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Flashcards in Urinary System(A&P) Deck (28):
1

Urinary-Excretory System(Function)

-excretion of wastes(nitrogenous waste=protein metabolism)
-fluid and electrolyte balance
-acid base balance(ph balance)
-normal range: 4.8-6(acidic)
-regulation of Bp
-aldosterone: cause kidney to reabsorb sodium; water allows kidney to get rid of potassium
-posterior pituitary: ADH all kidney to get rid of water
-stimulated erythropoiesis
-kidney activates vitamin D in fortified milk, helps calcium absorption

2

Organs of the urinary system

1)Kidney
2)Ureters
3)Urinary Bladder
4)Urethra

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Kidney(Location)

-retropentoneal in the upper portion of the abdominal cavity at about the level of T12/L1
-r. kidney is usually lower than the L kidney

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Kidney(Description)

-reddish brown bean shaped organs
-4inch long, 2inch wide, 1inch thick
-medial structure has an indentation called the hilus which is the point at which blood vessels enter and exit from the kidney. it also has a point where the uterers exit the kidney
-covered with renal capsule(fibrous membrane) embedded in adipose tissue and the renal fascia which also anchors the kidney to the peritoneum and the abdominal wall

5

Renal Cortex:
Kidney internal structure

-outer layer made up of renal corpuscles and convoluted tubules

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Renal Medulla:
Kidney internal structure

-inner layer of tissure made up of Loop of henle and collecting tubules
-tubules form cone shaped structures called renal pyramids
-the tips(apex/papilla) of the renal pyramid points toward the renal the renal pelvis

7

Renal Pelvis

-funnel shaped cavity that forms the upper part of the ureter
-collects urine made by the kidney and directs it towards the ureter
-edges of the renal pelvis are cup/funnel shapes called calyces.
-urine flows from the renal pyramid to the calyces to the renal pelvis to the ureter

8

Blood Supply

-kidney is perfused by the renal artery
-kidney recieves 20-25% of cardiac output
-in the kidney the renal artery branches into a number of arteries which branch into a number of arterioles
-arterioles came in contact with the nephrons
-venules in the kidney unite to form veins
-veins in the kidney merge to form the renal vein which leaves the kidney and joins the inferior vena cava

9

Nephron(Microscopic structures)

-structural and functional unit of the kidney
-each kidney contains about 1 million nephrons
-each nephron makes urine

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nephron

made up of two parts
1)tubular structure(a tube w/ capsule at one end)
2)vascular structure(network of blood vessels
-function of the nephrons depends on the way in which the tubular component and the vascular component are arranged in relationship to each other

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Filtration(Function of nephron)

-movement of water and solutes from the glomerulus to bowmen's(glomerular capsule)

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Secretion(Function of nephron)

-additional waste products and unneeded electrolytes are moved from the bloodstream into the forming urine

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reabsorption(function of nephron)

-water,electrolytes, and additional needed materials are moved from the forming urine into the bloodstream.

14

Renal Corpuscle

2 parts
-glomerulus=vascular/capillary
-glomerular(bowmans) capsul=tubular

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glomerulus(renal corpuscle)

-cluster of capillaries
-afferent-arteriole brings blood to the renal corpuscle and branch into large number of capillaries; the afferent arteriole has a wider diameter which takes blood away from the renal corpuscle
-capillaries merge to form the efferent arteriole which take blood away from the renal corpuscle

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bowmans/glomerular capsule(renal corpuscle)

-part of the tubular structure
-surrounds the glomerulus and receives the filtrate
-renal corpuscle is the site of filtration

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renal tubules

-long tubular structure that is surrounded by the peritublar capillaries
-renal tubules are the site for:
SECRETION: waste products and unneeded electrolytes are moved from the bloodstream into the forming urine
REABSORPTION: water, electrolytes and additional needed materials are moved from the forming urine into the bloodstream

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proximal convoluted tubule

-first part of renal tubules after the glomerular capsule
-site of most reabsorption
-normally 100% of the filtered glucose, amino acids and other useful metabolizes are absorbed

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loop of henle

-hair pin, u shaped structure
-has a descending limb and an ascending limb
-reabsorption of K,NA,Cl and the beginning of H20 reabsorption occurs in the loop of henle

20

distal concoluted tubule

-extension of the ascending limb of the loop of henle
-reabsorption of NACL and h2o continues
-DCT is the site for the action of aldosterone
-DCT is the site of tubular secretion
-site of most secretion

21

collecting tubule

-formed by the union of the dct from seceral nephrons
-collecting tubules empty into the calyces of the renal pelvis

22

physiology of urine production

-urine is formed as water and solutes
-more btw the vascular and the tubular structure of the nephron
-urine formation involves 3 process:
-glomerular formation
-tubular reabsorption
-tubular secretion

23

glomerular filtration

-occur b/c the pressure in the glomerulus is higher than the pressure in the glomerular capsule
-recall that afferent arteriole is wider in diameter than the efferent arteriole
-glomerular filtration is dependent on Bp
-glomerular filtration involves movement of water and solutes from the bloodstream into the bowmans capsule
-what passes into the filtrate is dependent on the size of the pores of the filter
-normally electrolytes,urea,creatine,and glucose pass easily into the filtrate
-normally rbc and large proteins do not pass into the filtrate
-glomerular filtration depends on Bp and the amount of blood that reaches the kidneys
-normal urine production is 1-2Liters a day

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glomerular filtration is

125ML/min or 180L/day
-normal urine production is 1-2Liters a day
-approx. 99% of the filtrate gets reabsorbed

25

Tubular reabsorption

-as filtrate passes through the tubules water and other useful substances move from the tubules to the peritubular capillaries(99% of the filtrate is reabsorbed)
-most tubular reabsorption takes place in the proximal convoluted tubule(PCT)
-the kidneys regulate both the substances and the quantity of these substances that gets reabsorbed

26

reabsorption takes place by

-diffusion: movement of solute from high to low concentration
-active transport: movement of solute from low to high(need atp and pump)(against diffusion gradient)
-osmosis: diffusion of water from high to low across semipermeable membrane(from dilute solution to concentrated solution)
-na is reabsorped by active transport
-cl by diffusion
-water by osmosis follows the sodium
-na is the single most important electrolyte that is involved in fluid balance and fluid distribution in the body
-all of the glucose in the filtrate gets reabsorbed by active transport
-all the amino acids and small proteins in the filtrate get reabsorbed by active transport
-PTH promotes the reabsorption of calcium(PTH dissolves bone)
-waste do not get reabsorbed comes back by osmosis
-for many of the substances that are reabsorped by the renal tubules there is a threshold level limit for reabsorption

27

Tubular secretion

-actively moves material from the blood stream to the tubules
-H+(ph balance), K+, ammonium ion, urea, uric acid, creatine, drugs and metabolites

28

concentration of urine volume

-additional fluid balance and bp regulation
-concentration of urine depends on:
Osmosis
ADH secreted by the posterior pituitary
Aldosterone(secreted by the cortex of the adrenal gland)
ADH makes