Urinary

Question 1

Two fluid compartments in humans

Answer 1

• Inside the cells (Intracellular; ICF)
• Outside the cells (Extracellular; ECF)
  - Interstitial Fluid
  - Plasma
  - Other (Lymph, CSF, Mucus)

Question 2

How do we obtain water?

Answer 2

• Ingested in solids and liquids
• Metabolically derived
• Thirst influences intake of water

Question 3

How do we lose water?

Answer 3

• Excretion in urine
• Excess water and excess or harmful solutes removed
• Evaporation from the lungs and skin
• Sweating
• In feces

Question 4

Kidney functions

Answer 4

• Remove metabolic wastes from the blood
• Adjust fluid balance in the body
  - Water-Salt balance
  - Acid-Base balance
• Horomone secretion
  
  • Produce erythropoietin
  • Produce renin
  • Converts vitamin D to a form that facilitates calcium absorption and blood calcium levels (Calcitriol)

Question 5

How do the kidneys remove metabolic wastes

Answer 5

• CO2: major metabolic waste; exhaled in respiratory system
• Breakdown of protein produces wastes including:
  - Ammonia (toxic) converted to urea (in Liver); half is reabsorbed in the kidney
  - Creatinine made by muscle cells from the breakdown of creatine phosphate
• Breakdown of nucleic acid produces uric acid
• Kidneys maintain the electrolytic balance of ions

Question 6

Maintenance of water-salt and acid-base balance

Answer 6

• Both are homeostatic mechanisms
• Water-salt balance helps to maintain blood pressure
• Excretes hydrogen ions and reabsorbing bicarbonate ions this maintains acid-base balance (blood pH ~7.4)

Question 7

Kidneys (filtration)

Answer 7

• Pair of bean-shaped organs
• Outer cortex
• Inner medulla
• Outer covering: renal capsule
• Central cavity: renal pelvis

Question 8

Urine storage and excretion

Answer 8

• Pair of ureters
• Urinary bladder
• Urethra

Question 9

Renal Capsule

Answer 9

Tough outer covering of the kidneys

Question 10

Hilus

Answer 10

A large renal artery enters and similarly large renal vein exits the kidney at the hilus and the kidney’s nerves and lymphatic vessels and ureters pass through here too.

Question 11

renal pyramids

Answer 11

cone-shaped structures formed from an accumulation of collecting ducts filled with urine

Question 12

renal pelvis

Answer 12

adjacent to the hilus, is where the formed urine is collected and passed to the ureters

Question 13

nephron

Answer 13

responsible for filtering a portion of the blood that passes through the kidney

Question 14

glomerulus

Answer 14

• is a knotted vessel at the beginning of each nephron
• It is formed from an incoming arteriole
• glomerular capsule (also called Bowman’s capsule) surrounds the glomerulus

Question 15

peritubular capillaries

Answer 15

• The blood vessel leaving each nephron then breaks into peritubular capillaries
• Wind around the entire nephron before collecting into venules and eventually the renal vein
• This capillary bed surrounds the nephron
• It is here that the urinary and cardiovascular systems are linked

Question 16

The nephron’s tubule has three sections

Answer 16

• The proximal convoluted tubule (PCT)
• A loop of Henle (also called the loop of nephron)
• A distal convoluted tubule (DCT) connected to a collecting duct
• The tubule that extends from the glomerular capsule is the proximal convoluted tubule

Question 17

collecting duct

Answer 17

• gathers newly formed urine from a series of nephrons and drains it to the renal pelvis

Question 18

Steps to Urine Formation and locations

Answer 18

• Filtration - occurs at the glomerular capsule
• Reabsorption - occurs all along the tubular part
• Secretion - occurs at the distal tubule

Question 19

Th three criteria that must be met for Glomerular filtration to occur.

Answer 19

• the first step in urine formation
• Three criteria must be met in order to filter blood plasma through the glomerulus
  - Blood pressure must be high enough to force plasma out of the glomerular vessel walls
  - The fluid already in the glomerulus must have a low enough pressure to allow more fluid to be forced into the nephron tubules
  - The osmotic pressure of blood in the peritubular capillaries must be high enough to draw water back into the capillaries from the nephron tubule
  - (If these conditions are not met, the nephron cannot filter the blood, and the urinary system will fail)

Question 20

Glomerular Filtration

Answer 20

• Glomerular blood pressure is higher than systolic blood pressure
  - This is caused by the kinking and twisting of the glomerular vessels
  - The incoming afferent arterioles have a larger diameter than the outgoing efferent arterioles
  - This increases pressure in the glomerulus by creating back pressure
  - The total pressure on the blood forces most of the fluid into the capsule
• To filter the blood, the blood pressure must overcome the pressure of the fluid already in the capsule (capsular pressure) as well as the osmotic pressure of the blood itself
  - If the systolic pressure drops below 60 millimeters Hg, blood in the glomerulus will not be forced through the glomerular wall
  - Because glomerular pressure will not rise high enough to force plasma from the blood vessels