topic 9 (urinary system)

Question 1

Describe the gross anatomy of the kidney

Answer 1

• Location: Retroperitoneal space, on
  either side of the spine between T12
  and L3 vertebrae.
• Size: About 11 cm long, 6 cm wide, and 3
  cm thick.
• External Features: Renal capsule (fibrous
  covering), renal cortex (outer layer),
  renal medulla (inner region with renal
  pyramids).
• Internal Features:
  • Renal Pelvis: Funnel-shaped structure
    collecting urine from the kidney.
  • Renal Pyramids: Cone-shaped tissues
    within the medulla.
  • Renal Columns: Extensions of cortical
    tissue between pyramids.
  • Calyces (major and minor): Chambers
    receiving urine from the pyramids and
    passing it to the renal pelvis.

Question 2

Describe the anatomy and function of a nephron.

Answer 2

• Components:
  
  • Renal Corpuscle: Includes Bowman’s
    capsule and glomerulus; site of blood
    filtration.
  • Proximal Convoluted Tubule (PCT):
    Reabsorbs nutrients, ions, and water.
  • Loop of Henle: Descending and
    ascending limbs; concentrates urine
    by reabsorbing water and salt.
  • Distal Convoluted Tubule (DCT):
    Further modifies filtrate through
    reabsorption and secretion.
  • Collecting Duct: Collects urine from
    multiple nephrons, final adjustments
    to urine composition.
• Function: Filters blood, reabsorbs necessary substances, secretes waste products, and regulates fluid and electrolyte balance

Question 3

Explain and distinguish between filtration, absorption, and secretion.

Answer 3

• Filtration: Blood pressure forces water and solutes from the glomerulus into Bowman’s capsule, forming filtrate.
• Absorption: Movement of water and solutes from the filtrate back into the bloodstream, primarily in the PCT, loop of Henle, DCT, and collecting duct.
• Secretion: Transfer of substances from the blood into the filtrate for excretion, occurring mainly in the PCT and DCT.

Question 4

Discuss how renal function is evaluated.

Answer 4

Blood Tests:
* Serum Creatinine: Indicator of kidney
function; high levels suggest impaired
function.
* Blood Urea Nitrogen (BUN): Measures
urea levels; elevated levels indicate
reduced kidney function.

Urine Tests:
* Urinalysis: Examines the physical and
chemical properties of urine.
* Glomerular Filtration Rate (GFR):
Estimates the rate of blood flow
through the glomeruli; normal GFR is
90-120 mL/min.

• Imaging: Ultrasound, CT scan, or MRI to visualize kidney structure.
• Biopsy: Analysis of kidney tissue for diagnostic purposes.

Question 5

Describe urinary elimination.

Answer 5

Process:
* Urine Formation: Filtration,
reabsorption, and secretion in
nephrons.
* Urine Transport: Urine moves from
the kidneys through the ureters to the
bladder.
* Urine Storage: Bladder stores urine
until elimination.
* Micturition (Urination): Voluntary and
involuntary control mechanisms expel
urine from the bladder through the
urethra.

• Regulation:
  
  • Nervous System: Parasympathetic
    nervous system stimulates bladder
    contraction.
  • Sphincter Control: Internal
    (involuntary) and external (voluntary)
    sphincters control urine release.

Question 6

Describe the processes of filtration, absorption, and secretion in the nephron.

Answer 6

• Filtration: Blood pressure forces plasma through the glomerular capillaries into Bowman’s capsule, excluding cells and large proteins.
• Absorption: Essential substances (glucose, amino acids, ions) and water are reabsorbed from the filtrate back into the bloodstream, primarily in the PCT.
• Secretion: Additional waste products (hydrogen ions, potassium, creatinine) are secreted from the blood into the filtrate, mainly in the PCT and DCT.

Question 7

Describe the process of urinary elimination.

Answer 7

• Kidneys: Produce urine through filtration, reabsorption, and secretion.
• Ureters: Transport urine from the kidneys to the bladder using peristaltic waves.
• Bladder: Stores urine until it is excreted; stretches to accommodate varying volumes.
• Urethra: Conveys urine from the bladder to the outside of the body; sphincters regulate flow.
• Micturition Reflex: Triggered by bladder distension; involves both involuntary (internal sphincter) and voluntary (external sphincter) control.