11

Urinary SystemUrinary System

22

FunctionsFunctions

11. . Excretion

2. Elimination

3. Homeostatic Regulation

Metabolic WastesMetabolic Wastes

1.1. UreaUrea

2.2. CreatinineCreatinine

3.3. Uric AcidUric Acid

33

44

Urinary SystemUrinary System Kidney regions:Kidney regions:

1.1. CortexCortex Direct filtrationDirect filtration cortical nephronscortical nephrons juxtamedullary nephronsjuxtamedullary nephrons

2. 2. Medulla Medulla Reabsorption, SecretionReabsorption, Secretion

3.3. PelvisPelvisexcretionexcretion

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Overview of Urinary SystemOverview of Urinary System Flow Flow

1. Filtration2. Reabsorption3. Secretion

66

Glomerular FiltrationGlomerular Filtration Filtration membraneFiltration membrane

Net Filtration Pressure:Net Filtration Pressure:

Glomerular hydrostatic pressure (HPg) Glomerular hydrostatic pressure (HPg) (GBHB)(GBHB)

Colloid osmotic pressure (OPg) (BCOP)Colloid osmotic pressure (OPg) (BCOP)

Capsular hydrostatic presure (HPg) Capsular hydrostatic presure (HPg) (CHP)(CHP)

Glomerular Filtration Rate (GFR)Glomerular Filtration Rate (GFR)

77

Tubular ReabsorptionTubular Reabsorption

Reabsorption of organic nutrients

Reabsorption of ions, water, and some molecules.

Water reabsorption - osmotic changes due to active transport of sodium ions.

Molecule reabsorption - secondary active transport initiated by ions.

Types of Active Transport1. Co-transport

2. Countertransport

Types of carrier mediated transportTypes of carrier mediated transport

1.1. Facilitated diffusion Facilitated diffusion

2.2. Active Transport Active Transport (secondary active)(secondary active)

1.1. Cotransport Cotransport (symport)(symport)

2.2. Countertransport Countertransport (antiport)(antiport)

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99

Tubular SecretionTubular Secretion Disposes of unwanted solutes

Regulation of Urine Concentration and Volume•countercurrent mechanism

•osmotic gradients

•Diuretics

1010

Maintaining Homeostasis

Balances:

Water/saltpHBlood pressure