Urinary System (1)

What is the Urinary System composed of?

Kidneys, Ureters, Urinary Bladder, and Urethra

Kidney Function

Filter blood and convert filtrate into urine. Remove waste so that substances do not reach toxic levels within the blood. Balance ions levels like sodium and potassium. Maintain acid-base balance.

Ureters Function

The liquid waste is transported by the ureters (kidney —> urinary bladder)

Urinary Bladder Function

Stores urine until it is eliminated from the body

Urethra Function

Urine is eliminated through the urethra

Urinary System Functions

Elimination of metabolic wastes (filtration), Regulation of ion levels, Regulation of acid-base balance, Regulation of blood pressure, and Elimination of biologically active molecules

How does the Urinary System eliminate metabolic waste?

The kidneys remove waste within the filtrate (e.g., urea, uric acid) so these substances do not reach toxic levels within the blood. We constantly filter and eliminate waste.

How does the Urinary System regulate ion levels?

The kidneys help control the blood’s ion balance, such as sodium and potassium, calcium, and phosphate ions by eliminating them in the urine.

How does the Urinary System regulate acid-base balance?

The kidneys help maintain acid-base balance by altering blood levels of both hydrogen and bicarbonate ions.

How does the Urinary System regulate of blood pressure?

They help regulate blood pressure by excreting fluid in the urine. Regulating fluid lost in the urine helps regulate blood volume. The blood volume effects the blood pressure. The kidneys also produce “renin”, which is required for production of angiotensin II (a hormone that increases blood pressure)

Renin

Produced by the kidneys. Is required for production of angiotensin II, which is a hormone that increases blood pressure.

How does the Urinary System eliminate of biologically active molecules?

Small molecules (e.g., hormones, drugs) are filtered, but are not reclaimed, and then become part of the urine.

Kidney Sub-functions

Formation of calcitriol (hormone that increases the absorption of calcium from small intestine), Production and release of erythropoietin, and Potential to engage in gluconeogensis.

Gluconeogenesis

Creates glucoses. During fasting and starvation, the kidneys may engage in gluconeogenesis to produce glucose from noncarbohydrate sources to maintain normal blood glucose levels.

How does your kidney take care of your blood?

Removes unwanted materials from your body, maintaining blood plasma ions, regulating blood pH (with H+), altering blood volume, regulating the number of erythrocytes, and maintaining blood glucose levels during fasting. 

Hilum

The concave medial border of the kidneys. Where the vessels, nerves, and the ureter connect to the kidney.

Adrenal Gland

Gland that sits on top of the kidney

Why is the right kidney located inferior to the left kidney?

The liver pushed it down. The other side only has the spleen which is much smaller than the liver.

Where are the Kidneys located?

Along the posterior abdominal wall, lateral to the vertebral column. Also known as retroperitoneal.

What are the layers of the Kidney (from innermost to outermost)?

Fibrous Capsule (renal capsule), Perinephric fat (adipose capsule), Renal Fascia, and Paranephric Fat.

Why is there 2 layers of adipose tissues in the layers of the kidneys? (The Perinephric fat and Paranephric fat)

Because the organs are located so superficially

Fibrous Capsule (Renal Capsule)

Directly adhere to the external surface of the kidney. Mainly composed of dense irregular connective tissue. Maintains kidney’s shape, protects it from trauma, and prevents pathogens from penetrating the kidney.

Perinephric Fat (Adipose Capsule)

Adipose connective tissue. Provides cushioning and stabilization for the kidney.

Renal Fascia

Composed of dense irregular tissue. Anchors the kidney to surrounding structures.

Paranephric Fat

The outermost layer surrounding the kidney. Composed of adipose connective tissue. (cushioning and stabilization)

Renal Ptosis/Hydronephrosis

The “floating kidney”. The loss of adipose connective tissue in very thin elderly or individuals with anorexia may result in renal ptosis. Causes a “kink” in the ureter. This can decrease urine flow, backs up urine into the proximal part of the ureter, and enlarges the renal pelvis.

Parenchyma

“Functioning Tissue” in the Kidney. Can be visible when the kidney is sectioned (coronally). Two distinct regions: Outer renal cortex and an inner renal medulla.

Renal Columns

Extensions of the cortex. Project into the medulla and subdivide it into renal pyramids (medullary pyramids).

Corticomedullary Junction

The wide base of the renal pyramids. External edge of the medulla, where it meets the cortex.

Renal Papilla

Medially directed tip of the renal pyramid.

Renal Sinus

Urine drainage area. Minor and major calyces and renal pelvis.

The Functional Anatomy of the Kidney includes what?

Nephrons, Collecting tubules, Collecting ducts, and other associated structures.

Nephron

(Nephros=kidney). Microscopic, functional filtration unit of the kidney. Each nephron consists of two major structures: Renal Corpuscle and Renal Tubule. Almost all of them reside in the cortex (outer region)

Renal Corpuscle

An enlarged, round portion of a nephron housed within the renal cortex. Composed of two structures: glomerulus and glomerular capsule. Has two opposing poles: the vascular and tubular poles. 

Vascular Pole= where the afferent and efferent arterioles are attached to the Glomerulus

Tubular (Urinary) Pole= where the renal tubule orginate

Glomerulus

A thick tangle of capillary loops (glomerular capillaries). Blood enters this by an afferent arteriole and exits by an efferent (*think Exit) arteriole.

Glomerular Capsule

Also known as Bowman’s capsule. Formed by two layers: Visceral and Parietal Layers. Between the two layers is a capsular space that receives filtrate, which is then modified to form urine.

What makes up the Renal Tubule?

The proximal convoluted tubule, the nephron loop (Loop of Henle), and the distal convoluted tubule. The convoluted tubules usually resides in the cortex, whereas the loop of Henle typically extends from the cortex to the medulla.

The bladder can stretch to hold up ______ cups of urine.

Two