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Each kidney contains approximately 1 to 1.5 million functional units called
nephron
what are the two types of nephron
cortical and juxtamedullary
responsible for removal of waste products and reabsorption of nutrients
cortical nephron
which make up approximately 85% of nephrons, are situated primarily in the cortex of the kidney
cortical nephron
have longer loops of Henle that extend deep into the medulla of the kidney
juxtamedullary nephron
primary function is concentration of the urine
juxtamedullary nephron
The ability of the kidneys to clear waste products selec ively from the blood and simultaneously to maintain the body's essential water and electrolyte balances is controlled in the nephron by the following renal functions
renal blood flow glomerular filtration tubular reabsorption tubular secretion
who supplies blood to the kidney
renal artery
the human kidney receives approximately _____ of the blood pumped through the heart at all time
25%
renal blood flow path
blood enters the capillaries of the nephron through the afferent arteriole
it then flows through the glomerulus and into the efferent arteriole
before returning to the renal vein blood from efferent arteriole enters the peritubular capillaries and the vasa recta and flows slowly through the cortex and medulla of the kidney close to the tubules
through the cortex and medulla of the kidney close to the tubules. 5.The peritubular capillaries surround the proximal and distal convoluted tubules, providing for the immediate reabsorption of essential substances from the fluid in the proximal convoluted tubule and final adjustment of the urinary composition in the distal convoluted tubule
The vasa recta are located adjacent to the ascending and descending loops of Henle in juxtamedullary nephrons. In this area, the major exchanges of water and salts take place between the blood and the medullary interstitium
the varying sizes of these arterioles help to create the _________ differential important for glomerular filtration and to maintain consistency of glomerular capillary pressure and renal blood flow within the glomerulus
hydrostatic pressure
what increases the glomerular capillary pressure
smaller size if the efferent arteriole
major exchanges of water and salts take place between the blood and the medullary interstitium
loop of henle in juxtamedullary nephrons
the exchange of water and salts maintains the ____ in the medulla which is necessary for renal concentration
osmotic gradient
it provides the immediate reabsorption of essential substances from the fluid in the ____
proximal convulated tubulue
final adjustment of the urinary composition is in the _____
distal convulated tubule
what is the total renal blood flow
1200 mL/min
total renal plasma flow ranges
600 to 700 mL/min
normal values for renal blood flow and renal function tests depend on the
body size
what is the average body surface
1.73 m2
When dealing with sizes that vary greatly from the average 1.73 m2 of body surface, a correction must be calculated to determine whether the observed measurements represent normal function, the calculation is in the
glomerular filtration rate
what are the important function of the kidney
elimination of the end product of metabolism
elimination of the excess body water
elimination of foreign substances like drugs
maintenance of electrostatic balance
secretion of hormone (erythropoietin)
outer area of kidney
cortex
inner area of kidney
medulla
striated, triangular structure within the medulla whose bases face the cortex and tips point to the center of the kidney (renal papillae)
renal pyramid
cortical material that extends between the pyramids
renal columns
funnel-shaped structures that surround the tip of renal pyramid
minor calyx
union of minor calyces
major calyx
union of major calyces, large collecting funnel which narrows to form ureter
renal pelvis
notch in the concave center of the kidney through which a ureters leaves the kidney and blood vessels, nerve, lymph vessels enter and exit the kidney
hilus
Responsible for selective clearing of the waste product from blood
nephron
Responsible for the maintenance of essential water and electrolyte balance
nephron
Filtering apparatus of the kidney
glomerulus
Tuft of capillary blood vessels located in Bowman's capsule where filtration process occur
glomerulus
Containing glomerulus
Bowman's Capsule
Important in order for the glomerulus to form bundles of capillaries
Bowman's Capsule
Refers to small artery
Afferent Arteriole
Small branch of renal artery through which the blood flows to the glomerulus of the kidney
Afferent Arteriole
Smallerthan the afferent arteriole (for the creation of hydrostatic pressure necessary for the filtration process to occur
efferent arteriole
Branch of renal artery through which blood flows away from the kidney
efferent arteriole
parts of renal tubular system
pct dct loop of henle cd
Part of nephron where the final concentration of the urinary filtrate begins
distal convoluted tubule
Under the influence of the hormone aldosterone, reabsorbs sodium and secretes potassium
distal convulated tubule
Also regulates pH by secreting hydrogen ion when pH of the plasma is low
distal convoluted tubule
Only 10% of the filtered NaCl and 20% of water remains
distal convoluted tubule
tubules that are found nearest to the glomerulus
proximal convoluted tubule
Part wherein the reabsorption of essential substances begin
proximal convoluted tubule
Reabsorbs: water, glucose, amino acids, and sodium.
proximal convoluted tubule
the only tubule reabsorbs glucose
proximal convoluted tubule
PCT % in Na reabsorbed
65%
PCT % in H20 reabsorbed
65%
PCT % in filtered bicarbonate (HCO3)
90%
PCT % in Cl and K reabsorbed
50%
U-shaped structure of the renal tubule
loop of henle
It contains thin descending limb and thick ascending limb
loop of henle
Control the retention of water
loop of henle
Creates a gradient of increasing sodium ion concentration towards the end of the loop within the interstitial fluid of the renal pyramid
loop of henle
thin loop of henle
descending
thick loop of henle
ascending
impermeable to water
ascending
reabsorption of water without reabsorption of salt
descending
no reabsorption of water with reabsorption of salt
ascending
Loop of Henle % in Na reabsorbed
25%
Loop of henle % in water reabsorbed
15%
Loop of henle % in K reabsorbed
40%
Where the final concentration of urine takes place through the reabsorption of water
collecting duct
Allows for the osmotic reabsorption of water
collecting duct
makes collecting ducts more permeable to water-- produce concentrated urine
ADH
Non-selective process of filtration
glomerular filtration
In glomerular filtration, what are the several factors that affect the actual filtration process
cellular structure of the capillary walls and bowman's capsule
hydrostatic and oncotic pressure
feedback mechanism of the renin-angiotensin-aldosterone system
Controlsthe regulation of the flow of blood to and within the glomerulus
Renin-Angiotensin-Aldosterone System
how the RAAS system respond
The system responds to changes in blood pressure and plasma sodium content that are monitored by the juxtaglomerular apparatus
juxtaglomerular apparatus consists of ______
juxtaglomerular cells in afferent arteriole macula densa of DCT
Low plasma sodium content decreases _____within the circulatory system, resulting in a decreased overall blood volume and subsequent decrease in blood pressure
water retention
Renin secreted and reacts with the blood-borne substrate _______produce the inert hormone angiotensin I
angiotensinogen
passes through the lungs ------ angiotensin converting enzyme (ACE) changes it to the active form ______
angiotensin II
Angiotensin II corrects renal blood flow in the what ways
causing vasodilation of the afferent arterioles and constriction of the efferent arterioles
stimulating reabsorption of sodium in the proximal convoluted tubules, and triggering the release of the sodium-retaining hormone aldosterone by the adrenal cortex and antidiuretic hormone by the hypothalamus
Selective filtration
tubular reabsorption
The body cannot lose 120 mL of water-containing essential substances every minute. Therefore, when the plasma ultrafiltrate enters the proximal convoluted tubule, the nephrons, through cellular transport mechanisms, begin reabsorbing these essential substances and water
tubular reabsorption
reabsorption mechanism
active transport passive transport
The substance to be reabsorbed must combine with a carrier protein contained in the membranes of the renal tubular cells
active transport
Active transport is responsible for the reabsorption of
glucose, amino acids and salts ---- PCT chloride ----- ALH sodium ---- DCT
Movement of molecules across a membrane as a result of differences in their concentration or electrical potential on opposite sides of the membrane
passive transport
Passive reabsorption of water takes place in all parts of the nephron except _______the walls of which are impermeable to water
ascending loop of henle
is passively reabsorbed in the proximal convoluted tubule and the ascending loop of Henle
urea
passive reabsorption of sodium accompanies the active transport of _____ in the ascending loop
chloride
renal threshold for glucose
160-180 mg/dL
The plasma concentration at which active transport stops is termed
renal threshold
When the plasma concentration of a substance that is nor ally completely reabsorbed reaches an abnormally high level, the filtrate concentration exceeds the ________ of the tubules, and the substance begins appearing in the urine
maximal reabsorptive capacity (Tm)
Part/mechanism wherein there is a creation of acid-base balance
tubular secretion
Several parts of kidney will produce hydrogen ion
tubular secretion
Elimination of waste products not filtered by the glomerulus
tubular secretion
Many foreign substances cannot be filtered by the glomerulus because they are bound to plasma proteins. However, when these protein-bound substances enter the peritubular capillaries, they develop a stronger affinity for the tubular cells and dissociate from their carrier proteins, which results in their transport into the filtrate by the tubular cells
tubular secretion
The major site for removal of these nonfiltered substances is the
proximal convoluted tubule
Renal concentration begins in the descending and ascending loops of Henle, where the filtrate is exposed to the high _____ of the renal medulla
osmotic gradient
This selective reabsorption process is called the ________ and serves to maintain the osmotic gradient of the medulla
countercurrent mechanism
The sodium and chloride leaving the filtrate in the ascending loop prevent dilution of the medullary interstitium by the water reabsorbed from the _______
descending loop
Maintenance of this osmotic gradient is essential for the final concentration of the filtrate when it reaches the _______
collecting duct
The final concentration of the filtrate through the reabsorption of water begins in the late distal convoluted tubule and continues in the
collecting duct
Reabsorption depends on the osmotic gradient in the medulla and the hormone
vasopressin