Urinary System
Chapter 16
1
• Urology- the branch of
medicine that treats
male and female
urinary systems as well
as the male
reproductive system.
• Nephrology- the
scientific study of the
anatomy, physiology,
and pathology of the
kidney.
2
Major Functions of the
Urinary System
• Filter waste and excess material from the
blood.
• Regulate blood volume and composition.
• Help regulate blood pressure.
• Store urine.
• Discharge urine.
3
Urinary Organs
Kidney
Ureter
Urinary bladder
Urethra
4
Renal cortex
Renal
medulla
Renal
cortex
Renal
artery
Renal
vein
Nephrons
Renal
medulla
Ureter
Renal pelvis
5
The kidney consists of
~ 1 million nephrons
• Nephrons- the functional unit of the
kidney.
• Nephrons form urine.
• Nephrons consist of 2 parts along with a
surrounding capillary network.
– Renal corpuscle
– Renal tubule
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Nephron Anatomy
Bowman’s capsule
Efferent
arteriole
Glomerulus
Afferent
arteriole
Proximal convoluted
tubule
Distal convoluted
tubule
Renal artery
Renal vein
Peritubular capillary
network
Loop of
Henle
Collecting duct
Renal pelvis
7
Renal Corpuscle- part 1
of the Nephron
1) Renal Corpuscle- site where fluid (blood) is
filtered. Water, glucose, amino acids, urea,
uric acid, and salts move from the glomerulus
through a filter to Bowman’s space.
•
•
Glomerulus- a cluster of capillaries.
Bowman’s Capsule- cuplike structure that surrounds
the glomerulus.
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Renal Corpuscle
Bowman’s capsule
Bowman’s space
Proximal convoluted
tubule
Glomerulus
Afferent
arteriole
Efferent
arteriole
Pore
Basal lamina
Slit membrane
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Renal Tubules- part 2 of the Nephron
2) Renal Tubules- site of absorption and secretion.
• Proximal convoluted tubule
– Water, glucose, amino acids, and salts are absorbed from the
proximal convoluted tubule by the peritubular capillary network.
• Loop of Henle
– At this site water and salts are absorbed by the peritubular
capillary network.
• Distal convoluted tubule
– At this site water and salts are further absorbed by the
peritubular convoluted tubule.
– Drugs and hydrogen ions, secreted from the peritubular
capillary network, are absorbed.
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•Note- water is
absorbed in the
collecting
ducts.
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Renal pelvis
Urinary Bladder
• Anatomy
– Hollow muscular organ.
– Situated at the base of the pelvic cavity.
– Capacity average= 700-800 ml.
– Smaller in females because the uterus
occupies the space just superior to the
bladder.
– Rugae (folds) are present.
• Function- store urine.
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Urination
• The bladder fills with
urine.
• Nerve impulses are
sent to the spinal
cord and then the
brain.
• Motor nerve
impulses are
returned and signal
the bladder to
contract and the
sphincters to open.
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Hormones increase water
concentration in the blood.
• Reabsorption of water- 48
gallons of filtrate enters
Bowman’s space each day,
~47.5 is returned to the
blood.
• Antidiuretic hormone (ADH)
and Aldosterone cause
water to be absorbed into
the peritubular capillary
network.
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Diuretics decrease water
concentration in the blood.
• Diuretics- chemicals that
increase the flow of urine.
– Alcohol inhibits the
secretion of ADH
(antidiuretic hormone).
– Caffeine increases
glomerular filtration rate
and decreases absorption
of sodium.
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Maintaining Salt Balance
• Absorption of Salt- >99% of the sodium
filtered at the glomerulus is returned to the
blood.
– Atrial natriuretic hormone (ANH)- a hormone
secreted by the heart atria that promotes sodium
excretion.
– Aldosterone- a hormone secreted by the adrenal
glands that promotes sodium absorption.
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17
Reproductive System
Chapter 17
18
Early Developmental Anatomy
19
Male Reproductive System
• Testes- the male gonads, they produce
sperm (spermatogenesis) and sex
hormones.
• Epididymis- ducts where
sperm mature and some are stored.
• Vas deferens- conduct and store sperm.
• Seminal vesicles- secrete fructose, citric
acid, amino acids, and prostaglandins.
• Prostate gland- secrete alkaline fluid
that activates the sperm.
• Bulbourethral glands- secrete clear and
slippery fluid into semen.
• Urethra- tubular structure that expels
sperm.
Vas deferens
Head and body of
epididymis
Rete testis
Seminiferous
tubule
Scrotum
Tail of epididymis
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Male Reproductive System
Prostatic urethra
Spongy urethra
Membranous
urethra
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Posterior View
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Semen and Sperm
• Semen- mixture of sperm & seminal fluid
(60% seminal vesicles, 25% prostate, and
a ~1% from the bulbourethral).
– Slightly alkaline (7.2-7.7ph).
• Typical ejaculate is 2.5 to 5 ml in volume.
• Normal sperm count is 50 to 150
million/ml.
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Erection and Ejaculation
• Erection
– Sexual stimulation dilates the
arteries supplying the penis.
– Blood enters the penis
compressing the veins and
traps the blood.
• Ejaculation
– Muscle contractions close
sphincter at the base of the
bladder and move fluids
through vas deferens.
– Once the semen is in the
urethra, rhythmic muscle
contractions expel it.
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Hormonal Control of Testes
Gonadotropin-releasing
hormone
Luteinizing hormone
Follicle-stimulating hormone
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Female Reproductive System
• Ovaries- the female gonads, produce eggs (oogenesis)
and sex hormones.
• Oviducts- fallopian tubes, transport eggs (oocytes) to
uterus by cilia that line the tubes.
• Uterus- receives and nourishes the embryo.
– Uterine wall- muscle layer that stretches to accommodate the
developing baby; contracts during childbirth.
– Endometrium- lining of the uterus, built up and lost each month.
• Cervix- opening to uterus.
• Vagina- receives penis during sexual intercourse; serves
as birth canal and as an exit for menstrual flow.
• Clitoris- contributes to sexual arousal.
• Mammary glands- milk production and ejection.
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Mammary Glands
• Modified sweat glands that produce milk (lactation)
–
–
–
–
Amount of adipose determines size of breast.
Milk-secreting glands open by lactiferous ducts at the nipple.
Areola is pigmented area around nipple.
Suspensory ligaments suspend breast from deep fascia of pectoral
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muscles.
Female Reproductive System
31
Lining of the Uterine Tubes
33
Hormonal Concentrations
34
Ovarian Cycle
• Development of a vesicular follicle,
ovulation, and development of corpus
luteum, 28 day cycle.
– Under control of FSH and LH.
• Follicular Phase- FSH promotes development of a
follicle.
• Luteal Phase- LH promotes development of corpus
luteum.
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Hormonal Control of Ovaries
Gonadotropin-releasing
hormone
36
37
Uterine Cycle
• Twenty-eight day cycle.
–
–
–
–
Days 1-5= Menstruation
Days 6-13= Proliferative phase
Day 14= Ovulation
Days 15-28= Secretory phase
• Controlled by estrogen and progesterone.
• During menopause, usually between age 45 and
55 the uterine cycle ceases, and the ovaries no
longer produce estrogen and progesterone.
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• FSH stimulates
development of
follicles.
• LH surge triggers
ovulation & corpus
luteum formation.
• Follicle cells
secrete estrogen.
• Estrogen &
progesterone
stimulate
development of
endometrium.
• Corpus luteum in
ovary secretes
estrogen &
progesterone.
Infertility
• Infertility is defined as the failure of a couple
to achieve pregnancy after one year of
regular, unprotected intercourse.
– Estimated 15% of all couples.
• Female causes, 40%.
– Blocked oviducts.
– Endometriosis- presence of uterine tissue outside the uterus.
• Male causes, 40%.
– Low sperm count.
– Sperm abnormalities.
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From Fertilization to Implantation
41
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