Urinary system 3

Question 1

What are the three coats of the urinary bladder?

Answer 1

• Outer serous coat (peritoneum covering the superior surface)
• Middle muscular coat (three layers of muscle fibers: inner and outer longitudinal, and middle circular)
• Inner mucous coat (pale pink, continuation of the mucus membrane lining the ureter and urethra, composed of transitional epithelium)

Question 2

What forms the internal urethral sphincter?

Answer 2

• The circular fibers of the middle muscular coat form a thickened band around the urethral outlet, creating the internal urethral sphincter.

Question 3

What is the blood supply to the urinary bladder?

Answer 3

The internal iliac artery gives rise to several branches that supply the urinary bladder, including:

• Superior vesical artery: Supplies the upper part of the bladder.
• Middle vesical artery: Supplies the middle part of the bladder.
• Inferior vesical artery: Supplies the lower part of the bladder and the prostate gland in males.
• In females, the inferior vesical artery is replaced by the uterine artery and the vaginal artery.

Question 4

What are the two muscular sphincters surrounding the urethra?

Answer 4

• Internal urethral sphincter (involuntary smooth detrusor muscle, superior)
• External urethral sphincter (voluntary skeletal muscle fiber, inferior)

Question 5

What is the structure and function of the female urethra?

Answer 5

• The female urethra is a straight tubular organ about 4 cm long, emptying urine through the urethral orifice into the vestibule between the labia minora.
• It has a single function of transporting urine to the exterior.

Question 6

What are the three coats of the female urethra?

Answer 6

• Muscular coat (continuation of the urinary bladder, surrounded by the external urethral sphincter)
• Thin layer of spongy tissue (contains a plexus of veins)
• Inner layer of mucous membrane (composed of transitional epithelium)

Question 7

What are the functions of the male urethra?

Answer 7

The male urethra functions in both the urinary system (urine flow) and the reproductive system (semen flow).

Question 8

How long is the male urethra and what are its three parts?

Answer 8

1. Prostatic urethra (about 2.5 cm long, passes through the prostate gland)
2. Membranous urethra (shortest and narrowest part, about 0.5 cm long, extends from the prostate gland to the bulb of the penis)
3. Spongy urethra (longest part, about 15 cm long, situated within the corpus spongiosum of the penis, terminates at the external urethral orifice)

Question 9

What are the three processes involved in urine formation? A: The three processes involved in urine formation are:

Answer 9

Simple filtration
Selective reabsorption
Secretion

Question 9

What are the main functions of the kidneys?

Answer 9

1. Remove waste products of protein metabolism (e.g., urea, creatinine)
2. Regulate the volume and composition of extracellular fluid
3. Play a part in regulating the production of red blood corpuscles
4. Maintain normal blood pressure

Question 10

simple\glomerular filtration

Answer 10

• Blood is filtered through the glomerulus, a network of capillaries within the nephron.
• This process separates the smaller molecules in the blood, such as water, ions, glucose, amino acids, and urea, from the larger molecules, such as proteins and red blood cells. The filtered fluid is called glomerular filtrate.

Question 11

Tubular or selective reabsorption

Answer 11

• As the glomerular filtrate passes through the tubules of the nephron, many of the useful substances are reabsorbed back into the bloodstream.
• This includes water, glucose, amino acids, ions, and other essential substances.
• The reabsorption process is regulated by hormones such as antidiuretic hormone (ADH) and aldosterone.

Question 12

Tubular secretion

Answer 12

• Some substances, such as hydrogen ions, potassium ions, and certain drugs, are secreted from the blood into the tubules to be excreted in the urine.
• This process helps to maintain the body’s acid-base balance and eliminate waste products.

Question 13

Micturition in babies

Answer 13

• The process of urination in a baby, also known as micturition, is primarily an involuntary reflex controlled by the peripheral nervous system (PNS).
• Due to the underdeveloped central nervous system (CNS) in infants, they cannot yet consciously control their bladder.
• As the urinary bladder fills with urine, stretch receptors in its wall are stimulated, sending signals to the micturition center in the spinal cord.
• This triggers an involuntary response: the detrusor muscle (which contracts the bladder) contracts while the internal sphincter (which controls the flow of urine) relaxes, resulting in urination.

Question 14

micturition in adults

Answer 14

• Voluntary contraction of the external urethral sphincter muscle and
  micturition reflex from midbrain and cerebral cortex will inhibit
  urination.
• However, following the decision to urinate, the external urethral
  sphincter via the pudental nerve is relaxed by impulse from the pons
  and hypothalamus.
• The detrusor muscle contracts and internal urethral sphincter relaxes
  expelling urine through the urethra.
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