Urinary System Overview - Anatomy & Physiology

Urinary System Overview

• The urinary system regulates electrolyte and fluid balance, preventing imbalances that can be fatal.
• It comprises two kidneys, ureters, a urinary bladder, and a urethra.
• The kidneys filter blood, reabsorb ions, and produce urine.
• Ureters transport urine from the kidneys to the bladder.
• The urinary bladder stores urine.
• The urethra conveys urine to the exterior.

General Objectives

• Students should understand the anatomical structures and physiological processes involved in the urinary system.
• They should apply knowledge for nursing care and holistic approaches to health.
• They should connect anatomical/physiological concepts to real-world situations and lifestyle choices.

Learning Objectives

• Understand the internal and external anatomy and physiology of the kidneys.
• Know the process of urine formation.
• Appreciate the importance of renal blood flow.
• Describe the pathway of vital substance reabsorption or secretion.

Functions of the Urinary System

• Eliminating waste products and maintaining the body's fluid and electrolyte balance.
• Excreting nitrogenous wastes, drugs, and toxins.
• Maintaining blood volume and concentration. This includes salt/water balance in the blood.
• Regulating the proper concentrations of body fluids, ensuring balanced sodium, chloride, potassium, calcium and phosphate ions.

Kidney Structure and Function

• Kidneys: Bean-shaped organs located in the abdominal cavity. The right kidney is slightly lower than the left, due to the liver.
  • Hilum: Entrance/exit for structures such as blood vessels, nerves, and the ureter.
  • Renal Capsule: Innermost layer, provides protection.
  • Adipose Capsule: Middle layer, cushions the kidney.
  • Renal Fascia: Outermost layer, anchors the kidney.
• Renal Cortex: Outer region.
• Renal Medulla: Inner region, composed of renal pyramids.
• Renal Pyramids: Triangular structures containing collecting tubules.
• Renal Papillae: Tip of the renal pyramids that drain into the minor calyces.
• Calyces: Minor and major are funnel-shaped ducts that collect urine and drain into the renal pelvis.
• Renal Pelvis: Expanded region connecting to the ureter.

Nephrons- Functional Units

• Nephrons are the microscopic functional units of the kidneys.
• They are involved in filtering blood and producing urine.
• Bowman's Capsule: A double-walled structure where filtration takes place.
• Glomerulus: A network of capillaries inside Bowman's capsule where filtration occurs.
• Renal Tubule: A series of tubules where reabsorption and secretion take place.
• Proximal Convoluted Tubule: Initial portion of the renal tubule for reabsorption and secretion.
• Loop of Henle: U-shaped portion of the renal tubule promoting water reabsorption.
• Distal Convoluted Tubule: Final portion of the renal tubule for reabsorption and secretion.
• Collecting Duct: Collects urine from many nephrons and empties into the renal pelvis.

Blood Supply to Kidneys

• Renal arteries deliver blood to the kidneys.
• Afferent arterioles branch from the renal arteries, feeding into the glomeruli (capillary network in Bowman's capsule).
• Efferent arterioles leave the glomerulus and branch into peritubular capillaries that surround the renal tubule, providing blood to support reabsorption.
• Filtration in the glomerulus forces water and small solutes into the Bowman's capsule
• Kidneys receive 1200ml of blood per minute.

Composition of Urine

• Primarily water (95%), with dissolved waste products like urea, uric acid, and electrolytes.
• Daily urine production is typically 0.6-2.5 liters.

Urine Formation Processes

• Glomerular Filtration: Blood filtration in the glomerulus.
• Tubular Reabsorption: Recovering valuable substances (e.g., water, glucose, amino acids) from the filtrate back into the blood.
• Tubular Secretion: Removing excess substances from the blood into the filtrate.

Urine Passage

• Urine flows via the calyces, renal pelvis, and ureters into the urinary bladder.

Explore the intricate structures and functions of the urinary system, focusing on the kidneys, ureters, bladder, and urethra. This quiz will help you understand urine formation, renal blood flow, and the importance of electrolyte balance for maintaining health. Perfect for nursing students and anyone interested in human anatomy.