abdominal cavity and bulges posteriorlyThe urethra is a fibromuscular glandular structure also lined with transitional epitheliumThe male urethra is larger (20cm) than the female (4cm)Males are more prone to urethritis (swelling & irritation of urethra due to viral or bacterial infection; painful urination, blood may be in the urine)Females are more prone to cystitis – bladder inflammation, usually bacterial (UTI)
5Kidney Structure IThe kidneys are about the size of a clenched fist and lie against the back abdominal wall just above the waistlineThe kidney consists of filtering capsules, tubules, and blood vessels tightly packed together into what is called the parenchyma.The outer covering of the kidney, called the capsule, is thin but tough and fibrousWhen cut open, two regions appear and outer cortex and inner medulla.A microscopic view will reveal the unit of kidney function, the nephron
6Kidney Structure IIThe cortex consists of convoluted tubules and filtering capsulesThe apex of each medullary pyramid forms a papilla which fits into a cup-shaped funnel called the minor calyxThese funnels open up into a major calaces which then open into the renal pelvis in the area called the renal sinus. The renal pelvis narrow to form the proximal ureter, sharing the area with the renal artery and vein
7Renal Blood FlowRenal blood flow (the amount of blood that flows through the kidney) is app 1300mL per minute (through both kidneys)About mL of plasma is filtered into the renal tubular systems each minute.Less that 1% of the filtered plasma (~0.7mL) is actually excreted as urine, demonstrating the important role kidneys play in water conservation.
8The NephronThe functional unit of the kidney is a nephron; There are about 1 million per kidneyA uriniferous tubule consists of a nephron and a collecting tubule
10Nephron Structures & Functions Renal Artery: carries blood to the kidneyGlomerulus: cluster of capillary like vessels where filtrate leaves bloodBowman’s (renal) capsul: surrounds the glomerulus; accepts/collects filtrateProximal Convoluted Tubule: where tubular reabsorption begins; NaCl, HCO3-, H2O, glucose & Aas, poisons & H+ filtered (secreted for removal)Loop of Henle: H2O reabsorbed going down, NaCl reabsorbed going up; first passively than activelyDistal Convoluted Tubule: more NaCl and bicarbonate reabsorbed; some drugs & poisons filteredCollecting Tubule: carries urine to ureter; also further reabsorption of H2O, NaCl & urea
13UrineUnder normal resting conditions, the kidneys, comprising less than 0.5% of the body weight, receive 25% of the cardiac output.Of the 1300mL of blood that enter through the renal arteries every minute, mL leave through the renal veins. The remaining 1-2mL leave as urine via the ureter.Urine is primarily water, salt, small amounts of acid and a variety of waste products such as urea, however urine composition and volume change to compensate for any fluctuation in volume or composition of body fluids.Kidneys are the “guardians” of the internal environment, reworking the body fluids 15x/day (hydration, pH etc.)
14Normal Characteristics of Urine: Color & Transparency Ranges from yellow to amber depending on urochrome (pigment resulting from hemoglobin destruction) concentrationThe more concentrated the urine, the deeper the yellow colorAbnormal coloration (pink, brown, smoky tinge)may result from eating certain foods (beets) or presence of bile pigments or blood in the urineSome drugs and vitamins alter urine color (riboflavin causes the bright “neon” yellow/green)Cloudy urine may indicate infection in the urinary tract
15Normal Characteristics of Urine: Odor & pH Fresh urine should be only slightly aromaticLeft to stand, an ammonia odor will develop as bacteria metabolize urea solutesSome drugs and vegetables alter odor (asparagus)Diseases may also alter odor (diabetes mellitus can produce a fruity odor due to acetone content)Normally urine is slightly acidic (pH ~6)Metabolic or dietary changes can alter range (~4.5-8)Diets high in protein and whole wheat lowers pHDiets high in vegetables raise pH4Prolonged vomiting or urinary tract infection creates alkaline urine
16Normal Characteristics of Urine: Specific Gravity Because urine is water plus solutes, it is more dense and weighs more than distilled water.Specific gravity is the comparison of the weight of a substance to the weight of an equal volume of distilled water.The specific gravity of distilled water is 1.0, the specific gravity of urine ranges from to 1.035, depending on solute concentrationIn extremely concentrated urine, solutes will precipitate out of solution
17Normal Characteristics of Urine: Chemical Compostion Approximately 95% of the volume of urine is water, the remaining 5% is solutesThe largest component of urine, by weight, is urea, derived from the normal break down of amino acidsOther nitrogenous wastes include uric acid (from nucleic acid metabolism) and creatinine (from CP metabolism)Normal solute constituents in order of decreasing concentration are: urea, sodium, potassium, phosphate and sulfate ions. Much smaller and variable amounts of calcium, magnesium & bicarbonate ions may also be found.Abnormally high concentration of any solute may indicate pathology.Certain diseases cause dramatic changes in composition: glucose, blood proteins, RBCs, hemoglobin, WBCs (pus) or bile pigments. Such substances are a sign of disease and useful in diagnosis.