1. Introduction
The urinary system acts as a purification plant, cleaning the blood of waste materials.
The kidneys filter blood, reabsorb and secrete ions and produce urine. In doing this, they remove waste products, and control the balance of fluids and electrolytes in the body.
Without these functions death would occur in a few days!

2. Structures of the urinary system
Kidneys (2): filter blood
Ureters (2): tubes that carry urine from the kidney to the bladder
Bladder: expandable sac that holds urine
Urethra: tube that carries urine from the bladder to the outside of the body
Urinary meatus: the opening to the outside of the body
4.01 Remember the structures of the urinary system

3. Physiological aspects of the Urinary System
The job of the urinary system is to make urine. Producing urine accomplishes all of the following: 1) Controls the body’s fluid & electrolyte balance, 2) eliminates waste products, and 3) controls blood pressure.
4.01 Remember the structures of the urinary system

4. 3 processes of urine production
Filtration: Blood is passed through a “filter”, but only some components of blood. What passes through is called FILTRATE.
Reabsorption: Part of the filtrate is sent back to the bloodstream.
Excretion: Part of the filtrate is excreted from the body as urine.
4.01 Remember the structures of the urinary system

5. Structures of the urinary system
Kidneys
Most important excretory organ
Bean-shaped
Located between peritoneum and the back muscles (retroperitoneal)
Held in position by connective tissue
Enclosed in an adipose capsule
Protected by the ribs
Filter the blood to make urine
4.01 Remember the structures of the urinary system

6. Structures of the urinary system
Kidneys
External structures
Renal capsule : a fibrous layer of connective tissue
Renal hilum: the indentation that gives the kidney its bean shape;( the arteries, veins & ureters attach here)
Internal structures
Renal cortex: The outer layer. Grainy in appearance & where blood filtration occurs
Renal medulla: The middle layer. Contains a number of triangular striped areas called renal pyramids. Adjacent pyramids are separated by narrow renal columns that are extensions of cortical tissue.
Renal pelvis: The innermost layer. A funnel, divided into 2 or 3 large collecting cups called calyx. Each major calyx is divided into several minor calyx's, forming a cup-shaped area around the tips of the pyramids to collect the urine that continually drains through the pyramids.
4.01 Remember the structures of the urinary system

7. 4.01 Remember the structures of the urinary system
Exterior View
External kidney
Renal fascia (capsule)
Fibrous layer of connective tissue
Renal hilum
Indentation that gives the kidney its bean-shaped appearance
4.01 Remember the structures of the urinary system

8. 4.01 Remember the structures of the urinary system
Internal view
Internal kidney
Renal cortex
Outer layer
Renal medulla
Middle layer
Renal pelvis
Innermost layer
4.01 Remember the structures of the urinary system

9. Structures of the urinary system
Renal cortex
Composed of millions of microscopic functional units called nephrons
4.01 Remember the structures of the urinary system

10. Structures of the urinary system
Nephron ( Inside the Renal Cortex)
Functional unit of kidney
Renal corpuscle
Bowman’s capsule
Glomerulus
Renal tubule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting tubules
See handout on Nephron
Each kidney contains about
1.3 MILLION nephrons!
4.01 Remember the structures of the urinary system

11. Structures of the Urinary system
Renal medulla
Inner, striated layer
RENAL PYRAMIDS are the striated cones.
Base of each pyramid faces cortex, while apex empties into cuplike cavities called CALYCES
Renal columns
Located between the pyramids
Cortical tissue
4.01 Remember the structures of the urinary system

12. Structures of the urinary system
Renal pelvis
Funnel shaped structure at the beginning of the ureter
The kidney is essentially a combination of a filtration and collection system.
Blood is filtered by millions of tiny filters in the cortex, and the filtrate flows through timey tubules in the medulla and collects in the renal pelvis. The renal pelvis is an enlarged proximal portion of the ureter, ( the tube that carries urine to the bladder).
Blood vessels:
A good supply to the kidney is essential for proper function. A single renal artery enters each kidney at the hilum and branches into five segmental arteries. Segmental arteries branch into lobar arteries. Lobar arteries branch into interlobar arteries, which pass through the renal columns. Arcuate arteries originate from the interlobar arteries and arch around the pyramids in the renal medulla. Interlobular arteries branch off of arcuate arteries and give rise to afferent arterioles. There are afferent and efferent arterioles. Each afferent arteriole leads to a ball of capillaries called a glomerulus. Efferent arterioles leave from the glomerulus and travel to a specialized series of capillaries called the peritubular capillaries and vasa recta that are associated with the renal nephron, the functional unit of the kidney. Peritubular capillaries wrap around the collecting tubules of the nephron allowing efficient movement of ions between blood and the fluid in the nephron Blood flow out of the kidney: From each set of peritubular capillaries, blood flows out the interlobular veins. From there, the blood flows out a series of veins that are the direct reverse of the arteries with the exception that there are no segmental veins. The blood finally leaves the kidney via the renal vein.
4.01 Remember the structures of the urinary system

13. Structures of the urinary system
Urinary bladder
Hollow muscular organ
Located in pelvic cavity
Made of elastic fibers and involuntary muscles
4.01 Remember the structures of the urinary system

14. Structures of the urinary system
Ureters
Muscular tube extending from each kidney to the urinary bladder
Lined by a mucous membrane
10-12” long
Ureters
4.01 Remember the structures of the urinary system

15. Structures of the urinary system
Female
Urethra
Connects the bladder to the outside of the body
Female 1-2” long
Male 4-6” long
Urinary meatus
Opening to the outside of the body
Male
4.01 Remember the structures of the urinary system

16. 4.01 Remember the structures of the urinary system Essential Question
What are the structures of the urinary system?
4.01 Remember the structures of the urinary system