Lecture 23 Flashcards Preview

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Flashcards in Lecture 23 Deck (39):
1

Urine flows

Urine flows --> kidney --> down its ureter --> bladder --> the outside via the urethra

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Urinary system =

kidneys, ureters, urinary bladder, and urethra

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Filter:

the blood and return most of water and solutes to the bloodstream

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Overview of Kidney Functions:

1. Regulation of blood ionic composition, blood pH, osmolarity, and glucose, blood volume, blood pressure
2. Release of erythropoietin and calcitriol
3. Excretion of wastes & foreign substances

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Regulation of blood ionic composition:

Na+, K+, Ca+2, Cl- and phosphate ions

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Regulation of blood volume:

conserving or eliminating water

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Regulation of blood pressure

-secreting the enzyme renin
-adjusting renal resistance

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Drainage system fills

renal sinus cavity

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Drainage system minor and major calyces...

empty into the renal pelvis which empties into the ureter

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Blood & Nerve Supply of Kidney: Abundantly supplied with

-blood vessels
-receive 25% of resting cardiac output via renal arteries

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Functions of different capillary beds:

1. glomerular capillaries
2.peritubular capillaries
3. vasa recta

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glomerular capillaries:

-where filtration of blood occurs
-vasoconstriction & vasodilation of afferent & efferent arterioles produce large changes in renal filtration

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peritubular capillaries:

carry away reabsorbed substances from filtrate

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vasa recta:

supplies nutrients to medulla without disrupting its osmolarity form

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Blood & Nerve Supply of Kidney: regulate blood flow & renal resistance by altering arterioles

Sympathetic vasomotor nerves

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Blood Vessels around the Nephron:

Glomerular capillaries
Efferent arterioles

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Glomerular capillaries are formed between

the afferent & efferent arterioles

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Efferent arterioles give rise to

the peritubular capillaries and vasa recta

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The Nephron:

1.Renal corpuscle
2.Renal tubule
3. Collecting ducts and papillary ducts

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Renal corpuscle =

site of plasma filtration

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Renal corpuscle: 2 components

1. glomerulus is capillaries where filtration occurs
2. glomerular (Bowman’s) capsule is double-walled epithelial cup that collects filtrate

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Renal tubule=

-proximal convoluted tubule
-loop of Henle dips down into medulla
-distal convoluted tubule

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Collecting ducts and papillary ducts:

drain urine to the renal pelvis and ureter

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Cortical Nephron:

-80-85% of nephrons are cortical nephrons
-Renal corpuscles are in outer cortex and loops of Henle lie mainly in cortex

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Flow of Fluid through a Cortical Nephron:

Glomenular capsule --> Proximal convoluted tubule --> Descending limb of the loop of Henle --> Ascending limb of the loop of Henle --> Distal convoluted tubule

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Juxtamedullary Nephron:

-15-20% of nephrons are juxtamedullary nephrons
-Renal corpuscles close to medulla and long loops of Henle extend into deepest medulla: excretion of dilute or concentrated urine

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Flow of Fluid through a Juxtamedullary Nephron:

Glomenular capsule --> Proximal convoluted tubule --> Descending limb of the loop of Henle --> Thin Ascending limb of the loop of Henle --> Thick ascending limb of the loop of Henle --> Distal convoluted tubule

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Histology of the Nephron & Collecting Duct:

-Single layer of epithelial cells forms walls of entire tube
-Distinctive features due to function of each region

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Distinctive features due to function of each region:

microvilli
cuboidal versus simple
hormone receptors

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Structure of Renal Corpuscle:

Bowman’s capsule
Glomerular capillaries

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Structure of Renal Corpuscle:Bowman’s capsule

-surrounds capsular space
1. podocytes
2. simple squamous

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podocytes cover

capillaries to form visceral layer

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simple squamous cells form

parietal layer of capsule

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Glomerular capillaries arise from what and form what?

afferent arteriole & form a ball before emptying into efferent arteriole

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capsule space is where

filtrate accumulates

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Number of Nephrons:

1. Remains constant from birth
2. If injured, no replacement occurs

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any increase in size of kidney is

size increase of individual nephrons

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Dysfunction is not evident until function:

declines by 25% of normal

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Removal of one kidney causes

enlargement of the remaining until it can filter at 80% of normal rate of 2 kidneys