Urinary System - Anatomy and Physiology

Comprehensive vocabulary flashcards covering the gross anatomy, histology, physiology, fluid pressures, and pathological disorders of the human urinary system.

Urinary Tract

The collective system formed by the ureters, urinary bladder, and urethra that transports, stores, and eliminates urine from the body. [Slide 3]

Kidney

Filters blood and produces urine

Ureters

transport urine from kidneys to bladder

Urinary bladder

Stores up to 1 L of urine

Urethra

Fibromuscular tube that carries urine from the bladder to the outside of the body

urinary tract

Contains ureter, bladder, and urethra

Female Urethra

A short fibromuscular tube measuring about $3\text{ to }4\,\text{cm}$ ($1.5\,\text{inches}$) that extends from the bladder neck to the external urethral orifice situated anterior to the vaginal opening and inferior to the clitoris, serving exclusively to excrete urine. [Slide 4]

Male Urethra

A fibromuscular canal measuring about $15\text{ to }20\,\text{cm}$ ($7\text{ to }8\,\text{inches}$) extending from the base of the bladder through the prostate gland, pelvic floor, and penis, fulfilling a dual physiological role by conveying both urine and semen. [Slide 4]

Retrograde Ejaculation

A clinical condition occurring when the internal urethral sphincter fails to contract and close tightly during orgasm, diverting semen backward along the path of least resistance into the bladder instead of expelling it forward through the penis. [Slide 6]

Sperm path

Sperm is made in the testicles, move through small tubes, called the vast deferens, and mixes with fluids from the prostate, and Seminal vesicle to form semen

Urine path in men

Urine travel straight from the bladder

Main symptom of retrograde ejaculation

A dry orgasm followed by cloudy urine. Next time they urinate.

Unharmful And not painful, but it’s a main cause of male infertility

Internal Urethral Sphincter (IUS)

An involuntary ring of smooth muscle located at the bladder neck that tonically prevents urine extravasation and contracts during male ejaculation to prevent semen from refluxing into the bladder. [Slide 6]

External Urethral Sphincter (Rhabdosphincter)

A ring of voluntary skeletal muscle encircling the membranous urethra inferior to the prostate gland that maintains tonic constriction for urinary continence and undergoes relaxation during voluntary voiding and ejaculation. [Slide 6]

Urinary Continence

The ability to voluntarily control release of urine, relies on healthy pelvic floor muscles, sphincter muscles, and nerves working together to store urine and release it voluntarily[Slide 7]

Kidney Anatomical Location

Positioned retroperitoneally on the upper posterior abdominal wall on both sides of the vertebral column between the $T<em>{12}$ and $L</em>3$ vertebrae, partially protected by the 11th and 12th ribs, with the right kidney situated slightly lower than the left due to the liver.

10 to 13 cm in length [Slide 8]

Peritoneum

The largest continuous serous membrane in the human body,

Lines the abdominal and pelvic cavities and covers most of the organs within them.

Helps with organ support, protection, and the transport of blood vessels and nerves [Slide 10]

The two continuous layers of peritoneum

parietal peritoneum and visceral peritonaeum

Parietal peritoneum

Outer layer that lines the internal walls of the abdominopelvic cavity, sensitive to localized pain, pressure, and temperature

Visceral peritoneum

Inner layer that wraps around the internal organs(Viscera), Has autonomic nerve supply, pain is diffused and hard to localize

peritoneal cavity

Potential space between parietal and visceral layers, Has small amount of serious fluid 50 to 100 ML which allows organs to slide freely against each other without friction

Five folds which weave between viscera binding organs together

Greater Omentum

Lesser omentum

Falciform ligament

Mesentry

MesoColon

Mesentery

A double layer of visceral peritoneum that attaches the intestines to the posterior abdominal wall and provides pathways for neurovascular structures. [Slide 14]

Omenta

Specialized peritoneal folds, including the greater omentum hanging like an apron over the intestines and the lesser omentum (connecting the stomach to the liver). [Slide 14]

Ligaments

Double layers of peritoneum that connect organs to each other or to the abdominal wall

Intraperitoneal

Organs that are almost completely covered by visceral peritoneum such as the stomach, liver, spleen, jejunum and Ilium

Retroperitoneal

Located outside the peritoneal cavity, Typically behind the Parietal peritoneum, such as kidneys, pancreas, and portions of the duodenum and Colon

Peritonitis

Dangerous inflammation or infection of the peritoneum, often caused by a ruptured organ like the appendix

Ascites

Abnormal buildup of excess fluid within the peritoneal cavity, frequently due to liver disease

SAD PUCKER

A medical mnemonic for retroperitoneal organs:

S= Suprarenal glands

A= Aorta/inferior vena cava

D= Duodenum

P= Pancreas

U= Urinary bladder and ureters

C= Colon

K= Kidneys

E= Esophagus

R= Rectum

The elimination of metabolic waste by kidney

Remove waste products, such as urea and uric acid

Prevent prevents toxic buildup in the blood

Regulation of ion levels by the kidney

Maintain balance of ions in blood, such as sodium, potassium, calcium, and phosphate

Adjust ion excretion based on dietary intake

Regulation of acid base balance by the kidney

Maintains blood pH by controlling:

Hydrogen ions and bicarbonate ions (HCO3-), adjust excretion of these ions in urine

Regulation of blood pressure by the kidneys

Controls blood volume by adjusting fluid loss in urine

Releases renin Which leads to formation of angiotensin II

ANGIOTENSIN II INCREASES BLOOD PRESSURE

Elimination of biologically, active molecules by the kidneys

Removes substances like hormones, and drugs

These are filtered, but not reabsorbed. They are excreted in urine.

Calcitriol Synthesis

The formation of active Vitamin $D_3$ enabled by the kidneys producing the final enzyme ($1\alpha\text{-hydroxylase}$), which functions to increase intestinal calcium absorption and raise blood calcium levels. [Slide 19]

Erythropoietin (EPO)

A hormone released by the kidneys in response to low blood oxygen levels that stimulates red bone marrow to produce erythrocytes. [Slide 19]

Gluconeogenesis (During starvation)

Produces glucose from non-carbohydrate sources, helps maintain blood glucose during fasting

Overall role of kidneys

Maintaining healthy blood composition

Healthy blood depends on properly functioning kidneys

Renal Hilum

A concave medial opening of the kidney that serves as the entry and exit point for blood vessels, nerves, and the ureter. [Slide 22]

Lateral/outer border

Is convex

Renal Pelvis

A funnel-shaped internal structure that collects urine emerging thru the hiking to join ureter, Hilum is the doorway while the pelvis is a structure passing through it[Slide 23]

Fibrous Capsule

directly attached to the kidney surface, composed of dense irregular connective tissue that maintains shape, protects against trauma, and prevents pathogen entry. [Slide 26]

Perinephric Fat

A layer of adipose tissue surrounding the fibrous capsule that cushions the kidney and stabilizes its physical position. [Slide 26]

Renal Fascia

A layer of dense irregular connective tissue external to the perinephric fat that anchors the kidney to surrounding anatomical structures. [Slide 26]

Paranephric Fat

The outermost adipose layer surrounding the renal fascia that provides extra cushioning and stabilization for the kidney. [Slide 26]

Functional anatomy of the kidney

Includes nephrons, collecting tubules, collecting ducts, and their associated structures

Nephron

The microscopic structural and functional working unit of the kidney responsible for filtering blood and forming urine, consisting of a renal corpuscle and a renal tubule. [Slide 27]

Renal Corpuscle

The spherical filtration unit located in the renal cortex, composed of the capillary cluster called the glomerulus and the surrounding double-walled glomerular capsule. Where blood filtration begins [Slide 27]

Renal tubule

Contains PCT, DCT, and nephron loop

This part modifies the filtrate to form urine

Locations of the nephron and nephron loop

Nephron is in the cortex, nephron loop extends down into the medulla

Overall function of renal corpuscle

Filter blood

Overall function of renal tubule

Process filtrate into urine

Renal corpuscle

Round part of the nephron within kidney cortex, composed of the glomerulus and glomerular capsule

Glomerulus

A tangled ball of capillaries fed by the afferent arteriole and drained by the efferent arteriole, where blood plasma is forced across a filtration barrier into the capsular space. [Slide 31]

Glomerular capsule

Surrounds glomerulus, has 2 layers:

Visceral-inner/PERMEABLE

Parietal-outer/LESS permeable

Capsular space

Space btwn the 2 layers of the capsule

COLLECTS filtrate (fluid that becomes urine)

Rental tubule

Leftover part of the nephron

Composed of simple epithelium

3 parts: PCT, DCT, Nephron loop

PCT/DCT-In cortex

Nephron loop- extends into the medulla

Proximal Convoluted Tubule (PCT)

The first segment of the renal tubule lined by simple cuboidal epithelial cells with dense microvilli (brush border) that maximize surface area for tubular reabsorption. [Slide 33]

Nephron Loop (Loop of Henle)

A U-shaped hairpin loop extending from the cortex into the medulla with a descending limb and an ascending limb, each containing thick simple cuboidal and thin simple squamous segments. [Slide 34]

Distal Convoluted Tubule (DCT)

The terminal portion of the renal tubule lined by simple cuboidal epithelium with sparse, short microvilli, ending where it empties into a collecting tubule. Starts after ascending limb

Cortical Nephron

The nephron type situated almost completely within the renal cortex featuring short nephron loops that only penetrate slightly into the medulla. [Slide 36]

Juxtamedullary Nephron

A nephron positioned close to the corticomedullary junction and a long nephron loop extending deep into the renal medulla. [Slide 36]

Where nephrons drain

Into each collecting tubule or junctional tubule

Where collecting tubules empty into

Collecting ducts

Juxtaglomerular (JG) Apparatus

A specialized regulatory complex positioned where the afferent arteriole contacts the distal convoluted tubule near the glomerulus, functioning to control urine formation and regulate blood pressure. [Slide 38]

Juxtaglomerular apparatus composition

extraglomerular mesangial cells

Mascula densa (of DCT)

Granular Cells (of Afferent arteriole)

Urine formation

Urine is made in kidneys by filtration, reabsorption, and secretion

Glomerular Filtration

A passive process (no energy required) occurring in the glomerulus where blood hydrostatic pressure forces water and dissolved small solutes (glucose, ions, urea) across the filtration membrane into the capsular space to form filtrate.

Tubular Reabsorption

occurs in renal tubules, glucose, amino acids, most water, important ions - move back into blood,

Uses processes like diffusion, osmosis, and active transport

TAKING BACK WHAT THE BODY MEEDS

Tubular Secretion

occurs in renal Tubules, waste and excess substances move from blood into tubule; hydrogen ions, potassium, drugs/toxins

Requires active transport

ADDING MORE WASTE TO BE REMOVED

Filtration Membrane

A three-layered porous barrier consisting of fenestrated glomerular capillary endothelium, a porous basement membrane, and visceral layer podocytes with membrane-covered filtration slits. [Slide 45]

Glomerular Hydrostatic Pressure ($HP_g$)

The blood pressure inside glomerular capillaries ($\approx 60\,\text{mm Hg}$) that drives fluid out of the blood into the capsular space, elevated because the afferent arteriole is wider than the efferent arteriole. [Slide 46]

Blood Colloid Osmotic Pressure ($OP_g$)

The osmotic pull ($\approx 32\,\text{mm Hg}$) exerted by retained plasma proteins that opposes filtration by drawing water back from the capsular space into glomerular blood. [Slide 47]

Capsular Hydrostatic Pressure ($HP_c$)

The mechanical back pressure ($\approx 18\,\text{mm Hg}$) exerted by accumulated filtrate inside the glomerular capsule that opposes outward fluid movement. [Slide 48]

Net Filtration Pressure (NFP)

The overall driving pressure that determines whether filtration occurs, calculated as $NFP = HP<em>g - (OP</em>g + HP_c) = 60 - (32 + 18) = 10\,\text{mm Hg}$. [Slide 48]

Renal Failure

Severely diminished or absent kidney function caused by the destruction of roughly $90\%$ of functional renal tissue, requiring dialysis or transplantation. [Slide 50]

Peritoneal Dialysis

An internal artificial blood-cleansing procedure where dialysis fluid is infused through a catheter into the peritoneal cavity to absorb metabolic wastes across the peritoneum before being drained and replaced. [Slide 51]

Hemodialysis

An extracorporeal procedure where patient blood is circulated through an artificial dialysis machine to remove waste solutes and excess fluid, typically performed $3\text{ to }4$ times per week for approximately $4\,\text{hours}$ per session. [Slide 52]

Urinary Tract Infection (UTI)

An infection caused primarily by bacteria such as Escherichia coli that can involve the urethra, the bladder (cystitis), or the kidneys (pyelonephritis), presenting with dysuria, urgency, and cloudy urine. [Slide 53]

Kidney Stones (Renal Calculi)

Hard crystalline masses formed in the kidneys from precipitated calcium oxalate, uric acid, or phosphate that can obstruct the ureter and produce severe flank pain, nausea, and hematuria. [Slide 53]

Glomerulonephritis

Inflammation of the renal glomeruli triggered by infectious or autoimmune mechanisms, characterized by hematuria, proteinuria, peripheral edema, and hypertension. [Slide 54]

Acute Kidney Injury (AKI)

A sudden, rapid decline in renal filtration capacity caused by dehydration, toxins, shock, or urinary tract obstruction, presenting with a steep drop in urine output and fluid retention, which can be reversible if treated early. [Slide 55]

Chronic Kidney Disease (CKD)

A progressive, long-term loss of renal function commonly driven by diabetes mellitus or hypertension, resulting in fatigue, edema, and reduced urine excretion. [Slide 55]

Glomerular Filtration Memory Trick

'Push - (Pull + Back pressure) = Filtration', reflecting $60\,\text{mm Hg}$ pushing outward opposed by $50\,\text{mm Hg}$ inward resistance to give $10\,\text{mm Hg}$ of filtration pressure. [Slide 49]

End-Stage Renal Disease (ESRD)

The terminal stage of irreversible renal parenchymal destruction wherein the kidneys cannot sustain fluid-electrolyte or metabolic homeostasis, presenting with uremia, edema, and confusion, necessitating renal replacement therapy. [Slide 56]