Urinary System and Kidney Anatomy

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Questions and Answers

What is one of the primary functions of the urinary system?

Storage of vitamins

Production, storage, and transportation of urine (correct)

Hormone production

Nutrient absorption

Which structure does NOT enter or exit through the renal hilum?

Adrenal gland (correct)

Renal vein

Ureter

Renal artery

Which function is NOT associated with the urinary system?

Erythrocyte production stimulation

Regulation of cholesterol levels (correct)

pH regulation of bodily fluids

Filtration of blood and waste removal

What is the nephron primarily responsible for?

Filtration of blood and urine formation (B) Signup and view all the answers

What role does the urinary system play in blood pressure regulation?

Adjusting the volume of blood plasma (B) Signup and view all the answers

What is the most active form of vitamin D produced by the kidney?

Calcitriol (C) Signup and view all the answers

What type of muscle is the internal urethral sphincter made of?

Smooth muscle (D) Signup and view all the answers

How does the parasympathetic pelvic nerve affect the detrusor muscle?

Increases contraction (B) Signup and view all the answers

Why is there an increased risk of cystitis in biological females?

Shorter urethra (B) Signup and view all the answers

Where is the urinary bladder located in relation to the uterus in biological females?

Anterior and inferior (C) Signup and view all the answers

How many sections is the male urethra divided into?

Three (A) Signup and view all the answers

What is the function of the sympathetic hypogastric nerve concerning the detrusor muscle?

Inhibits contraction (B) Signup and view all the answers

How does the kidney contribute to vitamin D synthesis?

It converts a skin precursor to calcitriol (A) Signup and view all the answers

What role does aldosterone play in the renal system?

Increases Na+ and water reabsorption (A) Signup and view all the answers

How does antidiuretic hormone (ADH) primarily affect water reabsorption?

Inserts aquaporins in the collecting duct (A) Signup and view all the answers

What is the primary function of angiotensin II?

Increases vasoconstriction and blood pressure (B) Signup and view all the answers

What physiological effect results from increased levels of atrial natriuretic hormone (ANH)?

Increased excretion of sodium leading to lower blood pressure (B) Signup and view all the answers

What structure allows urine to exit the body?

Urethra (D) Signup and view all the answers

What triggers the release of renin from juxtaglomerular (JG) cells?

Low blood pressure (B) Signup and view all the answers

What is the primary function of the transitional epithelium lining the ureters?

Allows for the expansion and contraction of the ureters (A) Signup and view all the answers

How does the renin-angiotensin-aldosterone system (RAAS) primarily affect the glomerular filtration rate (GFR)?

Increases blood pressure to maintain GFR (A) Signup and view all the answers

What is primarily transported by the ureters?

Urine (B) Signup and view all the answers

What type of muscle action assists in moving urine through the ureters?

Peristalsis (C) Signup and view all the answers

What is the normal pH range of urine?

4.5–8.0 (A) Signup and view all the answers

Which component is typically NOT found in normal urine?

Protein (A), Glucose (B), Blood (D) Signup and view all the answers

What role does the detrusor muscle play in the micturition reflex?

It contracts to expel urine. (A) Signup and view all the answers

Which nerve is primarily responsible for voluntary control of urination?

Pudendal nerve (B) Signup and view all the answers

How does an enlarged prostate gland affect urine flow?

It restricts urine flow. (C) Signup and view all the answers

What indicates a potential diabetic condition in urine analysis?

Presence of glucose (D) Signup and view all the answers

Which statement about the external urethral sphincter is true?

It allows urine to flow when relaxed. (D) Signup and view all the answers

Which abnormal urinary finding would suggest a urinary tract infection (UTI)?

Presence of leukocytes (D) Signup and view all the answers

What effect does a longer urethra have in biological males?

Decreases risk of cystitis. (C) Signup and view all the answers

What condition is indicated by the presence of ketones in urine?

Body using fat as an energy source (B) Signup and view all the answers

What is the primary function of the renal corpuscle in the nephron?

Filtration of blood (C) Signup and view all the answers

What characterizes the glomerulus as a fenestrated capillary?

It has openings that enable filtration of larger substances (B) Signup and view all the answers

Which component of the nephron is primarily involved in the active secretion and reabsorption of solutes?

Proximal convoluted tubule (A) Signup and view all the answers

What is the role of aquaporins in the nephron?

Permitting water movement through membranes (B) Signup and view all the answers

What structures separate the renal pyramids in the renal medulla?

Renal columns (D) Signup and view all the answers

What effect does hypertension have on the glomerular filtration rate (GFR)?

Increases GFR by damaging glomeruli (C) Signup and view all the answers

What structure is NOT a part of the nephron itself, but influences solute and water reabsorption?

Collecting duct (B) Signup and view all the answers

Which type of nephron makes up the majority in the kidney?

Cortical nephrons (B) Signup and view all the answers

Which layer of the kidney is responsible for maintaining its shape?

Fibrous capsule (C) Signup and view all the answers

What is the primary function of the renal medulla?

Main site for urine formation (A) Signup and view all the answers

Which factor does NOT influence glomerular filtration rate (GFR)?

Hydration level of the body (B) Signup and view all the answers

What are the filtration slits in the renal corpuscle formed by?

Podocyte pedicels (C) Signup and view all the answers

Which segment of the nephron is primarily responsible for the absorption of water and solutes?

Proximal convoluted tubule (A) Signup and view all the answers

What is the primary function of tubular reabsorption in the kidneys?

To return filtered materials back into the blood (B) Signup and view all the answers

Which pressure is primarily associated with promoting filtration into the glomerular capsule?

Glomerular hydrostatic pressure (A) Signup and view all the answers

What does the term 'countercurrent multiplier' refer to in kidney function?

The mechanism by which nephron loop increases osmolarity of interstitial fluid (D) Signup and view all the answers

Which substances are entirely reabsorbed in the proximal convoluted tubule (PCT)?

Glucose and amino acids (C) Signup and view all the answers

What role does the juxtaglomerular apparatus (JGA) play in renal physiology?

It regulates blood pressure to maintain glomerular filtration rate. (D) Signup and view all the answers

Which mechanism aids sodium reabsorption in the renal tubule?

Secondary active transport (B) Signup and view all the answers

How does the parathyroid hormone (PTH) affect calcium reabsorption in the kidneys?

It increases calcium reabsorption in the distal convoluted tubule. (C) Signup and view all the answers

In which part of the nephron is water predominantly reabsorbed via aquaporins?

Loop of Henle (D) Signup and view all the answers

What is the typical glomerular filtration rate (GFR) for healthy adults at rest?

80–140 mL/minute (D) Signup and view all the answers

Which process allows for the removal of excess substances from the blood into the renal tubule?

Tubular secretion (A) Signup and view all the answers

What happens to urine volume in the collecting ducts when blood osmolarity is high?

Urine volume decreases due to increased water reabsorption. (D) Signup and view all the answers

What type of transport do sodium ions undergo in the thick ascending limb?

Secondary active transport (D) Signup and view all the answers

What triggers the secretion of erythropoietin (EPO) by the kidneys?

Hypoxemia (A) Signup and view all the answers

Study Notes

Urinary System Functions

Production, storage, and transport of urine
Blood filtration and waste removal
Regulates bodily fluid pH
Regulates blood pressure
Regulates solute concentration in blood
Stimulates erythrocyte production
Vitamin D synthesis

Kidney Anatomy (Gross and Microscopic)

Paired, retroperitoneal organs on either side of the vertebral column
Located outside the abdominal cavity, slightly lower on the left than the right (due to liver positioning)
Protected by muscle, fat, and ribs
Adrenal glands located on the superior margin
Renal hilum: Medial surface, entry/exit point for structures (renal artery, vein, nerves, ureter, lymphatics).
External layers of the kidneys: fibrous capsule, perinephric fat, renal fascia (anchors kidneys to abdominal wall) .

Nephrons and Blood Supply

Nephron: functional unit of the kidney
Blood vessels: renal, segmental, interlobar, arcuate, interlobular arteries and their corresponding veins.
Arteriole part of the nephron: afferent arteriole (delivers blood to nephron), glomerulus (filters blood), efferent arteriole (exits glomerulus), peritubular capillaries (exchange of nutrients/wastes), vasa recta (drains peritubular capillaries)

Internal Kidney Anatomy

Renal cortex (superficial layer) covers the renal medulla (deeper layer).
Renal pyramids and columns divide the medulla.
Renal papillae drain urine into minor calyces.
Minor calyces merge to form major calyces, which merge to form the renal pelvis.

Renal Corpuscle

Glomerulus: fenestrated capillary network (filters blood)
Bowman's capsule: captures the filtrate (glomerular capsule)
Composed of a parietal layer (simple squamous epithelium) and a visceral layer (podocytes).

Filtration Membrane

Limits filtration of blood cells, platelets, and large plasma proteins.
Composed of fenestrated endothelium, basement membrane, and filtration slits formed by podocytes.

Tubular System

Proximal convoluted tubule (PCT): actively secretes and reabsorbs solutes.
Nephron loop (loop of Henle): divided into descending and ascending limbs – varying permeability to solutes and water.
Distal convoluted tubule (DCT): reabsorbs and secretes fewer solutes and water.
Collecting ducts: not part of nephron, but influence solute and water reabsorption; several nephron DCTs empty into a single collecting duct.

Glomerular Filtration Rate (GFR)

Volume of filtrate formed per minute.
Average: 80–140 mL/minute.
Influences: gender, age, diet, metabolism.

Pressures Influencing GFR

Glomerular hydrostatic pressure: promotes filtration.
Capsular hydrostatic pressure: opposes filtration.
Blood colloid osmotic pressure: opposes filtration.

Tubular Reabsorption and Secretion

Reabsorption: filtered substances returned from tubules to blood.
Secretion: wastes secreted from blood to tubular fluid to become part of urine.
PCT, nephron loop, and DCT primary sites for reabsorption.
Most filtered material is reabsorbed.
Solutes actively reabsorbed, water follows osmotically.

Countercurrent Multiplier

System in nephron loop builds osmotic gradient in interstitial fluid, enabling water reabsorption.

Juxtaglomerular Apparatus (JGA)

Regulates glomerular blood hydrostatic pressure and GFR.
Composed of macula densa cells (DCT) and juxtaglomerular cells (afferent arteriole).
Macula densa: responds to elevated GFR, leading to afferent arteriole constriction.
Juxtaglomerular cells: respond to low blood pressure, releases renin which activates hormonal pathways for higher blood pressure.

Collecting Ducts

Regulate urine volume and osmolarity.
Principal cells: reabsorb sodium and secrete potassium.
Intercalated cells: reabsorb potassium and bicarbonate, secrete hydrogen ions.

Hormones Influencing Urine Formation

Renin-angiotensin-aldosterone pathway (RAAS): regulates blood pressure and GFR.
Antidiuretic hormone (ADH): increases water reabsorption.
Natriuretic hormones (e.g., ANP): stimulate sodium excretion and decrease blood pressure.

Ureters, Urinary Bladder, and Urethra

Ureters transport urine from kidneys to bladder.
Urinary bladder temporarily stores urine.
Urethra eliminates urine from the body.

Urine Characteristics

Color: pale yellow to amber.
Odor: odorless (at first).
Volume: 750-2000 mL/24 hrs
pH: 4.5-8.0
Glucose, blood, and proteins should not be present in normal urine.

Urinalysis

Examination of urine to assess kidney and overall health by presence of certain substances.

Additional Kidney Functions

Erythropoietin (EPO) production (stimulates red blood cell production in response to low oxygen).
Vitamin D activation.
Calcium regulation.

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Description

Explore the vital functions of the urinary system, including urine production, blood filtration, and the regulation of bodily fluids. Learn about kidney anatomy, from gross structures to microscopic details, and understand the role of nephrons and blood supply in kidney function.