Clinical Anatomy - Urinary System Week 10 Part A

Clinical Anatomy and Physiology for Veterinary Nurses - Urinary System

• Week 10, Part A focuses on the urinary system.

Outline of Today's Topics

• Why do we need to know this? Urinary problems (UTIs, kidney failure, incontinence) are common in veterinary practice. Understanding normal urine and urination, and recognizing abnormalities, is crucial. Diagnostic tools, treatment rationale, and patient monitoring also depend on knowledge of the urinary system.

• Overview of the urinary system and its functions: The urinary system filters blood, removes waste products (e.g., urea), regulates the composition and volume of body fluids (osmoregulation), and secretes hormones.

• Location and anatomy of the kidneys: Bean-shaped organs located in the abdomen, generally with the right kidney slightly more cranial than the left. They are retroperitoneal.

• Anatomy of the nephron: Functional units of the kidney, microscopic in size. There are variations in number by species.

• Renal histology: The microscopic anatomy and cellular structure of the kidney's tissues. Features include cortex, medulla, and renal pelvis. Different cell types in the structures will be highlighted.

• The adrenal gland: The adrenal glands are critical for blood pressure control.

• Blood pressure: The body maintains proper blood pressure levels for healthy blood flow to vital organs including the kidney.

• The ureters, bladder and urethra: These structures transport urine from the kidneys to the bladder and out of the body through the urethra.

• Micturition: The process of urination.

• Urine composition and urinalysis: Analysis of urine in terms of composition and indicators of diseases or abnormalities.

The Urinary System

• Components: Kidneys, ureters, bladder, urethra

Functions of the Urinary System

• Regulate: Chemical composition and volume of body fluids. ('osmoregulation')
• Remove: Waste products (e.g., urea), and excess water.
• Secrete: The hormone erythropoietin.

The Kidneys

• Shape: Bean-shaped in most mammals, except for the right kidney in horses.
• Location: In the abdomen, typically with the right kidney slightly more cranial (forward) than the left.
• Position: Retroperitoneal position.
• Hilus: The concave area where blood vessels and the ureter enter and leave the kidney.
• Blood Supply: Oxygenated blood is supplied to the kidneys by renal arteries. Deoxygenated blood is removed by renal veins. Kidneys receive approximately 20-25% of cardiac output at rest.

Anatomy of the Kidneys

• Capsule: Protective connective tissue around the kidney.
• Cortex: Outer layer of the kidney, includes renal corpuscles (glomeruli) and convoluted tubules.
• Medulla: Inner layer of the kidney, divided into renal pyramids. Contains collecting ducts and loops of Henle.
• Pelvis: Funnel-shaped structure collecting urine from calyces before draining into the ureter.

Renal Pelvis

• Minor calyces: Small, cup-shaped structures surrounding renal papillae (at the tip of each pyramid). Collect initial urine.
• Major calyces: Larger structures formed by the merging of several minor calyces. Transport urine to the renal pelvis.

The Nephron

• Functional Units: The nephrons are the filtering units of the kidney which produce urine.
• Filtration: Removes waste from blood.
• Waste Products, Toxins, and Drugs: Are removed by the nephron.
• Size: Microscopic in size, varying in number by species.
• Examples of Nephron Numbers by Animal:
  • Equine: Over 1 million
  • Canine: 400,000
  • Feline and birds: 200,000
  • Rabbits: 170,000

Areas of the Nephron

• Glomerulus: Capillary network within Bowman's capsule, filtering blood.
• Bowman's capsule: Cup-shaped structure surrounding the glomerulus.
• Proximal convoluted tubule (PCT): Reabsorbs essential nutrients and water. Filters blood to remove waste and excess substances.
• Loop of Henle: Regulates water reabsorption, concentrating urine.
• Distal convoluted tubule (DCT): Further regulates electrolyte balance and pH.
• Collecting duct: Final concentration of urine before draining into the renal pelvis.

Glomerulus and Bowman's Capsule

• Structure: Bowman's capsule surrounds the glomerulus, allowing for filtration.
• Function: Filtration of blood to create glomerular filtrate, separating water and small molecules.
• Mechanism: High blood pressure forces the fluid from blood into the filtration system.

Proximal Convoluted Tubule (PCT)

• Resorption: Significant reabsorption of essential substances (e.g., glucose, amino acids, water, sodium, potassium, chloride).
• Excretion: of waste products.

The Loop of Henle

• Regulation: Regulates the amount and concentration of urine, focusing on water balance.
• Mechanism: Water is reabsorbed through the descending loop, while substances are removed as the loop ascends.

Distal Convoluted Tubule (DCT)

• Hormonal regulation: Regulates electrolyte balance and acid-base balance through hormone action (e.g., aldosterone, parathyroid hormone (PTH)).

Collecting Duct (CD)

• Final Regulation: Regulates the final concentration of urine.
• Hormonal Response: Responds to hormones like aldosterone and ADH, impacting urine concentration and electrolyte balance.

Renal Histology

• Tissue Structure: Provides microscopic examination of kidney tissues: cortex, medulla, pelvis. Detailing elements within the cortex and medulla such as glomerulus or renal tubules.
• Microscopic views: Include visualizations from different anatomical regions of the kidney and highlight specific cells or structures.

This quiz covers the urinary system as part of Clinical Anatomy and Physiology for Veterinary Nurses. Week 10 emphasizes understanding urinary functions, common disorders, and the anatomical details of the kidneys and nephrons. Knowledge of these topics is essential for effective diagnosis and treatment in veterinary practice.