Urinary System

1. Urinary System

2. Identify the primary function of the urinary system. filter blood to remove waste products to maintain normal pH.

3. State the location and function of each of the structures of the urinary system: kidneys bean shaped organs R slightly lower than L - adrenal glands sit on top of kidneys – Kidneys are located in upper abdominal cavity, lie in retroperitoneal position between dorsal body wall & parietal peritoneum

4. functions (1) to filter the blood and remove metabolic waste (2)regulation of fluid levels, electrolytes and blood ph (3) Gluconeogenesis during prolonged fasting (4)Produce hormones renin & erythropoietin to help regulate BP & stimulate RBC production (5)Metabolize vitamin D to its active form

5. 3 layers of supportive tissue surround each kidney: 1) The fibrous capsule- transparent, prevents infections in surrounding regions spreading to kidneys 2) The perirenal fat capsule – fatty mass that attaches the kidney to the posterior wall and cushions it against blows 3) The renal fascia- outer layer of dense fibrous connective tissue that anchors kidney and adrenal gland to surrounding tissues

6. ureters - two (2) slender tubes connecting kidneys to bladder – transport the urine from the renal pelvis to the bladder by means of peristaltic action and gravity enters bladder obliquely to prevent backflow of urine during bladder filling

7. urinary bladder Lies in true pelvis fibromuscular, smooth, collapsible sac , mucosa lined with transitional epithelium, openings of ureters and bladder form trigone (triangle), an area prone to infections – temporary storage area for urine - moderately full bladder holds 300-500 mls- can hold up to 1000 ml without injury

8. urethra - fibromuscular, glandular, tube lined with transitional epithelium except near the skin - contains sphincters which keep urethra closed – males = 20 cm long; three parts described in male prostatic, membranous, spongy females = 3-4 cm long - transports urine from the bladder to exterior of the body.

9. State the basic tissue layers of the urinary tract smooth muscle- walls of calyces, renal pelvis and ureter contain smooth muscle that contracts rhythmically to propel urine by peristalsis fibrous tissue= the outer layer of the urethra (adventitia) is fibrous Mucous membrane- bladder mucosa is lined with transitional epithelium

10. Identify the internal structures of the kidney. cortex – The most superficial region of kidney the renal cortex contains the nephrons, the functional units of the kidney, is highly vascular and is light in colour with a granular appearance

11. renal medulla – deep to the cortex Reddish-brown in colour Contains cone shaped tissue masses called medullary or renal pyramids- the apices of the pyramid empty into the calyces which are a funnel shaped extension of the renal pelvis These pyramids are separated by renal columns Each pyramid and its surrounding cortical tissue constitutes one of approximately 8 lobes of a kidney

12. renal pelvis – a funnel shaped tube collection area- the area which urine enters prior to entering the ureter for transport to the bladder renal calyces- branching extensions of the renal pelvis -area that the urine empties into prior to accessing the renal pelvis

13. ureter – a fibromuscular tube, is a continuation of the renal pelvis. Lined with transitional epithelium . It exits the renal pelvis to transport urine to the urinary bladder renal vein – (oxygen poor blood) returns the blood to general circulation after filtering renal artery – (Oxygen rich blood) delivers one fourth of the total cardiac output to kidneys each minute (about 1200 mls) hilum – where ureter, artery and vein join renal pelvis renal capsule – fibrous capsule covering the kidney, loosely attached, protects kidney.

14. Describe the structure of a nephron a. nephron – structural & functional unit of the kidney,over 1 million per kidney. Each nephron consists of a glomerulus

15. b. glomerulus ball of fenestrated capillaries from which blood plasma leaves the circulatory system (blood cells are too large to fit through the fenestrations) to be filtered by the glomerular capsule (Bowman's capsule) and convoluted tubules

16. Endothelium of glomerular capsule is fenestrated (lots of pores) External parietal layer is simple squamous epithelium Visceral layer consists of branching epithelial cells called podocytes, which terminate in octopus-like foot processes which cling to basement membrane of glomerulus

17. c. proximal convoluted tubules - site of absorption of necessary substances, while wastes and excess molecules continue to the collecting ducts is situated in the cortex of the kidney d. loope of Henle- straight portion of the proximal tubules and distal tubules e. distal convoluted tubules - empties into the collection ducts within the cortex f. collecting ducts - connect the distal convoluted tubules with a renal calyx

18. Process involved in urine formation glomerular filtration - blood enters the Bowman‟s capsule under pressure; water and small molecules pass through the semi permeable membrane (plasma minus plasma proteins) .

19. tubular reabsorption- occurs as the filtrate passes through the renal tubules; glucose, amino acids, hormones, minerals, salts, vitamins and water reabsorbed. This reabsorption assists in the regulation of the blood pH by maintaining fluid and electrolyte balance

20. tubular secretion - is the process whereby substances such as hydrogen and potassium ions move from the blood in the peritubular capillaries into the filtrate which then empties into the collecting tubules

21. Describe the process of micturition. (i)as the bladder becomes full and distends stretch-sensitive receptors in its walls are stimulated, and the person becomes aware of the fullness stimulation of the stretch receptors-initiates message to brain response is dilation of sphincters when the person is ready to urinate, or expel urine, the sphincter relaxes and urine flows from the bladder to the outside through the urethra.

22. (ii) Specify the normal constituents of urine and amount secreted by an adult 95% water 5% dissolved solids - nitrogenous waste e.g. urea, uric acid, creatinine - electrolytes e.g. Na+, K+ - bile compounds pH around 6 (slightly acidic) SG1.001-1.035 depending on solute concentration normal adult output in 24 hours = 1500 mL.

23. Revise what you have learnt by testing yourself. The functions of the urinary system are: a) remove waste products from the blood and body b) regulation of the volume of body fluids c) regulation of ph and electrolyte composition of the body

24. Bowman’s capsule is the structure in which blood is filtered to produce urine. Urine flows from the pelvis of the kidney down the ureters to the bladder. The bladder is situated in the pelvic cavity. It acts as a reservoir and a moderately full bladder can hold about 300-600 mls of urine. Urine leaves the bladder via a tube called the urethra. The act of passing urine from the bladder to the outside is called micturition. A sphincter muscle prevents urine from escaping from the bladder.

25. How much urine is water? A 80% B 96% C 75% D 67%

26. What is one of the waste products excreted by the kidney called? A Hormones. B Amino acids. C Urea. D Enzymes.

27. What is the average urinary output of an adult? A person would normally pass about 1500 mlsof urine in 24 hours.

29. 6. 7. 5. 4. 3. 2. 8. 1.