Anatomy & Physiology 34B Lecture
Chapter 25 - Urinary System Anatomy
I.
Overview
A. Overview of the Urinary System
B. Anatomy of the Kidney
C. Ureters, Urinary Bladder, & Urethra
D. Urine Formation
E. Urine and Renal Function Tests
F. Urine Storage and Elimination
II. Overview of the _______________ System
A. The urinary system, along with the respiratory, digestive, & integumentary systems,
excretes _________ from the body
B. Major Functions of the Urinary (________) System are:
1. _______ balance - blood volume is regulated by water retention or excretion
2. _______________ balance; blood pH is regulated via excretion of H+ and HCO33. Excretion of toxic ________________ compounds (e.g.: urea, uric acid, &
creatinine), other wastes, & drugs
4.
Regulates blood _______________ via the renin-angiotension pathway, which
increases blood pressure
C. _______________ functions include:
1. Calcitrol (vitamin ___) production
2. ____________________ production for erythrocyte production
3. ____________________ to increase blood glucose levels
D. Major components of the urinary system are the ________, ureters, urinary bladder and
urethra
1.
2.
3.
4.
Blood enters the kidneys via the __________ artery, is filtered, then exits via the
renal _________
Kidney _________ intertwine with vascular networks to enable urine formation
Urine moves from kidneys to __________ to the urinary bladder for storage
___________________ is the voiding of urine from the bladder through the urethra
III. Anatomy of the ____________
A. Kidneys are ____________________, not within the peritoneal cavity, between T12 &
L3 vertebrae. The right kidney is lower than the left (due to _______ displacement).
1. Kidney ____________ from the outside in include:
a.
b.
c.
Renal _____ - composed of dense irregular CT surrounds the
Renal adipose capsule - mass of ________ tissue around the
Renal __________ - transparent, fibrous membrane attached to the kidney
surface; continuous with the ureter.
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d.
Renal _________ - indented region through which the ureter, nerves, blood, and
lymphatic vessels enter kidney.
e.
Renal ______ – space in medial kidney, opening to the renal hilus; contains renal
vessels, nerves, fat, pelvis, & calices.
f.
Renal _________ - expanded portion of the ureter that enters at the hilus;
branches into major and minor _________.
g.
Renal __________ – Light colored, outer area of kidney
1.
2.
g.
Contains many _______ vessels.
Portions extending between the medullary pyramids are renal ____________
Renal ___________ – darker colored, inner region of kidney
1.
2.
Contains 5-11 renal (medullary) ______________
Renal ______________ are the tips of the pyramids that point inward toward
the minor calyces.
h.
i.
A kidney ______ includes a medullary pyramid & associated cortex
a.
b.
c.
d.
Renal _____ (R. & L.) - enters at the hilus and branches into
e.
f.
g.
____________ arteries arch over the bases of the renal pyramids and branch into
h.
i.
__________________ capillaries, reunite to form the
j.
________________ capillaries that surround the proximal convoluted tubule
and vasa recta that surround the loop of Henle, then reunite to form the
Each kidney contains about 1 mil. _________, the functional units of the kidney.
B. Microscopic Structures of the Kidney
1. Kidney ________ Supply - One quarter of the body’s blood supply is circulating
through the kidneys at a filtration rate of _____ ml of blood per minute. Blood
vessels include:
______________ arteries that enter the hilus and branch into
____________ arteries, which divide into
________________ arteries that pass through renal columns between the renal
pyramids, then branch into
_____________ arteries that enter the cortex and divide into
_____________ arterioles, which lead into the glomerulus, and divide to form
the
______________ arterioles that drain blood out of the glomerulus, then divide to
form the
k. ________________ veins, which converge to form
l. _______________ veins, which converge into
m. ________________ veins, which converge to form
n. _________ vein, which exits the kidney via the hilus and carrys blood to the
o. Inferior ______________, which takes blood to the heart
2.
Two major _______________ beds are found in the kidneys
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a.
In glomerular capillaries, water, wastes and other substances are ________ from
the blood into nephron tubules
b.
In peritubular capillaries ( and vasa recta), water and substances needed by the
body are _____________ from the tubules back into the blood
3. __________ - functional unit of the sys.; forms urine; consists of two main portions:
the renal corpuscle and the renal _______; performs 3 functions: filtration,
reabsorption, and secretion.
a.
Renal ____________ - found in the cortex, consists of a _____________
surrounded by a glomerular (__________) capsule; area of plasma
____________. The capsule has two epithelial layers
1) ________ layer composed of simple squamous epithelium
2) ___________ layer is a fenestrated (______) endothelial layer (impermeable
to blood cells) resting on a basement membrane. Podocyte cells cover an
outer slit membrane, forming slit pores between their pedicel extensions.
3) A capsular _______ between these two layers is where the glomerular filtrate
collects
b.
Renal _____ - collects blood plasma filtrate from Bowman’s capsule; filtered
water, glucose, amino acids, salts are __________, while excess H+, K+, and
NH4+ are ______ by peritubular capillaries. The tubule is composed of 3 regions:
1) ____________ Convoluted Tubule (PCT) - in the cortex; wall consists of
simple cuboidal epithelium with microvilli for reabsorption; from here, filtrate
goes to the
2) Descending & ascending Loop of _______ (nephron loop) - located mostly in
the medulla; filtrate then goes to the
3) ___________ Convoluted Tubule (DCT) - in the cortex; remaining filtrate
c.
with wastes passes to a collecting duct, through the papillary duct to the
minor calyx, to major calyx, to renal pelvis, into the ureter, then the
________
Two types of ___________ are found in the kidneys
1) ___________________ - have their glomeruli in the inner 1/3 of the cortex
2) ___________ - have their glomeruli in the outer 2/3 of the cortex
IV. Ureters, Urinary Bladder, & Urethra
A. ________ - two tubular retroperitoneal organs that take urine from the renal pelvis down
to the urinary bladder. Features include:
1.
The ureter wall has 3 _______, which from inner to outer are:
a.
____ - continuous with the renal tubules and urinary bladder, consists of
____________ epithelium, cells secrete mucus
b.
____________ - inner longitudinal & outer circular smooth ____________ layers
that promote peristalsis to move urine
c.
________________ - composed of loose CT surrounds and protects the
underlying layers and anchors the ureters in place
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2.
Renal ____________ (kidney stones) can form in the kidney and cause great pain as
they attempt to pass through the ureter to the urinary bladder
B. Urinary __________ - sac located between the pubic symphysis & rectum that receives
and stores urine from the ureters. Features:
1.
2.
In females, the bladder is in contact with the uterus & ________
3.
The bladder wall consists of 4 _________
4.
In males, the ___________ gland is inferior to the bladder and surrounds the exiting
urethra
a.
_________ - composed of transitional epithelium and rugae folds that stretch as
the bladder fills. The ___________ is formed between the two ureter openings
and the urethral opening
b.
c.
_______________ supports the mucosa
d.
_________________ - on the superior surface of the bladder is an extension of the
parietal peritoneum
____________ consists of 3 interlaced smooth muscle layers called the detrusor
muscle, which forms the internal _____________ at the neck of the bladder
Because a woman’s urethra is shorter than a man’s, she is more prone to urinary
bladder infection (_____________). To reduce infections, women should wipe the
anal area posteriorly
C. ____________ - tubular organ that conveys urine from the urinary bladder to outside the
body. Features:
1.
Has urethral ________ embedded in the wall that secrete protective mucus into the
urethral canal
2.
Two muscular _____________ surround the urethra
a.
b.
__________ sphincter formed by the detrusor muscle of the urinary bladder
___________ sphincter composed of skeletal muscle
3.
A female urethra is straight, about ____ in. long, and empties urine through the
urethral orifice into the vestibule between the labia minora
4.
A male urethra is curved, about ___ in. long, and serves both the urinary &
reproductive systems. It’s 3 sections are:
a.
Prostatic urethra - passes through the _____________ near the urinary bladder;
receives drainage from prostate ducts & 2 ejaculatory ducts
b.
________________ urethra - passes through the urogenital diaphragm &
proximal penis; the external urethral sphincter is found here
c.
Spongy (_________) urethra - longest portion, extends from the urogenital
diaphragm to the external urethral orifice on the glans penis.
1) It is surrounded by ____________ tissue, passing through the corpus
spongiosum of the penis
2) The ducts of the ________________ glands attach to the spongy urethra near
the urogenital diaphragm
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V. Urine Formation I: Glomerular ____________
A. The first step of urine formation is blood plasma filtration in the ______________
1. Blood enters the glomerular ___________, which are fenestrated
2. Water and small solutes form a glomerular filtrate that passes into the glomerular
capsule through the ____________________, which consists of
a. _____________ endothelium of the glomerular capillary walls
b. _____________ membrane of a proteoglycan gel
c. Flitration ________ formed by the pedicels of podocytes wrapped around the
glomerular capillaries
3. Solutes in the plasma filtrate include _________, amino acids, electrolytes, fatty acids,
vitamins, and _______________ wastes
4. Larger molecules, such as ___________, and blood cells are too large to pass through
the filtration membrane, thus remain in the glomerulus
5. Relatively high blood (___________) pressure in the glomeruli is what forces the
filtrate materials through the filtration membrane
6. _______________ ruptures the glomerular capillaries, leading to scarring
(nephrosclerosis) and eventual renal failure
7. The glomerular filtration rate (_____) is the amount of urine formed per minute by
both kidneys, which averages about 125 mL/min in men and 105 mL/min in women
II. _________________ of Glomerular Filtration
1. Renal _____________ is the ability of the kidneys to maintain a stable GFR, despite
MAP changes, without nervous or hormonal control via the following mechanisms
a. ____________ mechanism occurs in the afferent arteriole; as MAP increases, it
stretches the arteriole, which causes it to contract, reducing blood flow into the
glomerulus
b. _____________________ feedback is accomplished by the juxtaglomerular
apparatus
1) _______________ (JG) cells in the afferent arteriole dilate or constrict the
arteriole when stimulated by the macula densa. They also secrete ______ to raise
BP when BP drops
2) ______________ cells in the distal convoluted tubule sense changes in filtrate
flow and ____________. With slow flow or low osmolarity, JG cells are
signaled to vaso_________; fast flow or high osmolarity, cause JG cells to
vaso________
2. ____________ control – during strenous exercise or circulatory shock, sympathetic
nerves and epinephrine constrict the afferent arteriole, reducing _____ and urine
production
3. Renin-__________________ mechanism
a. When BP drops, sympathetic nerves stimulate JG cells to release _________ into
the blood stream
b. Renin converts to angiotensinogen to _______________
c. In the lungs and kidneys, angiotensin-converting enzyme (____) converts
angiotensin I to __________________, which increases BP by
1) Stimulates vaso______________ throughout the body
2) Constricts afferent and ______________ arterioles
3) Stimulates secretion of _____, promoting water reabsorption
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4) Stimulates the adrenal gland to secrete _____________, promoting sodium and
water retention
5) Stimulates thirst and _________ intake
VI. Urine Formation II: Tubular ____________ and ____________
A. ____________ Convoluted Tubule – ____________ about ___% of the glomerular
filtrate back into the peritubular capillaries, and removes other substances from the blood
to ___________ into the tubule for excretion in the urine
1. Substances the body needs, such as water, ___________, lactate, amino acids, and
varying amounts of ions (65% Na+) are ____________, mostly by active transport
across the tubule walls
2. Products not needed by the body, such as ________, uric acid, ammonia, creatinine,
H+ or HCO3-, and some drugs are _______ into the tubule from the peritubular
capillaries
3. If a solute, such as glucose, is filtered by the glomerulus faster than the ___ can
reabsorb it, the excess will pass out in the urine (e.g., glycosuria occurs in diabetes
mellitus)
B. The Nephron Loop (Loop of _________)
1. Primary function is to generate a ________ gradient that enables the collecting duct to
concentrate the urine and conserve water
2. The ___________ thin segment allows _______ to flow out to surrounding
peritubular capillaries (or vasa recta)
3. The ___________ thick segment is impermeable to water, but allows ___, K+, and
Cl- to be transported out, increasing salinity of the surrounding medulla tissues (which
increases ________ out of the descending segment)
4. About 25% of Na+, K+. and Cl- and 15% water are _________ by the loop
C. ____________ Convoluted Tubule & Collecting Duct
1. ____________ cells in the walls of both tubes have hormone receptors and are
involved in the reabsorption of _____ and salts
2. _______________ cells reabsorb K+, secrete __ into the tubule, and are involved in
acid-base balance
3. _____________ involved include the following
a. _____________ stimulates the DCT to reabsorb ____ and secrete K+
b. Atrial natriuretic peptide (____) increases salt and water excretion by increasing
___ and GFR, and inhibiting NaCl reabsorption by the collecting duct
c. Parathyroid hormone (___) acts on the nephron loop and DCT to promote ____
reabsorption, and acts on the PCT to promote phosphate excretion
VII. Urine Formation III: ______ Conservation in the collecting ducts
A. The collecting duct (CD) ________ varying amounts of water to leave the urine as dilute
as 50 mOsm/L or as concentrated as 1,200 mOsm/L, depending upon the body’s state of
hydration
B. The CD is permeable to ______, but not to _____. As it passes through the medulla, it
loses water to surrounding tissues, and urine becomes more concentrated
C. _____ controls the rate of water loss by the CD
1. ADH stimulates the installation of _________ water transporters in CD cells,
increasing CD permeability to water
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2. High ADH causes urine to be _______ and highly concentrated
3. Low ADH causes increased dilute urine (_________)
D. The ______________ multiplier mechanism of the nephron loop maintains the salinity
gradient of the renal medulla
VIII. Urine & Renal Function Tests
A. ______________ is the examination of the physical and chemical properties of urine,
which is a valuable diagnostic procedure
B. Composition & Properties of _________
1. Appearance – varies from colorless to _____, depending on the body’s state of
hydration. Cloudiness might indicate ________ growth
2. ______ – fresh urine should have a distinctive, but not repulsive, smell. As urine
stands, bacteria degrade urea to ____________, producing a more pungent odor
3. Specific _______, the ratio of the density (g/mL) of a substance to the density of water
(1.000 g/mL); urine SG ranges from 1.001 when dilute to 1.028 when concentrated
4. Osmolarity, concentration of dissolved _______, varies from 50 mOsm/L in a
hydrated person, to 1,200 mOsm/L in a dehydrated person
5. pH ranges from 4.5-8.2, but is usually about ___ (mildly acidic)
6. Chemical composition – urine averages 95% ______ and 5% _________ by volume.
Components include
a. ________, NaCl, KCl are in greatest concentration
b. _________, uric acid, phosphates, sulfates, and traces of Ca2+, Mg2+, and sometimes
HCO3- are found in lesser amounts
c. Biliruben or urobilin, breakdown products of ____________, may be found
d. It is abnormal to find ___________, hemoglobin, albumin, or ketones in urine.
Their presence may indicate kidney dysfunction
C. Urine Volume in an average adult is ______ per day. Abnormally high output is
___________; low output is anuria.
D. ___________ is any chronic polyuria of metabolic origin. Forms of diabetes include
1. _________ (juvenile or insulin dependent) diabetes mellitus – pancreatic beta cells are
destroyed and no longer produce _____
2. ______ (adult-onset or insulin independent) diabetes mellitus – beta cells may still
produce insulin, but insulin __________ on effector organs are deficient
3. Gestational diabetes – sometimes occurs during __________, but usually disappears
after pregnancy. Can predispose the mother to develop Type II diabetes later in life
4. The above types of diabetes are characterized by ___________ (glucose in the urine),
poly______ (extreme thirst), poly_____ (excess urination), poly_______ (excessive
hunger)
5. Diabetes ________ – characterized by polydipsia and polyuria due to a deficiency in
ADH
E. _____________ are chemicals that increase urine output. Some examples are
1. ___________ – inhibits the release of ADH, reducing tubular reabsorption
2. ___________ – dilates the afferent arteriole and increases GFR
3. Diuretic drugs are used to treat ____________ and congestive heart failure because
they reduce the body’s fluid volume and blood pressure
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F. Renal ___________ Tests are performed to diagnose and monitor kidney diseases. Two
frequently used methods are
1. Glomerular Filtration Rate (___) is the amount of urine formed per minute(about 125
mL/min) by both kidneys. This can be measured by injecting a substance that is not
reabsorbed nor secreted (e.g., inulin) then measuring the rate of urine output and
concentrations of the substance in the blood and urine.
2. Renal ____________ (RC) – the volume of blood plasma from which a particular
substance (e.g., urea) is completely removed in 1 minute. It is calculated by: RC =
UV/P, where
a. U = concentration (mg/ml) of the substance in the _______
b. V = the _____________ of urine formation (ml/min)
c. P = the concentration of the same substance in the _______
d. A normal renal clearance value for _____ is about 60 mL/min, meaning of the 125
mL/min GFR, ___% is cleared of urea
IX. Urine Storage and Elimination
A. ______________ (urination) – is the process by which urine passes from bladder through
___________. Events include:
1. The urinary bladder becomes _____________ with urine
2. ________ receptors in the bladder wall send sensory impulses to the spinal cord, then
to the micturation center in the ______
3. Parasympathetic impulses from the pons go to the __________ muscle & internal
urethral sphincter
4. The detrusor muscle contracts & internal __________ relaxes
5. The need to urinate is sensed as _________
6. Urination is prevented by voluntary contraction of the ________ urethral sphincter
7. When urinating, the external sphincter is relaxed, the detrusor muscle contracts, &
urine is expelled through the ________
8. Neurons of the micturation center are inactivated, the detrusor muscle relaxes, & the
urinary ___________ fills again.