Urinary System Overview and Anatomy

Urinary System Overview

• The urinary system is a subsection of the excretory system
• Key functions include nephrogenesis, calcitriol production, nephrectomy, and regulation of renal blood pressure.
• Also, urine production, and maintenance and regulation of blood and electrolytes.

Other Excretion Methods

• Mammals excrete waste through sweat, exhaled gases, and feces.

Basic Anatomy of the Urinary System

• Kidneys are retroperitoneal, except in pigs and grasscutters, where they are more cranial.
• The urinary system includes kidneys, ureters, bladder, and urethra.
• Anatomy diagrams demonstrate the position and connection of these structures within the body.

Renal Biopsy Procedure

• Renal biopsies may be performed using laparoscopy.
• The biopsy needle is carefully inserted into the kidney cortex to collect a sample for diagnosis.

Basic Function: Homeostasis

• The renal system keeps blood (and cell function) balanced by regulating: fluid, pH, electrolytes, and nitrogenous wastes.

Kidney Function Analogy

• Cleaning a refrigerator is a good analogy for the general function of the kidneys.
• Filters the blood, reabsorbs “good” items, removes waste products, and filters and removes any unnecessary water. Urine is the byproduct.

Hormone Production

• Erythropoietin (EPO) and Prostaglandins (PGs) relate to blood pressure and water regulation.
• Renin - helps in blood pressure regulation by regulating water and sodium retention. Also affected by ADH and aldosterone.

Gross Anatomy

• Cystotomy in spayed female dogs is a common procedure discussed in the lab.

Renal Cortex and Medulla

• The renal cortex and medulla have specific structures, such as pyramids and columns, and blood vessels for proper kidney function.

Nephron Structure/Function

• The nephron is the functional unit of the kidney, filtering blood to produce urine.
• Important blood vessels accompany the nephron.
• Key parts of a nephron include the glomerulus, Bowman's capsule, proximal convoluted tubule, loop of Henle, and distal convoluted tubule.
• A series of intricate processes happen in these parts, creating a filtrate and reabsorbing useful materials for the body.

Renal Blood Vessels

• Blood vessels (arteries and veins) are meticulously arranged for the flow of blood through the kidneys.

Renal Vasculature

• The renal vasculature includes a complex array of arteries and veins.
• The flow of blood through the kidneys is essential for filtration, reabsorption, and secretion processes.

Another View of Kidney Vessels

• Various blood vessels, such as interlobular, arcuate, interlobar, and segmental arteries and veins, lead to a complex network of capillaries for effective blood filtration.

Nephron Relation to Blood

• The nephrons are closely associated with blood and its vessels, which plays a critical role in kidney function.

Kidney Functional Unit - Nephron

• Sections explain the nephron, showing details of its components involved in filtering blood and creating urine.

Nephron Function Details

• How the nephron, in a short overview, works to create a concentration gradient in the medulla for urination and reabsorption.
• The nephron steps show what components are involved during the creation and excretion of urine.

Filtration, Reabsorption, and Secretion

• Filtration, reabsorption, and secretion are the processes of the kidney that filter blood, reabsorb necessary components, and secrete unnecessary waste products.
• Parameters such as glomerular filtration rate (GFR) are considered when discussing filtering, reabsorbing, and secreting waste products.
• The various processes occur within the nephron to produce urine and reabsorb necessary components.
• The key layers involved in the processes and substances that need to be moved across these layers are examined in detail.

Renal Blood Supply - Glomerulus

• The glomerulus receives blood for filtration.
• The afferent arteriole brings blood into the glomerulus, and the efferent arteriole carries filtered blood away.

Filtration, Reabsorption, Secretion Processes

• Big fenestrations in caps of glomerulus allow small molecules to pass through into the bloodstream.

Podocytes and Bowman's Capsule

• Podocytes are specialized cells in the inner lining of Bowman's capsule that are crucial to filtration.
• These cells form a filtration barrier.

Additional Filtration, Reabsorption, Secretion Details

• Specific values (e.g., GFR in mL/min) and daily volume data (e.g., total urine output) help illustrate the processes.

Filtration, Reabsorption, Secretion Summary

• Detailed overview of the various specific substances that are filtered, reabsorbed, or secreted, including ions (Na+, K+, Ca2+, Mg2+), glucose, amino acids, bicarbonate, water, etc.
• Active and passive transport mechanisms play a role in getting the needed components into and out of the bloodstream.
• Detailed diagrams show the movement of different substances between the layers and into the bloodstream.

Ureters and Urethra

• Peristalsis in ureters involves continuous movement of urine.
• The urethra in females is short and straight while it is longer and curved in males.
• Ureters enter the bladder obliquely to prevent backflow.
• Specialized transitional epithelium lines the urethra in both sexes.

Ectopic Ureters

• This is an abnormality where the ureter opens at an incorrect location, potentially leading to damage.

Urinary Bladder Structure

• The bladder stores urine and has a muscular structure, a neck region with a trigone, and transitional epithelium.
• Bladder anatomy diagrams illustrate these features.

Micturition (Urine Elimination)

• The process of urine discharge involves several phases including spinal reflex, external/internal sphincter activity.
• Factors such as urine accumulation, stretch receptors, motor signals to detrusor muscles, and the sensation to “go pee” are involved.

Kidney Disease - Acute vs. Chronic

• Clinical chemistry results aid in the diagnosis.

Imaging Techniques

• Radiographic imaging (lateral abdominal radiograph), IV urography, and cystoscopy can aid in diagnosis.

Other Clinical Notes

• Detailed information about the diseases and imaging techniques for clinical assessments.