Chapter 25 Urinary System Pt 1

Urinary system overview

1. Functions of the urinary system

a. ______ volume and _______ concentration regulation

b. Regulation of ____ ___________ in the ECF (extracellular fluid)

c. ____ regulation

d. Removal of __________ and certain drugs and ______

e. Production of certain _________

i. __________ - important for regulating RBC production

ii. _________ - important for regulating BP

f. Activation of vitamin ________ - by converting it to its active form

g. _______________ during fasting

*Roughly _________ filtered daily

Urinary system overview

1. Functions of the urinary system

a. Water volume and solute concentration regulation

b. Regulation of ion concentrations in the ECF (extracellular fluid)

c. pH regulation

d. Removal of metabolic wastes and certain drugs and toxins

e. Production of certain hormones

i. ___erythropoietin ___ - important for regulating RBC production

ii. ___renin_____ - important for regulating BP

f. Activation of vitamin ___D_ - by converting it to its active form

g. Gluconeogenesis during fasting

*Roughly 200L_ filtered daily

1. Organs of the urinary system

a. _____________- paired tubes that transport urine from the kidneys to the urinary bladder

b. _______________- a temporary storage reservoir for urine

c. ___________ - a tube that carries urine from the urinary bladder to the body exterior

d. ___________ - (Functions listed above) – these form urine

1. Organs of the urinary system

a. Ureters_- paired tubes that transport urine from the kidneys to the urinary bladder

b. Urinary Bladder__- a temporary storage reservoir for urine

c. Urethra __ - a tube that carries urine from the urinary bladder to the body exterior

d. Kidneys__ - (Functions listed above) – these form urine

Kidney overview

1. Location & external anatomy

a. Retroperitoneal

i. Partially protected by the _____________________

ii. Right kidney displaced by _____ and lies slightly ______ than the left kidney __

b. External gross anatomy

i. ______ - ureter, renal blood vessels, lymphatic vessels, and nerves join at the _______ and occupy the sinus (medial concave side)

ii. The _________ _______ sit on the superior surface of each kidney

iii. Tissue covering each kidney as protection:

1. Renal________ outer dense fibrous connective tissue

2. ________ ___ ______ cushioning fat

3. ____________ __________ - transparent capsule shields from infection

Kidney overview

1. Location & external anatomy

a. Retroperitoneal

i. Partially protected by the lower part of the rib cage_____

ii. Right kidney displaced by liver and lies _____slightly lower than the left kidney __

b. External gross anatomy

i. Hilum - ureter, renal blood vessels, lymphatic vessels, and nerves join at the hilum and occupy the sinus (medial concave side)

ii. ___The adrenal gland____ sit on the superior surface of each kidney

iii. Tissue covering each kidney as protection:

1. ____Renal Fascia- __ outer dense fibrous connective tissue

2. ___Perirenal Fat Capsule- ____ cushioning fat

3. Fibrous Capsule __ transparent capsule shields from infection

Kidney overview

1. Internal gross anatomy

a. Renal cortex – Houses __________ for filtration and urine formation.

b. Renal medulla – has cone-shaped massed called _____________; maintains osmotic gradients from cortex → medulla → allows for variations in ________________ helping the body conserve water or ____________________ as needed.

i. Renal ____________– appear striped bc of parallel bundled of urine-collecting tubules and capillaries; the base faces the cortex while the apex (the renal papilla)…

1. Renal papilla – faces/points internally

ii. Renal ____________ - inward extensions of cortex tissue - separate the pyramids.

c. **Renal pyramid + adjacent renal columns = _____ (approximately 8)

d. Renal pelvis - funnel-shaped cavity that collects _______ from the kidney and channels it into the __________; continuous with the ureter at the ___________

1. _________ collect urine from papillae → drains into them before flowing through the renal pelvis and into the ureter.

ii. Major calyces - Branching extensions (2-3) of the renal pelvis that collect urine → drain into ______ _________

iii. Minor calyces – cup shaped area that holds _________ of renal pyramids – these drain the urine into the _______ __________

Kidney overview

1. Internal gross anatomy

a. Renal cortex – light colored; granular appearance; Houses nephrons for filtration and urine formation.

b. Renal medulla – darker region; has cone-shaped massed called renal pyramids; maintains osmotic gradients from cortex  medulla  allows for variations in urine concentration, helping the body conserve water or excrete excess salts as needed.

i. Renal pyramids – appear striped bc of parallel dunfled of urine-collecting tubules and capillaries; the base faces the cortex while the apex (the renal papilla)…

1. Renal papilla – faces/points internally

ii. Renal columns - inward extensions of cortex tissue - separate the pyramids.

c. **Renal pyramid + adjacent renal columns = lobe (approximately 8)

d. Renal pelvis - funnel-shaped cavity that collects urine from the kidney and channels it into the ureter; continuous with the ureter at the hilum

1. calyces collect urine from papillae  drains into them before flowing through the renal pelvis and into the ureter.

ii. Major calyces - Branching extensions (2-3) of the renal pelvis that collect urine  drain into renal pelvis.

iii. Minor calyces – cup shaped area that holds papillae of renal pyramids – these drain the urine into the major calyces

Kidney overview

1. Blood supply -

a. Renal artery – (if resting) renal arteries bring ___ of total cardiac output to the kidneys

i. ___________ arteries (5) - branch off of a renal artery as it approaches a kidney.

1. Interlobar arteries – branch off of __________ arteries (within the renal sinus)

a. Smaller vessels – at the cortex medulla junction: interlobar arteries → arcuate arteries → small cortical radiate arteries (supply cortical tissue)

b. Afferent arteriole** - branch from cortical radiate arteries; they start a complex arrangement of microscopic blood vessels

c. Glomerulus (glomerular capillaries)**

d. Efferent arteriole**

e. Peritubular capillaries or vasa recta

f. Larger vessels – cortical radiate vein → arcuate vein→ interlobar vein

g. Interlobar veins → renal vein

i. No segmental veins

h. Renal vein - exit from the kidneys and empty into the inferior vena cava

2. Nerve supply

a. Renal plexus

i. _____________ nerve fibers and ganglia

1. Primarily _NS

Kidney overview

1. Blood supply -

a. Renal artery – (if resting) renal arteries bring ¼ of total cardiac output to the kidneys

i. Segmental arteries (5) - branch off of a renal artery as it approaches a kidney.

1. Interlobar arteries – branch off of segmental arteries (within the renal sinus)

a. Smaller vessels – at the cortex medulla junction: interlobar arteries  arcuate arteries  small cortical radiate arteries (supply cortical tissue)

b. Afferent arteriole** - branch from cortical radiate arteries; they start a complex arrangement of microscopic blood vessels

c. Glomerulus (glomerular capillaries)**

d. Efferent arteriole**

e. Peritubular capillaries or vasa recta

f. Larger vessels – cortical radiate vein arcuate veininterlobar vein

g. Interlobar veins  renal vein

i. No segmental veins

h. Renal vein - exit from the kidneys and empty into the inferior vena cava

2. Nerve supply

a. Renal plexus

i. ___autonomic__ nerve fibers and ganglia

1. Primarily SN S

1. Disorders

a. ___________- condition where the kidneys fall or drift below their normal anatomical position;

b. ___________ - swelling of one or both kidneys caused by a buildup of urine, usually resulting from a blockage or obstruction in the urinary tract or backward flow (reflux); can be caused by kidney stones, tumors, enlarged prostate, etc.

c. _________________- Infections or inflammations that affect the kidney

i. Elevated risk in females - usually caused by fecal bacteria that spread from the anal region to the urinary tract

1. Disorders

a. Renal ptosis - condition where the kidneys fall or drift below their normal anatomical position;

b. Hydronephrosis - swelling of one or both kidneys caused by a buildup of urine, usually resulting from a blockage or obstruction in the urinary tract or backward flow (reflux); can be caused by kidney stones, tumors, enlarged prostate, etc.

c. Pyelitis and pyelonephritis - Infections or inflammations that affect the kidney

i. Elevated risk in females - usually caused by fecal bacteria that spread from the anal region to the urinary tract

Overview of nephrons

1. ________ and __________ units of the kidney

2. More than __________ in each kidney

3. Two major components of each nephron:

a. ____________ - Completely within the renal cortex

b. _______________

i. Begins in renal cortex and extends into the renal medulla

ii. Some extend further into renal medulla (discussed later)

iii. Returns to the renal cortex

4. Each nephron drains into a ____________

Overview of nephrons

1. structural and functional units _ of the kidney

2. More than 1 million____ in each kidney

3. Two major components of each nephron

a. ____Renal corpuscle __

i. Completely within the renal cortex

b. Renal Tubule

i. Begins in renal cortex and extends into the renal medulla

ii. Some extend further into renal medulla (discussed later)

iii. Returns to the renal cortex

4. Each nephron drains into a collecting duct

Renal corpuscle

1. Consists of two parts

a. Glomerulus (glomerular capillaries)

i. Fenestrations - the capillaries are extremely ______ (allows large amounts of solute-rich but pretty much protein-free fluid to pass from blood → _____ _______

ii. Filtrate - fluid that comes in through the fenestrations; the raw material that the tubules process to form ____.

b. ________ __________ (glomerular capsule, nephron capsule)

i. Parietal layer

1. Simple squamous epithelium – contributes to _______ but doesn’t play any role in forming filtrate

ii. Visceral layer - attached to glomerular capillaries; has modified, branching epithelial cells called podocytes

1. Podocytes - have foot processes that cling to the basement membrane of the glomerulus

2. Foot processes – these are the ends of the podocyte that help them grip

3. Filtration slits - openings between the foot processes this is where ___________________

4. Capsular space - The hollow interior region of a glomerular capsule

Renal corpuscle

1. Consists of two parts

a. Glomerulus (glomerular capillaries)

i. Fenestrations - the capillaries are extremely porous (allows large amounts of solute-rich but pretty much protein-free fluid to pass from blood glomerular capsule

ii. Filtrate - fluid that comes in through the fenestrations; the raw material that the tubules process to form urine.

b. Bowman’s capsule (glomerular capsule, nephron capsule)

i. Parietal layer

1. Simple squamous epithelium – contributes to structure but doesn’t play any role in forming filtrate

ii. Visceral layer - attached to glomerular capillaries; has modified, branching epithelial cells called podocytes

1. Podocytes - have foot processes that cling to the basement membrane of the glomerulus

2. Foot processes – these are the ends of the podocyte that help them grip

3. Filtration slits - openings between the foot processes this is where filtrate enters the capsular space

4. Capsular space - The hollow interior region of a glomerular capsule

Renal tubule and collecting duct

1. Tubule consists of three primary zones; proximal convoluted tubule → nephron loop → distal convoluted tubule

a. Proximal convoluted tubule (PCT)

i. Simple cuboidal epithelium – luminal surface has very dense _________ (brush border)

ii. _____________ border on luminal surface – increases surface area to increase capacity for reabsorbing ________ and __________ from the filtrate and secreting substances into it.

b. _________________ (Nephron loop) – U-shaped

i. Descending limb

1. Simple squamous epithelium

ii. Ascending limb

1. Thin

a. Simple squamous epithelium

2. Thick

a. Simple cuboidal to simple columnar epithelium

c. Distal convoluted tubule

i. Simple cuboidal epithelium – these are thinner and __ ___ ____ __________

Renal tubule and collecting duct

1. Tubule consists of three primary zones; proximal convoluted tubule  nephron loop  distal convoluted tubule

a. Proximal convoluted tubule (PCT)

i. Simple cuboidal epithelium – luminal surface has very dense microvilli (brush border)

ii. Brush border on luminal surface – increases surface area to increase capacity for reabsorbing water and solutes from the filtrate and secreting substances into it.

b. Loop of Henle (Nephron loop) – U-shaped

i. Descending limb

1. Simple squamous epithelium

ii. Ascending limb

1. Thin

a. Simple squamous epithelium

2. Thick

a. Simple cuboidal to simple columnar epithelium

c. Distal convoluted tubule

i. Simple cuboidal epithelium – these are thinner and do not have microvilli

Renal tubule and collecting duct

1. Several renal tubules drain into a collecting duct.

a. Cells of the collecting duct:

i. Principal cells – more numerous than intercalated; these have sparse _______ and they maintain the body’s ____ and _______balance

ii. Intercalated cells – cuboidal cells with a lottt of __________ that maintain the ____ balance of the blood

1. pH regulation

b. Each _____________ receives filtrate from multiple nephrons (they are side by side and give the ______________their stripes)

i. As collecting ducts get closer to renal pelvis → fuse together → deliver urine into ________ ________ via _________ of pyramids

Renal tubule and collecting duct

1. Several renal tubules drain into a collecting duct.

a. Cells of the collecting duct:

i. Principal cells – more numerous than intercalated; these have sparse microvilli and they maintain the body’s sodium and Na+ balance

1. Water and sodium balance

ii. Intercalated cells – cuboidal cells with a lottt of microvilli that maintain the pH balance of the blood

1. pH regulation

b. Each collecting duct receives filtrate from multiple nephrons (they are side by side and give the medullary pyramids their stripes)

i. As collecting ducts get closer to renal pelvis  fuse together  deliver urine into minor calyces via papillae of pyramids

Renal tubule and collecting duct

1. Classes of nephrons

a. ___________ nephrons

i. Approximately 85% of nephrons

ii. Almost entirely within the cortex _

b. _____________ nephrons

i. Very long loops of Henle

ii. Important for production of ____concentrated urine_, which conserves water

Renal tubule and collecting duct

1. Classes of nephrons

a. Cortical nephrons

i. Approximately 85% of nephrons

ii. Almost entirely within the cortex _

b. Juxtamedullary nephrons

i. Very long loops of Henle

ii. Important for production of ____concentrated urine_, which conserves water

Capillaries involved with nephrons

- Each renal tubule is associated with _____ _______ ______

o ____________ produces the filtrate

o Second capillary bed is a combo of __________ _________ ___________and ______ _________, and it reclaims most of the filtrate

Capillaries involved with nephrons

- Each renal tubule is associated with two capillary beds

o Glomerulus produces the filtrate

o Second capillary bed is a combo of peritubular capillaries and vasa recta, and it reclaims most of the filtrate

Capillaries involved with nephrons

1. Glomerulus

a. Unique in that it is flanked on each side by ________________ (_____ and ________) – this maintains the high pressure needed for ________

i. Filtration produces lots of fluid and __% is reabsorbed by the renal tubule cells → returned to blood in _______ capillary beds

2. ___________ capillaries

a. Associated with cortical nephrons primarily

b. Absorb ____________ from the tubule cells as the substances are reclaimed from the filtrate

3. Vasa recta

a. Associated with juxtamedullary nephrons

b. Supply ___________ to cells of long loops of Henle

c. Large role in formation of ______________ (later) -

i. Also supply oxygen and nutrients to the tissue through which they pass (the _______ ________)

Capillaries involved with nephrons

1. Glomerulus

a. Unique in that it is flanked on each side by ___arterioles ____ (afferent and efferent arterioles) – this maintains the high pressure needed for filtration

i. Filtration produces lots of fluid and 99% is reabsorbed by the renal tubule cells  returned to blood in peritubular capillary beds

2. Peritubular capillaries

a. Associated with cortical nephrons primarily

b. Absorb water and solutes from __the tubule cells as the substances are reclaimed from the filtrate _

3. Vasa recta

a. Associated with juxtamedullary nephrons

b. Supply nutrients to cells of long loops of Henle

c. Large role in formation of concentrated urine (later) -

i. Also supply oxygen and nutrients to the tissue through which they pass (the renal medulla)

Juxtaglomerular apparatus (JGA) or the Juxtaglomerular complex (JGC)

- Every nephron has a JGC/JGA – where the most distal part of the ascending limb lies against the afferent arteriole (that feeds the glomerulus)→ where the afferent arteriole and ascending limb meet, they are both modified

Juxtaglomerular apparatus (JGA) or the Juxtaglomerular complex (JGC)

- Every nephron has a JGC/JGA – where the most distal part of the ascending limb lies against the afferent arteriole (that feeds the glomerulus)→ where the afferent arteriole and ascending limb meet, they are both modified

Juxtaglomerular apparatus (JGA) or the Juxtaglomerular complex (JGC)

1. A point where the ________ end of the _________ limb of the ________ “kisses” the ________ arteriole and composed of highly modified cells

3. Parts of the JGA/JGC

a. Macula densa

i. Cells of the ________ limb of the ______________

ii. Cells are chemoreceptors that monitor ________ concentration of filtrate

b. ______________ cells (JG cells) – enlarged smooth muscle cells with prominent _______ ________that contain the enzyme ____

i. ________ cells located in the afferent (and sometimes efferent) arteriole

ii. The JG cells act like mechanoreceptors that sense the ___________(stretch) of the _______ arteriole

c. ________________ cells

i. Connected by gap junctions → _______What is their function?____________

Juxtaglomerular apparatus (JGA) or the Juxtaglomerular complex (JGC)

1. A point where the distal end of the ascending limb of the loop of Henle “kisses” the afferent arteriole and composed of highly modified cells

2. ***Please note that the way most nephrons are drawn are for clarity for students, but do not accurately depict the layout of an actual nephron

3. Parts of the JGA/JGC

a. Macula densa

i. Cells of the ascending limb of the loop of Henle

ii. Cells are chemoreceptors that monitor NaCl concentration of filtrate

b. Juxtaglomerular cells (JG cells) – enlarged smooth muscle cells with prominent secretory granules that contain the enyme renin

i. Granular cells located in the afferent (and sometimes efferent) arteriole

ii. The JG cells act like mechanoreceptors that sense the blood pressure (stretch) of the afferent arteriole

iii. Stretch and renin

c. Extraglomerular mesangial cells

i. Connected by gap junctions  pass regulatory signals between macula densa and granular cells