The Urinary System

UNIT 6.12

Objectives:

Define, pronounce, and spell all key terms.

Label a diagram of the Urinary System.

State the functions of the ureter, bladder, and urethra.

Explain the action of the Nephron. Explain why the urethra is

different in males and females.

Introduction

The parts of the Urinary System are:

2 kidneys 2 ureters 1 bladder 1 urethra

Lets begin! The Urinary System is

also known as the Excretory System.

Function: responsible for removing certain wastes and excess water from the body and for maintaining the body’s acid-base balance.

Controls the volume and pressure of body fluids by eliminating wastes not needed in our body

Filters the blood and maintains balance of pH in the blood

Kidneys

2 bean shaped organs

4-6 ounces each

4 inches long, 2-3 inches wide, 1 inch thick

Left is slightly larger than the right

Protected and enclosed by adipose (fat pads)

Located on each side of the vertebral column, behind the upper part of the abdominal cavity

Kidneys… Divided into 2 main

sections: the cortex and the medulla

Cortex-the outer section that contains most of the nephrons (aids in the production of urine)

Medulla-is the inner section with 12-18 medullary pyramids that contains most of the collecting tubules (which carry the urine from the nephrons through the kidneys)

Kidneys…

Each kidney has a Hilum (hilus)-an indented area where the ureter, nerves, blood vessels such as the renal artery and the renal vein enter and leave the kidney

Renal pelvis-funnel shaped reservoir of the calyces that collect urine and funnel it into the ureter

Kidney-Anatomy Nephrons-is the

functional unit of the kidney.

They are approx 1 million in each kidney

They are microscopic filtering units

Each contain a glomerulus, Bowmans capsule, a proximal tubule, a distal tubule, and a collecting duct (tubule)

Function of the Nephron The renal artery carries

blood to the kidney

Branches of the renal artery pass thru the medulla to the cortex

Blood then enters the first part of the nephron called the glomerulus

Glomerulus-( a cluster of capillaries)as blood enters , water, mineral salts, sugar, metabolic products, and other substances are filtered out of the blood and then leaves the glomerulus.

Nephron function Next!

The now filtered blood enters the renal vein and carries it away from the kidney

The substances that were filtered by the glomerulus enters the Bowmans capsule

The Bowmans’s capsule-is C-shaped, picks up the substances filtered from the blood and glomerulus then passes it to the tubules

Nephron function Now in the tubules-

substances that are needed by the body are reabsorbed and returned to the blood capillaries

The excess substances (including urea, uric acid, and creatine) remain in the tubule and becomes a concentrated liquid called urine!

Ureters 2 muscular tubes Approx 10-12

inches long Extends from the

renal pelvis to the bladder

Peristalsis-rhythmic wave-like motion of muscle that moves the urine through to the bladder

Bladder Receives urine from the ureters

Hollow muscular sac

Surrounded by mucous membranes in folds called rugae

The urge to urinate begins when it holds approx 250 cc of urine (about a cup)

When full, receptors will send out a reflex action which opens the muscle

Infants have no control over this reflex action

Children learn to control the reflex

Urethra Tube that carries the

urine from the bladder to the outside

The external opening is the urinary meatus

Females-the urethra is approx 1 to 1 ½ inches in length that opens in front of the vagina

Males-the urethra is approx 8 inches long, passes thru the prostate gland, and out thru the penis. It carries both urine and semen.

Urine A liquid waste

Approx 95% water

Mostly urea, uric acid, creatine, and mineral salts

Urea is produced as a break down product of protein and creatine is metabolic by product of muscle metabolism

Sugar found in the urine usually indicates disease (diabetes)

Approx 1 ½ - 2 quarts of urine is produced daily

Key Terms

BLADDER

BOWMANS CAPSULE

CORTEX

EXCRETORY SYSTEM

GLOMERULUS

HILUM

KIDNEYS

MEDULLA

NEPHRONS

RENAL PELVIS

URETERS

URETHRA

URINARY MEATUS

URINARY SYSTEM

URINE

You survived again!!!

Good job!!!