Urinary System Overview Quiz

Study Notes

The urinary system eliminates waste products and toxins from the body by filtering blood plasma and returning water and solutes to the bloodstream.
The system comprises two kidneys, two ureters, a urinary bladder, and a urethra.
Urine flows from each kidney to the ureters, then to the bladder, and finally exits via the urethra.

Identify the anatomy of different urinary organs (kidney, ureter, bladder, urethra).
Describe the position of the kidneys.
Describe the external and internal structure of the kidney.
Identify and describe the key differences between male and female urinary systems.

Kidneys are bean-shaped and lie just above the waist, between the peritoneum and posterior abdominal wall on each side of the vertebral column, at about the level of the first lumbar vertebra (L1).
They are protected by the 11th and 12th ribs.
The right kidney is slightly lower than the left due to the liver's presence on the right side, which compresses the kidney downwards.
The kidney is enclosed by a fibrous capsule (renal capsule), which separates it from the adrenal gland.
The kidney's parenchyma (functional tissue) is divided into the renal cortex and renal medulla.
The renal medulla contains triangular structures called renal pyramids.
The apex of each renal pyramid is a renal papilla.
Urine drainage (in the renal sinus) system includes cup-like structures called minor calyces, which collect urine from the papillary ducts.
Minor calyces empty into major calyces which empty into the renal pelvis, and finally drains into the ureter.
Kidney functions include filtering blood, regulating blood volume, regulating blood pressure (by secreting the enzyme renin), releasing erythropoietin (stimulating red blood cell production), maintaining acid-base balance, and playing a role in vitamin D synthesis.

The nephron is the functional unit of the kidney, with over 1 million nephrons in each kidney.
Each nephron is composed of a renal corpuscle and a renal tubule.
The renal corpuscle contains glomerular capillaries where filtration occurs.
Bowman's capsule is a cup-shaped structure that collects the filtrate.
The renal tubule consists of the proximal convoluted tubule, loop of Henle (descending and ascending limbs), and the distal convoluted tubule.

A renal corpuscle has a glomerulus (a network of capillaries), which is enclosed by Bowman's capsule.
Bowman's capsule is surrounded by a layer of specialized cells called podocytes, creating a filtration barrier.
The glomerulus is highly permeable.
The glomerulus and Bowman's capsule are separated by a basement membrane.

A urinary catheter is a flexible tube inserted into the bladder to drain urine, commonly used for patients unable to urinate on their own, those needing continuous urine output monitoring, or after surgery.
Common catheter types include indwelling (Foley), intermittent (straight), and suprapubic catheters.

The urinary bladder is a distensible, muscular organ shaped like a three-sided pyramid.
The inferior angle of the pyramid is known as the neck.
Its capacity is typically 500-700 ml.
It is located in the pelvic cavity, posterior to the pubic symphysis, anterior to the vagina and inferior to the uterus in females; anterior to the rectum in males.

The urethra is a tube that carries urine from the bladder to the outside of the body.
The male urethra has both urinary and ejaculatory functions
The male urethra is slightly longer (19-20cm).
It has three parts: prostatic, membranous, and penile urethra.
The penile urethra is the narrowest part and opens externally at the urethral meatus.
The female urethra is shorter (approximately 4cm).
It has only urinary functions and opens externally at the external urethral orifice, anterior to the vaginal opening.