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Renal and Endocrine Biology > REB 19. Elements of Renal Function and Circulation > Flashcards

REB 19. Elements of Renal Function and Circulation Flashcards

1
Q

What is the key organ in body homeostasis?

A

Kidney

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2
Q

What are the primary functions of the kidney? [2]

A

[1] regulate VOLUME + COMPOSITION of the extracellular fluid (ECF)

[2] eliminate potentially toxic metabolite wastes and foreign compounds

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3
Q

What are some other functions of the kidney (besides its primary functions)? [9]

A

[1] maintaain water balance in body

[2] maintaining proper plasma volume (regulation of blood pressure)

[3] maintain osmolarity (solute concentration) of body fluids
— primarily by regulating water balance

[4] regulating quantity and concentration of most extracellular fluid ions (Na+, K+, Cl-, Ca2+, PO4 3-)

[5] Maintaining Acid-Base Balance
— pH

[6] Excreting Waste Products of Metabolism

  • – urea (from metabolism of amino acids)
  • – uric acid (from metabolism of nucleic acids)

[7] Excreting Foreign Compounds
— drugs, food additives

[8] Converting Vitamin D to Active Form (by proximal tubule cells)
— regulation of Ca2+/bone

[9] Producing Eryhtropoietin (cells interstitium of cortex/outer medulla)
— hormone stimulates red blood cell production

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4
Q

How much body mass does the ECF take up in comparison to the ICF? What does the ECF consist of?

A 
ICF = 2/3 of body mass
ECF = 1/3 of body mass

ECF is fluid OUTSIDE of cells…
[1] plasma which surrounds the blood cells
[2] interstitial fluid which surrounds the cells of all other tissues

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5
Q

What is able to diffuse through from the interstitial fluid to the plasma (and vice versa)? What cannot diffuse through?

A
  • water and solutes can undergo free exchange

- PROTEINS cannot undergo free exchange between the interstitial fluid and plasma

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6
Q

What 2 factors does the distribution of fluid depend on?

A

[1] Hydrostatic Force

[2] Osmotic Force

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7
Q

What cation and anion make up the majority of the ECF?

A

Na+ (accounts for ~93% of cations in ECF)

Cl-

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8
Q

What cation and anion make up the majority of the ICF?

A

K+

PO4 3-

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9
Q

If there is a change in the composition of the plasma what would happen to the composition of the interstital fluid?

A
  • there would be a similar change in the composition of the interstitial fluid
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10
Q

What accounts for the majority of the ionic/osmotic content? What allows for water movement?

A

Na+ accounts for it

- it cause the movement of water and also the movement of Cl-

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11
Q

Is there a tendency for the content of the ECF (and therefore, blood) to change?

A 
YES
why it may be affected:
[1] food contains salt and water - leads to continuing tendency for levels of salt and water to rise
[2] exercise (sweating) 
[3] other causes: vomiting, diarrhoea

KIDNEYS offset this effect by excreting salt + water in amounts appropriate to intake

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12
Q

What is a nephron?

A

functional unit of the kidney

- approx. 1 to 1.2 million nephrons in each kidney

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13
Q

What are the parts of the nephron?

A

[1] Renal Corpuscle

(a) Tuft of Capillaries (Glomerulus)
(b) Bowman’s capsule

[2] Renal Tubule

  • fluid filled tube formed by single layer of epithelial cells
  • vascular supply
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14
Q

What does the vascular supply of the nephron consist of?

A

[1] Afferent Arteriole - providing blood to glomerular capillaries

[2] Efferent Arteriole - sending blood away from glomerular capillaries

[3] Vasa Recta (descending + ascending)

[4] Peritubular Capillaries

[5] Veins

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15
Q

What are the 3 basic functions/processes performed by the nephron?

A

[1] filtration of blood

[2] tubular reabsorption

[3] tubular secretion

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16
Q

The first step in the nephron is:

A

Ultrafiltration

17
Q

In ultrafiltration, the first process in the nephron what happens?

A
  • strong hydrostatic pressure is generated in the nephron (glomerulus - blood vessels)
  • blood supply to the kidneys is through the renal arteries

side note: blood flow to the kidneys is around 1L/min (very high: 1/5 of cardiac output)

18
Q

Explain how the renal artery supplies nephrons and then forms the efferent arteriole.

A
  • renal artery subdivides to form many afferent arterioles
  • each arteriole will supply a nephron
  • arterioles form a capillary ball (glomerulus)
  • glomerular capillaries rejoin as an efferent arteriole
19
Q

How much plasma from the blood is filtered into Bowman’s capsule?

A

around 20%

- filtrate then flows through tubular system where substances of value are reabsorbed to peritubular plasma

20
Q

What can pass through the filtration barrier and into the nephron’s tubular system for filtration?

A

ALL components of plasma (useful + waste) pass through except:

  • cells
  • proteins
21
Q

If there are proteins in the urine what is this a sign of?

A

renal dysfunction

- proteins are normally not even supposed to be able to enter the tubules

22
Q

How much of filtrate is formed per day? How much urine is excreted? How much litres of filtrate must be absorbed?

A
  • 180 L of filtrate forms per day
  • the entire ECF is treated around 10x a day
  • approx. 1.5 L of urine is excreted
  • therefore, approx. 178.5 L of filtrate must be reabsorbed (returned to blood per day)
23
Q

What substances are reabsorped through active transport? (aka requiring energy)

A

[1] Glucose
[2] Amino Acids
[3] Na+
- movement during one or more steps against a gradient

24
Q

What substances are reabsorbed throug passive transport?

A

[1] Water
[2] Chloride Ion
- occurs down electrochemical or osmotic gradient

25
Q

List the steps of the trans-epithelial transport?

A

[1] substance leaves tubular fluid

[2] passes through cytosol of tubular cell

[3] crosses basolateral membrane

[4] diffuses through interstitial space

[5] penetrates capillary wall to enter bloo plasma

26
Q

What is present between the tubular cells to prevent substances from moving in-between cells?

A

Tight Junctions

- between tubular cells prevent substances from moving in between cells

27
Q

What is mainly reabsorbed in the proximal tubule?

A 
Na+ = 67%
H2O = 65%
28
Q

What is mainly reabsorbed in the Loop of Henle?

A 
Na+ = 25%
H2O = 15%
29
Q

What is mainly reabsorbed in the Distal Tubule + Collecting Tubule?

A 
Na+ = 8%
H20 = 20%
30
Q

What substances undergo the tubular secretion?

A
  • transfer from the peritubular capillaries into the tubular lumen

Substances:

  • H+
  • potassium
  • organic ions
  • drugs
  • food additives
  • environmental pollutants
31
Q

What is urine comprised of?

A 
[1] H2O
[2] Urea (formed in liver as end product of protein metabolism) 
[3] creatinine
[4] phenol
[5] other (Na+. K+)

side note: around 1mL/min of urine is formed

Renal and Endocrine Biology (25 decks)

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