Urinary Study Guide: Lecture and In-Class Notes

Please please please Please please pleasePlease please pleasePlease please pleasePlease please pleasePlease please pleasePlease please pleasePlease please please

Kidney function

adjust solute and water concentration (Excretion and Regulation)

Ureter function

• A muscular tube leading from renal pelvis to bladder (Elimination)

• Conduit for formed urine

• Differ in length

Bladder function

• Muscular sac on the pelvic floor (Elimination)

• Distensible and expands

• Opening of two ureters and the urethra mark the triangular area (trigone

Urethra function

Discharge of waste to the external environment

The primary functions of the urinary system include:

• Regulating blood volume.

• Regulating the chemical makeup of blood. (filtration, reabsorption, secretion)

• Acid-base balance

• detoxification

Secondary functions of the urinary system are

• Metabolism of vitamin D (calcitriol)

• Production of renin.

• Production of Erythropoietin.

• Gluconeogenesis (glucose production from noncarbohydrate precursors (e.g., amino acids, fatty

acids).

Renal capsule

a fibrous transparent structure directly adherent to the kidney surface.

Adipose capsule

fatty mass that attaches the kidney to the posterior body wall and provides cushioning

Renal fascia

an outer layer of dense fibrous CT that anchors the kidney and adrenal gland to surrounding structures

The frontal section reveals 3 distinct regions, which are (superficial to deep)

renal cortex, medulla, pelvis

The most superficial region is the

renal cortex

Urine formation occurs in the

renal cortex

The region which is deep to the cortex is the

renal medulla

Why does the renal medulla appear striped?

It is primarily composed of urine-conveying tubes called collecting ducts

After urine is formed in the renal cortex, what happens next?

It travels through collecting ducts in the renal medulla

After traveling thru the collecting ducts in the renal medulla, what happens next?

Urine continuously drips out of the renal papillae

After urine continuously drips out of the renal papillae, what is the flow of urine afterwords (in order)?

Into the minor calyces → Flows into major calyces → Flows into the renal pelvis → Flows into the ureter → Flows into and is stored in the urinary bladder → Exits the body via the urethra

The walls of the calyces, pelvis, ureter, bladder, and urethra all contain _____ muscle, which assists with moving urine

smooth

Since the kidney’s main function is the regulation of the volume and composition of the blood, the blood supply of the kidneys are typically

extensive in blood supply

Nephron

the basic organizational unit of the kidney

The nephron is composed of

glomerulus (specialized capillary bed), Bowman’s capsule (urinary epithelium), and tubules (specialized epithelial cells)

In humans, there are roughly ______ nephrons

1,000,000

The majors functions of the nephron are

glomerular ultrafiltration and tubular reabsorption/secretion

Glomerulus

delivering a pure ultrafiltrate of plasma to the tubule, supplies the substrate for urine formation

proximal tubule

reclaims the bulk of the ultrafiltrate (this process does not change the tonicitybut does change its composition)

loop of Henle

absorbs less than one-fifth of the ultrafiltrate volume but does so by separating the reabsorption of salt from water

distal tubule

handles less than 15% of the ultrafiltrate volume, and performs the final adjustments to urine concentration and dilution

The glomerular capillaries receive blood through the

afferent arteriole

Blood received in the glomerus is drained by the

efferent arteriole

The glomerular filtration barrier consists of

1. glomerular endothelial cell

2. glomerular basement membrane

3. urinary epithelial cell

What is the purpose of the glomerular filtration barrier?

allows for the free entry of water and small molecular weight solutes, yet excludes the passage of cells and proteins

_________ of ultrafiltrate volume is reabsorbed in the proximal tubule.

two-thirds

Examples of ions reabsorbed in the proximal tubule

Na+ , Cl -, HCO3-, H2O,Ca+, amino acids, phosphate, and glucose

Which ion is secreted into the lumen?

H+ (hydrogen)

The two limbs of the loop of henle are..

Thin descending limb and thick ascending limp

True or False: A major portion of calcium reabsorption occurs in the loop.

True

Water and NaCl are passively absorbed in which limb?

Thin descending limb

Reabsorption of NaCl is active and energy-dependent in which limb?

Thick ascending limb

Which limb is impermeable to water?

Thick ascending limb

The luminal fluid leaving the thick portion is made hypotonic by the

active salt reabsorption

Distal convoluted tubule is responsible for __% reabsorption, secretion, and excretion

15-25%

Which two hormones control the distal convulated tubule?

Aldosterone and ANF

What is the role of aldosterone in the distal convulated tubule?

Sodium (Na) reabsorption

What is the role of ANF in distal convulated tubule?

Sodium excretion

What are the major functions of the distal convulated tubule?

1. active secretion of ions, acids, drugs, toxins

2. selective reabsorption of sodium and calcium ions from the tubular fluid

3. selective reabsorption of water

Collecting duct function

“fine-tuning" of tubular fluid composition

The four main functions in renal physiology are

filtration, reabsorption, secretion, and excretion

Every time blood enters the glomerulus, about __% of the contained fluid is filtered and becomes filtrate

20%

The reason for the large volume of filtrate is

the high blood pressure within the glomerular capillaries

Two intrinsic mechanisms that maintain GFR are

myogenic regulation and tubuloglomerular feedback mechanism

You ended on page 5