Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PHGY 210 > Renal > Flashcards

Renal Flashcards

1
Q

What are the functions of the kidneys?

A
  1. Regulation of water, inorganic ion balance and acid-base balance
  2. Removal of metabolic waste products from blood (excretion in the urine)
  3. Removal of foreign chemicals from the blood (excretion in the urine)

4.Production of hormone/enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which 3 major hormones/enzymes are produced by the kidneys?

A
  1. Erythropoietin : hromone controlling erythrocyte production
  2. Renin: enzyme controlling formation of angiotensin + influences blood pressure + Na+ balance
  3. 1,25-dihydroxyvitamin D: active vitamin that influences calcium balance
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the weight of the kidneys?
Where are they?

A

150 gram/kidney (everyone has a pair, not variation of weight)

Placed behind the peritoneum on each side of vertebral column against posterior abdominal wall
(bottom of the back)
Under the diaphragm, connected to the bladder

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the different parts of the kidneys?

A

Renal cortex (outside layer)
Renal medulla (inside the cortex)
Renal pelvis (part in the middle) –> poors into the ureter

Renal Artery and Renal veins supply blood to the kidneys separate into interlobar artery –> arcuate artery –> interlobular artery

Filtration unit of the kidney = Nephron which is supplied by interlobular artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are Nephrons?
How many are there in each kidney?

A

Each kidney has 1 million subunit

Each Nephron has:
Renal corpuscle –> Glomerulus (capillary loops) and Bowman’s capsule
Tubule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the renal corpuscule composed of?

A

Afferent arterioles (Glomerulus) + Bowman’s capsule (surrounded by layer of epithelial cells)

Around the Glomerulus, Bowman’s capsule visceral layer (podocytes) directly on the glomerulus, inside of the bag, Bowman’s space, on the outisde –> Bowman’s capsule’s parietal layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the Glomerular capillary wall look like?

A

REVIEW SLIDES 17-21

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 3 processes of urine formation?

A
  1. Glomerular filtration (blood filtered by gloumerulosa, no urine made)
  2. Tubular secretion
  3. Tubular reabsorption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What consists in the Glomerular filtration phase of urine formation?

A

Filtration of plasma from the glomerular capillaries in to the bowman’s space

Glomerular filtrate = fluid in Bowman’s space, is cell-free + contains all substances from plasma except for proteins (about same concentrations)

fluid goes from Glomerular capillary (afferent arteriole) to the Bowman’s space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What consists in the Tubular secretion/reabsorption phase of urine formation?

A

Reabsorption: Tubules –> Peritubular capillaries

Secretion: Peritubular capillaries –> tubules

*peritubular capillary is a efferent arteriole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What determines the amount of a substance excreted in urine?

A

Amount excreted = amount filtered (in glomerular filtration) + amount secreted - amount reabsorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the difference between PAH (para-amino-hippurate), sodium, water and glucose in the formation of urine?

A

PAH : a little bit filtrated, none reabsorbed, the rest secreted (none in the blood left)

Na+ and water: a bit filtrated, almost all reabsorbed, non secreted (a little bit in urine)

Gluose: a little bit filtrated, all reabsorbed, none secreted, none in urine except if diabeties

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is filtrated by glomerular filtration?

A

Plasma –> Filtrate
- Water
- Low-molecular weight

What is not filtrated:
Cells (RBC, lymphocytes, Leukocytes)
Proteins (albumin, globulins)
Protein bound subtsances (1/2 calcium ion, fatty acid)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Which forces are involved in filtration?

A

Glomerular capillary blood pressure (Filtration, goes from capillary to Bowman’s space) = 60 mmHg

Fluid pressure in Bowman’s space (opposing to filtration) = 15 mmHg
Osmotic force bc proteins in plasma (wants to keep liquid in to reduce osmotic pressure, opposing to plasma) = 29 mmHg
*osmotic pressure also called oncotic pressure

Net glomerular filtration pressure = P(GC) - P(BS) - osmotic pressure(GC) = 16 mmHg

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the glomerular filtration rate?

A

GFR is regulated by:
- net filtration pressure
- membrane permeability (can get lower in pathological conditions)
- surface area available for filtration

Normal GFR (70kg person) = 180L/day (125mL/min)
N.B plasma volume of this person = 3.5L so plasma filtered 51%/day (180/3.5)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What mechanisms regulate GFR?

A

Deceased GFR:
Constriction before filtration site (afferent arteriole)
Dilatation of the efferent arteriole (after the site)

Increased GFR:
Constriction of the efferent arteriole (after filtration site)
Dilatation of the afferent arterioles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What determines the filtered load?

A

Filtered load = GFR * plasma concentration of the substance (g/day)

Filtered load > amount excreted: net absorption
Filtered load < amount excreted: net secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is tubular reapsorption?
(General facts)

A

2 types: paracellular (directly from tubular lumen to peritubular capillaries) *accross tight junctions

transcellular (from tubular lumen through tubular epithelial cell, to peritubular capillaries)

Facts:
1. Filtered load are enormous, generally greater than amount of the substance in the body

  1. reabsorption of waste products in relatively incomplete (urea = 44% reabsorbed)
  2. reabsoprtion of most useful plans components is relatively complete (ex: water (99%), ionrganis ions, organic nutrients, Na+ (99.5%), glucose (100%))
  3. Reabsorption of some substances NOT regulated (ex: glucose, amino acids), some other are highly regulated (water, inorganic ions)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What are the 2 mechanisms of reabsorption?

A

Diffusion and Mediated transport

Reabsorption by diffusion often across tight junctions connecting the tubular epithelial cells

Reabsorption by mediated transport ONLY across tubular cells (trans cellular epithelial cells), requieres participation of transport proteins in plasma membrane of tubular cells
*Usullay coupled to reabsorption of Na+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is transport maximum (Tm)?

A

Limit when membrane transport proteins become saturated, tubule can not reabsorb substance any more

ex: people with diabetes mellitus have such high concentration of glucose that filtered load of glucose&raquo_space; capacity if the tubules to reabsorb glucose (Tm exceeded) so glucose in urin (glucosuria)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

How does tubular secretion work?
Where does it happen?

A

Mediated by 2 mechanisms: diffusion and transcellular mediated transport
*Tubular secretion usually coupled with reabsorption of Na+

Most important substances secreted by tubules: H+ and K+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the different roles of different parts of tubules?

A

In proximal tubule: reabsorbs most filtered water and solutes + major site of secretion for various solutes (except K+)

Henle’s loop: reabsorbs relatively large qties of major ions (less water)

DCT/CD: volume of water and masses of solutes reaching here are relatively small. (Fine-tuning)
Determines the final amounts excreted in the urine by adjuting reabsorption (and secretion in few cases)
*HOMEOSTATIC controls here

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is clearance?

A

Clearance = volume of plasma from which that substance is completly removed by the kidney/unit time

Clearance of substance S (Cs) = Mass of S (excreted/time)/plasma concentration of S

Where mass of S excreted/time = Urine concentration of S (Us) * Urine volume/time (V)

Cs = Us*V/Ps

24
Q

What is the importance of inulin in clearance measurement? (not insulin)

A

Inulin = polysaccharide administered intravenously, freely filtered at glomerulus, but NOT reabsorbed, NOT secreted or NOT metabolized by tubule

Cinulin = GFR
*most accurate marker of GFR

25
Q

What is the importance of creatinine in clearance measurement?

A

Creatinine = waste product produced by muscle

Freely filtered at glomerulus and NOT reabsorbed
Secreted at the tubule but amount is very small
Not metabolized

GFR clinical marker (easier bc body produces it so no need to inject, just take a blood and urine test)

26
Q

What are the different source of water intake and outputs of the body?

A

Intake:
- Liquids (1200 mL)
- Food (1000mL)
- Metabolically produced (350mL) (don’t count it, normally just subtract it to insensible loss)

Output:
- Insensible loss (skin and lungs) (900mL - metabolically produced = 500 mL)
- Sweat (50mL)
- Feces (100mL)
- Urine (1500mL) –> most important output

Total of 2550mL in and out/day

27
Q

What are the different source of Sodium intake and outputs of the body?

A

Intake:
- Food (10.50g) –> varies drastically depending on diet (areas in the world)

Outputs:
- Sweat (0.25g)
- Feces (0.25g)
- Urine (predominant output on NaCl, depends on intake, the others don’t) (10.00g)

*We are in water and Na balance (output = intake)

28
Q

Between what values can water and NaCl output varie in a day?

A

Water: 0.4L/day - 25L/day

NaCl: 0.05 g/day - 25 g/day

29
Q

What happens with the filtration, secretion and reabsorption of water and Na? (general)

A

freely filtered, 99% reabsprobed, NO secretion

Majority of sodium and water reabsorption occur int the proximal tubule (2/3)

Major hormonal control of reabsorption occur in the DCT and CD

30
Q

How do the general mechanisms of reabsorption of water and Na function?

A

Na reabsorption = ACTIVE process occuring in ALL tubular segments (except the descending thin limb of Henle’s loop)

Water reabsorption is by DIFFUSION and in dependent upon Na reabsorption

31
Q

How (in details) does the Active sodium reabsorption occur?

A

On the basolateral membrane:
Active Na+/K+ - ATPase pumps transport sodium out of the cells and keep the intracellular concentration of sodium low

On the apical (luminal) membrane:
Sodium moves downhill from the tubular lumen –> the tubular epithelial cells (bc Na+ intracellular concentration is low)
Each tubular segment has different mechanisms

ex: proximal tubule have Na+-H+ antiporter and Na+-glucose cotransporter
In the CCD, diffusion via Na+ channels

32
Q

What is sensing total body sodium?

A

Sodium in the major extracellular solute –> Changes in total body sodium –> changes in extracellular fluid volume (so we can use extracellular fluid volume sensors)

Total body water (60% of BW) –> extracellular fluid (20% of BW) –> 3/4 = interstitial fluid + 1/4 = plasma
(40% of BW is intracellular fluid)

Total body sodium is sensed as INTRAVASCULAR FILLING by baroreceptors in the cardiovascular system

Attention: plasma concentration of Na is NOT a marker for total body Na
PNa only reflects the relative relationship of total body Na and water

33
Q

Which system is responsible for regulation of sodium in the body/ in the kidneys?

A

The reabsorption = major role
GFR = minor role

34
Q

How does the GFR influence the renal regulation of sodium?

Example, what happens when diarrhea?

A

3 sets of baroreceptors to activate renal sympathetic nerves depending on volume of plasma (intravascular volume)

↑ Na+ and H2O loss due to diarrhea (so less of them) → ↓ in plasma volume → ↓venous pressure → ↓venous return → ↓atrial pressure → ↓ ventricular end-diastolic volume → ↓Stroke volume → ↓ Cardiac output → ↓ Arterial blood pressure

(or →↓ venous pressure → directly to)

↑ activity of renal sympathetic nerves → IN THE KIDNEYS: ↑ constriction of a.a. → ↓Net GF pressure → ↓GFR → ↓Na+ and H2O excreted

35
Q

How is renal sodium regulated by reabsorption?

A

Key hormone: aldosterone (steroid hormone secreted by adrenal cortex, zona glomerulosa)

Aldosterone stimulates Na reabsorption in the DCT and CCD

No aldosterone → 2% of filtered load is excreted (35g of NaCl)
High aldosterone → 0% of filtered load is excreted

36
Q

Where in the Kidneys does Na reabsorption occur?

A

In proximal tubule → 67%
In thick ascending limb → 25%
DT → 4%
Cortical collecting duct → 3% *Hormone control at the CCD

37
Q

How does aldosterone affect different pumps of the Na reabsorption?

A
  • Aldosterone increases H+ secretion
  • Aldosterone increases all transport proteins → Na more reabsorbed
38
Q

How does renin-angiotensin system work?

A
  • Liver secretes angiotensin → blood
  • Kindeys secrete renin → blood
  • In the blood → angiotensin + renin → Angiotensin I
  • In blood → angiotensin converting enzyme + angiotensin I → angiotensin II
  • Angiotensin II → into adrenal cortex → secreted aldosterone
39
Q

What is the Juxtaglomerular apparatus?

A

It is a structure responsible for renin secretion and ensures a proper gromerular flow
Contains gromerular afferent and efferent arterioles

Sympathetic nerves innervate the juxtaglomerular cells, 3 different stimulation sources:
- Tubules
- Afferent nerves
- Macula densa (sends signal to the tubular lumen)

40
Q

How does regulation of renin secretion by extracellular fluid volme influence Na balance?

A

↓ Plasma volume : ↑ Activity of renal sympathetic nerves (3 baroreceptors), ↓ Arterial pressure (less stretch, afferent arterioles collapse), ↓ GFR → ↓ flow macula densa → ↓ NaCl delivery to macula densa (transmit signal to renin secreting cells)

All of that leads to Renal juxtaglomerular cells ↑ Renin secretion!!! → ↑ plasma renin → ↑ plasma angiotensin II → ↑ Aldosterone (in Adrenal Cortex) → ↑ Plasma aldosterone → ↑ Sodium reabsorption (in CCD) → ↓ Na excretion

*Aldosterone does NOT stimulate H2O reabsorption directly in the CCD

41
Q

What are other factors than renin secretion that influence renal sodium excretion?

A

Atrial natriuretic peptide (ANP):
*opposit as tubular aldosterone, act when too much salt and atria expands
ANP = peptide hormone secreted by cells in the cardiac atria
Acts on the tubules to inhibit Na reabsorption and increase GFR
Increased total body Na (↑ extracellular fluid/plasma volume stimulates ANP secretion

Blood Pressure:
↑ blood pressure → ↑ Na excretion (pressure natriuresis) (can be pathological)

42
Q

What is the process by which the ANP influences Na reabsorption?

A

*ANP = opposit than aldosterone
↑ Plasma volume → ↑ distension (in cardiac atria) → ↑ ANP secretion → ↑ plasma ANP → :

  • ↓ plasma aldosterone
  • ↓ Na+ reabsorption ( in tubules of the kidneys, in CCD?)
  • afferent dilatation + efferent constriction → ↑ GFR

All of that increases Na excretion

43
Q

What is a Hypoosmotic, Isoosmotic and Hyperosmotic solution?

A

Hypoosmotic: total solute concentration less than normal 300 mOsm (more water, less solute)

Isoosmotic : total solute concentration equal to that of normal extracellular fluid

44
Q

Where is the majority of water reabsorption done in the kidneys?
Where is hormonal control?

A

2/3 → in the proximal tubule

Major hormonal controle of reabsorption in the CD

45
Q

What does Water reabsorption mainly depend on ?

A

Depends on Na reabsorption in the proximal tubule (which affects osmolarities of tubular lumen and interstitial fluid)

*water reabsorption done by osmosis

  1. Na reabsorbed from tubular lumen → interstitial fluid across epithelial cells
  2. Local osmolarity of lumen ↓ as local osmolarity of intersitium ↑
  3. Difference in osmolarity causes net diffusion of water from lumen → interstitial fluid via tubula cell’s plasma membranes (tubular epithelial cells) and via tight junctions
  4. From interstitum, H2O, Na and everything else dissolved in interstitial fluid move together by bulk flow into peritubular capillaries

In tubular lumen, local osmolarity in low when Na is reabsorbed → H2O is reabsorbed by osmosis to make solutions in interstitial fluid (hyperosmotic) and in tubular lumen isosmotic

46
Q

Where does dynamic regulation of water reabsorption takes place?

A

in the Collecting duct, 2 critical components:
1. high osmolarity of the medullary interstitium
2. Permeability of CD to water (regulated by vasopressin)

47
Q

How does urine concentraiton function?

A

Countercurrent multiplier system:

  • The kidney has ability to concentrate urine up to 1400 mOsm/L
  • Urinary concentration → as tubular fluid flows through the medullary collecting duct (starts in the cortex but mainly in medullary CD)
  • Urinary concentration depends on hyperosmolarity of the interstitial fluid. Vasopressin → water diffuses out of duct → interstitial fluid in the medulla to be carried away.
48
Q

What does water permeability of the tubules depend on?

A
  • Water reabsorption depends on the water permeability of the tubules
  • Permeability of the epithalium depends on the tubular segment ex: proximal tubule = high permeability to H2O
  • Permeability depends on presence of aquaporins in plasma membrane
  • H2O permeability in CCD and MCD is subject to physiological control + vasopressin
49
Q

Where is water reabsorbed in the kidneys?

A

Proximal tubule = 67%
Descending thin limb of Henle = 15% (freely permeable)
NOTHING in TAL (impermeable, NaCl reabsorption)

CCD and MCD → hormonal controle (vasopressin)

50
Q

What is Vasopressin?
aka anti-diuretic hormone (ADH)

A
  • Peptide hormone
  • Produced by group of hypothalamic neurons
  • released from posterior lobe of pituirary gland

Couples to GPCR V1 (smooth muscle) + V2 (kidney)
Stimulates insertion of aquaporins in the luminal membrane of CD cells and increase water permeability

When vasopressin → CD becomes permeable to water → reabsorption of water
when no present → impermeable → water diuresis

51
Q

By what is diabetes insidious (DI) caused?

A

By malfunction of vasopressin system (vasopressin des NOT work) : mutation of V2 receptors in kidneys (don’t respond) or enzymes degrade of digest vasopressin
*usually in complaction of pregnancy

52
Q

What is the role of vasopressin?
How is its secretion regulated?

A

Vasopressin regulates excretion of water by regulating its reabsorption rate from the tubules.

2 mechanisms regulate vasopressin secretion:
1. Osmoreceptor control (most important) - senses filling
2. Baroreceptor control (less sensitive)

53
Q

How do osmoreceptors control vasopressin secretion?

A

*Opposit than osmoreceptors

Excess H2O ingested → ↓ Body fluid osmolarity (more H2O oncentration) → ↓ Firing by hypothalamic osmoreceptors →
In the posterior pituitary: ↓ Vasopressin secretion → ↓ Plasma vasopressin
In Collecting ducts: ↓ Tubular permeability to H2O → ↓ H2O reabsorption
→ ↑ H2O excretion

54
Q

How do baroreceptors control vasopressin secretion?

A

*Opposit than osmoreceptors

↓ Plasma volume → ↓ Venous, atrial and arterial pressures → Reflexe mediated by cardiovascular baroreceptors →
In the posterior pituitary: ↑ Vasopressin secretion → ↑ Plasma vasopressin
In Collecting ducts: ↑ Tubular permeability to H2O → ↑ H2O reabsorption
→ ↓ H2O excretion

*Vasopressin stimulates keeping H2O in the body by making tubual reabsorption membrane more permeable to H2O

*Baroreceptors = safety net if plasma very low, not in tiny changes

55
Q

What makes you feel thirsty?

A

Mostly ↑ Plasma osmolarity → osmoreceptors → increase thrist

Dry mouth, throat → increase thrist
↓ Plasma volume → Baroreceptors (but less sensitive) → increase thirst

Metering of water intake by IG tract (when drink, immediately stop being thirsty even though not absorbed)

56
Q

What mechanism follows severe sweating?

A

Sever sweating → Loss of hypoosmotic salt solution (loss of H2O > loss of Na) → ↓ Plasma volume + ↑ Plasma osmolarity (decrease H2O concentration)

↓ Plasma volume → :
↓ GFR + ↑ Plasma aldosterone → ↓ Na excretion
↑ Plasma vasopressin → ↓ H2O excretion

PHGY 210 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions