Urinary System Study Guide

Major function of the Urinary System

Major function of the Urinary System

• Filter blood and create urine as a waste-product

• Organs: kidneys, ureters, bladder, urethra

• NAME AND LOCATE ON DIAGRAM

What does "renal” mean?

Relating to the kidneys

Discuss ways in which the kidney maintains the blood composition

The kidneys control the amount of water, ions, and other substances in the blood by excreting more or less of them in urine. The kidneys also secrete hormones that help maintain homeostasis.

Name the functional unit of the kidney

The Nephron

Distinguish between a renal corpuscle and renal tubule, and identify each component of a nephron

• Renal Corpuscle: contains the glomerulus and the glomerulus capsule

• Renal Tubule: extends to the collecting duct

1. List the two major steps involved in urine formation

2. Name the portion of the nephron where each occurs, and discuss each process fully.

1. Glomerular Filtration and Reabsorption Secretion

2. GF: filters the blood/top of nephron RS: Ca+, Na+, glucose, and amino acids are reabsorbed in the nephron/loop of henle

Why are proteins are not filtered out of the blood in the glomerulus?

proteins are not filtered out by the glomerulus because they are too large to fit through the thin slits in the walls of the capillaries of the glomerulus.

Name the force responsible for glomerular filtration, explain how this force makes dialysis possible.

Hydrostatic pressure → processes the blood

Discuss the differences between male and female urethras.

• female: shorter

• male: longer

Explain the structure, location, and function of the ureters and urinary bladder

• Ureters: connects the kidneys to the bladder

• Urinary Bladder: holds the urine

List the wastes excreted in urine, and explain what metabolic processes these by-products result from

• urea

• uric acid

• creatinine - determines functioning of kidney

Explain the significance of antidiuretic hormone (ADH) and which portion of the nephron it targets

• Function: Bring water content back into the bloodstream

• Targets the collecting duct of the nephron

Explain the process by which reabsorption occurs in the PCT and DCT, and list the substances that are reabsorbed here

• Reabsorbs water and electrolytes

renal capsule

tough fibrous shell around kidney

renal cortex

outer portion of kidney

renal medulla

inner portion of kidney

renal pyramids

cone shaped masses of tissue in renal medulla

ureter

tube leading from kidney

renal pelvis

superior end of ureter which is expanded to form a funnel shape

major calyces

divisions of renal pelvis (2-3 tubes);

minor calyces

divisions of major calyces.

Functions of Kidney

to remove metabolic wastes from blood & excrete them outside (urine).

The functional unit of a kidney

nephron

Structure of the Nephron

renal corpuscle and a renal tubule.

Renal Corpuscle

glomerulus (filtration unit) within Bowman's capsule.

Renal Tubule

1. proximal convoluted tubule

2. descending loop of Henle

3. ascending loop of Henle

4. distal convoluted tubule

5. 5. collecting duct

Juxtaglomerular Apparatus (JGA)

point of contact between the afferent arteriole and distal convoluted tubule (DCT).

Macula Densa

cells in DCT in contact with afferent arterioles.

Juxtaglomerular cells

smooth muscle cells in afferent arteriole.

Urine formation involves three major steps:

1. Glomerular Filtrate

2. Tubular Reabsorption

3. Tubular Secretion

Tubular Reabsorption:

the process by which substances are transported from the glomerular filtrate (through the walls of the renal tubule) to blood in the peritubular caps.

Reabsorbed substances pass from the…

lumen of the renal tubule through the epithelial cells (PCT) and into the lumen of a peritubular capillary where they are returned to the bloodstream.

Reabsorbed substances include:

1. glucose

2. amino acids

3. water

4. ions (sodium, chloride, phosphate, sulfate, potassium)

5. others (creatine, lactic acid. citric acid, urea, uric acid, ascorbic acid)

Tubular secretion:

the process by which substances are transported from the blood in the peritubular caps into the DCT.

Composition of Urine

95% water

Other 5% includes:

1. urea,

2. uric acid,

3. trace amino acids

4. electrolytes.

Micturition

the process by which urine is expelled from urinary bladder to outside

Elimination of Urine Order

Starts at glomerulus where glomerular filtrate is collected in  Bowman's capsule → PCT → loop of Henle → DCT → collecting duct (urine) → minor calyx → major calyx → renal pelvis → ureter → urinary bladder → urethra → outside