Urinary system pt 2

Filtration Membrane

Composed of fenestrated glomerular capillary walls, a basal lamina, and filtration slits formed by podocytes.

Nitrogenous Wastes

Substances readily filtered by the kidneys including urea, ammonium ions (NH_4^+), creatinine, and uric acid.

Glomerular Filtration Rate (GFR)

The amount of filtrate formed by both kidneys in one minute, normal value is approximately 125 ml/min (180 liters/day).

Net Filtration Pressure (NFP)

Determined by the difference between Glomerular Hydrostatic Pressure and the sum of Glomerular Colloid Osmotic Pressure and Capsular Hydrostatic Pressure.

Glomerular Hydrostatic Pressure (GHP)

Blood pressure in the glomerulus that favors filtration, approximately 50 mm Hg.

Glomerular Colloid Osmotic Pressure (GCOP)

Pressure created by proteins like albumin that pulls water back into capillaries, approximately 30 mm Hg.

Capsular Hydrostatic Pressure (CHP)

Pressure of fluid in the capsular space that opposes filtration, approximately 10 mm Hg.

What is the formula for Net Filtration Pressure (NFP)?

NFP = GHP - (GCOP + CHP); example: 10 = 50 - (30 + 10).

Regulation of GFR

Involves autoregulation, myogenic mechanism, tubuloglomerular feedback, hormonal regulation, and neural regulation.

RAAS

Renin-Angiotensin-Aldosterone System; increases systemic blood pressure and GFR.

Atrial Natriuretic Peptide (ANP)

Hormone released in response to high fluid volume that increases GFR by dilating afferent arterioles and constricting efferent arterioles.

What happens during Acute Renal Failure?

It is a short-term condition that resolves with treatment.

What is Uremia?

Condition when GFR is less than 50% of normal, leading to waste buildup and potential death.

Proximal Tubule (PCT)

Part of nephron that reabsorbs large quantities of ions and nearly 100% of vital nutrients.

What is Glycosuria?

Presence of glucose in urine due to exceeding the transport maximum (TM) for glucose.

Nephron Loop Function

Reabsorbs about 20% of water in the descending limb and 25% of sodium and chloride in the ascending limb.

Facultative Water Reabsorption

Water reabsorption in the distal tubule and collecting system based on the body's needs.

Aldosterone

Hormone that increases sodium reabsorption and potassium secretion.

Antidiuretic Hormone (ADH)

Hormone that promotes water reabsorption, reducing urine output.

What does ANP do?

Stimulates sodium excretion and inhibits aldosterone and ADH.

Collecting System Function

Medullary collecting ducts are permeable to urea and impermeable to water unless ADH is present.