PHSC1122 Physio II - Chapter 26 Renal System (26.2-26.3) pt 2

Renal corpuscle

spherical structure consisting of glomerular (Bowman's) capsule and glomerulus (capillary network)

Glomerular capsule and glomerulus

What does the renal corpuscle consist of?

Bowman's capsule

another name for the glomerular capsule

Glomerular capsule

forms outer wall of renal corpuscle, encapsulates glomerular capillaries, and is continuous with initial segment of renal tubule

Initial segment of renal tubule

What is the glomerular capsule continuous with?

Glomerulus

consists of about 50 intertwined capillaries

50

About how many intertwined capillaries make up the glomerulus?

Afferent arteriole

delivers blood to the glomerular capillaries

Efferent arteriole

how blood exits the glomerular capillaries

Filtration membrane

used for filtration in renal corpuscle, blood pressure forces water and small solutes across this into capsular space

Blood pressure forces water and small solutes across membrane into capsular space

During filtration, what happens at the filtration membrane?

Water and small solutes

What crosses the filtration membrane during filtration in the renal corpuscle?

Larger solutes like plasma proteins

What cannot cross the filtration membrane?

Protein-free filtrate

What solution is produced via filtration in the renal corpuscle?

Renal tubule

made up of two convoluted segments, as filtrate travels along this, its composition changes

Proximal convoluted tubule (PCT) and Distal convoluted tubule (DCT)

two convoluted segments of the renal tubule

Nephron loop or loop of Henle

a U-shaped tube that extends partially into the medulla and separate the two convoluted segments of the renal tubule

Renal medulla

What does the nephron loop or loop of Henle extend partially into?

Changes in composition due to reabsorption and secretion

What happens to the tubular fluid (filtrate) as it passes through the renal tubule?

Proximal convoluted tubule (PCT)

first segment of the renal tubule made of simple cuboidal epithelium; its entrance lies opposite where the afferent and efferent arterioles connect with the glomerulus; microvilli on apical surfaces with a primary function to reabsorb ions

Simple cuboidal epithelium with microvilli

proximal convoluted tubule (PCT) epithelium

Reabsorption of ions

proximal convoluted tubule (PCT) primary function

Descending

limb of the nephron loop where fluid flows toward the renal pelvis

Renal pelvis

Where does fluid flow toward when in the descending limb of the nephron loop?

Ascending

limb of the nephron loop where fluid flows toward the renal cortex

Renal cortex

Where does fluid flow toward when in the ascending limb of the nephron loop?

Descending thin limb (DTL), Ascending thin limb (ATL), and Thick ascending limb (TAL)

3 segments of the nephron loop limbs and whether thick or thin epithelia

Ascending limb

Which part of the nephron loop has thick and thin epithelia?

Distal convoluted tubule (DCT)

third segment of the renal tubule, initial portion passes between afferent and efferent arterioles, and its primary function is reabsorbing water and selected ions

DCT has smaller diameter and no microvilli

How does the distal convoluted tubule (DCT) compare to the proximal convoluted tubule (PCT)?

Reabsorption of water and selected ions, secretion of undesirable substances

primary functions of the distal convoluted tubule (DCT)

Collecting system

a series of tubes that carries tubular fluid away from nephrons

Away

Do the collecting system tubes carry tubular fluid to or away from the nephrons?

Collecting ducts

tubes that receive fluid from many nephrons

Each collecting duct begins in cortex and descends into medulla, carrying to the papillary duct

Where are collecting ducts and what do they do?

Minor calyx

Where does the papillary duct drain the fluid from the collecting duct?

Cortical and juxtamedullary

two types of nephrons

Cortical nephrons

make up 85 percent of all nephrons, located mostly within superficial cortex of kidney, relatively short nephron loop, and efferent arterioles deliver blood to a network of peritubular capillaries

85

percent of nephrons that are cortical nephrons

Within superficial cortex of the kidney

Where are cortical nephrons located?

To a network of peritubular capillaries

Where do cortical nephron efferent arterioles deliver blood?

Juxtamedullary nephrons

make up 15 percent of nephrons, nephron loop extends deep into medulla, and efferent arterioles connect to vasa recta

15

percent of nephrons that are juxtamedullary nephrons

To vasa recta

Where do juxtamedullary nephron efferent arterioles connect?

Maintain homeostasis

goal of urine production

Involves regulation of the volume and composition of blood

How does urine production help maintain homeostasis?

Urea, creatinine, uric acid

three metabolic wastes

Urea

most abundant organic waste)

Creatinine

metabolic waste from the breakdown of creatine phosphate

Uric acid

metabolic waste from recycling nitrogenous bases

Organic wastes

dissolved in bloodstream, eliminated only when dissolved in urine, and removal is accompanied by water loss

Bloodstream

Where are organic wastes dissolved?

Only when dissolved in urine

When are organic wastes eliminated?

Water loss

What accompanies the removal of organic wastes?

Concentrated

What kind of urine do the kidneys usually produce?

1200 mOsm/L

typical urine osmotic concentration (4x that of plasma)

Concentration of filtrate and reabsorption and retention of valuable materials

kidney functions

Fatal dehydration within hours

What can failure to concentrate filtrate by the kidneys lead to?

Sugars and amino acids

examples of valuable materials the kidney might reabsorb and retain

Filtration, reabsorption, secretion

three basic processes of urine formation

Filtration

process where blood pressure forces water and solutes across walls of glomerular capillaries

Reabsorption

process where movement of water and solutes is from filtrate to peritubular fluid

From filtration to peritubular fluid

Where do water and solutes move in reabsoprtion?

Secretion

transport of solutes from peritubular fluid to tubular fluid

From peritubular fluid to tubular fluid

Where does secretion transport solutes?