Bio 120 Presentation #9

Urinary SystemChapter # 9

by: Precious Blanton

Introduction

The urinary System is responsible for maintaining a stable internal environment for the body. Urinary System , system of organs that produces and excretes urine from the body. Urine is a transparent yellow fluid containing unwanted wastes, mostly excess water, salts, and nitrogen compounds. The major organs of the urinary system are the kidneys , a pair of bean-shaped organs that continuously filter substances from the blood and produce urine. Urine flows from the kidneys through two long, thin tubes called ureters. With the aid of gravity and wavelike contractions, the ureters transport the urine to the bladder, a muscular vessel. The normal adult bladder can store up to about 0.5 liter (1 pt) of urine, which it excretes through the tubel ike urethra.

Functions of the urinary systemExcretion metabolic waste products.Maintaining the balance of tissue fluid and

electrolyte.Secretion of some substances.

Composition:Kidneys- The main organUreter – Urinary Bladder – Excretory ducts Urethra -

Kidneys: The kidney is composed of several layers and is covered

with a fibrous capsule, the renal capsule. The outer layer of the kidney is the cortex. It contains the major (upper) portion of the nephrons. The middle layer of the kidney is the medulla. It is composed of the triangular shaped pyramids and the renal columns. The pyramids contain the collecting tubules and loops of Henle, the lower portion of the nephrons. These tubules run nearly parallel to one another and give the pyramids a grain which leads to their points or papillae. The renal columns are regions between the pyramids in which blood vessels run to and from the cortex. The papilla of each pyramid projects into a funnel-shaped area known as the calyx. The calyces (plural of calyx) collect the urine released from the papillae and allow it to drain into a large area known as the renal pelvis and then into the ureter.

The position of the Kidney

Nephron: Proximal tubule -proximal convoluted

tubule. thick descending limb

Henle’s loop.Henle’s loopthin descending &

ascending limbs.Distal tubule thick ascending limb

Henle’s loop.distal convoluted tubule macula densa in DCTCollecting tubule & duct

Nephron The kidneys remove urea from

the blood through tiny filtering units called nephrons. Each nephron consists of a ball formed of small blood capillaries, called glomerulus, and a small tube called a renal tubule. Urea, together with water and other waste substances, forms the urine as it passes through the nephrons and down the renal tubules of the kidney.

UretersSlender tubes that

convey urine from the kidneys to the bladder.

Ureters enter the base of the bladder through the posterior wall.

This closes their distal ends as bladder pressure increases and prevents backflow of urine into the ureters.

Urinary bladderUrinary Bladder -The bladder wall

has three layers. Transitional epithelial mucosa. A thick muscular layer A fibrous adventitia The urinary bladder stores

urine prior to micturition, the urethra expels urine from the bladder, the ureters bring urine to the bladder. But the function of the kidneys is NOT to make urine, it is to maintain homeostasis of the blood: excreting wastes, keeping nutrients, maintaining electrolytes, acid base balance, and other things.

urethra STRUCTURE NARROW LONG TUBES WITH EXPANDED

UPPER END LOCATED INSIDE THI KIDNEY AND LINED WITH MUCOUS MEMBRANE .

APPROXIMATELY ¼ INCH IN DIAMETER AND

10-12 INCHES IN LENGTH FUNCTION—TO DRANIN URINE FROM

THE KIDNEYS TO THE BLADDER

Take a Closer look at the Urethra

Stages of Urine ProductionFiltration

Blood pressure Water and solutes across glomerular

capillaries .Reabsorption

The removal of water and solutes from the filtrate.

SecretionTransport of solutes from the peritubular fluid

into the tubular fluid .

An Overview of Urine Formation

Conclusion !When a loved one’s kidneys fail, you are also affected. You

both face life changes because of kidney disease and its treatments. How you adapt to these changes depends on many things. I hope my presentation help give you a better understanding of the urinary system . The urinary System is responsible for maintaining a stable internal environment for the body. Urinary System , system of organs that produces and excretes urine from the body. Urine is a transparent yellow fluid containing unwanted wastes, mostly excess water, salts, and nitrogen compounds.