41 Questions
What is the primary function of the kidneys in regulating ion concentrations?
Maintaining electrolyte balance in extracellular fluid
Which structure surrounds the kidney and prevents the spread of infection?
Fibrous capsule
What is the term for the process by which the kidneys regulate long-term acid-base balance?
Acid-base homeostasis
What is the pathway through which urine exits the body?
Ureters → Urinary bladder → Urethra
What is produced by the kidneys to regulate blood pressure?
Renin
What is the region where the ureters, renal blood vessels, lymphatic vessels, and nerves enter and exit the kidney?
Renal hilum
What is the major function of the kidney related to acid-base balance?
To maintain pH levels through the reabsorption and secretion of bicarbonate ions
How is the countercurrent multiplier system involved in urine concentration?
It creates a concentration gradient in the renal medulla
Which structure is responsible for the preliminary filtration of blood in the kidney?
Glomerulus
What is the primary function of the peritubular capillaries and Vasa recta?
Reabsorption of water and solutes
Which hormone plays a central role in the renin-angiotensin-aldosterone system?
Aldosterone
Which class of nephron is responsible for regulating urine concentrations during periods of dehydration or low fluid intake?
Juxtamedullary nephrons
Which structure in the nephron plays a crucial role in regulating glomerular filtration rate (GFR) and maintaining blood pressure?
Juxtaglomerular apparatus (JGA)
Which hormone plays a crucial role in regulating water and salt balance in the body and is released in response to low blood pressure or low salt concentration in the fluid flowing through the JGA?
Renin
How does the countercurrent multiplier system of the nephron contribute to the ability of the kidneys to produce concentrated urine?
It increases the reabsorption of water in the descending limb of the loop of Henle
Which layer of the glomerular capsule, also known as Bowman's capsule, consists of branching epithelial podocytes with filtration slits that allow filtrate to pass into the capsular space?
Visceral layer
Which part of the nephron is responsible for regulating the excretion of hydrogen ions (H+) and maintaining acid-base balance in the body?
Collecting duct
What is the term for the volume of blood flowing through the glomerulus per unit time, which is an important measurement of overall kidney function?
Effective renal plasma flow (ERPF)
What is the primary pathway through which urine flows from the renal pyramid to the ureter?
Renal pyramid → Minor calyx → Major calyx → Renal pelvis
What is the term for the over 1 million functional units in the kidney responsible for forming urine?
Nephrons
What is the name of the artery that branches off the aorta and supplies blood to the kidney?
Renal artery
What is the name of the vein that drains blood from the kidney and flows into the inferior vena cava?
Renal vein
What is the term for the tuft of capillaries that make up part of the renal corpuscle and are responsible for filtration?
Glomerulus
What is the term for the process by which the kidneys regulate the concentration of urine?
Countercurrent multiplier system
What is the primary function of the kidney in regulating acid-base balance?
Ensuring long-term acid-base balance
What is the region of the kidney where the ureters, renal blood vessels, lymphatic vessels, and nerves enter and exit?
Renal hilum
What surrounds the kidney and prevents the spread of infection?
Fibrous capsule
What is the pathway of blood flow through the kidney?
Renal artery → glomerulus → renal vein
What is the structure that temporarily stores urine?
Urinary bladder
What is the number of layers of supportive tissue that surround the kidney?
3
What is the function of the juxtamedullary nephrons in the kidneys?
Producing concentrated urine
Which structure plays a crucial role in regulating blood pressure and maintaining glomerular filtration rate (GFR)?
Macula densa
Which pathway is primarily responsible for secreting hydrogen ions (H+) and maintaining acid-base balance in the body?
Tubular secretion
How does the countercurrent multiplier system contribute to the ability of the kidneys to produce concentrated urine?
By increasing the surface area for reabsorption
Which process is primarily responsible for the preliminary filtration of blood in the kidneys?
Glomerular filtration
What is the role of the Vasa recta in the kidneys?
To maintain a concentration gradient in the renal medulla
What percentage of nephrons do cortical nephrons make up?
85%
What is the primary function of juxtamedullary nephrons in the kidneys?
Production of concentrated urine
Which hormone is released in response to low blood pressure or low salt concentration to regulate water and salt balance?
Renin
What is the range of normal values for osmolarity of urine?
400–1000 mOsmol/kg
What is the usual color of normal urine?
Pale yellow to deep amber
Study Notes
Urinary System Gross Anatomy
- The kidney is divided into three regions: renal cortex, renal medulla, and renal pelvis
- Renal cortex: granular-appearing superficial region
- Renal medulla: deep to cortex, composed of cone-shaped medullary (renal) pyramids
- Renal pelvis: funnel-shaped tube continuous with ureter
- Minor calyces: cup-shaped areas that collect urine draining from pyramidal papillae
- Major calyces: areas that collect urine from minor calyces, empty into renal pelvis
- Urine flow: renal pyramid → minor calyx → major calyx → renal pelvis → ureter
Blood Flow Through the Kidney
- Aorta → Renal Artery → Segmental Artery → Interlobar Artery → Arcuate Artery → Cortical Radiate Artery (aka Interlobular Artery) → Afferent Arteriole → Glomerulus → Efferent Arteriole → Peritubular capillaries or Vasa Recta → Cortical Radiate Veins (aka Interlobular Veins) → Arcuate Vein → Interlobar Vein → Renal Vein → Inferior Vena Cava
Nephrons
- Nephrons are the structural and functional units that form urine
- > 1 million per kidney
- Two main parts: Renal corpuscle and Renal tubule
- Renal corpuscle: composed of glomerulus and Bowman's capsule
- Glomerulus: tuft of capillaries composed of fenestrated endothelium
- Bowman's capsule: cup-shaped, hollow structure surrounding glomerulus
- Consists of two layers: parietal layer and visceral layer
- Filtration slits allow filtrate to pass into capsular space
Urinary System Functions
- Kidneys, a major excretory organ, maintain the body's internal environment by:
- Regulating total water volume and total solute concentration in water
- Regulating ion concentrations in extracellular fluid (ECF)
- Ensuring long-term acid-base balance
- Excreting metabolic wastes, toxins, drugs
- Producing erythropoietin (regulates blood pressure) and renin (regulates RBC production)
- Activating vitamin D
- Carrying out gluconeogenesis, if needed
Clinical Evaluation of Urine
- Urinalysis: urine is examined for signs of disease
- Can also be used to test for illegal substances
- Assessing renal function requires both blood and urine examination
- Normal values:
- Color: pale yellow to deep amber
- Odor: odorless
- Volume: 750-2000 mL/24 hour
- pH: 4.5-8.0
- Specific gravity: 1.003-1.032
- Osmolarity: 40-1350 mOsmol/kg
- Urobilinogen: 0.2-1.0 mg/100 mL
- White blood cells: 0-2 HPF (per high-power field of microscope)
- Leukocyte esterase: none
- Protein: none or trace
- Bilirubin: none or trace
Learn about the key structures in the renal system including the glomerular capsule, renal tubule, and collecting duct. Understand the components of the glomerular capsule such as the parietal and visceral layers, filtration slits, and podocytes. Explore the histology and functions of the renal tubule.
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