Ch. 17 Urinary System

Question 1

Functions of the urinary system:

Answer 1

• Filter salts and waste from the blood
• Helps maintain normal concentrations of electrolytes and water
• Regulates pH and body fluid volume
• Helps control red blood cell production and blood pressure

Question 2

Organs of the urinary system:

Answer 2

• Kidneys (2)— (Functional organ of the urinary system) Filter the blood
• Ureters (2)— (Passageway) Transport urine from the kidneys to bladder
• Urinary bladder (1)— Stores urine
• Urethra (1)— Conveys urine to the outside of the body

Question 3

Kidneys (2)—

Answer 3

(Functional organ of the urinary system) Filter the blood

Question 4

Ureters (2)—

Answer 4

(Passageway) Transport urine from the kidneys to bladder

Question 5

Urinary bladder (1)—

Answer 5

Stores urine

Question 6

Urethra (1)—

Answer 6

Conveys urine to the outside of the body

Question 7

The kidney:

Answer 7

• A reddish brown, bean-shaped organ, 12 cm long
• Enclosed in a tough, fibrous capsule

Question 8

Locations of the kidneys:

Answer 8

• Kidneys are retroperitoneal, behind the (posterior) parietal peritoneum
  - [Parietal peritoneum: Lines the abdominal cavity]
• Lies along the vertebral column, between the 12th thoracic and 3rd lumbar vertebrae
• Right kidney is positioned slightly inferior to the left kidney
  - Because the liver is the largest organ in the abdominal cavity
• Held in place by connective tissue and adipose tissue

Question 9

Location and layers: Kidneys

Answer 9

• Kidneys are located in the retroperitoneum along posterior abdominal wall
• Three layers of supportive tissues around kidney—They are held in place by connective tissue
  - (1) Fibrous Renal Capsule (innermost)
  - (2) Perirenal Fat/Adipose Capsule (middle)
  - (3) Renal Fascia, aka Gerota fascia (outermost)

Question 10

Frontal/Coronal Cross section throughout the kidney:

Answer 10

• Frontal/Coronal Cross section throughout the kidney:
  
  • Renal cortex— Outer area/border of the kidney when you cut inside the kidney
  → Extends inward, dividing the middle portion into triangular areas, this inward extension is called the:
  • Renal column— The inward extension of the renal cortex
  • Renal medulla/pyramids— Triangular areas
  • Renal papillae— Apex of the renal medulla
  → Opens into a cup shaped structure to become:
  • Minor calyx
  → 2-3 Minor calyxes join to form
  • Major calyx
  → Open into a dilated area of the proximal/superior portion of the ureters called the:
  • Renal pelvis (Continuation of the ureters)
  → The urine goes inside, extends downward to become:
  • Ureters

Question 11

Each kidney has 2 major regions:

Answer 11

• Renal medulla:
  - Consists of cone-shaped structures called renal pyramids
  - Renal papillae form tips of pyramids
  - Striated (striped) appearance, due to presence of long, microscopic tubules
• Renal cortex:
  - Surrounds the renal medulla
  - Extensions of the cortex, called renal columns, dip between the renal pyramids
  - Granular appearance, due to presence of tiny, round structures called renal corpuscles, which are part of the functional units of the kidneys, the nephrons

Question 12

Renal medulla:

Answer 12

• Consists of cone-shaped structures called renal pyramids
• Renal papillae form tips of pyramids
• Striated (striped) appearance, due to presence of long, microscopic tubules

Question 13

Renal cortex:

Answer 13

• Surrounds the renal medulla
• Extensions of the cortex, called renal columns, dip between the renal pyramids
• Granular appearance, due to presence of tiny, round structures called renal corpuscles, which are part of the functional units of the kidneys, the nephrons

Question 14

Renal Sinus: (consist of)

Answer 14

• Minor calyces
• Major calyx
• Fat
• Blood vessels
• Nerves and lymphatic vessels

Question 15

Kidney functions:

Answer 15

• Regulate the volume, composition, and pH of body fluids
• Remove metabolic wastes from the blood in the process, forming urine
• Help control the rate of red blood cell formation by secreting the hormone erythropoietin
  
  • Low oxygen levels:
    - Kidneys and liver will release erythropoietin
    - [Erythropoietin: A hormone that RBCs utilize when oxygen levels are low to remain constant due to a negative feedback mechanism]
    - Targets red bone marrow to produce RBCs
• Regulate blood pressure and volume by secreting the enzyme renin
  - [Blood pressure— The pressure of the circulating blood on the wall of arteries]
• Help in activation of vitamin D to form calcitriol, which promotes calcium absorption in the small intestines

Question 16

Renal blood supply:

Answer 16

• The abdominal aorta gives rise to renal arteries, which supply blood to the kidneys
• Renal arteries receive 25% of the cardiac output
  - [Cardiac output— Amount of blood pumped by the heart during left ventricular systole in one minute]
• As renal arteries pass into the kidneys, they branch into successively smaller arteries: segmental arteries, interlobar arteries, arcuate arteries, interlobular arteries, and afferent arterioles, which lead to the nephrons
• Afferent arteriole gives rise to capillary cluster, a glomerulus
  - [Glomerulus: Ball of capillaries]
• Blood not filtered by glomerulus enters efferent arteriole, and then peritubular capillaries
• Venous blood is returned through a series of vessels that correspond to the arterial pathways
• The renal vein then joins the inferior vena cava in the abdominal cavity

Question 17

Nephron:

Answer 17

• Functional unit of the urinary system
• Can produce urine independently
• About one million nephrons per kidney
• Consists of a renal corpuscle and a renal tubule

Question 18

Renal corpuscle:

Answer 18

• Filtration takes place here
  - [Filtration— Water and dissolved material forced through a membrane from high to low pressure]
• Consist of the glomerulus and bowman’s capsule (Together, these are called the renal corpuscle)
• Then it goes into the renal tubule
• Filtration structure in renal cortex, which performs the first step of urine formation
• Consists of cluster of capillaries, the glomerulus, and a bowman’s capsule, a cup-shaped sac that receives filtrate
  - [Glomerulus: Ball of capillaries]
• Glomerular capsule is actually the expanded proximal end of a renal tubule

Question 19

Renal tubule consists of the following parts, in this order:

Answer 19

• Glomerular capsule
• Proximal convoluted tubule
• Loop of henle
• Distal convoluted tubule
• Collecting duct

Question 20

Urine formation involves 3 processes:

Answer 20

• Glomerular filtration
• Tubular reabsorption
• Tubular secretion

Question 21

Glomerular filtration:

Answer 21

• First step of urine formation
• Glomerulus filters water and small substances from blood plasma, and transports it into the glomerular capsule as glomerular filtrate
• Filtrate then moves into the renal tubules
• Produces about 180 liters of fluid per day

Question 22

Tubular reabsorption:

Answer 22

• Process by which useful filtered substances are transported from the filtrate to the blood of the peritubular capillaries
• Most useful substances are returned to blood by this process

Question 23

Tubular secretion:

Answer 23

• Process by which additional wastes from the blood are moved from the peritubular capillaries into the renal tubule

Question 24

Amount of a substance excreted in urine:

Answer 24

Amount filtered by glomerulus
– amount reabsorbed by renal tubule
+ amount secreted by renal tubule

Question 25

End product/Waste of protein metabolism:

Answer 25

• Urea
• Uric acid

Question 26

Ureters:

Answer 26

• Smooth muscles— Tube-like
• Cannot be scanned but pathologies can
• Conveys urine from the kidney to the urinary bladder
• Begins at the funnel-shaped pelvis
• Muscular peristaltic waves transport urine to the urinary bladder
• Wall of the bladder acts as as one-way valve, propelling the urine into the bladder, but preventing it from flowing backward

Question 27

Wall of the ureter is composed of 3 layers:

Answer 27

• Inner mucosa (Transitional epithelium)
• Muscularis
• Outer adventitia