Anatomy & Physiology: Urinary System Unit 13

Prayer Before Class

• The prayer is directed to the Holy Spirit, the source of light and wisdom.
• It asks for the dissipation of darkness (sin and ignorance).
• It requests a penetrating mind, retentive memory, method, and ease of learning.
• Guidance is sought for work progress, and completion.
• The prayer concludes with a request through Jesus Christ, a plea for divine help, and a concluding phrase.

Anatomy and Physiology with Pathophysiology: Unit 13 - The Urinary System

• The module is part of a course in Anatomy and Physiology with Pathophysiology at UST General Santos.
• It covers Unit 13: The Urinary System.

Course Content

• Urinary System Physiology
• Urine formation and characteristics
• Diseases relevant to the Philippines
• Urinary disorders relevant to medical technologists
• Diagnostic tests relevant to medical technologists

Unit Intended Learning Outcomes

• Explain the urinary system in its normal state and pathophysiologic state.
• Discuss the physiological tests and procedures.
• Apply knowledge to actual health situations.

Formative Assessment: Guess the word (Multiple assessments)

• Somioso
• Rutbalu
• Barptoeinor
• Yiksden
• Umrlugolse

Overview of the Urinary System

• The urinary system involves two kidneys, two ureters, the urinary bladder, and the urethra.
• The diagram provides a visual representation of these organs.

Each kidney filters a large volume of blood

• Kidneys filter a large volume of blood.
• Wastes are collected and form urine.
• An anatomical illustration of the kidney is presented.

Urine Characteristics

• Urine typically consists of approximately 95% water.
• Key components such as urea, chloride, sodium, and potassium are also present in urine, along with peptides, proteins, and other inorganic substances.

Functions of the Urinary System

• Excretion: removes waste products from the blood.
• Regulates blood volume and pressure.
• Regulates blood solute concentrations.
• Regulates extracellular fluid pH.
• Regulates red blood cell synthesis (EPO).
• Regulates vitamin D synthesis.

Urinary System Function: Excretion

• Kidneys filter waste products from the blood.
• Fluid and waste are captured and transported through tubes throughout the kidney.
• Large molecules remain in the blood, while smaller molecules and ions are filtered.
• Blood is transformed into urine.

Urinary System Function: Regulation of Blood Volume and Pressure

• Hydration status determines urine production.
• Large volume → dilute urine.
• Small volume → concentrated urine.
• Urine is a mechanism to regulate blood pressure.

Urinary System Function: Regulation of Blood Solute Concentrations

• Kidneys regulate major ions in the blood's concentration.
• A diagram illustrating solute concentration regulation within the kidney is presented.

Urinary System Function: Regulation of Extracellular Fluid pH

• Kidneys secrete variable amounts of H+ to regulate extracellular fluid pH.
• This process helps maintain a balanced pH level.

Urinary System Function: Regulation of Red Blood Cell Synthesis

• EPO (erythropoietin) promotes RBC synthesis in the red bone marrow.
• This process addresses anemia conditions.

Urinary System Function: Regulation of Vitamin D Synthesis

• Kidneys control calcium levels indirectly by regulating vitamin D synthesis.
• UV radiation on the skin facilitates vitamin D production.

Renal Cortex

• The outer region of the kidney.
• Location of blood filtration structures.

Renal Medulla

• The inner region of the kidney
• Cone-shaped pyramids, tubes, and ducts are part of the medulla, functioning in fluid transport.
• Urine modification takes place here.

Nephron

• Functional unit of the kidney.
• 1.3 Million nephrons.
• Distributed throughout the cortex and medulla.

Nephron Structures

• Renal corpuscle (glomerulus & Bowman's capsule)
• Proximal convoluted tubule (PCT)
• Loop of Henle
• Distal convoluted tubule (DCT)

Renal Corpuscle

• Filters blood.
• Returns filtered substances to the blood.
• Helps conserve water and solutes.
• Rid the blood of wastes.

Urine Production

• Glomerular filtration.
• Tubular reabsorption.
• Tubular secretion.
• Kidney sorts substances from the blood for either removal in the urine or return to the blood.

Filtration

• Blood pressure forces fluid and small molecules out of the blood.
• Filtered fluid is known as filtrate.
• First step in urine production, where most substances except blood cells and proteins are filtered.
• Filtration is indicated by the percentage of blood sent across the kidneys.

Filtration Membrane

• Fenestrated glomerular capillaries
• Basement membrane (visceral and parietal layers of Bowman's capsule)
• Podocytes of the visceral layer of Bowman's capsule
• Prevents larger molecules from passing through.

Filtration Diagram and Pressures

• Diagrammatic representation of glomerular capillary and capsular hydrostatic pressures and blood colloid osmotic pressure.
• Filtration pressure is calculated as the difference between capillary and osmotic pressures.

Tubular Reabsorption

• Movement of water and solutes from filtrate to blood.
• Osmosis is essential in movement towards solutions with higher solute concentration.
• Critical for preventing dehydration.

Tubular Reabsorption: PCT

• Majority of reabsorption occurs in the PCT
• Solutes and water are actively transported into the interstitial fluid and then into peritubular capillaries.

Tubular Reabsorption: Loop of Henle

• Descending limb: permeable to water.
• Ascending limb: impermeable to water and solutes.

Tubular Reabsorption: DCT & Collecting Duct

• K+ and H+ reabsorbed.
• Reabsorption is hormonally controlled (ADH).
• ADH increases water reabsorption; without ADH, water is not reabsorbed.

Tubular Secretion

• Reabsorption in reverse.
• Movement of non-filtered substances from the blood.

Tubular Secretion: Hydrogen Ions

• Hydrogen ions are secreted to maintain blood pH.

Checkpoint

• Organs of the urinary system.
• Functions of the urinary system.
• Steps in urine formation.

Urine Movement

• Urine flow pathway.
• Micturition reflex mechanism.

Micturition Reflex

• Bladder stretches when filled triggering reflex.
• Walls of the bladder contain folds for expansion.
• Transitional epithelium accommodates large volumes.
• Smooth muscle contraction leads to urination.

References

• VanPutte and Seeley (2020). Seeley's Anatomy & Physiology (12th ed.). McGraw-Hill

This quiz tests your knowledge on Unit 13 of the Anatomy and Physiology course focused on the Urinary System. You will explore urinary system physiology, urine formation, and pathophysiological conditions as they relate to medical technologists, with a special emphasis on diseases in the Philippines.