RETAKE - Midterm 4

Question 1

Topic 40. Basics of physiokogical functions of the kidney

Answer 1

1. Filtration - a. EFP b. permability of barriers
2. Reabsorption - small fraction 0,5%-1% becomes urin cause of reabsorbtion
3. Secretion - Plasma (leaving the glomerulus)-> Efferent arteriole -> further substances –> Lumen at site of the peritubular cappilaries. Trans/paracellular
4. Excretion= URINATION, result of filtration. as a result of.1,2,3 in the end of tubular system = 4. Secondary filtrate of 4.
   Extretion investigated: CLEARANCE

Function
1.) Maintaining the homeostasis - Isovolemia
… Elimination of H+, regulatiob of Acid/base equilibrium-> isohydria
-
2.) Excretory function: eli of natural by products, medicines, toxic materials
3.) Regulates circulation -> Angiotensin II synthesis
4.) Endocrine organ:
- Formation blood(erythropoetin),
- Bone metabolism(d-hormone),
- Heat prod (activation of.thyroud gland hormones)
Functional unit: Nephron!

Question 2

Topic 41- Glomerular filtration rate (GFR), extraction, clearance

Answer 2

GFR

1. GFR - Amount of filtrate produced per unit time by all of the nephrones from both kidneys.
2. Measurement: INULIN - Only filtrated (Dog-Creatinine)
3. Autoregulation: Constant! = Tubulo-Glomerular feedback. MACULA DENSA
4. Extraction = E= (Pa-PV)/Pa
   - The ability of the kidney to ELI a substance from a organism.
   - Whole kidney or nephron
   - Max and Min extraction DRAWING E=1 and E=0
5. Clearance = C=U/P*V
   - To investigate EXTRACTION
   - Inulin (entirely filteres) = GFR = Clearance
   - PAHA (enterely secreted) = RPF = Clearance
   - Clearance of
   PAH
   INULIN
   UREA
   GLUCOSE

Question 3

Topic 42. Renal Plasma flow (RPF), Filtration fraction

Answer 3

-Renal plasma flow -> Para-Amino-Hyppuric Acid
- Amount of plasma flowing through the kidney(RPF)
- Based on ficks law (conservation of matter)
Drawing
- Clearance: Filtered and Excreted = PAH
- RPF=U*V/(Pa-Pv)
- Autoregulation (GFR & RPF)
- Renal Blood Flow (RBF)= RPF/1-HLc = 1200 ml/min
- Distribution of BF in tissue layers

Question 4

Topic 43: Transport process in the proximal tubule

Answer 4

• 70% filtered
• Permable to manny subst, but imperbable to: Creatinine
  Urea
  HCO3-
  Proteins

REABSORPTION OF NA+ & INDIRECTLY HCO3-
SECRETION OF H+ (into lumen)

AQP-1 Channels - allow free movement H2O

DRAWING

1.) The basolateral Na+/K+ ATPase pump =
Main energy source for SECONDARY active trasport: Glucose & Amino acids
- Moves Na+ from tubular cells –>
Interstitium –> Cells
2.) The secreted H+ –> CO2 & H20 w/ luminal HCO3- in the precense of CARBONIC anhydrase

3.) CO2 Diffuses back into the tubular cell –> Transformed to HCO3- –> Interstitium by (Na+/3HCO3- co trasporter

GLUCOSE & AMINO AC: 100% withdrawn from proximal tubule + Na+ by the secondary active symport of Na+/K+ ATPase pump

UREA= ca 1/2 of urea passively reabsorbed

PROTEINS - some –> Lumen, majority of these get back to the tubular cells = PINOCITOSIS

Question 5

Topic 44: Transport in loop of henle & Distal loop

Answer 5

1.) Decending part of Henle loop (DTL- Thin dec)
High permability
2.)Thick ascending limb of Henle loop (TAL)
Reabsorbs 25% of filtered substances
Symport protein: Na+/K+/2cl- transporter
Furosemid sensitive
Na+/K+ ATPase pump, pumps Na+ from the cell to the interstitium (reabsorbtion), and from the interstitium to the cell: aginst conc. gradient

3.) TAL is Impermable to WATER and Urea! -> lumen= hypoosmotic.

K+ & Cl- will passively leave the cell at basolateral side. Na+ is eliminated here also by a very active ATPase pump

4.) DCT - NaCl withdrawal/reabsorbtion takes place.
Na+/cl- symport protein absobes a further 5% of filtered Na+ on luminal side .
- Can be inhibited by TIAZIDE derivates = Causes DIURESIS-> urination
- Cl carried out by a special K+/cl- cotransporter
Ca2+ transport directly by Parathormone (PTH)

DRAWING

Question 6

Topic 45: Transport in distal CNT and collecting tubule (CCT/MCT)

Answer 6

The formation of the hormonally regulated final URIN takes place.

1. CNT, CCT = Mineralcorticoid dependent Na+ reabsobtion.
2. CCT= ADH-dependent water reabsorbtion
3. MCT= ADH- delendent water and urea.reabsorbtion, ANP-dependent Na+ excreton

• Regulation of acid/base and K+ BALANCE

1. Mineralcorticoid dependent Ma+/K+ transport
2. Active water transport
3. Acid-base balance
4. K+ transport

Question 7

Topic 46: Osmoregulation in kidney, the countercurrent system

Answer 7

1. Osmotegulation
   - Hyperosmosis
   - Hypoosmosis
2. ADH- Mechanism
3. The countercurrent system
   Responsible for creation and maintainance of the osmotic layering. (Countercurrent multiplyer & exhange mechanism)
4. Osmotic gradient of the kidney
5. Factors creating the osmotic gradient
   Vasa recta=countercurrent+Exhange
6. Effect of the osmoticgradient-possible change
   5stk
7. Clearance of free water

Question 8

Topic 47. The.maintance of isosmosis, the ADH mechanism

Answer 8

ANTI DIURETIC HORMONE

• Reduced volume as a result of a decreased fluid or injury = DEHYDRATED
  1. ) Conc of salt dissolved in blood increases = Osmotic pressure rise = Reseptors in hypothalamus -> Osmotic pressure shift -> Trigger the posteriour lobe of pituary to activate ADH
  2. ) At same time- Thirst senter in Hypothalamus responds -> Stimulating ADEQUATE STIMULUS = Extra cellular HYPER OSMOSIS

3.) Role of ADH maintaining isosmosis

A- Experimentaly perfusing kidney -> hypoosmotic urine. Lack.of endocrine mechanisms: ADH readjusts ISOSMOSIS

B- Damaged hypothalmic ADH secteting locus
-> HYPOOSMOTIC Urine. DIABETES

C- INCREASED DIURESIS Following extra H20 load -> BLOCKED by ADH

D- HYDROPENIA result in immeditiate blood: ADH INCREASE

ADH mechanism of action: level: CNT distal + CD
- Result: Resets H2O permability (rebsobtion)

Osmoregulation

• Hyperosmosis
• > Isoosmotic hyperosmosis
• Hypoosmosis: ADH innhibition
• > Isoosmotic hypovolemia

VERNEYS EXPERIMENT - DIURESIS (DOG)

Question 9

Topic 48. The maintanance of Isovolemia: Reninangiotension system, ANP, Aldosterone

Answer 9

1. Volume regulation: ISOVOLEMIA
2. Renin Angiostin System (RAS)
   effects:
   - Renin
   - Angiotensin I
   - Angiotensin II
   - Angiotensin III

ANP figure

Other hormonal regulations:

• Prostaglandings -> Strong vasodilator
• Kalikrein-kinin system -> Strong vasodilator, Result in Bradykinin production

Aldosterone
- most importaint member of mineralocorticoids
- Steroid hormone (prod: zona glomruloza, adrenal cortex)
- Key enzyme: 18-aldolase
- MAIN EFFECT: Na+ reabsorbtion & K+ excretion
essential in the sodium and water retention
- ADH–>Primary role: setting plasma osmolarity
- Aldosterone–> Regulate the entire Na+ content of the body (EC volume) as a member of RAS.
- Independent role: Keep K+ conc of plasma within limits.
- Mainsite: DCT + CCT and collecting ducts.

ANP
- Atrial Natriuretic Peptide
Secreted in cardiac atrium
Function: Increased Na+ excretion

Question 10

Topic 49 The process of Urination

Answer 10

1. ) Urin:
   - Produced in kidney continiously
   - Pericordial process
   - Faciliated - kept in urinary bladder - urination takes place = Micturation

2.) Urinary process:
Figure
Rythmical contraction: Calyx -> pelvis
Speed 2-3cm/s
Normaly no urinary reflux

3.) Regulation
- Emptying bladder - Controlled by PONS -> mechanoreceptors in the bladder.
- Execution carried out by:
Lumbal (Sympathethic)
Sacral ( Parasympwthetic)
Appropriate somatic motor center (m. abd, perineum, outher spincether)

A. Saturational
B. At urination