Unit 5- urinary system

What are the four organs of the urinary system?

• Kidneys

• Ureters

• Urinary bladder

• Urethra

What are the six major functions of the urinary system?

• Removes metabolic wastes

• Regulates water balance

• Regulates electrolytes

• Regulates blood pressure

• Regulates blood pH

• Produces erythropoietin and activates Vitamin D

Which organ filters the blood and produces urine?

Kidneys

Which organ transports urine from the kidneys to the bladder?

Ureters

Which organ stores urine?

Urinary bladder

Which structure carries urine out of the body?

Urethra

What is the function of the renal cortex?

• Outer region of kidney

• Contains glomeruli

• Site where filtration begins

What is the function of the renal medulla?

Contains:

• Loops of Henle

• Collecting ducts

Functions:

• Concentrates urine

• Conserves water

What is the function of the renal pyramids?

Contain loops of Henle and collecting ducts that transport urine toward the papilla.

What is the renal papilla?

The tip of a renal pyramid where urine drains into a minor calyx.

What is the function of the minor calyx?

Collects urine from one renal papilla.

What is the function of the major calyx?

Collects urine from several minor calyces.

What is the function of the renal pelvis?

Funnels urine into the ureter.

What is the path of urine from the nephron to outside the body?

Collecting duct
→ Papillary duct
→ Minor calyx
→ Major calyx
→ Renal pelvis
→ Ureter
→ Bladder
→ Urethra
→ Outside

What is the path of blood through the nephron?

Afferent arteriole
→ Glomerulus
→ Efferent arteriole
→ Peritubular capillaries (or vasa recta)
→ Venules

What is the nephron?

The functional unit of the kidney that forms urine.

What are the two types of nephrons?

• Cortical nephron

• Juxtamedullary nephron

Which nephron is most common?

Cortical nephron (about 85%)

Which nephron is responsible for producing concentrated urine?

Juxtamedullary nephron

What is the glomerulus?

A tuft of capillaries where blood filtration begins.

What surrounds the glomerulus?

Bowman’s (glomerular) capsule

What is the function of Bowman’s capsule?

Collects the filtrate produced during filtration.

Which nephron segment performs the MOST reabsorption?

Proximal convoluted tubule (PCT)

What is reabsorbed in the proximal convoluted tubule?

Most:

• Water

• Glucose

• Amino acids

• Sodium

• Vitamins

What is the function of the Loop of Henle?

Creates a concentration gradient that allows the kidneys to conserve water and concentrate urine.

What is the function of the distal convoluted tubule?

Tubular secretion and hormone-regulated reabsorption.

What is the function of the collecting duct?

Makes the final adjustments to urine concentration before it leaves the kidney.

What are the three steps of urine formation?

1. Filtration

2. Reabsorption

3. Secretion

Where does glomerular filtration occur?

Glomerulus/Bowman’s capsule

Where does most tubular reabsorption occur?

Proximal convoluted tubule

Where does most tubular secretion occur?

Distal convoluted tubule

What is GFR?

Glomerular Filtration Rate
The amount of filtrate formed each minute by the kidneys.

How does blood pressure affect GFR?

↑ Blood pressure → ↑ GFR

↓ Blood pressure → ↓ GFR

What does the Juxtaglomerular Complex (JGC) do?

Monitors blood pressure and helps regulate GFR and blood pressure by releasing renin.

What is the function of the macula densa?

Detects sodium chloride (NaCl) concentration in the filtrate.

What is the function of granular (juxtaglomerular) cells?

Release renin when blood pressure is low.

What are the normal characteristics of urine?

• Clear

• Pale yellow

• Slightly acidic

• Mostly water

• Sterile

What is glucosuria?

Glucose in the urine

Usually indicates diabetes mellitus.

What is hematuria?

Blood in the urine

May indicate infection, kidney stones, or trauma.

What is proteinuria?

Protein in the urine

Usually indicates kidney damage.

What is micturition?

The process of urination.

Why are females more likely to develop UTIs?

Because the female urethra is much shorter, making it easier for bacteria to reach the bladder.

Compare the male and female urethra.

Male

• ~20 cm

• Carries urine and semen

Female

• ~4 cm

• Carries urine only

What are diuretics?

Substances that increase urine production.

Examples:

• Caffeine

• Alcohol

• Furosemide (Lasix)

Differentiate urinary retention from urinary incontinence.

• Urinary retention: inability to empty the bladder completely.

• Urinary incontinence: loss of voluntary control over urination.

Which part of the nephron is MOST responsible for reabsorbing glucose?

Proximal convoluted tubule

Which nephron is especially important for conserving water during dehydration?

Juxtamedullary nephron

A patient has glucose in their urine. What is the medical term, and what disease is most commonly associated with it?

Glucosuria
→ Most commonly associated with diabetes mellitus.

Which kidney structure actually performs filtration—the cortex or the medulla?

Cortex, because it contains the glomeruli.

If blood pressure suddenly drops, what substance is released by the kidney to help increase it?

Renin, released by the granular (juxtaglomerular) cells.