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Human Biology, 13th Edition - Sylvia S. Mader > Ch 10 - Urinary System > Flashcards

Ch 10 - Urinary System Flashcards

1
Q

What is the primary nitrogenous waste product of amino acid metabolism?

A

Urea

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2
Q

What is urea composed of?

A

In the liver, the breakdown of amino acids releases ammonia, a toxic compound. The liver combines ammonia with carbon dioxide to produce urea, a less harmful substance

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3
Q

What is uremia?

A

A condition that causes cardiac arrhythmia, vomiting, and respiratory problems due to high levels of urea in the blood

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4
Q

What is creatine and where is it created?

A

A waste product from the breakdown of creatine phosphate, a high-energy reserve molecule in muscles. The kidneys secrete creatine

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5
Q

What is uric acid?

A

The kidneys secrete uric acid. It’s formed from the metabolic processing of nucleotides, such as adenine and thymine. If too much is present in the blood, crystals form and precipitate out.

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6
Q

What is gout?

A

Sometimes there’s too much uric acid in the blood, and crystals form that collect in the joints. Painful.

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7
Q

What are the main functions of the urinary system?

A
  1. Excretion of metabolic wastes
  2. Maintenance of water-salt balance
  3. Maintenance of acid-base balance
  4. Secretion of hormones
  5. Vitamin D synthesis
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8
Q

How do the kidneys maintain the water-salt balance, and why is that important?

A

Salts regulate osmosis, and thus blood pressure, in the urinary system. By regulating the concentration of certain ions, namely sodium (Na+) and potassium (K+) in the blood, the kidneys regulate blood pressure. If there are a lot of salts in the blood, blood pressure goes up because salts attract water, so more water enters the blood stream.

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9
Q

How do the kidneys regulate the acid-base balance of the blood? What are two other ways that our bodies do this? Which has the biggest effect?

A
  1. The kidneys excrete hydrogen ions (H+) and reabsorb bicarbonate ions (HCO3-) as needed to keep blood pH at 7.4
  2. Chemical buffers: These are chemicals that can take up excess H+ or excess hydroxide ions (OH-). For example, bicarbonate ions (HCO3-) creates H2CO3 when H+ is added
  3. Respiratory center in the medulla oblongata increases the breathing rate if the hydrogen ion concentration of the blood rises.

H+ + HCO3- ——> H2CO3 —–> H2O + CO2

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10
Q

What are different types of chemical buffers?

A
  1. Bicarbonate ions (HCO3-) —-> (i.e. if you add H+ to the blood, this is the reaction that occurs:

H+ + HCO3- ——> H2CO3 (later this can be broken down into H2O and CO2 to be exhaled in the lungs

  1. Once created, H2CO3 actually acts as another buffer
  2. Phosphate buffers hydrogen ions in urine
  3. Ammonia (NH3) buffers and removes hydrogen ions in urine

H+ + NH3 —–> NH4+

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11
Q

What are the organs of the urinary system?

A

Kidneys
Ureters
Urinary bladder
Urethra

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12
Q

What covers the kidneys?

A

A tough capsule of fibrous connective tissue called a renal capsule. Masses of adipose tissue adhere to each kidney

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13
Q

What are the vessels entering and exiting the kidney called?

A 
Entering = renal artery
Exiting = renal vein
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14
Q

What are the walls of the ureters composed of?

A

Three layers:

  1. An inner mucosa
  2. Smooth muscle
  3. Outer fibrous coat of connective tissue
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15
Q

How is the bladder wall expandable?

A

It contains of middle layer of circular fibers of smooth muscle and two layers of longitudinal smooth muscle. Folds in the mucosa called rugae disappear as the bladder enlarges. A layer of transitional epithelium enables the bladder to stretch.

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16
Q

What’s the max capacity of the bladder?

A

Between 700 and 800 mL

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17
Q

Which enzyme produced by the kidney stimulates the release of a hormone from the adrenal glands? Which hormone is secreted?

A

Renin is the enzyme that stimulates the release of aldosterone

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18
Q

What’s another word for urination?

A

Micturition

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19
Q

What’s different about a female urethra vs. male urethra?

A

In females, the urethra is about 4cm and in males it’s about 20 cm. The urethra of a male is encircled with the prostate gland.

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20
Q

What is the role of the prostate gland?

A

It produces and adds a fluid to semen as semen passes through the urethra.

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21
Q

What is the structure of the kidney?

A

Outermost layer = renal cortex
Middle layer = renal medulla
Innermost layer = renal pelvis

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22
Q

What is contained in the renal cortex and the renal medulla?

A

Renal cortex: Nephrons, proximal & distal convoluted tubule, peritubular capillary network, beginning of the collecting duct

Renal medulla: Loop of nephron (descending and ascending limb), peritubular capillary network, the collecting duct, renal pyramids

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23
Q

Where do the collecting ducts empty into? What is continuous with that cavity?

A

The renal pelvis, which is continuous with the ureters

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24
Q

Where does filtration first occur in the kidneys?

A

In the glomerular capsule/the glomerulus (a knot of capillaries)

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25
Q

Via which vessels does blood travel to and from the glomerular capsule?

A

Afferent arteriole = going into the glomerulus
Efferent arteriole = leaving the glomerulus
Both are arterioles because it’s oxygenated blood, just filtered

26
Q

When molecules get reabsorbed within the nephron, where are they reabsorbed?

A

The peritubular capillary network

27
Q

What are other names for the loop of nephron and the glomerular capsule?

A

Loop of nephron = loop of Henle

Glomerular capsule = Bowman’s capsule

28
Q

What gets absorbed in the glomerular capsule? What doesn’t get absorbed? Where do the non-absorbed elements go?

A 
Filterable:
Water
Nitrogenous wastes (urea, uric acid)
Nutrients (glucose, amino acids)
Salts (ions)

Non-filterable:
Formed elements (blood cells & platelets)
Plasma proteins
(These elements leave via the efferent arteriole)

29
Q

How does osmolarity affect water absorption?

A

If the osmolarity of the blood is high, water will diffuse into the blood. Osmolarity of the blood is high when there are a lot of salts in the blood

30
Q

What gets absorbed in the proximal convoluted tubule?

A

Most H2O
Nutrients
Required salts (ions)

31
Q

In which part of the loop of nephron does water get reabsorbed? What about salts?

A

Water is reabsorbed in the descending limb to make the medullary less salty and salts are reabsorbed in the ascending limb

32
Q

What happens in the distal convoluted tubule?

A

Ion exchange. More reabsorption of nutrients and water

33
Q

Under what conditions will H2O leave the collecting duct for absorption?

A

If the collecting duct is very porous (has aquaporins) then more H2O will be absorbed. ADH and ANH hormones cause this to be porous or not.

34
Q

What is glomerular filtrate?

A

The filterable blood components after being filtered in the glomerulus

35
Q

How much water per day do the kidneys filter?

A

180 liters/day

36
Q

What are symport and antiport?

A

Symport = When the movement of sodium across membranes (to be absorbed) is couple to the movement of larger solutes, such as glucose and amino acids. Both solutes are being moved in the same direction.

Antiport = An antiport protein moves Na+ ions into the cell, while transporting H+ ions out of the cell. They go in opposite directions. As sodium ions move, chloride ions (Cl-) follow passively. NaCl increases the osmolarity of the blood. Removing H+ ions from the cell reduces the acidity of blood.

37
Q

In which part of the nephron do nutrients like glucose and amino acids primarily get absorbed? How is this a selective process?

A

The proximal convoluted tubules. It’s selective because only molecules recognized by carrier proteins are actively reabsorbed. For example, glucose.

38
Q

What happens in diabetes mellitus when the liver and muscles fail to store glucose as glycogen?

A

Blood glucose level is above normal, and glucose appears in the urine. The presence of excess glucose in the filtrate raises its osmolarity, and thus less water is reabsorbed into the peritubular capillary network. These patients frequently urinate and are thirsty when their diabetes isn’t treated.

39
Q

What is tubular secretion?

A

A second way by which substances are removed from the blood and added to the tubular fluid. H+, creatinine and drugs like penicillin are some substances moved by active transport from blood into the kidney tubule.

40
Q

What do sweat glands excrete?

A

Water, salt and some urea

41
Q

What are aquaporins?

A

Water channels within a plasma membrane protein where water is able to pass through during reabsorption.

42
Q

What is aldosterone?

A

A hormone excreted by the adrenal glands, which sit atop the kidneys. This hormone promotes ion exchange at the distal convoluted tubule. Potassium ions (K+) are excreted, and Na+ is reabsorbed into the blood.

Aldosterone secretion increases blood pressure by increasing reabsorption of ions, and thus water.

43
Q

What is the juxtaglomerular apparatus, and why is this important?

A

It’s the region of contact between the afferent arteriole and the distal convoluted tubule. When blood volume (and therefore, blood pressure) falls too low for filtration to occur, the juxtaglomerular apparatus can respond to the decrease by secreting renin.

44
Q

What is renin? What role does it play?

A

Renin is an enzyme that leads to secretion of aldosterone by the adrenal glands.

Remember: Aldosterone secretion increases blood pressure by increasing reabsorption of ions, and thus water.

45
Q

What is ADH? (Hint* the AD stands for antidiuretic, not diuretic) Where is it produced? What causes it to be secreted?

A

Antidiuretic hormone (ADH) is produced in the hypothalamus and secreted by the pituitary gland based on the osmolarity of the blood. It helps us retain water when we haven’t been hydrating a lot throughout the day by moving water from the distal convoluted tubule and the collecting duct into the blood.

  1. Osmolarity of the blood is very low
  2. ADH is secreted by pituitary gland
  3. Aquaporins open
  4. Salt & thus H2O is absorbed
  5. Blood pressure increases, allowing exchange of nutrients/gases/H2O to continue taking place
46
Q

What is ANH? Where is it produced? What causes it to be secreted? Hint A = atrial

A

Atrial natriuretic hormone (ANH) is a hormone secreted by the atria of the heart when cardiac cells are stretched due to increased blood volume. ANH inhibits renin and aldosterone secretion so that water will not be absorbed, but rather will be excreted along with salts.

  1. Blood pressure is very high due to water and salt retention
  2. ANH is secreted by the atria of the heart
  3. Renin decreases, thereby decreasing aldosterone secretion
  4. Salt and water reabsorption decreases
  5. Blood pressure decreases
47
Q

How do ADH and ANH affect water absorption? How do diuretics affect this?

A 
ADH = increases H2O absorption
ANH = decreases H2O absorption

Alcohol, coffee and other diuretics inhibit ADH from working.

48
Q

What affect to hydrogen ions have on the acid-base composition of the blood?

A

Hydrogen ions make the blood more acidic.

49
Q

As we go deeper into the medulla via the loop of nephron or the collecting duct, what happens to the osmolarity of the medulla?

A

Osmolarity increases the further we go into the medulla due to the increasing concentration of salt. Thus, water continues being absorbed until the end/bottom of the loop

50
Q

Why is water reabsorbed in the descending limb of the loop of nephron but not the ascending?

A

The ascending limb doesn’t contain aquaporins, and thus water cannot pass through these channels. The ascending limb is optimized for ion/salt exchange, and its purpose is to establish the solute concentration gradient.

51
Q

Under what circumstances will water be reabsorbed in the collecting duct?

A

If aquaporins are open, H2O will be reabsorbed. Aquaporins are controlled by ADH

52
Q

Why is maintaining blood pressure important for the urinary system?

A

Without adequate blood pressure, exchange across capillary walls cannot take place, nor is glomerular filtration possible in the kidneys.

53
Q

What is alkalosis? Acidosis?

A

Alkalosis = if the blood pH increases above our optimal upper level of 7.45

Acidosis = if the blood pH decreases below our optimal lower level of 7.35

The optimal pH range for enzymes to function properly is 7.35-7.45

54
Q

What are chemical buffers?

A

These are chemicals that can take up excess H+ or excess hydroxide ions (OH-). For example, bicarbonate ions (HCO3-) creates H2CO3 when H+ is added

55
Q

How does the kidney respond when blood oxygen is low?

A

It secretes EPO = erythropoietin, which increases red blood cell synthesis by stem cells in the bone marrow

56
Q

What is an infection called that’s located in the urethra?

A

Urethritis

57
Q

What is an infection called that’s located in the urinary bladder?

A

Cystitis

58
Q

What is an infection called that’s located in the kidneys?

A

Pyelonephritis

59
Q

What are kidney stones?

A 
Hard granules make of calcium, phosphate, uric acid and protein. They can block the renal pelvis or ureter and pressure can build up and destroy the nephrons. Kidney stones can be caused by:
UTIs
Enlarged prostate glands
pH imbalances
Excessive calcium intake
60
Q

What is uremia?

A

The accumulation of urea and other waste substances in the blood

61
Q

What is of greater concern than the build-up of waste substances in the blood?

A

Edema, water and salt retention/accumulation in the body tissues. An imbalance in the ionic composition of body fluids can lead to loss of consciousness and heart failure

62
Q

What is hemodialysis?

A

Using either an artificial kidney or continuous ambulatory peritoneal dialysis (CAPD) in patients with renal failure. In a dialysate, substances more concentrated in the blood diffuse into the dialysate, and substances more concentrated in the dialysate diffuse into the blood. In CAPD, a fresh amount of dialysate is introduced directly into the abdominal cavity from a bag that’s temporarily attached to a permanently implanted plastic tube.

Human Biology, 13th Edition - Sylvia S. Mader (16 decks)

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