Lecture 8: Urinary System Flashcards
What are the 3 main roles/ functions of the urinary system
- Excretion / elimination of waste
- Maintain water, solute, etc.. Homeostasis
- Production of various molecules - enzymes, hormones & conversion of vitamins
How does the hormone Renin work in the urinary system
-Kidneys detect a fall in BP
-renin
-angiotensinogen
-angiotensin I
(there is an angiotensin converting enzyme)
-angiotensin II
-vasoconstriction
How does erythropoietin work in urinary system
-Hypoxia from decreased RBC count, decreased amount of Hb, or decreased availability of O2
-Kidney (and liver) release erythropoietin
-erythropoietin stimulates red bone marrow
-enhanced erythropoiesis increases RBC count
O2 carrying ability of blood rises
How does vitamin D work in urinary system
- Hypocalcemia
- increase release of parathyroid hormone
- increased osteoclast activity = release Ca+ into blood OR increased Ca+ reabsorption in kidney tubule OR increased activity of vitamin D by kidney = increased Ca+ absorption from food in small intestine
- all = incressed Ca+ in blood
What are the 4 main organs that make up the urinary system
- kidney
- ureter
- urinary bladder
- urethra
What is the location of the kidneys
- superior region (12th thoracic vertebra, 3r lumbar vert.)
- R kidney is LOWER than L kidney bcs of presence of liver
What are landmarks of the kidneys
Renal hilus
-region where blood and lymphatic vessels, ureters & nerves enter & exit
What are the 3 structures on the exterior of the kidneys
- Fibrous capsule (protects kidney from surrounding infection)
- Renal Fasciae (anchors kidneys to surrounding structures
- Renal fat pad (heavy cushion of fat around each kidney)
What are 6 main layers inside of the kidneys
- renal cortex
- renal medulla
- renal pelvis
- renal pyramid in renal medulla
- fibrous capsule
Describe the renal cortex
- frm external edge of kidney to top of renal pyramid (Malpighi)
- the part that lies btw the renal pyramids is called renal columns
- ramification of renal veins and arteries
Describe the renal medulla
-region including renal pyramids (have stripped appearance as tubules cross them)
–base of pyramid is oriented twrd cortex
-apex has the renal papilla
(converge at minor calyx, release urine)
What is the renal pelvis
a funnel shaped tube that communicates with the ureters
what are the branching extensions of the renal pelvis
Major Calyx
Minor Calyx
(pleural is calyces)
What does the renal pelvis do
conducts filtrate (urine) away from the kidney (collecting duct and hose)
Where is smooth muscle present in the urinary system
- pelvis
- major and minor calyces
- ureters (assists with urine propulsion
Where does blood enter the kidneys
through renal arteries
how much blood from heart enters the kidneys
1/5th
what % of blood enters and supplies (irrigates) the CORTEX
90% - most of the filtration (nephrons)
what are the 2 capillary beds of the kidneys
- Glomerulus
- Peritubular / vasa rectus
What does the Glomerulus capillary bed do
filtration from high pressure to produce filtrate
what do the Peritubular and Vasa Rectus capillary beds do
- absorption from low pressure
- recuperate majority of fluid (water retention)
What is flow of blood circulation through kidney
IN: 1. Renal artery 2. Segmental arteries 3. Interlobar artery 4. Arcuate artery 5. Cortical radiate artery OUT: 1. Cortical radiate vein 2. Arcuate vein 3. Interlobar vein 4. Renal vein
What is structure of the ureter
2 tubes that transport urine from the kidneys (extension of the pelvis) to the bladder
What are the 3 layers that make up the walls of the ureters
- Mucosa
- Muscularis
- Adventicia
Wat assists the flow of urine in the ureter
contraction and gravity
What innervates / communicates with the ureter
- parasympathetic nervous system
- sympathetic nervous system
- central nervous system
What are important stimulus in the ureter
- stretching of smooth muscle
- sense of the urinary urgency
What is the bladder
muscular reservoir that temporarily stores urine
What are the 3 layers of the bladder
- Mucosa
- Muscularis
- Adventicia
what is the name of the muscle in the bladder muscularis layer
Detrusor muscle
what are the 3 intermingled layers of the Bladder muscularis
- internal (longitudinal)
- external (longitudinal)
- middle (circular)
What is the structure of the adventicia layer of the bladder
-fibroelastic as a site for attachment
What are the landmarks of the bladder
- wall has folds called rugae (present when bladder is empty and absent when bladder is full)
- can retain up to 1L of liquid (at about 700ml the bladder may uncontrollably urinate)
what are the Trigone of the bladder
3 openings (2 ureters and 1 urethra) leading out of the bladder
What i the function of the urethra
a tube that transport urine from bladder to exterior by way of the urethral orifice
properties of the male urethra
- 20cm
- transports urine and semen
properties of the female urethra
3-4 cm
-transport urine
what are the 3 segments of the urethra
- Prostatic 2.5cm (pass thru prostate)
- Membranous 2cm (pass thru urogenital diaphragm)
- Spongy or penile 15cm (pass thru corpus spongiosum of penis)
what is the urethra lined with
mucous membrane
what is the internal urethra sphincter made of
smooth muscle
- involuntary
- prevents flow between voiding (micturition / urination)
is the external urethra sphincter voluntary or involuntary
voluntary
how many nephrons are there per kidney
1 million
what is the function of the nephrons
exchange molecules btw the urine and the blood
urine composition is based on
- the needs of the organism
- all based upon the composition of the blood
what is the microscopic functional unit
nephrons
what comprises the bulk of the kidneys
nephrons
what are the 2 regions that make up each nephron
renal corpuscle
renal tubule
each nephron connects to qhat?
a shared collecting duct
what makes up the renal corpuscle
- glomerulus
- Bowman capsule
what is the Bowman capsule
cup-shaped mouth of the nephron that houses the glomerulus
-formed by parietal and visceral walls with a space btw them
anatomy of the nephron route of the urine from artery to collecting duct
- renal corpuscle (glomerulus)
- proximal convoluted tubule
- descending limb
- loop
- ascending limb
- thick segment
- distal convoluted tubule
- collecting duct
what do the collecting ducts form when they fuse together
papillary ducts that bring urine to the minor calyces vis the renal papilla
what are the 2 types of nephrons
- cortical nephron
- juxtamedullary nephron
what type of nephron are the majority
- 85% cortical
- almost all are in the cortex
where are the juxtamedullary nephrons
- renal corpuscle at the cortex-medulla junction
- penetrates deep into the medulla
What is the structure of the glomerulus capsule
- double layered
- parietal layer (external; simple squamous epithelia = structural)
- visceral layer (internal; part of filtration membrane)
- layers separated by the capsular space
what is the 1st raw material of urine
Filtrate derived from the blood plasma
what happens after blood circulates into the glomeruli
filtration
- reabsorption by the renal tubules
- secretion = urine
Where is the filtration membrane
in the visceral layer of nephron
what is visceral layer of the nephron made of
modified epithelial cells called podocytes
what is structure of podocytes
packed closely together to form filtration slits; a slit diaphragm prevents the filtration lslits from enlarging under pressure
what do cytoplasmic extensions do for podocytes
unite one another
what is the pedicels or foot processes of podocytes
branching of the extensions to bind to the basal lamina of the glomerular capillaries
what are the 3 layers of the filtration membrane
- capillary endothelium
- basement membrane
- foot processes of podocytes of glomerular capsule
properties of the endothelium of fenestrated (glomerular) capillaries
- very porous due to fenestrations (pores)
- allow passage of substances but not blood cells
substances that pass from blood to capsular space are collected where
renal tubule
what are the renal tubules associated with (closely connected to)
capillaries that exchange with them all along their legnth
- peritubular capillaries (cortical nephrons)
- vasa recta (juxtamedullary nephrons)
what is structure of renal tubules
formed by single layer of epithelial cells (variety of forms) resting on a basal membrane
A & P of Proximal convoluted tubule (PCT)
- cuboidal cells
- brush border (microvilli)
- filter through renal corpuscles and arrives here where reabsorption occurs
- 65% H2O & ~100% solutes
A & P of Distal Convoluted Tubule (DCT)
- cuboidal cells
- almost no microvilli
- function: secretion
A & P of Loop (of Henley)
- descending limb: thin segment, simple squamous cells (preamble to H2O)
- ascending limb: thick segment, cuboidal to columnar cells (preamble to solutes)
A & P of collecting duct (CD)
- 2 types of cuboidal cells
- intercalated cells with microvilli, maintain acid-base equilibrium of blood
- principal cells with no microvilli, maintain equilibrium of H2O, NA+ of organism
What are the 2 types of cells that make up the juxtaglomerular complex
- Macula Densa cells
2. Granular (or Juxtaglomerular) cells
What are the Macula Densa cells
- initial cells of DCT in contact w/ cells of afferent & efferent arterioles
- these act as osmoreceptors detecting changes in solute content of filtrate
hat are the granular (juxtaglomerular) cells
- smooth muscular cells present in the arteriole wall containing granules filled w/ renin
- these act as mechanoreceptors detecting changes in pressure and adjust the rate of renal filtration
