• Filters blood to produce urine and rid of nitrogenous waste
• regulates pH
• regulates blood volume
• regulates blood electrolyte levels
• secretes erythropoietin
• activates vit. D (for Ca+ synthesis)

180 L produced

only secrete ~ 1.5L

• H2O
• Na+
• Cl-

Function of Distal convulted tubule?

This is NOT part of the Nephron!

but one function of it

Collecting Duct-

absorbtion under horomonal control

1. Fenestation between glomerular endothelial cells
2. filtration slits between podocytes
3. thin basement membrane between both cell groups

3 reasons why the filtration

membrane excels at fitration

1. increase surface area
2. high hyrostatic pressure in glomerulus
3. large capillary permability

1. Filtration
2. Reabsorption
3. Secretion

• occurs in renal corpuscle
• lots of plasma components become filtrate
• 180 L/day

Reabsorption of urine formation

(2 step process)

• filtrate components move from tubule into peritubular capillaries
• efferent arteriole drains into peritubular capillaries

HP and OP in peritubular capillaries

(each due to?)

Low HP due to low blood vol

high OP due to albumin

-Both support reabsorption

Explain secretion of urine formation

(one sentence)

Net Filtration Pressure

it:

• Promotes filtation in glomerulus b/c of HP

(HPg)

2 opposing pressures of

HP in glomerule(HPg):

(and their ammounts)

1. Osmotic pressure is 30 mmHg (OPg)
2. HP in capsular space is 15 mmHg (HPc)

Net Value (NFP)promoting filtration formula

and average

NFP=HPg- (OPg+HPc)

average is 10 mmHg

What is GFR?

av. amount?

3 Promoting factors of glomerular

 filtration rate(GFR)?

1. Increases surface area available for filtration
2. increases capillary permability
3. NFP (net value filtration)

*NFP is directly linked to GFR

intrinsic control of

glomerular filtration rate (GFR)

-2 specific

• autoregulatory
• adjusts for minor changes in local BP and blood flow
• Myogenic contol
• tubuloglomerular control mechanism

Extrinsic control of glomerular filration rate

-2 specific types

when arteriole blood pressure drops below 80 mmHg

or rise above 120 mmHg

sympathetic activation

RAAS- Renin Angiontensin Aldosterone S           ystem

What happens in myogenic(intrinsic) control of GFR?

(if its too high)

 an increase stretch in afferent arteriole which increases NFP b/c there is too much volume and increases GFR.

The afferent arteriole vasoconstricts and 

This decreases the flow into glomerules and decreases NFP

The final outcome is decrease in glomerular filration rate

The macula densa cells act as chemoreceptors for Na+  and Cl- concentrations

• An increase in GFR decreases reabsorption and increases Na+ and Cl- concentrations which is then detected by the macula densa cells. They secrete ATP which stimulates afferent arteriole to vasoconstrict and final outcome is decrease in flow , NFP and GFR

• increase in hyrostatic pressure which pushes excess fluid into ISF
• Low osmotic pressure (not enough pressure to pull H2O back into vessel)
• Block or removed lyphatic vessel (lymphedema)
•  Increased capillary permability (lets proteins and excess fluid into ISF)

Excesss K+ decreases membrane permability,

too little K+ increases hyperpolarization.

High K+ (hyperkalemia) causes and ion shift and leads to acidosis (as K+ moves out of cell H+ moves in).

aldosterone stimulates K+ secretion

How is Ca+ increased in blood?

(Gland that does this and 3 ways)

Parathyroid gland targets bone (release Ca+ from bone),

 kidney reabsoption

 and small intestine to raise Ca+ levels

high calcium

hypercalciumia

Horomones that effect sodium balance?

(5 and what they do)

• Aldosterone(regulate)
• Atrial naturalitc peptide -ANP(regulate)
• glucocorticoids(conserve)
• estrogens(increase reabsorption)
• progesterone(decrease reabsorption)

hypernatremia

low sodium

hypoatremia

2 functions of sodium

Has greatest osmotic influience on H2O movement b/w compartments

and

nerve and muscle functions

Flow of movement during reabsorption in kidneys

tubule lumen to simple cubodial epithelial cells to ISF to peritubular capillary

osmolarity

number of solutes deissolved in 1 Kg of water

measured in milliosmoles (mOsm)

counter current exchange

due to permabilty of ascending limb of nephron loop

role is to concentrate urine

counter-current multiplier

dure to vasa recta

flow is slow and sluggish, very permable to H2O

role is to concentrate urine

counter current mechanism

maintained by nephron loop and vasa recto to adjusts concentration of urine

2 types:

conter current exchange and

 counter current multiplier

During secretion of urine,

things we get rid of: (3)

1. Drugs and metablolic wastes (urea)
2. electrolytes under hormomal control
3. HCO-3 & H- to maintain acid/base balance of blood

stimuli of the extrinsic regulation of GFR (3)

• Detection of low [Na+] by macula densa cells
• decreased stretch detected by granular cells
• direct stimulation by Bi adrenergic receptors on kidneyy blood vessel walls

What happens during sympathetic activation

during extrinsic regulation of GFR?

ststemic casoconstrict to increase BP which causes an increase of flow to the kidneys to maintain GFR

What is the function of the RAAS mechanism during

extrinsic regulation of GFR?

RAAS is Renin Angiotension-Aldosterone system

1. first granular cells secrete renin
2. hepatocytes produce angiontension
3. angiotension converts to angiontensinI by renin which then travels to blood

How does RAAS work in the lungs?

AngiontensinI is converted to AngiontensinII by angiontensin converting horome (ACE)

What is the extrinsic regulation of GFC

when BP rises?

(5 step process)

1. Detected by barorectors
2. the R atrium secretes atrial naturietic peptide
3. this stimulates vasodilation
4. this promotes Na+ secretion and H2O follows
5. Drop in BV and BP

Explain reabsorption in the proximal

convuluted tubule

 most reabsorption occurs here

reabsorbs:

all glucose and amino acid

65% Na+ and H2O

60% Cl-

55% K+

90%HCO3-

2 important features involved in

reabsorption in the nephron loop

descending limb in only permable to H2O

acsending limb is only permable to Na+ and Cl-

Reabsorption in the nephron loop

happens because,

Na+ moves in b/c ISF becomes dilute w/ H2O from ascending limb of nephron loop.

H2O enters which dilutes blood

• counter current mechanism steps in which includes counter current exchange and counter current multiplier

functions of parathyroid in secretion

Ca 2+ is reabsorbed

PO4^3- phosphate is secreted

function of aldosterone in

secretion

Na+ is reabsorbed

K+ is secreted

what is the main regulator

of urine concentration?

antidiuretic horomone

What role does antidiuretic horomone play in regulation urine concentration?

inserts aquaporins into wall of distal convuluted tuble

collectiong duct

What happens with ADH in

Diabetes inspidus

ADH is not secreted

ADH cannot insert aquaporins

drastic increase in urine output -18 L/day

tissue in urinary bladder

transitional epithelium

what is the control of concentration of urine?

under horomonal control

rugulates water and electrolyte reabsorption and secretion

process of peeing is called..

micruition

Process of micruition

parasympathetic spinal cord reflex

1. increase stretch of detruser muscle to spinal cord
2. parasympathetic nerve relaxes internal uretheral sphincter
3. external uretheral sphincter relaxes(voluntary)

2 main fluid compartments

intracellular fluid ICF

extracellular fluid ECF

What are fluids mostly composed of?

H2O

also:

electrolytes and nonelectrolytes

ex: Na+  and     Glucose

intracellular fluid

cytosol, its the biggest compartment, contains most of fluid

extracellular fluid makes up what?

(7)

in plasma

interstitial fluid

cerebral fluid

aqueous and venurous fluid

lymph

synovial fluid

What 2 horomones

 regulates water balance?

ADH and aldosterone

water imbalance is called what?

too little water

too much water

too little: dehydration 

too much:hypotonc hydration

what happens during dehydration

excessive loss of EC fluid

increase osmotic pressure in extracellular fluid compartment

water drawn out of cells and the cells shrivel

explain what happens during

hypotonic hydration

too much H2O in extracellular fluid

decreases OP

water moves into cell

cell swells and lyse

how does water balance  effect

blood volume when it increases?

if blood vol. rises then ADH secretion decreases and

urine output increases and this decreases blood vol.

This is detected by osmoreceptors

how does water balance effect blood volume

when it decreases?

decrease in blood volume-->triggers osmoreceptors-->

triggers hypothalamus--> triggers post. pituitary--> ADH secretion-->inserts aquaporians in wall of PCT--> increases H2O reabsorption and increases blood volume

What stimulates aldosterone

during water regulation?

angiotensin II

which drectly stumulated by increase in K+ levels

(Na+ reabsorption and K+ secretion occurs stimultaneously)

What must be present for H20 reabsorption

when also reabsorbing sodium?

special channel called an aquaporin

What drives sodium

 reabsorption at lumenal end ?

events that occur at the basolateral membrane

Explain the events that occur at the basolateral

membrane during sodium reabsorption

(*learn process then see pic in notes)

1. Na+-K+ pump at the basolateral membrane
2. 3 Na+ pumped from cell into ISF
3. use facilliated transport to enter capillary
4. creates osmotic gradient, H2O follows
5. 2K+ pumped into cell from ISF, then deffuses right back out of cell into ISF
6. Overall (-) charge of cell attracts Na+ at luminal end
7. Na+ enters thru 2nd degree active transport with some other solute (CO-transport)