Urinary system Lecture A&P 2

peepee poopoo type shi

What is the urinary system made up of

pair of kidneys and urinary tract

What makes up the urinary tract

pair of ureters, urinary bladder, and a single urethra

Where does urine exit the kidneys

through the ureters

Where does each ureter empty into

The urinary bladder on the pelvic floor

Where does urine exit the urinary bladder

through the urethra

What functions do the kidneys do

Filter blood, Regulate fluid and electrolyte balance, Regulate blood pH, Release EPO (erythropoietin)

What do kidneys look like

beans, both in shape and color

Where are the kidneys found

outside and posterior to peritoneal membrane

How does the right kidney differ from the left kidney in location

Right kidney is found in a slightly inferior position due to liver

Where is the adrenal gland located (in humans)

on top of each kidney

How many external layers of the kidney are there

3

What are the three external layers of the kidneys from deep to superficial

Renal capsule, Adipose capsule, Renal fascia

What is the Renal capsule

The deepest external layer, made of a thin layer of dense irregular connective tissue

What is the Adipose capsule

The middle external layer, protects from physical trauma

What is the Renal fascia

Outermost external layer, anchors each kidney to peritoneum and musculature of the posterior abdominal wall

What is the Hilum

opening on medial surface of kidney, where vessels, nerves, and ureters enter and exit

What makes up the urine-forming part of the kidney

Renal cortex and the renal medulla

Where are most the kidneys blood vessels found

The renal cortex

Where is the renal cortex

Located between the renal capsule and the renal medulla

What are the renal columns

extensions of renal cortex, separating the renal pyramids within the kidney

What is the functional unit of a kidney

Nephrons

How many nephrons are in each kidney

Over 1 million per kidney

Where is the Renal corpuscle found

In the renal cortex

Where is the renal tubule found

mostly in cortex with some tubules dipping into medulla

Where are renal pyramids found

found within renal medulla separated by renal columns

In what order does the renal pyramid taper into a slender papilla

minor calyx, major calyx, renal pelvis, ureter

How does urine get propelled towards ureter

Smooth muscle tissue contraction

How do capillaries in the kidneys differ from the rest of the body

arterioles both feed and drain capillaries

what order does blood travel through the capillaries in the kidneys

afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries

What is a Nephron made of

A renal corpuscle and a renal tubule

What does the renal corpuscle do

Filter blood

What is the renal corpuscle made of

A Glomerulus, Glomerular capsule, and a Capsular space

What is a Glomerulus

group of looping fenestrated capillaries inside a glomerular capsule

What is a Glomerular capsule

sac that surrounds the glomerulus, consists of outer parietal & inner visceral layer

What is capsular space

hollow region between parietal and visceral layers of glomerular capsule

Where does filtrate from the glomerular capsule go

It enters the renal tubule

What makes up the renal tubule

Proximal convoluted tubule (PCT), Nephron loop (desc/asc loop), and Distal convoluted tubule (DCT)

What does the proximal tubule do(pct)

Does most of the reabsorption in the kidney nephron, made of simple cuboidal epithelium with microvilli

What is the nephron loop made of

A thin descending limb of the nephron loop and thick ascending limb of the nephron loop

What does the nephron loop do

It does reabsorption and slightly dips into the medulla

What does the distal tubule do (dct)

reabsorption and secretion, made of cuboidal epithelium but has very few microvilli

What is the Juxtaglomerular apparatus made of

made of macula densa and juxtaglomerular (JG) cells

What is Macula densa

A group of cells in contact with modified SMC (which are JG cells)

What does the JGA do

regulates blood pressure and the glomerular filtration rate (GFR)

How does JGA regulate BP

When BP is low the JG cells secretes renin which triggers the RAAS system which causes vasoconstriction which increases BP

What is the collecting system

Both medullary collecting duct (cd) and papillary duct further modify filtrate before it exits kidney

What is the order of the collecting system

cortical collecting duct → medullary collecting duct → papillary duct

When does filtrate get classified as urine

Once filtrate enters papillary duct

Where does urine exit the papillary duct

at the papilla of a renal pyramid and into a minor calyx

What are the 2 types of nephrons

Cortical nephrons, and Juxtamedullary nephrons

What are Cortical nephrons

Make up about 80% of nephrons, their renal corpuscles are found in the outer renal cortex and have short nephron loops that barely enter the renal medulla

What are Juxtamedullary nephrons

Less common then Cortical nephrons, their renal corpuscles are found near the boundary of the renal cortex and renal medulla, they have long nephron loops that go deep in the renal medulla

What is Nephrolithiasis

Formation of kidney stones, which are composed most commonly of calcium oxalate salts

How are kidney stones formed

Formed when concentrations of ions are present in filtrate in higher than normal amounts (supersaturation)

What are nitrogenous wastes

Small substances that are readily filtered (creatine Uric acid etc)

What does the Glomerular Filtration Rate (GFR) mean

Amount of filtrate formed by both kidneys per minute

What is the GFR

125ml/min (180L a day)

What is the Net Filtration Pressure (NFP)

The total pressure that moves fluid and solutes out of the glomerular capillaries into the glomerular capsule

What forces determine the NFP

Glomerular hydrostatic pressure (GHP), Glomerular Colloid osmotic pressure (GCOP), and Capsular hydrostatic pressure (CHP)

What is GHP (glomerular hydrostatic pressure)

Blood pressure that’s higher than the average capillary bed hydrostatic pressure

What is GCOP

created by albumin and pulls water can into glomerular capillaries

What is CHP

Generated as capsular space fills with new filtrate

What is the NFP combination equation

GHP - (GCOP+CHP)

what is the myogenic mechanism

constriction of smooth muscle in blood vessel wall when BP increases

What is tubuloglomerular feedback

Uses macula densa in distal renal tubule to control pressure in glomerulus in response to NaCl concentration of filtrate

What is the Renin-angiotensin-aldosterone system (RAAS)

Complex system that maintains BP

What does ANP do

Released by the heart it lowers BP and reduces Blood volume, and reduces water and sodium retention

When does renin release

When

What does renin do

Initiates the raas system by converting angiotensinogen into angiotensin 1

What does angiotensin 2 do

It functions as a vasoconstrictor and stimulates aldosterone

What does aldosterone do

It increases sodium reabsorption and water retention, it also promotes potassium excretion which raises BP and BV

What part of the ANS nervous system regulates GFR

SNS (sympathetic nervous system)

What happens when GFR decreases

Renal failure, build up of waste and acid base imbalances

What is tubular reabsorption

Substances pass from filtrate into interstitial fluid then into peritubular capillaries to re enter blood

What is tubular secretion

Substances move from blood to interstitial fluid than into tubule with filtrate (requires ATP)

When do substances pass from filtrate to re enter blood

Tubular reabsorption

When do substances move from blood to enter filtrate

Tubular secretion

What is the main function of the pct

Reabsorption

What does the PCT reabsorb

Ions vital to electrolyte homeostasis and 100% of neutrients

What percent of water and electrolytes are reabsorbed into the blood once filtrate reaches nephron loop

60-70% of water and electrolytes

What percent of water and sodium are specifically reabsorbed by nephron loop

20-25%

where is aldosterone released from

Adrenal cortex

Wnag does ADH do

Causes water reabsorption and reduces urine

Where is ADH released from

Hypothalamus and secreted by posterior pituitary

What does ANP inhibit the release of

Aldosterone and ADH

What is the medullary collecting system

The last chance for the body to regulate filtrate before it becomes urine

What do the cells of the proximal tubule secrete

Hydrogen ions to maintain blood pH

What do the distal tubule and collecting duct reabsorb

Most of the remaining water

What does the ascending limb of the nephron loop reabsorb

Sodium and Chloride

What does the descending part of the nephron loop reabsorb

Water only

When do the kidneys produce dilute urine

when the solute concentration of ECF is too low

What causes solute concentration in ECF to be too low

Less ADH (less water reabsorption)