Anatomy and Physiology of Urinary System: A Comprehensive Overview

Running head: BIOLOGY
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BIOLOGY1
Introduction- Anatomy refers to the study of the different body parts and the
relationship between them, which is in contrast to physiology that encompasses exploration
of the function of the body parts. All systems located in the body are interconnected and any
change in one creates mild or devastating effect on another. Hence, the understanding of
anatomy and physiology is imperative to understand the multifaceted nature of the human
body.
Urinary system- It is also referred to as the renal system and comprises of the kidneys,
urethra, ureter, and urinary bladder. The main function of this system is elimination of
nitrogenous waste products from the body, with the aim of controlling blood pressure and
volume, pH, and electrolyte balance. Bean shaped kidneys are present at the back of
abdominal wall and filter the blood that is sent by renal arteries, thus removing unwanted
substances. From the kidneys, the urine moves to the urinary bladder through ureter. Two
ureters located on each side are thin and long tubes comprising of smooth muscles and they
push the urine downwards. The urinary bladder acts as a temporary reservoir and contains
detrusor muscle and different folds called rugae. The urethra acts as the passage of urine
outside the human body (Rehfeld, Nylander & Karnov, 2017). The mouth of the urethra is
guarded by sphincter muscles which when relaxed, help in urine expulsion or micturition.
The chief functions of the urinary system are to control blood composition and volume,
regulate blood pressure, maintain homeostasis of blood, help in red blood cell production,
facilitate synthesis of calcitrol (vitamin D active form), and storage of uric acid and urea.
Major factors influencing fluid and electrolyte balance- Reabsorption of sodium
occurs from the renal filtrate, in addition to the excretion of potassium to the filtrate that is
present in the renal collecting tubule. Two hormones play an important role in maintaining
the level of electrolytes namely, aldosterone and angiotensin II. Aldosterone increases
potassium excretion and sodium reabsorption in distal tubule. Increase in potassium or