bio 142 chapter 25 part 2

What is the function of a nephron?

clear the blood of metabolic waste products, excess ions, and toxins,

while reclaiming vital nutrients and water back into the cardiovascular system.

The Two Major Components of a Nephron

Renal Corpuscle

Renal Tubule

Renal Corpuscle function

filtering unit. It allows water and small solutes to pass through while keeping large molecules (like proteins) and blood cells in the bloodstream.

Renal Tubule function

Reabsorption & Secretion: It processes the filtrate. It reclaims needed substances (like glucose, water, and ions) back into the blood and secretes additional wastes into the fluid to become urine.

what parts make up the renal corpsule

Glomerulus

Bowman’s Capsule

what parts make up renal tubule

Proximal Convoluted Tubule

Loop of Henle

Distal Convoluted Tubule

Glomerulus of the Renal Corpuscle

A high-pressure, fenestrated (leaky) capillary bed where blood plasma is physically filtered.

The "coffee grounds basket" holding the blood.

Afferent Arteriole of Renal Corpuscle

The wide blood vessel that brings blood into the glomerulus.

Afferent = Arrives.

Efferent Arteriole of Renal Corpuscle

narrow blood vessel that takes blood out of the glomerulus. Its small size creates a pressure bottleneck.

Efferent = Exits.

Capsule (Parietal Layer) of Renal Corpuscle

outer, simple squamous epithelial wall of Bowman’s capsule. Forms the boundary of the space that catches filtrate.

Capsule (Visceral Layer) of Renal Corpuscle

inner layer made of specialized cells called podocytes that wrap directly around the leaky capillaries.

Pedicel of Renal Corpuscle

The thousands of finger-like "foot processes" extending from podocytes that interlace around the capillaries.

Slit Pore Corpuscle

microscopic gaps between the interlocking pedicels that allow water and small solutes to pass but block big proteins.

Proximal Convoluted Tubule (PCT) epithelium

Simple cuboidal epithelium with prominent microvilli

Loop of Henle (Nephron Loop) epithelium

Simple squamous epithelium.

Distal Convoluted Tubule (DCT) & Collecting Duct:

Simple cuboidal epithelium

Juxtaglomerular Apparatus (JGA)

kidney's built-in quality-control sensor. It is the physical spot where the exit tube of the nephron loops back and touches the entry pipe

components of JGA

Juxtaglomerular (JG) Cells

Macula Densa

Juxtaglomerular (JG) Cells Description

Enlarged, specialized smooth muscle cells

Macula Densa Description

group of tall, closely packed, specialized epithelial cells in the distal renal tubule wall wall right next to the JG cells.

Juxtaglomerular What does it respond to?

Low blood pressure in the afferent arteriole

Sympathetic nervous system stimulation.

Macula Densa What does it respond to?

* Changes in the NaCl (salt) concentration and flow rate of the fluid moving through the tubule (acting as chemoreceptors).

Juxtaglomerular What effect does that have?

* They secrete the enzyme renin into the blood to activate the RAAS pathway (which raises blood pressure).

Macula Densa. What effect does that have?

If salt/flow is too high: They release chemicals to constrict the afferent arteriole, slowing down filtration.

* If salt/flow is too low: They signal the JG cells to release renin.