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Human Biology > Module 15: The Urinary System > Flashcards

Module 15: The Urinary System Flashcards

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1
Q

Retroperitoneal

A

Behind the parietal peritoneum.

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2
Q

What two serous membranes lubricate the organs so that they experience very little friction?

A

The parietal and visceral peritoneum.

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3
Q

Perirenal

A

A layer of adipose tissue that holds the kidneys firmly in place.

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4
Q

What two regions is the interior of the kidney split into?

A

The outer region, called the cortex, and the inner region, called the medulla.

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5
Q

Where does blood enter the nephron?

A

The renal corpuscle, which is in the cortex of the kidney.

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6
Q

What are the seven functions of the kidneys?

A
  1. Urine formation
  2. pH control
  3. Water regulation
  4. Stimulation of erythropoiesis
  5. Activation of vitamin D
  6. Transport of urine
  7. Storage and release of urine
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7
Q

Juxtaglomerular apparatus

A

A group of cells that regulates the blood pressure.

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8
Q

Erythropoiesis

A

The production of red blood cells.

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9
Q

What happens when cells in the kidneys detect low oxygen?

A

They produce the hormone erythropoietin, which travels via the blood to the bone marrow and signals the red bone marrow to increase red blood cell production.

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10
Q

What are the four steps of nephron function?

A
  1. Filtration
  2. Reabsorption
  3. Secretion
  4. Water reabsorption
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11
Q

Where does filtration in the nephron occur?

A

Within the renal corpuscle. Fluid leaves the blood capillaries, called the glomerulus, and passes through a filtration membrane to enter the lumen of the Bowman’s capsule.

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12
Q

Filtrate

A

Blood plasma minus the proteins, filtered by the nephrons of the kidneys.

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13
Q

How does reabsorption in the nephron work?

A

Reabsorption means moving molecules out of the nephron and back into the blood. As blood passes through the many capillaries running along the nephron, the useful molecules that the blood needs are reabsorbed across the wall of the nephron. This reabsorption is controlled by a series of complex transport processes that ensure that useful molecules are reabsorbed and to their proper levels.

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14
Q

How does secretion in the nephron occur?

A

In the secretion step, certain chemicals still in the blood must be removed from the blood and put into the nephron for excretion in the urine. We don’t want those chemicals in the plasma, so they must be secreted into the nephron.

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15
Q

How does water reabsorption work in the nephron?

A

The processes that occur in the nephron regulate the water volume in the body. The water enters the nephron, and then the blood reabsorbs exactly the amount of water it needs and leaves the rest. The remaining water is the principal component of urine.

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16
Q

Renal blood flow rate

A

The rate at which blood flows through the kidneys ( liter/min).

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17
Q

Name and describe the two layers of the Bowman’s capsule.

A
  1. The outer layer, the parietal layer, is a solid layer composed of simple squamous epithelium.
  2. The inner layer, called the visceral layer, is porous. It is composed of podocytes, which are specialized cells that actually attach to the glomerular capillaries by means of small processes called foot processes.
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18
Q

What is the filtration membrane of the renal corpuscle composed of?

A

The filtration membrane is composed of the porous wall of the glomerular capillaries, the basement membrane of the glomerular capillaries, and the podocytes.

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19
Q

What is the function of podocytes?

A

Since the capillaries are so porous in the renal corpuscle, they need to be held together. The podocytes perform that function by acting like netting.

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20
Q

Glomerular filtration rate

A

The rate at which filtrate is produced in glomerular filtration (125 mL/minute).

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21
Q

What are the two reasons the kidneys filter so much fluid so fast?

A
  1. The filtration membrane is highly permeable, allowing the filtrate to leave the glomerular capillaries quickly.
  2. There is high blood pressure within the capillaries, which helps push the plasma through the filtration membrane.
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22
Q

Why is the pressure in glomerular capillaries high?

A

The efferent arteriole, which carries blood out of the glomerulus, is narrower than the afferent arteriole, which carries blood into the glomerulus. This causes a backup of blood, increasing the pressure of the blood behind it.

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23
Q

What is the relationship between GCP and GFR?

A

There is a direct relationship. When the GCP goes down, the GFR will go down as well. When the GCP increases, the GFR will increase. The rate of plasma filtration in the kidneys is influenced by changes in the glomerular capillary pressure.

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24
Q

What are the two factors that oppose the GCP?

A
  1. Capsular pressure. The Bowman’s capsule pushes back against the glomerulus. This results in capsular pressure, which fights against the GCP, (about 10 mmHg)
  2. Colloid osmotic pressure. The water in the filtrate is attracted back to the higher concentration of proteins. As a result, it crosses the filtration membrane and goes back into the capillaries. This oppose the GCP, which is pushing water out of the capillaries (about 30mmHg).
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25
Q

Peritubular capillaries

A

The capillaries that wrap around the tubules of the nephron. As the filtrate passes through the tubules of the nephron, substances that the blood needs pass across the wall of the tubule and back into the capillaries.

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26
Q

What makes reabsorption efficient?

A

The walls of the nephron tubules are thin and have a lot of surface area with the brush border.

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27
Q

Describe the composition of the proximal tubule wall.

A

The wall is composed of simple cuboidal epithelium. The epithelium must be cuboidal, not squamous, because there must be room for cellular machinery in the epithelium to facilitate the reabsorption.

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28
Q

Where does most of the reabsorption occur?

A

The proximal tubule.

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29
Q

Describe the composition of the loop of Henle.

A

Simple squamous epithelium.

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30
Q

Describe the composition of the distal tubule.

A

Simple cuboidal epithelium.

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31
Q

Describe the composition of the collecting duct.

A

Simple columnar epithelial tissue.

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32
Q

What are the two types of absorption in the tubules of the nephron?

A
  1. Active reabsorption: requires ATP and a carrier.

2. Passive reabsorption: occurs without any cellular energy being expended.

33
Q

What kinds of substances must be actively reabsorbed in the tubules of a nephron?

A

All of the nutrients and minerals that the body needs. Examples are glucose, amino acids, water-soluble vitamins (C and B), and minerals such as sodium ion, potassium ion, and calcium ion.

34
Q

How are proteins actively reabsorbed into the blood?

A

Pinocytosis.

35
Q

Tubular maximum (T-max)

A

The maximum rate of reabsorption by active transport through the nephron tubules.

36
Q

Why is T-max important?

A

This is the way the kidney can control whether or not substances get reabsorbed into the blood and at what level the reabsorption happens.

37
Q

What happens during secretion (during the formation of urine)?

A

Waste products that did not get filtered are specifically sent into the nephron.

38
Q

Where does secretion occur?

A

It mostly occurs in the distal tubule.

39
Q

What are the two major substances that get secreted?

A

Potassium ions (K+) and hydrogen ions (H+).

40
Q

How is the interstitial fluid deep in the kidneys different from the interstitial fluid in most of the body?

A

It is more concentrated. Typical fluid has a solute concentration of 300 mOsm/kg, and the kidney fluid is higher.

41
Q

Why is the concentration of solutes so high in the medulla?

A

There is a high concentration of urea in the interstitial fluid of the medulla.

42
Q

What happens to the filtrate as it travels down the loop of Henle?

A

The descending limb of the loop is permeable to water and solutes, so water gets pulled out of the loop and solutes go into the loop. As the filtrate travels down the loop, then, it becomes more and more concentrated.

43
Q

Vasa recta

A

The blood vessel that reabsorb the water that left the nephron.

44
Q

Since the ascending segment of the loop of Henle is not permeable, what are the only three substances that leave it?

A

Sodium ions, potassium ions, and chloride ions.

45
Q

What happens to the concentration of solutes in the filtrate of the thick ascending limb?

A

It goes down. Ions are actively transported out of the loop of Henle, and (though this is not normal) water molecules cannot follow them. This decreases the concentration of the filtrate.

46
Q

Where is ADH (antidiuretic hormone) produced and controlled?

A

ADH is produced in the posterior pituitary and controlled by the hypothalamus of the brain.

47
Q

When the blood contains too much water, how does ADH production change?

A

ADH production is limited and lots of urine is produced.

48
Q

How does ADH enable the body to conserve or get rid of water, depending on the body’s needs?

A

It makes the distal tubule and collecting duct permeable to water. The more ADH present, the more permeable to water the distal tubule and collecting duct are.

49
Q

How is ADH released?

A

When you are dehydrated, all your cells shrink slightly because they have less water in them. The shrinking of cells in a particular part of the hypothalamus stimulates hypothalamic neurons, whose axons go to the posterior pituitary. This stimulation causes those hypothalamic neurons to release ADH.

50
Q

What are the mucosa of the bladder made of?

A

Transitional stratified epithelium. This means the bladder can stretch without tearing.

51
Q

How does the parasympathetic division of the nervous system interact with the urinary system?

A

When the bladder stretches as it fills with urine, information is sent to the spinal cord, and it is integrated there. Emptying the bladder is part of the rest-repose division of the autonomic nervous system, the parasympathetic division. Parasympathetic impulses contract the smooth muscle in the bladder, and the bladder empties through the urethra.

52
Q

What is the function of the external urethra sphincter?

A

The sphincter is a ring of skeletal muscle around the external end of the urethra. The sphincter is normally contracted, keeping the bladder closed.

53
Q

How do the kidneys affect blood pressure?

A

The volume of blood in the body ultimately determines the blood pressure. In the same way, more fluid in the blood vessels increases blood pressure. Since kidneys determine the amount of water in the blood, they affect the blood pressure.

54
Q

Renin

A

An enzyme that activates angiotensinogen. A drop in blood pressure or a decrease in blood sodium ion levels can be detected in the afferent arteriole by the juxtaglomerular cells, and when these cells detect a change, they respond by releasing renin.

55
Q

Angiotensinogen

A

An inactive protein of the blood that is made in the liver.

56
Q

Angiotensin I

A

The result of the interaction between renin and angiotensinogen. It is a peptide.

57
Q

Angiotensin II

A

The activated form of angiotensin I. This is an active substance and affects the blood pressure

58
Q

What are the four things angiotensin II does?

A
  1. It increases vasoconstriction throughout the body.
  2. It makes a person thirsty.
  3. It increases salt appetite.
  4. It causes the release of aldosterone.
59
Q

Aldosterone

A

A hormone produced by the adrenal cortex that increases sodium ion reabsorption in the kidneys.

60
Q

Atrial natriuretic hormone

A

A hormone that lowers the blood pressure and comes from the atria of the heart. When blood volume is high, the excess blood actually stretches the two atria. This triggers the release of atrial natriuretic hormone, which inhibits the nephrons from reabsorbing ions. That decreases the amount of water reabsorbed, lowering blood pressure.

61
Q

Acidosis

A

A condition in which the pH of the blood drops from 7.35 down toward 7.0.

62
Q

What are the effects of acidosis?

A

It decreases nervous function, ultimately leading to coma and death.

63
Q

Alkalosis

A

The condition in which the pH of the blood rises above 7.45.

64
Q

What are the effects of alkalosis?

A

It causes over-excitation of the nervous system, which can lead to convulsions. Convulsions are uncontrolled skeletal muscle contractions that occur when the overly excited nervous system stimulates such activity.

65
Q

What change in blood pH does gastric vomiting lead to?

A

When you vomit, you lose a lot of stomach acid. This can lead to alkalosis because losing acid will raise pH.

66
Q

What change in blood pH occurs with diarrhea?

A

In diarrhea, you lose bicarbonate from the intestine. Since bicarbonate is a basic substance, severe diarrhea can lead to acidosis.

67
Q

How does the blood pH change with intestinal vomiting?

A

Intestinal vomiting leads to loss of bicarbonate because you lose bile and pancreatic juice which contain bicarbonate, which is basic. This leads to acidosis.

68
Q

How does kidney dysfunction change the blood pH?

A

The kidneys control the amount of H+ in the blood. This can cause the pH to rise or drop, depending on the diet. If the diet is high in acid, it will lead to acidosis because the kidney is not getting rid of the acid.

69
Q

How does respiratory dysfunction lead to imbalances in the blood pH?

A

The respiratory system exerts control over the pH of the blood because of its control of CO2.

70
Q

What three ways does the body control the acid-base balance?

A
  1. Buffer systems
  2. Through the respiratory system
  3. The actions of the kidneys. Kidneys secrete H+ into the filtrate. The more H+ they secrete, the higher blood pH becomes, and the lower the urine pH. The opposite is also true.
71
Q

Buffer system

A

A mixture of an acid and a base that resists changes in pH.

72
Q

Why does a buffer system resist changes in pH?

A

In order to dramatically change the pH of a solution, you need to alter the H+ concentration. A buffer solution contains a weak base and a weak acid. That way, if an acid is added, the weak base neutralizes the acid before it can lower the pH much. If a base is added, the weak acid neutralizes it before it can raise the pH much.

73
Q

What are the three buffers in the body?

A
  1. The bicarbonate buffer system.
  2. The phosphate buffer system.
  3. The protein buffer system.
74
Q

Describe the bicarbonate buffer system.

A

The system is composed of carbonic acid and the bicarbonate ion. This buffer is found in the extracellular fluids. The carbonic acid neutralizes bases that enter the extracellular fluids, while the bicarbonate ions neutralize the acids that are found in the fluids.

75
Q

Describe the phosphate buffer system.

A

The system is composed of dihydrogen phosphate (the weak acid) and monohydrogen phosphate (the weak base). This system is found in two places: Inside the cells because phosphate is a common substance inside the cells, and in the nephron tubules.

76
Q

Describe the protein buffer system.

A

This system is found inside the cells and in blood plasma. Proteins are single-molecule buffers because they are composed of amino acids. An amino acid is a molecule that has both a weak acid and a weak base.

77
Q

When the cells of the distal tubules of the nephrons detect a decrease in pH of the interstitial fluid (which reflects blood pH), what happens?

A

They increase the amount of H+ that they secrete into the urine.

78
Q

What triggers an increase in the reabsorption of the bicarbonate ion?

A

A decrease in blood pH. The bicarbonate ion is a base. If more base is reabsorbed into the blood, the pH will go up.

Human Biology (16 decks)

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