Week 13 Content Flashcards
The Urinary System
Role in maintaining homeostasis
Key organ: Kidneys
- Maintain the chemical consistency of blood
- Process blood, filters liters of fluid
Kidneys as Filters
Remove toxins, metabolic wastes, and excess water
Main waste products are nitrogenous waste products
1. Urea
2. Uric acid
3. Creatinine
Kidney Function
Acid-base balance
Water balance
Erythropoiesis
Toxin removal
Blood pressure
Electrolytes
D - Vitamin D metabolism
Mnemonic: A WET BED
Organs of the Urinary System
Upper Urinary Tract
- Kidneys
- Ureters
Lower Urinary Tract
- Urinary bladder
- Urethra
Kidney Position
Located retroperitoneally
Lateral to T12-L3 vertebrae
Average kidney is 12 cm tall, 6 cm wide, and 3 cm thick
External Anatomy of Kidneys
- Hilum
- Fibrous capsule
- Perirenal fat capsule
- Renal fascia
Hilum
Indented area on medial surface
Vessels enter and exit
Renal Artery: Oxygenated blood in
Renal Vein: Filtered blood out
Ureter: Transports urine to bladder
Nerves and Lymphatics: Support kidney function and drainage
Fibrous Capsule
Renal capsule
Tough, protective layer of connective tissue
Surrounds the kidney
Protects against damage and infection
Maintains kidney shape and structure
Perirenal Fat Capsule
Adipose tissue surrounds the kidney
External to fibrous capsule
Cushions and protects kidney
Provides insulation
Anchors kidney in place
Renal Fascia
Connective tissue surrounds kidneys
External to perirenal fat capsule
Anchors kidneys
Protects from movement and trauma
Separates from surrounding tissues
Kidney Diagram
Internal Gross Anatomy of the Kidneys
- Renal cortex
- Renal medulla
- Renal pelvis
- Renal arteries
- Nerve supply
Renal Cortex
Outer layer beneath capsule
Contains nephrons and blood vessels
- Granular appearance
Site of blood filtration and urine formation
Produces erythropoietin
Renal Medulla
Inner kidney beneath cortex
Has cone-shaped renal pyramids
Urine exits through renal papillae
Contains loops of Henle and collecting ducts for urine
Reabsorbs water and salts
Transports urine to renal pelvis
Renal Calyces
Minor Calyx: Collects urine from renal pyramids (renal papillae)
Major Calyx: Formed by merging minor calyces
- Funnel urine into renal pelvis
Renal Pelvis
Funnel-shaped cavity in center of kidney
Collects urine from calyces
Channels urine to ureter for elimination
Proximal Pathway of Urine Conduction
Kidney Diagram
Gross Vasculature
Renal artery carries oxygen-rich blood from aorta to kidney
Branches into segmental arteries
- Interlobar arteries between renal pyramids
- Arcuate arteries around base of renal pyramids
- Cortical radiate arteries: Supply renal cortex
Venous Drainage
Cortical radiate veins - Arcuate veins - Interlobar veins
Renal vein returns deoxygenated blood to the inferior vena cave
Supports filtration
Waste removal
Regulates blood pressure
Path of Blood Flow through Renal Blood Vessels
Nerve Supply of the Kidneys
Controls blood flow and urine production
Renal Plexus: Main nerve network, autonomic fibers
Branches from the celiac plexus
Sympathetic innervation from…
- Thoracic splanchnic nerve
- Lumbar splanchnic nerve
Mechanisms of Urine Production
Filtration: Blood filtered in kidney capillaries, forms filtrate
Resorption: Reclaims nutrients, water, and ions into blood
Secretion: Removal of unwanted molecules from blood into filtrate
Microscopic Anatomy of the Kidneys
Nephron is the functional unit of the kidney
- More than 1 million nephrons in each kidney
Nephron Structure
- Renal corpuscle
- Renal tubule
Filtration Membrane
Filter between glomerulus and capsular space
Prevents passage of proteins
Permits water, ions, glucose, amino acids, and urea
Renal Corpuscle
First part of nephron
Filters blood to form filtrate
- Glomerulus-fenestrated capillaries
- Glomerular (Bowman’s) capsule
- Surrounds glomerulus, captures filtrate
- Parietal layer (structural outer layer)
- Visceral layer (podocytes for filtration)
Renal Tubule
Second part of nephron
Long, coiled tube that processes filtrate
Sections
1. Proximal convoluted tubule
2. Nephron loop (Loop of Henle)
3. Distal convoluted tubule
Proximal Convoluted Tubule (PCT)
Immediately after glomerular capsule
Highly coiled
Main site for reabsorption
- Water
- Nutrients
- Essential ions
Loop of Henle
U-shaped, descending and ascending limb
Descending limb reabsorbs water, concentrates filtrate
Ascending limb actively reabsorbs Na+ and Cl-, dilutes filtrate
Concentrates urine and maintains osmotic gradient for water reabsorption
Collecting Ducts
Extends from DCT through medulla to renal pelvis
Large, straight tube collects urine from multiple nephrons
Reabsorb H2O and Na+
Secrete K+ and H+
Final urine formation (volume, concentration, electrolyte content)
Distal Convoluted Tubule (DCT)
In renal cortex after Loop of Henle
Shorter and less convoluted than PCT
Reabsorbs Na+, CL-, Ca2+
Secretes K+, H+, and NH3
Regulates blood pH and electrolyte balance
Nephron Structure Diagram
Classes of Nephron
- Corical nephrons (~85%)
- In cortex
- Short loops of Henle
- Filtration and reabsorption - Juxtamedullary nephrons (~15%)
- At cortex-medulla border
- Long loops of Henle
- Concentrate urine
Blood Vessels Associated with Nephrons
Nephrons associate with 2 capillary beds
1. Glomerulus
2. Peritubular capillaries (Cortical nephrons) or vasa recta (Juxtamedullary nephrons)
Glomerulus
Filters blood to form urine
Afferent glomerular arteriole brings blood in
Efferent glomerular arteriole drains blood
1L filtrate made every 8 minutes
- 99% resorbed
Peritubular Capillaries
From efferent arterioles of cortical glomeruli
Adapted for absorption
Low-pressure, porous
Secrete molecules into urine
Vasa Recta
From efferent arterioles of juxtamedullary nephrons
Thin-walled, looping vessels
Descend into medulla, concentrate urine
Juxtaglomerular Complex
Regulates blood pressure
Between ascending limb and afferent arteriole
Granular cells secrete renin
Renin released in response to low blood pressure
Macula Densa
End of nephron loop next to granular cells
Monitor Na+ and signals granular cells to secrete renin
Initiates renin-angiotensin mechanism
Mesangial Cells
Specialized cells at base of glomerulus
- Regulate blood flow
Intraglomerular Mesangial Cells between glomerular capillaries
Extraglomerular mesangial cells between macula densa and afferent arteriole
Ureters
Transport urine from kidneys to urinary bladder via peristalsis
One per kidney
Extend from renal pelvis, behind peritoneum, enter bladder obliquely
Prevent backflow of urine
25-30 cm long in adults
Ureter Structure
Mucosa: Epithelium stretches as urine passes
Muscularis: 2 smooth muscle layers (longitudinal and circular) contract to move urine
Adventitia: Connective tissue, anchors ureters
Urinary Bladder
Stores urine
Hollow muscular organ
In pelvic cavity behind symphysis pubis
- Sits on pelvic floor
Same layers as ureter (mucosa, muscularis, adventitia)
Bladder Capacity
300-600 mL of urine
Triangular when empty
Spherical when full, expands into abdominal cavity
Bladder Structures
Openings of ureters
Trigone: Triangular area at base of the bladder
Detrusor muscle contracts to expel urine
Prostate
Non-urinary structure in males
Below the bladder, surrounds urethra
Affects urine flow
Enlarged prostate can cause retention, difficulty, or frequent urination
Urethra
Carries urine from bladder to outside
Smooth muscle and epithelial tissue
Internal urethral sphincter: Junction between bladder and urethra, involuntary
External urethral sphincter: Below internal sphincter, voluntary
Male Urethra
20 cm long, transports urine and seminal fluid
Urinary and reproductive structure
- Prostatic urethra
- Through the prostate - Intermediate part of urethra
- From prostate to penis bulb - Spongy urethra
- From penis to external urethral orifice
Female Urethra
4 cm, shorter than male urethra
Urinary only
Runs along the anterior vaginal wall
External urethral orifice: Opens anterior to the vaginal opening and posterior to the clitoris
Urinary System Diagram
Micturition
Bladder emptying
Voiding or urination
Controlled by the brain through autonomic and somatic pathways
Nervous System Control of Micturition
Parasympathetic: Contracts bladder (Detrusor muscle), relax internal sphincter
Sympathetic: Inhibits bladder contraction, maintains continence
Somatic: Controls external sphincter, voluntary urination
Nervous System Control of Micturition Diagram
Urinary Tract Infection (UTI)
More common in females
- Shorter urethra
Burning during micturition
Frequent urge to urinate
Cloudy or smelly urine
Lower abdominal discomfort
Caused by E.coli
Can cause cystitis
Renal Calculi
Kidney stones
- Hard minerals deposits in the kidneys
Severe pain
Blood in urine (Hematuria)
Nausea
Frequent urination
Caused by dehydration, high calcium or uric acid
Bladder Cancer
3% of cancers
- More common in men
Blood in urine (Hematuria)
Frequent urination
Pain during urination
Risk factors
- Smoking
- Industrial chemicals
- Chronic bladder infections
Kidney Cancer
Renal cell carcinoma
Blood in urine
Side pain
Sudden weight loss
Fatigue
Risk factors
- Smoking
- Obesity
- High blood pressure
- Genetics
Kidney Disease
Progressive loss of kidney function, often from diabetes, hypertension, or genetics
End-Stage Renal Disease (ESRD): Kidneys can’t filter waste, requires intervention
Dialysis
Replicates kidney function until transplant or improvement
Hemodialysis: Machine filters waste, excess fluids, and salts from the blood
Kidney Transplant: Replace damaged kidney with a donor kidney
Urinary System Maturation
Birth: Kidneys functional but immature
Age 2: Kidneys mature
Childhood: Bladder capacity increases, improved micturition control
Age 18: Kidneys are adult size
Renal Aging
Decline in kidney bladder function after 40
Nephrons decrease in size and number
Less efficient tubules
Filtration declines
Loss of bladder muscle tone
Frequent urination
Incontinence (Involuntary Urination)
The Reproductive System
Primary sex organs
- Testes
- Ovaries
Accessory sex organs
- Glands
- External genitalia
Male Reproductive System Overview Diagram
Scrotum
Houses the testes
Skin and superficial fascia
~3 degrees cooler than body temperature
Muscle Layer of the Scrotum
Dartos muscle
- Smooth muscle; wrinkles scrotal skin
Cremaster muscle
- Bands of skeletal muscle; elevates testes
Deep Tissues of the Scrotum
Testes: Produce sperm and testosterone
Epididymis: Stores and matures sperm
Ductus deferens: Transports sperm to urethra
Spermatic cord: Contains arteries, veins, nerves, and ductus deferens
Testes Structure
Tunica vaginalis: Outer serous sac around testis
Tunica albuginea: Inner fibrous capsule, divides testis into lobules
Lobules: Houses seminiferous tubules for sperm production
Seminiferous Tubules
Coiled tubules in testis lobule
Site of spermatogenesis
Highly folded, occupy most of the testis
Contract to drain into rete testis
Rete Testis
Network of tubules connecting seminiferous tubules to efferent ductules
Transports sperm
Absorbs fluid and concentrates sperm
Epididymis
6 meters
Sperm journey takes ~20 days
Seminiferous tubules - Rete testis - Efferent ductules - Epididymis
Connects to the vas deferens (ductus deferens)
The Spermatic Cord
Passes through inguinal canal
Connects testes to abdominal cavity
1. Vas deferens
2. Testicular vessels
3. Nerves
4. Lymphatic vessels
Vas Deferens
Ductus deferens
Stores and transports sperm from epididymis to urethra for ejaculation
Muscular tube
Passes through inguinal canal, over bladder, and connects to ejaculatory duct
Vascular and Nerve Supply of the Testes
Testicular arteries: Supply oxygenated blood
Pampiniform plexus: Cools arterial blood, drains via testicular veins
Innervation: Parasympathetic and sympathetic control
Testis Diagram
Male Urethra
Transports sperm from ejaculatory ducts to outside body
- Prostatic urethra
- Through prostate gland - Intermediate part of urethra
- From prostate to penis bulb - Spony (Penile) urethra
- Through penis, opens at the external urethral orifice
Male Urethra Diagram
Semen
Sperm and fluid from accessory glands
- Provides nutrients
Neutralizes acidity of female reproductive tract
~2-5 mL per ejaculation
20-150 million sperm per mL
Accessory Glands
- Seminal vesicle
- Prostate
- Bulbourethral glands
Seminal Vesicle
Posterior aspect of bladder
Secrete 65% of semen volume
Has fructose sperm motility enhancers, prostaglandins, immune system suppressors, and enzymes
Prostate
Encircles prostatic urethra
Has 20-30 glands
Secretes milky fluid (~25% semen volume)
Has sperm motility enhancers and enzymes
Prostate Diagram
Bulbo-Urethral Gland
Small gland beneath the prostate
Produce mucus
Neutralize acidic urine and lubricate urethral
1% semen volume
Sperm
10% semen volume
Produced in seminiferous tubules of the testes
Head: Contains DNA and acrosome
Midpiece: Contains mitochondria
Tail (Flagellum): Enables movement
Sperm Production and Function
Fertilize the egg to start embryonic development
Survives 1-3 days in the female tract
~400 million sperm produced daily
Begins at puberty
75 days to develop
Sperm Overview Diagram
External Anatomy of the Penis
Shaft (Body): Main length of the penis
Glans Penis: Distal, expanded tip
Prepuce (Foreskin): Fold of skin covering the glans
External Anatomy of the Penis
Urethral opening (Meatus): Tip of glans; urine and semen exit
Corona: Rounded ridge at base of glans
Frenulum: Tissue band on underside, connects glans to the shaft
Internal Anatomy of the Penis
3 erectile bodies
- Corpus spongiosum (1)
- Corpora cavernosa (2)
Corpus Spongiosum
Surround spongy erethra from base to glans
Cylindrical body on underside of penis
Prevents urethra compression during erection
Passage of semen and urine
Corpus Cavernosa
Most of the penis
Two columns on dorsal side from base to glans
- Crus penis: Spongy tissue with blood vessels and sinuses
Fills with blood during arousal; rigidity during erection
Male Sexual Response - Erection
Controlled by parasympathetic nervous system
Vasodilation in corpora cavernosa
Increased blood flow and penile engorgement
Vein compression maintains erection
Male Sexual Response - Ejaculation
Controlled by the sympathetic nervous system
Smooth muscle contraction in prostate, seminal vesicles, and vas deferens
Semen moved into urethra
Expelled via pelvic floor muscle contractions
The Male Perineum
Contains scrotum, root of penis, anus
Diamond-shaped area
Borders
- Pubic symphysis anteriorly
- Coccyx posteriorly
- Ischial tuberosities laterally
Male Reproduction System Diagram
Male Reproduction System Diagram
Overview of Female Reproductive System Diagram
The Female Reproductive System
Produces gametes (ova) in ovarian follicle
Supports embryo development
Changes according to the menstrual cycle
Menstrual Cycle
Menstrual phase (Days 1-5): Uterine lining sheds (menstruation)
Follicular phase (Days 1-13): Follicles mature, estrogen thickens uterine lining
Ovulation (Day 14): Egg released, triggered by LH surge
Luteal phase (Days 15-28): Corpus luteum secretes progesterone, prepares for pregnancy (resets if no pregnancy)
Main Structures of Female Reproductive System
- Ovaries
- Uterine tubes
- Uterus
- Vagina
- Vulva
Ovaries
Small, almond-shaped organs
Produce ova
Secrete hormones (estrogen and progesterone)
Ovaries - Support and Blood Supply
Held by ligaments
1. Broad ligament
2. Suspensory ligament
3. Ovarian ligament
Blood supply: Ovarian arteries
Innervated by sympathetic and parasympathetic ANS
Internal Structure of the Ovaries
Tunica albuginea: Fibrous capsule
Ovarian cortex: Contains follicles with oocytes
Ovarian medulla: Loose connective tissue with blood vessels, lymphatics, and nerves
Hilus: Blood vessel and nerve entry/exit
Fimbrae
Finger-like projections at the distal end of uterine tubes
Guide egg into tube after ovulation
Lined with cilia
Uterine Tubes
Fallopian tube
- Receives ova, facilitates fertilization
Infundibulum
- Distal end with fimbriae
Ampulla
- Middle third, fertilization site
Isthmus
- Proximal third, connects to uterus
Uterus
Anterior to rectum, posterior to bladder
Fundus: Rounded superior portion
Cervix: Neck of uterus
Cervix
Lower part of uterus, above vagina
Cervical canal: Connects to vagina inferiorly
Internal OS: Opening connecting with uterine cavity
External OS: Inferior opening of cervix
Support of the Uterus
Mesometrium: Anchors uterus to lateral pelvic walls
Transverse ligaments: Horizontal ligaments from cervix and vagina
Round ligaments: Attach uterus to anterior body wall
Uterine Wall Composition
Perimetrium: Outer serous layer
Myometrium: Smooth muscle, contracts during childbirth
Endometrium: Inner lining where embryo implants
Endometrium
- Functional layer: Thickens for implantation, sheds during menstruation
- Basal layer: Permanent layer, regenerates functional layer
Blood Supply of Uterine Wall
Uterine arteries branch into arcuate arteries then radial arteries
Divide into…
1. Straight arteries (basal layer)
2. Spiral arteries (functional layer, regenerate and degenerate)
Endometrial Veins
Drain blood from endometrium
Form venous sinuses in functional layer
Important for nutrient and waste exchange, and implantation
Endometrium Diagram
Vagina
Muscular tube connecting uterus to external vaginal orifice
Lined with ruguae for elasticity
Posterior to bladder and urethra
Anterior to rectum and anal canal
Sexual intercourse, childbirth and menstruation
Layers of Vagina
- Adventitia
- Outer fibrous connective tissue - Muscularis
- Middle smooth muscle layer - Mucosa
- Inner layer with transverse folds
Vaginal Structures
Fornix: Recess around upper vaginal portion
Hymen: Incomplete mebrane at vaginal opening
Vulva
External female genitalia
1. Mons pubis
2. Labia (majora and minora)
3. Clitoris
4. Vestibule
5. Vaginal opening
6. Urethral opening
7. Perineum
8. Bartholin’s glands
External Genitalia
Mons pubis: Fatty tissue over pubic symphysis
Labia majora: Outer skin folds, contains sweat and sebaceous glands
Labia minora: Inner skin folds, enclose vaginal and urethral openings
External Genitalia
Clitoris: Sensitive organ at the top of the labia minora, contains erectile tissue
Vaginal opening: Entry to vaginal canal
Vestibule: Houses urethral opening, vaginal opening and Bartholin’s glands
Female Reproductive System Diagram
External Genitalia
Female perineum: Area between vaginal opening and anus
Bartholin’s Glands: Beside vaginal opening, secrete mucus for lubrication during intercourse
Female Perineum Diagram
Female Perineum Deep Structures Diagram
Female Reproductive System Diagram
Mammary Glands
Modified sweat glands that produce milk
Glandular and adipose tissue
Undeveloped in nonpregnant women
Hormones trigger growth during pregnancy and lactation
Milk ducts transport milk to nipple to feed infant
Male Reproductive System Disorders
Erectile dysfunction (ED)
- Difficulty achieving or maintaining erection
- Often vascular, neurological, or psychological
Prostate Disorders
Benign prostatic hyperplasia (BPH)
- Non-cancerous prostate enlargement, causes urinary issues
Prostatitis: Inflamed prostate, causes pain, fever, and urinary problems
Testicular Torsion
Twisting of spermatic cord, cuts off blood flow to the testes
Permanent damage or testicle loss if untreated
Varicocele
Enlarged scrotal veins
Causes discomfort and swelling
Potentially reduce sperm quality and cause infertility
Female Reproductive System Disorders
Polycystic ovary syndrome (PCOS): Hormonal imbalance with irregular cycles, cause ovarian cysts
Ovarian cysts: Fluid-filled sacs in ovaries
Fibroids
Non-cancerous uterine growths
Cause heavy bleeding, pain, and fertility issues
Endometriosis
Uterine tissue growth outside uterus
Causes pain, inflammation, and fertility issues
Pelvic Inflammatory Disease (PID)
Infection of reproductive organs, often from STIs
Can lead to infertility
Infertility
Difficulty conceiving
Low sperm count or poor sperm quality
Low egg count or poor egg quality
Blocked ducts or fallopian tubes
Ovulation disorders
Uterine issues
Hormonal imbalances
Reproductive System Cancers in Males
Testicular cancer
- Affects 1 in 250 males, cured in 95%
- Cancer of spermatogenic cells
Prostate cancer
- Affects 1 in 9 males, high 5-year survival rate
- Slow-growing, arises from peripheral glands
- Early detection through prostate exams
Reproductive System Cancers in Females
Ovarian cancer: Cancer of germinal epithelium, affects 1 in 78 females, 45% survival
Endometrial cancer: Cancer of endometrium, affects 1 in 34 females, 81% survival rate
Cervical cancer: Cancer of cervix epithelium, slow-growing, caused by HPV, affects 1 in 156 females, 92% survival rate
Breast Cancer
Second-most common cause of cancer deaths in women
Affects 1 in 8
Less common in men (1 in 833)
90% of women have 5-year survival rate
Puberty
Between age 10-15
Reproductive organs reach adult size
Consistent sequence of events but timing varies
Influenced by genetics, nutrition, and environmental factors
Male Secondary Sex Characteristics
Scrotum and testes enlarge (~age 13)
Growth of pubic, axillary, and facial hair
Voice deepens
Increased muscle mass
Mature sperm in semen
Female Secondary Sex Characteristics
Breasts develop (~age 11)
Menarche (First meunstral period)
Increase subcutaneous fat
Pelvic girdle widens and lightens
Axillary and pubic hair growth
Estrogen-induced growth spurt (age 12-17)
Labia enlarge
Male Reproductive Age and Fertility
Sperm production begins at puberty and continues throughout life
Fertility declines (~age 40)
Lifestyle, diet, and health affect fertility
No age limit to father children
