Untitled Flashcard Set

URINARY SYSTEM

Principles of Health Science

• Course: Spring 2022

Anatomy and Physiology

Overview of Urinary Elimination

• Urinary elimination is the process dependent on the following structures:   - Kidneys
    - Ureters
    - Bladder
    - Urethra

Kidneys

• Characteristics of Kidneys:
    - Paired organs
    - Reddish-brown color
    - Bean-shaped
    - Located on either side of the vertebral column
    - Extend to the 12th thoracic and 3rd lumbar vertebrae
    - The left kidney is normally positioned higher than the right due to the anatomical position of the liver

• Health Functions of Kidneys:
    - Filtration of waste products of metabolism that accumulate in the blood.   - Blood reaches the kidneys via the renal artery, branching from the abdominal aorta.   - Approximately 20-25% of cardiac output circulates daily through the kidneys.   - Each kidney contains approximately 1 million nephrons that perform filtration and urine formation.

Hormonal Functions of Kidneys

• Erythropoietin:
    - A hormone produced by specialized glomerular cells in response to decreased RBC oxygenation.   - Stimulates erythropoiesis (production of mature red blood cells) in the bone marrow.

• Renin:
    - Another hormone produced by the kidneys, primarily involved in regulating blood flow during renal ischemia (decreased blood supply).

Anatomy of the Kidney

• Cortex:
    - The hard outer layer of the kidney.

• Medulla:
    - The fleshy portion of the kidney.

• Pyramids:
    - Triangular-shaped open areas within the kidney's medulla.

• Nephrons:
    - Microscopic units that form urine.

• Renal Sinus/Pelvis:
    - The collection basin for urine at the base of the kidney.

Nephrons

• Definition:
    - The functional unit of the kidney responsible for urine formation.

• Components of Nephron:
    - Glomerulus: the initial site of blood filtration, initiating urine formation.   - Bowman’s Capsule: surrounds the glomerulus and starts the convoluted tubule.   - Proximal Convoluted Tubule
    - Loop of Henle
    - Distal Tubule
    - Collecting Duct

Glomerulus

• Function:
    - The site of initial filtration of blood and the beginning of urine formation.

• Filtration Process:
    - Capillaries are porous to allow filtration of:     - Water     - Glucose     - Amino acids     - Urea     - Creatinine     - Major electrolytes
    - Large proteins and blood cells cannot pass through normally, leading to the indicator of glomerular injury known as proteinuria.

• Filtration Rate:
    - Approximately 125 ml of filtrate is produced per minute.

Bowman’s Capsule

• Structure:
    - C-shaped structure that surrounds the glomerulus.

• Function:
    - Collects filtered materials and passes them into the convoluted tubule.

Tubules

• Process:
    - Reabsorption of filtered substances needed by the body occurs through capillaries.   - Reabsorption includes:     - Most sugars     - Water     - Salts
    - Waste products like urea, uric acid, and creatinine remain in the tubules.

Ureters

• Structure:
    - Tubular structures measuring 25-30 cm in length and 1.25 cm in diameter.

• Function:
    - Transport urine from the renal pelvis to the bladder using peristalsis of the muscular layer.

Bladder

• Description:
    - Hollow, distensible muscular sac located behind the symphysis pubis in the midline of the pelvic cavity.   - Lined with mucous membrane.

• Function:
    - Acts as a reservoir for urine; normally holds a minimum of 300 ml.

Urethra

• Function:
    - Tube that carries urine from the bladder to the outside of the body.

• External Opening:
    - Known as the urinary meatus (ME-AY-TUHS).

• Differences in Males and Females:
    - Male Urethra:     - About 8 inches long.
      - Passes through the prostate gland and penis.     - Carries both urine and semen.   - Female Urethra:     - About 1.5 inches long.
      - Opens above the vagina.     - Carries only urine outside the body.

Urine

• Production:
    - Approximately 1500 to 2000 ml (1.5 to 2 quarts) produced daily.
    - 150 quarts of liquid filtered through kidneys daily.

• Composition:
    - Made up of concentrated liquid of:     - Urea     - Uric acid     - Creatinine     - Mineral salts     - 95% water

• Function:
    - It is a liquid waste product produced by the urinary system.

• Bladder Capacity:
    - Holds about 1 cup of urine.

Urine Consistency

• Normal:
    - Clear and straw-colored.

• Cloudy:
    - May indicate presence of white blood cells or pus (infection).

• Color Variations:
    - Lighter color indicates more water content.   - Darker color indicates higher waste content.   - Pink or red: Blood presence in urine.

Act of Urination

• Influencing Brain Structures:
    - Involves the cerebral cortex, thalamus, hypothalamus, and brainstem to suppress bladder muscle contraction until a person decides to void.

• Sensation of Urge to Urinate:
    - Can be sensed when bladder contains approximately 150 ml of urine, stretching bladder walls and sending sensory impulses to the brain.

• Impulses and Muscle Activity:
    - Nerve impulses from the brain cause rhythmic contractions of bladder muscles while the urethral sphincter relaxes, allowing urine to enter the urethra without expelling yet.

• Decision to Void:
    - Once nerve impulses to the brain signal the need to urinate, the decision to void involves relaxing the external urinary sphincter and stimulating bladder contraction.

Diseases and Abnormal Conditions

Cystitis

• Definition:
    - Also known as urinary tract infection, it is an inflammation of the bladder typically caused by pathogens entering the urinary system.

• Diagnosis:
    - Persistent UTIs may involve a procedure known as cystoscopy to visualize bladder, which is also used to diagnose bladder cancer.

• Treatment:
    - Often involves antibiotics and increased fluid intake.

Renal Calculus

• Definition:
    - Commonly referred to as kidney stones, formed by precipitation of salts in the urine.

• Pathophysiology:
    - Small stones may be eliminated in urine, while larger stones often become lodged in the renal pelvis or ureter.

• Treatment Options:
    - Extracorporeal Shockwave Lithotripsy:
      - A procedure utilizing high-energy pressure waves to crush stones for elimination through urine.   - Surgery:
      - May be required for large stones removal.

Renal Failure

• Definition:
    - Condition in which kidneys stop functioning.

Types of Renal Failure:
  - Acute:
    - Can result from hemorrhage, shock, injury, poisoning, nephritis, or dehydration.   - Chronic:
    - Often results from progressive loss of kidney function.

Treatment for Renal Failure:
  - Hemodialysis:
    - A procedure to remove waste from the blood with a machine when kidneys are not functioning.

Urethritis

• Definition:
    - Also categorized under urinary tract infections, it is an inflammation of the urethra, typically caused by bacteria.

Careers Related to the Urinary System

• Dialysis Technician:
    - Operates machines that remove waste and excess fluids from the blood in patients whose kidneys cannot perform these functions.

• Nephrologist:
    - A doctor specializing in kidney health and diseases.

• Urologist:
    - A doctor specializing in the urinary system, including the bladder, urethra, and possibly the ureters.

Key Terms

• Nephritis:
    - Inflammation of the kidney.

• Nephropathy:
    - Disease affecting the kidney.

• Nephrolithiasis:
    - Condition of having kidney stones.

• Diuresis:
    - The excretion of large volumes of diluted urine, often caused by caffeine or alcohol.

• Urinary Incontinence:
    - Loss of bladder control; inability to hold urine.

• Urinary Retention:
    - Inability to release urine, often due to blockage.

• Anuria:
    - Absence of urine production.

• Polyuria:
    - Excessive urine production.

• Enuresis:
    - Bedwetting.

• Hematuria:
    - Blood in the urine.

• Nocturia:
    - Nighttime urination.

• Pyuria:
    - Presence of pus in the urine.

• Oliguria:
    - Scanty or insufficient urine output.

• Dysuria:
    - Painful or difficult urination.