Final Review

Examination Attendance

  • You don't need to pause unless you missed exam one, exam two, or exam three.

  • If you have taken all your exams, you do not need to show up. Use your time wisely: study, sleep in, or do something else.

  • Make sure to prepare for your next presence at 07:45 next week.

  • Only those needing makeup exams are required to be present on Thursday at 09:15.

Course Questions

  • Questions regarding the remainder of the course should be asked. Specific inquiries can be made via email.

Renal Anatomy and Physiology

Key Components to Remember

  • Renal Corpuscles: Important structures located in the cortex of the kidney.

  • Proximal Convoluted Tubule & Distal Convoluted Tubule: Always found in the cortex.

  • Cortex and Medulla: Be aware of what structures are situated in the cortex versus the medulla.

Glomerular Filtration Rate (GFR)

  1. If Glomerular Filtration Rate is too low:
       - Statement: Needed substances may pass quickly through renal tubules and are lost in urine.
       - Answer: False. If GFR is low, substances are reabsorbed too much because they don't pass through quickly enough.

  2. If Glomerular Filtration Rate increases:
       - It's important to understand the physiological changes that occur in both high and low rates.

  3. Filtration Process:
       - Glomerular filtration is not an ATP driven process but rather a passive, pressure-driven process. No energy is required.

Urine Formation Structures and Functions

  • Distal Tubule & Collecting Duct:
       - In the absence of hormones, both structures are relatively impermeable to water.
       - Collecting duct becomes impermeable to water in the presence of antidiuretic hormone (ADH).

  • Proximal Convoluted Tubule:
       - It does not connect to the collecting duct; that role is fulfilled by the distal convoluted tubule. It's important to remember the nephron's order of parts.

Mechanisms of Action

  1. Stretch Mechanism:
       - In response to too much pressure, the body constricts (contracts), not just stretches, to prevent damage to the glomerulus.
       - Importance of contraction post-stretch should be noted.

  2. Trigonode:
       - Named for the openings of the ureters and urethra, located on the inferior surface of the urinary bladder.

Key Concepts Related to Hormones and Blood Pressure

  • Angiotensin II's Function:
       - Incorrect statement: "Angiotensin II lowers blood pressure during stress."
       - Correct Fact: Angiotensin II actually increases blood pressure through vasoconstriction and stimulating release of aldosterone, which promotes sodium and water reabsorption.

  • Renin-Angiotensin-Aldosterone System (RAAS):
       - Essential for increasing blood volume and consequently blood pressure.

Urine Output Dynamics

  • Impact of Blocking Sodium Channels:
       - If sodium channels are inhibited, water cannot follow, leading to increased urine volume because sodium and water remain in the tubules.

  • Blood pH Regulation:
       - Secretion of hydrogen ions at the collecting duct is crucial for regulating blood pH. This is preferred over mere filtration as secretion allows for elimination of excess H+ ions.
       - Countercurrent Multiplication: Involves sodium bicarbonate in the medullary region to maintain osmotic gradients.

Urinary Structures and Order of Urine Collection

  • First Structure to Collect Urine:
       - Calyx, specifically, urine is formed in the collecting duct before entering a minor calyx, forming major calyx, then leading to the renal pelvis, ureter, and ultimately the urinary bladder.

  • Nitrogenous Waste:
       - Constitutes the largest solute component of urine due to its toxicity, necessitating removal.

  • Ureter Layers:
       - Endothelium is not a layer of the ureter. The ureter contains:
          1. Mucosal layer (inner)
          2. Muscularis layer (smooth muscle)
          3. Adventitia (outer layer)

Urinary Bladder Characteristics

  • The urinary bladder features rugae that allow it to stretch and relax as it fills and empties.

  • It is lined with transitional (urothelium) tissue.

  • Micturition is the term for voiding the bladder, which involves a reflex mechanism.

  • Comparison to incontinence, where the bladder cannot retain urine.

Differences Between Male and Female Urethra

  • Male Urethra:
       - Longer and shared with the reproductive system. Has 2 sphincters and is not connected to the renal pelvis.

  • Female Urethra:
       - Shorter, specifically dedicated to urinary function.

Conclusion

  • Ensure familiarity with all functional and anatomical terms regarding renal structures and their roles in urine formation and regulation of blood pressure, pH, and urinary physiology. Review the order and mechanisms involved in urine collection and excretion.