deck_17241517 Flashcards
components of urinary system
kidneys (2)
urinary tract:
–> ureters (2)
–> urinary bladder
–> urethra
2 kidneys receive ___% of CARDIAC OUTPUT
25%
(liver receives another 25)
two kidneys are major ___ organ of the urinary system
excretory organs
kidneys produce
Produce urine (fluid containing water,
ions, and small soluble substances)
ureters
receive urine from the kidneys
Conduct urine to the urinary bladder by gravity and peristalsis
urinary bladder
receives and stores urine
Contraction of muscle in walls drives urination
urethra
conducts urine from the
bladder to outside the body
In the penis, also conducts semen
8 MAJOR FUNCTIONS OF URINARY SYSTEM
1) regulate blood ions
Ca2+, Na+, K+, Cl-, PO43- (phosphate)
2) regulate blood pH
excrete H+
conserve HCO3- (remember: bicarbonate buffers H+ in blood)
3) regulate blood volume
excrete or conserve H2O
4) regulate blood pressure
secrete renin (+ renin = + bp)
5) regulate blood glucose
Site of gluconeogenesis —> new glucose
(in liver/kidneys)
6) maintain blood osmolarity
regulate loss of H2O & loss of solutes
Therefore, maintain 300 mOsm/L
—> # of dissolved particles/L of solution
7) produces hormones
calcitriol
erythropoietin (EPO)
8) excrete wastes
ammonia, urea, bilirubin, creatinine, uric acid, drugs, environmental toxins
kidney anatomy – COLOUR
reddish brown colour
kidney, dimensions and weight
~10 cm (4 in.) long; ~5.5 cm (2.2 in.) wide; ~3 cm (1.2 in.) thick
Weight: ~150 g (5.25 oz)
kidney is located in a ____ position
Located in a RETROPERITONEAL position
I.e.
Between the muscles of the posterior body wall and the parietal peritoneum
kidney location
Either side of vertebral column
kidney is protected by
Visceral organs (anteriorly)
(posteriorly and laterally)
Body wall musculature and the 11th and 12th ribs (posteriorly and laterally)
—> half covered by ribs
left kidney slightly superior to right kidney
WHY?
LIVER
kidneys connected to BLADDER by URETERS
Empty into the posterior, inferior
surface of the urinary bladder
KIDNEY SURROUNDED BY THREE connective tissue layers
1) renal (fibrous) capsule)
2) perirenal fat
3) renal fascia
1) renal (fibrous) capsule
Deepest layer
layer of collagen fibers on the outer surface of the kidney
Projects collagen fibers through the perinephric (PERIRENAL) fat to the renal fascia
2) perirenal fat (adipose capsule)
Thick layer of adipose tissue
Renal fascia (dense, fibrous outer layer)
Anchors the kidney to surrounding structures
hilum of kidney
Medial indentation
Point of entry/exit for the renal artery, renal nerves, renal vein, and the ureter
renal sinus
Lined with fibrous capsule
internal cavity within the kidney, filled with fat
—> PROTECTION
renal sinus (google)
“The renal sinus is a central part of your kidney where things go in (like nerves and arteries) and come out (like pee, veins and lymphatic channels).”
internal anatomy of kidney
…
The parenchyma of the kidney can be divided into an outer and inner region
Renal cortex
(Outer region)
Renal medulla
(Inner region)
renal cortex
LIGHTER red in colour
where renal corpuscles are found
(i.e. Where blood is filtered and urine is initially formed)
renal columns are …
Extensions of the cortex into medulla
renal medulla
darker brown in colour
with renal pyramids
separated by renal columns
renal medulla contains …
a) nephron loop
b) papillary ducts
c) collecting ducts (more later)
renal pyramids are …
Ends in RENAL PAPILLA (apex of pyramid, facing hilum)
renal columns separate
pyramids
kidney lobe or renal lobe
pyramid, the overlying cortex, and adjacent renal columns
each kidney contains how many lobes?
each kidney contains 6–18 lobes
Minor calyx
Collects urine from a single kidney lobe
major calyx
Forms from the fusion of 4–5 minor calyces
renal pelvis
Funnel-shaped structure that collects urine from major calyces
Continuous with the ureter
kidney anatomy: NEPHRONS
..
functional unit of kidney
NEPHRON
nephrons function
Nephrons produce urine in the process of removing waste and excess substances from the blood
how many nephrons per kidney?
~ 1 million nephrons per kidney
nephrons at birth
you are born with all nephrons oyu will have
can nephrons regenerate
no
(not if damaged beyond repair)
to what capacity of 2 kidneys can 1 kidney work if left on its own?
80%
do signs of kidney dysfunction generally show in early stages?
No.
do not show until <25% of normal function
Components of the NEPHRON
1) renal corpuscle
2) renal tubule
renal corpuscle
Blood pressure forces water/solutes out of the glomerular capillaries in a process called FILTRATION
Collected in the surrounding capsular space
filtration produces FILTRATE, which is
protein-free solution, similar to blood plasma
renal tubule
Tubular passageway up to 50 mm long
Receives FILTRATE and MODIFIES it to create urine
renal corpuscle consists of ___ & ___
“It consists of a knot of capillaries (GLOMERULUS) surrounded by a double-walled capsule (BOWMAN’S CAPSULE) that opens into a tubule.”
renal corpuscle
Glomerular capsule (Bowman’s capsule)
(Cup-shaped chamber)
+
Capillary network (glomerulus)
(Where filtration occurs)
the glomerular capsule (Bowman’s capsule)
STRUCTURE
epithelial cup, consists of
—>
a) parietal layer
b) visceral layer
c) capsular space
parietal layer of epithelial cup – structure
simple squamous epithelium
visceral layer of the epithelial cup
forms FILTRATION membrane
consists of PODOCYTES
podocytes structure
modified simple squamous epithelial cells
pedicels (podocyte feet)
wrap around endothelial cells and form filtration slits
c) CAPSULAR SPACE of epithelial cup
lumen of urinary tube
FILTRATION MEMBRANE (visceral layer of epithelial cup of GLOMERULAR CAPSULE)
structure
1) Fenestrated glomerular capillaries
—>
Contain large diameter pores
2) Dense layer
—>
Specialized basement membrane
3) PODOCYTE Filtration slits
the importance of preventing plasma proteins from slipping into c) CAPSULAR SPACE
is ensured via the combination of the THREE layers of the FILTRATION MEMBRANE
(of the VISCERAL layer of the EPITHELIAL CUP of the GLOMERULAR CAPSULE)
name the THREE components of the filtration membrane of the visceral layer of the epithelial cup of the glomerular capsule (OF THE RENAL CORPUSCLE)
1) fenestrated glomerular capillaries
2) basement membrane
3) podocytes slits
recall two components of nephron
RENAL CORPUSCLE
RENAL TUBULE
RENAL CORPUSCLE review
renal corpuscle (glomerular capsule + capillary network (GLOMERULUS)
glomerular capsule (epithelial cup)
—> parietal layer, visceral layer, capsular space
visceral layer (filtration membrane)
—> capillaries, basement membrane, podocytes
2) RENALE TUBULE
a) PCT (proximal convoluted tubule)
b) Nephron Loop
c) DCT (distal convoluted tubule)
proximal convoluted tubule
Reabsorbs nutrients from the FILTRATE (now called TUBULAR FLUID)
the PCT is entirely in which part of the kidney?
THE CORTEX
important structure of the PCT which helps with absorption
(hint: surface area)
MICROVILLI
increase SA
2) Nephron loop (aka loop of Henle)
Establishes osmotic gradient for water reabsorption
Each limb contains a thin segment and a thick segment
distal convoluted tubule
Adjusts tubular fluid composition by REABSORPTION and SECRETION
Kidney anatomy: COLLECTING SYSTEM
..
The filtrate enters ____ after ____
enters COLLECTING SYSTEM
after moving through the RENAL TUBULES
COLLECTING SYSTEM is …
Series of TUBES carrying filtrate away from the nephron
components of the COLLECTING SYSTEM
collecting duct
papillary duct
collecting ducts (of the collecting system)
Collects fluid from many nephrons
Carries fluid through the renal medulla
collecting ducts of collecting system are lined with TWO cell types
—> INTERCALATED CELLS (play a role in secreting and reabsorbing HYDROGEN and BICARBONATE ions)
—> PRINCIPAL CELLS (reabsorb water and SECRETE POTASSIUM)
which cells of the COLLECTING DUCT secrete POTASSIUM
principal cells
which cells of collecting duct reabsorb WATER
principal cells
which cells of the collecting duct are involved with maintaining pH homeostasis
Intercalated cells
(play a role in secreting and reabsorbing hydrogen and bicarbonate ions)
Papillary ducts of
order
glomerular capsule —> PCT –> descending nephron loop –> ascending nephron loop –> DCT –> colelcting ducts –> papillary ducts –> minor calyx –> major calyx —> renal pevlis –> ureter –> bladder –> urethra
PATHWAY OF FILTRATE / urine
Where is it filtrate?
where is it urine?
1) filtrate (@ nephron)
2) filtrate (@ collecting ducts)
3) filtrate (@ papillary ducts)
4) URINE afterwards until excretion
(from minor calyces until urethra)
TWO TYPES OF NEPHRONS
(microscopic functional units of the kidney)
1) Cortical nephrons
2) Juxtamedullary nephrons
what percentage of nephrons are CORTICAL NEPHRONS
85 percent of all nephrons
Located primarily in the cortex (cortical)
Responsible for MOST regulatory functions
2) Juxtamedullary nephrons
15 percent of all nephrons
Long nephron loop extending deep into medulla
Essential to producing concentrated urine
IMPORTANT FUNCTION OF JUXTAMEDULLARY NEPHRONS
Essential to producing concentrated urine
ARTERIAL SYSTEM (kidneys)
..
each kidney receives blood from a ___
RENAL ARTERY (R + L)
where do RENAL ARTERIES branch off of?
ABDOMINAL AORTA
renal arteries turn into ____
Segmental arteries
(Supply certain segments of the kidney)
segmental arteries become
Renal artery → Segmental arteries → Interlobar arteries
—> interlobar arteries run in between renal LOBES
INTERLOBAR ARTERIES become ____
ARCUATE ARTERIES
Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries
which
—>
arch along the boundary between the
arcuate arteries become ….
Cortical radiate arteries
—> extend into cortex
THEN, cortical radiate arteries become …
AFFERENT ARTERIOLES
afferent arterioles supply each nephron, specifically a capillary knot known as a glomerulus
glomerulus path of circulation
the glomerulus drains into EFFERENT ARTERIOLES and leaves the renal corpuscle (led into by AFFERENT ARTERIOLES)
renal circulation – recap
Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Cortical radiate arteries → afferent arterioles → glomerulus → efferent arterioles
blood flow of nephron
Afferent arteriole
—> Supplies blood to each individual nephron
Glomerulus
—> Inside the renal corpuscle
—> Where filtration takes place
Efferent arteriole
—> Carries blood from the glomerulus to the peritubular capillaries
where does efferent arteriole LEAD INTO?
Efferent arterioles —> peritubular capillaries (vasa recta) —> (Cortical radiate veins —> Arcuate veins —> Interlobar veins) —> Renal vein
—> in brackets is FYI
___
Renal artery → Segmental arteries → Interlobar arteries → Arcuate arteries → Cortical radiate arteries → afferent arterioles → glomerulus → efferent arterioles
Blood flow around a CORTICAL nephron
Peritubular capillaries:
–> Surround the entire renal tubule
–> Collect water and solutes absorbed by the nephron
–> Deliver other solutes to the nephron for secretion
–> Drain into cortical radiate veins
Blood flow around a JUXTAMEDULLARY nephron
Same blood flow until after the peritubular capillaries
—– Vasa recta (vasa, vessels + recta, straight) —–
Connected to the distal end of the peritubular capillaries
Long, straight capillaries that parallel the nephron loop
Transport water and solutes within the renal medulla
Drain into cortical radiate veins
renal veins drain into
The renal veins drain directly into the inferior vena cava
nerve supply to kidney
innervated by sympathetic and parasympathetic divisions of the ANS
sympathetic innervaiton of kidneys
vs parasympathetic innervation
Sympathetic innervation is most important,
parasympathetic function is not well understood
function of sympathetic innervation (SNS) on kidneys
vasodilate/vasoconstrict renal arteries to regulate blood flow through the kidneys
what does activating SNS do to kidneys
As a whole, activating sympathetic innervation to kidney increases water retention and leads to increased blood pressure
