14) Urinary System

Question 1

What are the major organs of the urinary system?

Answer 1

 KIDNEY
 URETERS
 BLADDER
 URETHRA

Question 2

What is the main function of the KIDNEY?

Answer 2

 Removal of metabolic wastes & toxins

 Elimination of excess nutrients & excess hormones

 Regulation of blood volume & pressure (Renin)

 Regulation of electrolytes & body pH and Ionic Balance

 Erythropoiesis (Erythropoietin) red blood cell (erythrocyte) production

 Aids in calcium absorption

Question 3

What are the main functions of the UTERERS?

Answer 3

 Carries urine from the kidneys to the bladder. Muscles in the ureter walls continually tighten and relax forcing urine downward, away from the kidneys.

 If urine backs up, or is allowed to stand still, a kidney infection can develop

Question 4

What is the main function of the BLADDER?

Answer 4

 Stores urine, allowing urination to be
infrequent and controlled

 The bladder’s walls relax and expand to store
urine, and contract and flatten to empty urine
through the urethra.

Question 5

What is the main function of the URETHRA?

Answer 5

 Allows urine to pass outside the body

Question 6

Describe the anatomy of the kidney

Answer 6

Surrounded by renal capsule
 tough fibrous dense irregular
connective tissue
 barrier against trauma and spread of
infections

Kidney splits into two regions

• Cortex –outer area, directly below renal capsule, houses filtration structures (nephrons)

 CORTEX contains mainly tubules; but
also RENAL CORPUSCLES

RENAL CORPUSCLES: functions to filter waste from the blood

• Medulla - interior section, houses 6-18 renal pyramids, parallel bundles of collection tubules 6

 MEDULLA is composed loops of Henle, collecting ducts, some tubules

Medulla contains NO CORPUSCLES

Question 8

Each kidney has a capsule and is divided into a ______ and a _______.

Answer 8

cortex
medulla

Question 9

What are loops of Henle?

Answer 9

The loop of Henle is a part of the nephron, the kidney’s filtering unit, that reabsorbs water and salt from the kidney tubules. The loop of Henle’s main function is to concentrate urine and conserve water for the body.

Question 10

What do RENAL CORPUSCLES do?

Answer 10

It’s the blood filtering component of the nephron

filters the wastes

Question 11

Which tubules are big and which are small? and how are they distinguished?

Answer 11

• Largest tubules are the collecting ducts
• Smaller tubules are thick & thin loops of Henle
• Each can be distinguished by the epithelium lining

Question 12

What are the TASKS of the major organs of the urinary system?

Answer 12

Kidneys – clean and filter blood

Ureters – tubes that take urine to bladder

Bladder – stores urine until eliminated

Urethra – removes urine from body

Question 13

What are the RENAL CORPUSCLES components?

Answer 13

Includes the Bowman’s capsule and the Glomerulus

 Filtration of blood is facilitated by
glomerular endothelium

 “Secretes” a filtrate of blood plasma → drains into nearby Proximal Convoluted Tubules (PCT)

Question 14

What are the wall layers of the URETERS?

Answer 14

 Mucosa with transitional epithelium

 Muscularis with two layers of smooth
muscle

 Adventitia, attaches to posterior body wall

Question 15

In the ureters, contractions occur every ___ seconds to force urine toward bladder

Answer 15

30

Question 16

Important facts about urothelium

Renal pelvis & ureter - lined by urothelium (transitional epithelium that has the unique ability to change shape as required)

Answer 16

• Urothelium & loose connective tissue = mucosa of urinary tract
• Urothelium superficially resembles a non-keratinized stratified squamous epithelium

 Note: epithelial cells nearest to the apical (outer/lumenal) surface are not flattened like squamous but rounded & cuboidal in shape

 Some surface cells are bi-nucleated

 5-7 layers of epithelium

Question 17

What are the wall layers of the BLADDER?

Answer 17

 Wall – thick and muscular -folded into rugae when empty (expands)

3 wall layers:

1. Mucosa with transitional epithelium
2. Muscularis with 3 layers of smooth muscle = detrusor muscle (contraction causes expulsion of urine from bladder)

 Detrusor muscle thickened around urethral opening to create the internal urethral sphincter (provides involuntary control over release of
urine)

3. Adventitia, fibrous, anchors bladder to pelvic floor

Question 18

URETHRA characteristics

Answer 18

 Single muscular tube, connects bladder to environment

 Lined with transitional epithelium

 Passes through band of skeletal muscle that forms external urethral sphincter, under voluntary control, relaxation results in micturition

Question 19

The epithelium of the urinary system

Answer 19

 Bowman’s Capsule – simple squamous epith.

 PCT– simple cuboidal epith. with microvilli

 DCT - simple cuboidal epithelium

 Collecting Duct – simple columnar epithelium (predominant type)

 Thick Loops of Henle – simple cuboidal epith.

 Thin Loops of Henle – simple squamous epithelium

 Ureter, Bladder, Urethra – urothelium (transitional epithelium)

Question 20

What hormone is released by the kidneys to help regulate blood pressure?
A) Insulin
B) Renin
C) Epinephrine
D) Cortisol

Answer 20

B) Renin

Question 21

What is the primary function of the kidneys?
A) Production of bile
B) Filtration of blood and removal of waste
C) Regulation of heart rate
D) Regulation of blood glucose levels

Answer 21

B) Filtration of blood and removal of waste

Question 22

Which of the following structures carries urine from the kidney to the bladder?
A) Urethra
B) Ureter
C) Renal pelvis
D) Nephron

Answer 22

B) Ureter

Question 23

Which part of the nephron is primarily responsible for filtering blood?
A) Glomerulus
B) Proximal convoluted tubule
C) Loop of Henle
D) Distal convoluted tubule

Answer 23

A) Glomerulus