EXAM 2 Nephrons; Renal corpuscle

Nephrons Def

Filtering and secreting systems

What is the basic functional unit?

Nephrons

Nephrons are composed of…

A renal corpuscle; A proximal convoluted tubule (PCT); A loop of henle; A distal convoluted tubule (DCT)

What are the three processes involving the nephrons and their blood supply in urine formation?

Glomerular filtration; Tubular reabsorption; Tubular secretion

What determines what happens inside and outside of the nephron?

Blood flow

What is a major cause of renal (kidney) failure?

Interruption of blood flow

What are two diseases associated with renal failure?

ARF (Acute Renal Failure; CRF (Chronic Renal Failure)

Where do nephrons start at?

The renal corpuscle

Where is the renal corpuscle start at?

In the cortex

What are the two primary compartments of the renal corpuscle?

Glomerulus; Bowman’s Capsule

What does the Glomerulus contain?

Tuft of cappillaries, Afferent arteriole, Efferent arteriol

What does Bowman’s Capsule contain?

Collects filtrate from glomerulus; “Glomerular filtrate”

What does urine start as?

As an ultrafiltrate of blood

What percentage of total CO each minute will enter the kidneys?

20%

Blood leaving the (glomerular) efferent capillaries goes to…

Peritubular capillaries (perfuse the nephron tubules)

What are the two functional counterparts to the glomerular filtration?

Glomeruli, Peritubular capillaries

What pressure does the Glomeruli have?

High hydrostatic pressure (HP)

Does the glomeruli favor filtration or reabsorption?

Filtration; High HP favors filtration

What pressure do the pertubular capillaries have?

Low Hydrostatic Pressure (HP)

Do the peritubular capillaries favor filtration or reabsorption?

Reabsorption; Low HP favors reabsorption

The peritubular capllaries perfuse with…

Blood coming from glomerular capillary bed

During urine formation in Bowman’s capsule, what portion gets forced out?

The liquid phase of blood

During urine formation in Bowman’s capsule, what acts as microfilters for the larger proteins?

Formed elements that are too large to get through capillaries and the thick combined basement membranes

Where does the fluid from Bowman’s space go?

Into the proximal convoluted tubule (PCT)

Glomerular membrane De

Where filtration occurs

Bowman’s capsule is seperated from the glomerulus by…

The glomerular filtration barrier

The glomerular filtration barrier is formed by…

Podocyte layer of Bowman’s capsule, the fenestrated endothelium of the glomerulus, and a thick, negatively charged basement membrane shared between the two cellular components

Podocytes Def

Specialized cells that cover outer surfaces of endothelial cells; Furhter filtrate

What are the structual difference of capillaries?

Have numerous large pores, Podocytes, Endothelial cells in capillaries are 100 times more permeable than other capillaries

How can you explain hydrostatic pressure within the glomerulus?

As fluid forms and collects, hydrostatic pressure is against the endothelial cells

What DOES fit through the glomerular filtrate?

Electrolytes, Nitrogenous waste, Small hormones, Water

What DOES NOT fit through the glomerular filtrate?

Cells, Plasma proteins

How fast plasma is filtered as it passes through glomerulus depends on…

Rate of blood flow to kindye (ml/min)

What would happen if all glomerular filtrate turned into urine?

Life-threatening dehydration

What branches are high pressule vessels?

Dorsal aorta

What are glomerular arterioles made up of?

Smooth muscle

What controls smooth muscle and causes it to constrict?

Renin

High glomerular pressures forces WHAT out of the blood?

Fluid and small molecules

High glomerular pressure forces fluid and small molecules out of the blood through…

Basement membrane pores and into capsule lumen

Although high glomercular pressure forces fluid + small molecules out of the blood, what STAYS?

RBCs, Plasma proteins, Hormones large and remain in blood

A rise in BP means a rise in WHAT?

A rise in afferent arteriole

If blood pressure rises, what happens to the outward filtration pressure?

Causes a greater outward filtration pressure within the renal corpuscle

If blood pressure drops, what happens to the outward filtration pressure?

lower outward filtration pressure due to a lower afferent arteriole pressure

Can BP affect the filtration an unranged amount?

No; If BP affected the filtration rate too much, there would be problems

How can kidneys regulate incoming BP?

Vasoconstricting of Vasodilating the afferent arteriole

Vasoconstriction

Decrease the BP entering the glomerular capillaries

Vasodilation

Increase the BP entering the glomerular capillaries

What happens when special cells in the kidneys detect change?

These special cells release renin (enzyme) into the blood stream

Renin converts inactive forms of angiotensin into…

Angiotensin I

Angiotensin I travels to the lungs and is converted into WHAT, which causes large changes in BP/increase/vasoiconstrictor?

Angiotensin II (via Angiotensin Converting Enzyme (ACE))

Angiotensin II stimulates the release of…

Aldosterone

Aldosterone Def

causes the kidneys to retain both salt and water, which - over time - increases the amount of water in the body

Where is renin released from?

the juxtaglomerular cells in the glomerular arterioles