Urinary System Summary

What are the Kidneys?

Primary organs of the urinary system

What are Accessory organs of the urinary system

Ureters, bladder, and urethra

What is the main function of the Urinary System?

Regulates blood plasma content to maintain the “dynamic constancy” or homeostasis of internal fluid environment.

What is the shape of the Kidneys?

Oval shape

What is the size of the Kidney?

11cm x 7cm x 3cm

What are the relative positions and sizes of the Left and Right Kidneys?

Left kidney Larger than right; right kidney is lower

Where are the Kidneys located?

Located in Retroperitoneal position between T12 and L3.

What are the Internal structures of kidney?

Cortex and medulla with renal pyramids and columns composed of medullary tissue

What is the Calyx?

Cuplike structure at renal papilla collects urine, forming renal pelvis, which narrows to become the ureter

What is the Renal artery?

Large branch of abdominal aorta; brings blood into each kidney

What are the Interlobular arteries?

Between the pyramids of the medulla and renal artery branches

What is the Blood flow through kidney?

abdominal aorta → renal artery → segmental arteries → lobar arteries → interlobar arteries → arcuate arteries → interlobular artery → afferent arteriole → glomerulus → efferent arteriole → peritubular capillaries (vasa recta) → interlobular veins → arcuate veins → interlobar veins → lobar veins → segmental veins → renal vein → inferior vena cava

What is the Glomerulus?

Where filtration happens

What is the Juxtaglomerular Apparatus?

Located where afferent arteriole brushes past distal tubule; secretes renin to maintain blood flow homeostasis when blood pressure in afferent arteriole drops

What is Renin?

Enzyme regulates the body’s water balance & pressure level

What is the Ureter?

Tube from kidney to bladder

What are the Three layers of Ureter?

Mucous lining, muscular middle layer, fibrous outer layer

What is the Urinary Bladder?

Collapsible bag behind pubic symphysis, smooth muscle tissue, rugae lining

What are the Functions of Urinary Bladder?

Stores urine and expels urine through the urethra

What is Voiding?

Voluntary relaxation of external sphincter, reflexive detrusor muscle contraction. Urine is flushed out of bladder and through urethra

What is the Urethra?

Small Mucous membrane-lined tube from bladder (trigone) to body exterior

What are Nephrons?

Functional units & make up bulk of kidney

What is Bowman’s capsule?

Cup shaped mouth nephron

What is the Nephrons Proximal Tubule?

First part of renal tubule nearest to Bowman’s capsule, follows a winding, convoluted course; also known as proximal convoluted tubule

What is the Loop of Henle?

Thin descending limb, a sharp turning, and a thick ascending limb

What is the Distal Tubule?

Convoluted tubule beyond loop of Henle, also known as distal convoluted tubule

What is the Collecting Duct?

Straight tubule joined by distal tubules; merges into larger ducts opening at renal papilla into a calyx

What is the Kidney Function?

Processes blood and forms urine via nephrons

What are the Nephrons?

Basic functional unit of kidneys

What are the Three processes of urine formation?

Filtration, tubular reabsorption, tubular secretion

What is Filtration?

First step in blood processing that occurs in the renal corpuscles

What is the Filtration Volume?

About 180 liters of water and solutes filtered into Bowman’s capsule daily; takes place through glomerular-capsule membrane

What is Antidiuretic hormone (ADH)?

Chemical produced in the brain causing kidney to release less water, decreasing amount of urine produced

What happens when there is High ADH?

Less urine

What happens when there is Low ADH?

High urine

Where does ADH come from?

Secreted by posterior pituitary & target cells of distal tubules & collecting ducts

What is Reabsorption?

Second step in urine formation; occurs as result of passive and active transport mechanisms from all part of renal tubules major portion of reabsorption occurs in proximal tubules

What is Reabsorption in proximal tubule?

Mostly water and solutes are recovered by blood, leaving only a small volume of tubule fluid to move on to the loop of Henle

What is the Urine Composition?

Approximately 95% water with dissolved substances

What are the Nitrogenous wastes in urine?

Result of protein metabolism. EX: urea, uric acid, ammonia, creatinine

What are the Electrolytes in urine?

Mainly followed by ions. Ex: sodium, potassium, ammonium, chloride, bicarbonate, phosphate, sulfate

What are the Toxins in urine?

During disease, bacterial poisons leave body in urine

What are the Pigments in urine?

Urochromes

What about Hormones in urine?

High hormone levels may spill into filtrate

What are the Abnormal constituents in urine?

Such as blood, glucose, albumin, casts, calculi

What is the relationship of the Urinary System and Homeostasis?

Maintains water and electrolyte balance with proper function of kidneys

What is the role of Nephrons in homeostasis?

Adjust blood content to maintain constant internal environment

What is the relationship of Urinary systems and the cardiovascular system?

Interdependent

What systems are required for Urinary function?

Requires proper endocrine and nervous system function for proper kidney function

What is one of the main Functions of the urinary system?

Regulates the volume and composition of body fluids.

What is a key function of the Urinary system in terms of materials?

It excretes unwanted materials.

Is the Urinary system the only system that excretes material?

The urinary system is not the only system that excretes unneeded substances.

Do other systems have any involvement in waste removal or adjustment?

Other systems also contribute to waste removal, but the urinary system finely adjusts water and electrolyte balance.

How is the Urinary System described?

Blood plasma balancer.

What does the Urinary system adjust in the blood?

water content and ion levels (sodium, potassium)

How are the Kidneys structured?

in perirenal fat and anchored by renal fasciae.

What is the hilum?

Notch where blood vessels enter/leave the kidney.

What does the kidney consist of?

renal cortex (outer region) and renal medulla (inner region).

What is the renal pyramid?

Medullary tissue.

What does the Renal papilla do?

Release urine into calyces, which begin the urinary system's plumbing.

How much Blood flows flow through kidneys?

Approximately 1200 ml

What do the Ureters do?

Convey urine from the kidneys to the bladder.

How are the Ureters set up?

Retroperitoneal and attaches to the bottom of the bladder.

Kidneys maintain what balance?

fluid, electrolyte, and acid-base

What results in Kidney Failure?

Homeostatic failure and death.

Besides influencing fluid and electrolyte balance, what else do Kidneys influence?

secretion of ADH and aldosterone.

What do kidneys synthesize

active vitamin D, erythropoietin, and certain prostaglandins.

How do Kidneys go form urine?

Kidneys filter much of the plasma and then reabsorb what should not be excreted before the filtrate becomes urine.

What controls Urination?

Urination (voiding or micturition) begins with involuntary contractions of the detrusor muscle.