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A & P Lecture: Dr. Shellhammer > Urinary System > Flashcards

Urinary System Flashcards

1
Q

What kind of pressure causes filtration in nephrons?

A

Net Filtration Pressure: blood pressure in glomerular capillaries

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2
Q

What kinds of pressure oppose glomerular filtration? What is there relationship to glomerular filtration?

A
  1. Blood colloid osmotic pressure
  2. Glomerular capsule pressure

As they increase, glomerular filtration increases

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3
Q

What is glomerular capsule pressure due to?

A

due to fluid already in the capsular space and renal tubule

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4
Q

Net filtration Pressure = ?

A

Net filtration pressure = glomerular capillary blood pressure - (blood colloidal osmotic pressure + glomerular capsule pressure.

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5
Q

What is the relationship of size between efferent arteriole and afferent arteriole? How do changes in BP affect the arterioles?

A

Efferent arterioles have a smaller diameter than afferent arterioles. This helps raise BP in glomerular capillaries. Slight Changes in BP do not affect arterioles because they can can keep a steady net filtration pressure to maintain normal filtration

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6
Q

How does constriction of afferent and efferent arterioles affect net filtration pressure?

A

constriction of affernt arteriole decreases blood flow into glomerulus and decreases net filtration pressure.

Constriction of efferent arteriole slows outflow of blood and increases net filtration pressure

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7
Q

What does GFR stand for?

A

Glomerular Filtration Rate: amount of filtrate that forms in both kidneys every minute

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8
Q

Why is a constant GFR important?

A

Kidneys need constant GFR to adequatly excrete the correct amount of waste.

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9
Q

What does a High GFR mean?

A

High GFR–> needed substances are unable to be reabsorbed because they pass so quickly through renal tubules, substances exit through urine

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10
Q

What does a low GFR mean?

A

Low GFR–> almost all filtrate being reabsorbed, and waste products not excreted adequatly.

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11
Q

What does ANP stand for?

A

Atrial natriuretic peptide: a hormone that promotes loss of sodium ions and water in urine bc it increases glomerular filtration rate.

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12
Q

What triggers ANP release?

A

If blood volume increases heart is stretched which triggers ANP release so that kidneys increase loss of sodium ions and water in urine -> reduces blood volume back to normal.

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13
Q

When neurons of blood vessels, specifically kidneys, are active what do they cause concerning diameter of vessel? and at rest?

A

(neurons supplied by symathetic and autonomic nervous system)

Active neurons: cause vasoconstriction.

At rest neurons: Afferent and efferent arterioles are dilated

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14
Q

With greater sympathetic stimulation, what happens to arterioles of kidneys?

A

(during exercise of hemorrhage)

Afferent arterioles are constricted more than efferent arterioles. so blood flow into glomerular capillaries is decreased

–>net filtration pressure decreases

–>GFR drops

–>Urine output is reduced so that blood flow to other body tissues is increased.

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15
Q

About how much water is reabsorbed as tubular fluid flows along the collecting duct?

A

about 99% is reabsorbed. About 1% of water leaves the body as urine.

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16
Q

How is tubular reabsorption carried out?

A
  • By Epithelial cells along renal tubules and collecting ducts
  • passive reabsorbtion by diffusion
  • or active transport reabsorption
17
Q

How does reabsorption of solutes promote reabsorption of water?

A

Solutes move into peritubular capillaries and solute concentration in tubules is decreased. Water then moves by osmosis into higher concentration of solutes in peritubular capillaries. Cells near proximal convoluted tubule regulate reabsorption to maintain level balances of water and selected ions.

18
Q

How does tubular secretion work between tubule cells and tubular fluid?

A

Passive Diffusion and active transport processes.

19
Q

What are secreted substances of tubular secretion?

A

Hydrogen ions

ammonia & urea (from amino acid breakdown)

uric acid from nucleic acid breakdown

bilirubin (from HGB breakdown)

creatinine (a waste from creatine phosphate in muscle cells)

drugs (like PCN)

20
Q

How are Ammonia & urea secreted from the body?

A
  • Ammonia= nitrogen containing poisonous waste product that is produced when amino groups are removed from amino acids.
  • Liver cells convert most ammonia to urea, a less toxic compound.
  • Both filtered at glomerulus and secreted into tubular fluof
21
Q

What is Tubular Fluid?

A

fluid in the proximal convoluted tubule

22
Q

How is potassium regulated in the body?

A
  • Excess potassium ions are secreted via tubular secretion through urine. Secretion varies based on dietary intake of potassium to maintain K+ stability in body
  • Aldosterone-stimulated secretion
    • major regulator of blood K+ level.
  • (elevated K can cause disturbances in heart rhythm)
23
Q

How does Tubular secretion help control blood pH?

A

To eliminate acids, cells of renal tubules secrete Hydrogen ions into tubular fluid. Because of the H+ secretions urine is usually acidic.

24
Q

Hormonal Regulation in Kidneys affect which ions?

A

Na+, Cl-, Ca2+, and K+

25
Q

What are 4 hormones that regulate ion reabsorption and secretion in the urinary system?

A
  1. Angiotensin II
  2. Aldosterone
  3. Atrial Natriuretic peptide (ANP)
  4. Antidiuretic hormone (ADH)
26
Q

What is the role of Angiotensin II in the urinary system?

A
  • Enhances Na+ and Cl- reabsorption in the proximal convoluted tubules.
  • Stimulates adrenal cortex to release aldosterone
27
Q

What is the role of Aldosterone in the urinary system?

A
  • triggered by angiotensin II
  • stimulates tubule cells at end of distal covoluted tubule and in collecting duct to reabsorb more Na+ and Cl- and secrete more K+
  • When Na and CL reabsorbtion increases, more water is reabsorbed by osmosis
  • Major regulator of K levels
28
Q

What is the role of ANP is the urinary system?

A
  • increases glomerular filtration rate
  • As GFR increases Na, CL, and water reabsorption decrease so more water and salt are lost in the urine…this eventually lowers blood volume.
29
Q

What is the role of ADH in the urinary system?

A

ADH= antidiuretic hormone. Operated by negative feedback.

30
Q

When and how is ADH secreted?

A

Secreted when water in blood decreases or there is a decrease in blood volume.

Release by posterior pituitary stimulated by osmoreceptors in hypothalamus when water in blood concentration decreases.

31
Q

How does ADH work?

A

Cells in Distal covoluted tubule and in the collecting duct become more permeable to water because proteins are inserted into tubule cell plasma membranes.

water molecules move from the tubular fluid into the cells, Water reabsorption increases and there is a increase in blood water concentration

32
Q

What is a Diuretic?

A

Substances that slow reabsorption of water by the kidneys and cause diuresis.

Elevated urine flow rate occurs. and Na+ reabsoption in inhibited.

33
Q

What is PTH? When is it stimulated?

A

Parathyroid Hormone.

Increase absorption of Ca2+

Stimulated when there is a low level of Ca2+ in the blood. Released by the parathyroid glands.

34
Q

How does PTH work?

A

Stimulates cells in early distal convoluted tubule to reabsorb more Ca into blood.

Promotes phosphate excretion by inhibiting its reabsorption in the proximal convoluted tubules

35
Q

How is a urinalysis useful?What are some abnml constituants found in urine?

A

UA’s can identify abnormalities in the body. Abnormal constituants found in the urine include:

  • albumin
  • glucose
  • RBCs
  • WBCs
  • Ketone
  • Bilirubin
  • Urobilinogen
  • Casts
  • Microbes
36
Q

How is urine moved through the urinary system?

A

Parastaltic contractions

37
Q

What is the difference between the internal and external urethral openings?

A

internal: autonomic with smooth muscle
external: voluntary with skeletal muscle

38
Q

How does aging affect the urinary system?

A

Kidney size shrinks, renal blood flow and filtration rate decline.

A & P Lecture: Dr. Shellhammer (10 decks)

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