Transcript Exercise 40 Urinary System

Exercise 40
Anatomy of the
Urinary System
OBJECTIVES
Function of urinary system
 Location & function of urinary
system organs
 Blood flow through kidney
 Nephron A&P
 Glomerular filtration, tubular
reabsorption, tubular secretion,
micturtion

URINARY
SYSTEM
Excretion of nitrogenous
wastes from the body
Maintains electrolyte,
acid-base, & fluid
homeostasis in the body
Filters & processes the
blood:
Removing toxins,
metabolic wastes, and
excess ions via urine
Retaining needed water,
ions, etc. & returning
them to blood
Fig 26-1
Fig 26-3
KIDNEYS

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
Fig 26-4
Renal capsule:
layer (collagen
fibers) covering
outer surface
Renal cortex:
superficial region
Renal medulla:
deep region, with
triangular
structures
KIDNEYS

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
Renal pyramid:
each triangle
Papilla of the
pyramids: tip of
each pyramid
Renal columns:
separate each
pyramid
Urine’s produced in
pyramid/cortex/
column areas
Fig 26-4
KIDNEYS

Calyces:


Fig 26-4
Minor calyx:
cup-shaped
drain (collects
urine) at each
papilla
Major calyx:
4-5 minors
merge into one
major
KIDNEYS

Fig 26-4
Renal pelvis:
2-3 major
calyces merge
into this region
KIDNEYS
Fig 26-4
KIDNEYS: Blood Vessels


Fig 26-5
Renal artery:
brings
oxygenated
blood to kidney
Segmental
arteries: enters
renal pelvis
area, 5
branches
KIDNEYS: Blood Vessels
Lobar artery


Fig 26-5
Lobar arteries:
next branches,
near papillae
Interlobar
arteries: next
branches, in
renal columns
KIDNEYS: Blood Vessels
Lobar artery


Fig 26-5
Arcuate
arteries: next
(arching)
branches, on
top of pyramids
Interlobular
arteries: next
branches, go
into the cortex
KIDNEYS: Blood Vessels

Fig 26-5
Afferent
arterioles: next
branches,
leads into
capillary
networks of
nephrons
(glomeruli)
KIDNEYS: Blood Vessels


Fig 26-5
Glomerulus:
capillary bed
inside each
nephron
Efferent arteriole:
leads out of the
glomerulus, back
into the cortex,
will flow into
capillaries around
tubules 
KIDNEYS: Blood Vessels

Fig 26-7
Peritubular
capillaries:
capillaries around
the renal tubules
of the nephrons,
will drain into
venules and go
out of kidney
(through veins) to
renal vein
KIDNEYS: Blood Flow
Lobar arteries
Blood flow to/from
nephron:
Fig 26-5
KIDNEYS: NEPHRONS


Nephron: a functional unit of the
kidney, urine is produced here—in
the cortex of each renal lobe
Each kidney has ~1.25 million!!
Fig 26-7
KIDNEYS: NEPHRONS

Glomerular (Bowman’s) capsule: round,
cup-shaped structure enclosing the
glomerulus
Fig 26-8
KIDNEYS: NEPHRONS

Proximal convuluted tubule: 1st segment of renal
tubule—absorb organic nutrients, ions, water,
plasma proteins from tubular fluid, release to
interstitial fluid around the tubule *reabsorption*
Convuluted
portions are in the
cortex
Fig 26-6
KIDNEYS: NEPHRONS


Descending limb
of Loop of
Henle: 2nd
segment of
renal tubule—
more
reabsorption of
water
Ascending limb
of Loop of
Henle: 3rd
segment—more
reabsorptionNa+, ClLoops extend into
the medulla
Fig 26-6
KIDNEYS: NEPHRONS

Distal
convuluted
tubule: 4th
segment of
renal tubule—
secretion of
ions, acids,
drugs, toxins;
some
reabsorption
(water, Na+,
Ca++)
Convuluted
portions are in
the cortex
Fig 26-6
KIDNEYS: NEPHRONS

Distal
convuluted
tubule
actually wraps
around the
glomerulus
Fig 26-7
KIDNEYS: NEPHRONS
Collecting
tubule: Final
segment of
renal tubule—
some
secretion of
ions (Na+, K+,
H+, HCO3-), &
some
reabsorption
of water

Fig 26-6
KIDNEYS: NEPHRONS

Juxtaglomerular apparatus: endocrine region
of each nephron, important in filtrate
formation—secretes the hormone
erythropoietin & the enzyme renin
Fig. 18-20
KIDNEYS: Juxtaglomerular
apparatus

Made up of:


MACULA DENSA CELLS: Epithelial cells of
distal convoluted tubule NEAR glomerulus
(are taller than the rest along DCT, & nuclei
are clustered together)
JUXTAGLOMERULAR CELLS: smooth muscle
fibers in the afferent arteriole walls
KIDNEYS: Juxtaglomerular
apparatus
Fig 26-8
Glomerular Filtration


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Passive transport
(filtration)
Blood (filtrate)
passes from
glomerulus
(capillaries) to
glomerular capsule
Then enters proximal
convoluted tubule
Fig. 26-9
Tubular Reabsorption




Mostly in proximal
convoluted tubule
Components of filtrate
move through tubule cells
& return to blood
(peritubular capillaries)
Passive (osmosis) or
active (highly
selective/specific)
transport, depending on
body’s needs and blood’s
composition at that time
Water, glucose, amino
acids, ions, some waste
products (urea)
Fig. 26-9
Tubular Secretion

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Reverse of Absorption
Mostly in distal conv
tubule & collecting
ducts
Components of blood
move from
peritubular capillaries
or tubular cells INTO
the tubule’s filtrate—
to be excreted in
urine
Active transport
H+, K+, creatinine,
drug metabolites
Fig. 26-9
Urine Flow
 From collecting
duct of renal
tubule goes to
minor calyx, to
major calyx, to
renal pelvis, to
 URETER: (1 for
each kidney)
drains urine from
kidney to urinary
bladder
Fig 26-8
BLADDER
 Trigone: triangular
region near uteral
openings and
entrance to the
urethra
Fig 26-19
 Internal urethral
sphincter: smooth
muscle
surrounding the
opening from
bladder to
urethra—
involuntary control
Fig 26-19
 External urethral
sphincter:
skeletal muscle
surrounding the
opening from
urethra to
outside—
voluntary control
(has resting muscle
tone, must be
voluntarily relaxed)
Fig 26-19
Micturition
 Process of urination
 There is a micturition reflex
 Urine moves through ureters to bladder by
peristaltic contraction
 Bladder fills with urine, stimulates stretch
receptors in bladder wall
 Afferent fibersspinal cord, brainbecome aware
of fluid pressure in your bladder
 Efferent fibers stimulate detrusor muscle (walls of
bladder), which elevates fluid pressure
 If internal (involuntary) and external (voluntary)
urethral sphincters BOTH relax urination
 If pressure builds too high, it can force the
internal sphincter to open, which leads to
reflexive relaxation of external sphincter
Bladder Location
MALE
Fig. 26-19
FEMALE