ch 19: renal system

RAAS system

system that constricts teh bv and forces the kidneys to retain H2O and salt

• increased NA resorption and adh relase for wtaer reseorption

• relase of aldosterone — resorption of NA= and H20

filtration

non-selective (except for size) movemtn of plasma from the glomerulus into bowman’s capsule (bloiod to lumen)

reabsorption

SELECTIVE; moving useful substances from the tubule lumen back into the peritubular capillaries (lumen → blood)

movement if water and solute from lumen to plasma

• proximal tubule and distal nephron

• relies on ACTIVE transport

secretion

selective transfer of molecules (ex. H+ and penicclin, K+) feom the blood directly inot the tubule

reatin penicillin

from plasma to lumen

excreation

removal of the final processed fluid urine from the body

lumen to external envrionemnt

excreation =

filtration - reabsorption + secretion

inulin

= GFR

diabetes and reabsoption and urine

glucose gets reabsorbed so a helathy perosn

100% reabsorption

0 is excreted

filtration barrier

glomerular Capillary Endothelium, Basal Lamina (negative charge repels proteins, prvents protein from going in urine), bowmans capsule, Podocyte Filtration Slits.

filtrated substances pass theough endothelial pores and idltration slits

the dirving force of filtration is

blood pressure

Autoregulation of GFR

maintains a nearly constant GFR when mean arterial blood pressure is between 80 and 180 mm Hg

• Myogenic Response (Muscle-driven):if BP rsies, afferent arterioles is stretched and the smooth muscle constricts to prevent the pressure in the glomerules (filter) from raising

  • if BP falls, affernet arterioles dilates and keep the BP up

• Tubuloglomerular Feedback (TGF): negative feedback!!! (GFR goes from high to lwo)

  • GFR increased → Flow past Macula Densa increased

    2. Macula Densa cells release Paracrines.

    3. Afferent Arteriole constricts → Resistance increases pH decreases → GFR decreases back to normal.

GFR (Glomerular Filtration Rate)

measures how much blood passes through the tiny filters (glomeruli) in your kidneys every minute

Hydrostatic Pressure ($P_H$)

the physical force exerted by a fluid (blood) against the walls of its container (the capillary or the Bowman's capsule).

If systemic BP is HIGH:

The kidney constricts the afferent arteriole to DECREASE the pressure inside the glomerulus

If systemic BP is LOW:

The body triggers the RAAS pathway and Sympathetic system to constrict vessels to INCREASE systemic BP (Global fix).

ANG II

vasoconstrictor in RAAS

ANP

dilate afferent arteriole → increases hydrostatic pressure in glomerulus

driving force of reabsorption

Na —needed for depolarization

alsoaterone

salt saving, potassium spilling hormone

glucose transport

second active transport

• need to be 100% reabsorbe din helathy perosn

glucose is

HIGH inside the cell in intensint and kidney

Renal Threshold

a concentration (mg/dL)—how much sugar in the blood makes the pumps fail.

transport maximum

a rate (mg/min)—how fast the pumps work.

secretion of organic anion

3rd active transport

handling

net secretion or net reabsoprtion

filtatuon rate of RBCs

0 — bc they large

For RBCs: 0(Filtered) - 0(Reabsorbed) = 0Excreted

filtartion rate of glucose

For Glucose: 100(Filtered) - 100(Reabsorbed) = 0 Excreted

• High filtration, zero excretion (because of 100% reabsorption).

clearance is

Volume of plasma cleared of substance (x) per time

• can estimate GFR with it

• how much dirty plasma has been cleraed out

Clearance of _____ or _____ estimates GFR

creatinine or inulin

urea clearance

50% is reabsorbed

net reasborption

filtration is greater than

excretion, there is net reabsorption.

penicllin clearance

net secretion

excretion is grater than filtration — net secretion

0% reabsorebed

micrurition

parasymptahtic neurons control; reflex when abbies are not fully mature in kiney — pee when bladder is full

reabsorption

apical/lumen → basolateral (ECF)

na is

low inside the cell

k is

high inside the cell

1 g =

1000 mg

1 L =

10 dL

What is false about filtration?

A) It is non-selective

B) Red blood cells can pass through

C) It is the movement of plasma water and solute from the glomerulus into the Bowman’s capsule

D) Water, salt, and plasma can pass through

E) The glomerular filtration rate is about 180L/day.

F) All above are correct.

B) Red blood cells can pass through

The glomerular filtration rate

180L/day

Control of the GFR is mainly regulated by

A) Local Control, Myogenic response

B) Global Control, ANG II

C) Global Control, E and NE

D) Local Control, Tubuloglomerular feedback

E) Local Control, ADH

D) Local Control (myogenic is apart), Tubuloglomerular feedback