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A & P II test 3 urine formation
urine formation
57
Anatomy
Undergraduate 2
04/17/2010

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Term
What are the three basic steps to urine formation?
Definition
filtration, reabsorption, secretion
Term
What is filtration?
Definition
- blood in the glomerulus is filtered through to the Bowman's capsule. Filtration is across a highly selective filtration membrane
Term
What is the filtration membrane made of? What does it not allow the passage of?
Definition
endothelium of the glomerulus and epithelium of the Bowman's capsule, it does not allow the passage of blood cells or large proteins
Term
What is reabsorption?
Definition
valuable substances are reclaimed from the filtrate and returned to the general circulation via the peritubular capillaries/vasa recta
Term
Where does reabsorption mostly occur?
Definition
in the proximal convoluted tubule
Term
What is prevented from being lost as waste?
Definition
water, glucose, salt, an amino acids
Term
What is secretion?
Definition
the movement of substances from the blood (in peritubular capillaries/vasa recta) into the filtrate in the tubular lumen
Term
Where does secretion mostly occur?
Definition
occurs mostly at the DISTAL convoluted tubule and the COLLECTING DUCT
Term
What does secretion allow for?
Definition
allows for the elimination of substances from the blood that wasn't filtered through the glomerulus
Term
What three pressures affect the filtering process?
Definition
glomerular capillary blood pressure, plasma colloid osmotic pressure, bowman's capsular hydrostatic pressure
Term
What is Glomerular capillary blood pressure (GCBP)?
Definition
fluid pressure exerted by the blood within the glomerulus, pushes fluid and solutes across the filtration membrane
Term
The GCBP is           pressure that            filtration (  55Hg)
Definition
The GCBP is POSITIVE pressure that FAVORS filtration (+55 Hg)
Term
What is Plasma Colloid Osmotic Pressure?
Definition

caused by large plasma proteins that are too big to pass across the filtration membrane

Presence of these proteins causes the osmotic movement of fluid toward the GLOM

Term
PCOP hinders the movement of               into the                                 and exerts a                pressure (    30 mmHg)
Definition
Plasma Colloid Osmotic Pressure hinders the movement of FILTRATE into the BOWMAN'S CAPSULE and exerts a NEGATIVE pressure (-30 mmHg)
Term
What is Bowman's Capsular Hydrostatic pressure?
Definition
caused by the turbulence of filtrate into the Bowman's capsule
Term
BCHP interferes with       moving into the                      and exerts a              pressure (  15 mmHg)
Definition
Bowman's Capsular Hydrostatic Pressure interferes with FLUID moving into the BOWMAN'S CAPSULE and exerts a NEGATIVE pressure (-15 mmHg)
Term

Adding the pressures together yields the             

          , which determines the G          F          R          

Definition
Adding the pressures together yields the net filtration rate which determines the Glomerulular Filtration Rate
Term

      GCBP +      PCOP +     BCHP =     mmHg = 

                      

Definition
(+55 GCBP) + (-30 PCOP) + (-15 BCHP) = +10 mmHg = Net Filtration Pressure (NFP)
Term

- Which numbers of Net Filtration Pressure calculation contribute to filtration?

-which ones hinder filtration?

-As long as the value of NFP is           the process of filtration is           .

Definition

-positive ones contribute to filtration

-negative ones hinder filtration

- as long as the value of NFP is positive, the process of filtration is favored

Term
The       filtrate you have the        urine you will have and vice verssa
Definition
The MORE filtrate you have the MORE urine you will have and vice versa.
Term
Any          in any of the pressures will cause a corresponding            in GFR and vice versa
Definition
Any INCREASE in any of the pressures will cause a corresponding INCREASE in GFR and vice versa.
Term
What are the two mechanisms for regulation of Glomulular Filtration Rate?
Definition
Renal Autoregulation/myogenic, and tubulo-glomerular feedback mechanism
Term
What happens during Renal Autoregulation of the GFR?
Definition

1. vascular smooth muscle reflexively contracts after it has been stretched

 2. if blood is flowing through the afferent arteriole at a high rate/ high volume, the afferent arteriole will be stretched, then reflexively contract

Term
What does the afferent arteriole being stretched then reflexively constrict have an effect on?
Definition
Slows blood flow to the glomerulus, preventing GCBP from becoming too high, therefore preventing GFR from becoming too high
Term
A            in flow rate/volume in the              arteriole will cause it to          .
Definition
A decrease in flow rate/volume in the afferent arteriole will cause it to dilute.
Term
The decrease in flow rate/volume in the afferent arteriole causes....
Definition
increases blood flow to the glomerulus, preventing GCBP from becoming too low, therefore preventing GFR from becoming too low
Term
What is tubulo-glomerular feedback mechanism?
Definition
involves a structure in the nephron called the juxtaglomerular apparatus
Term
What type of cells is the Juxtaglomerular apparatus made of?
Definition

vascular cells

and

tubular cells

Term
What is another name for vascular cells? why?
Definition
granular cells because they contain renin granules
Term
How is the RENIN in the vascular cells in the juxtaglomerular apparatus used?
Definition
Renin is released when the cells sense a decrease in GFR; caused presumably by a decrease in systemic blood pressure
Term
Angiotensin II causes:
Definition

- constriction of the Efferent arteriole

- posterior pituitary to release ADH

- adrenal cortex to release aldosterone

Term
Constriction of the         arteriole,         back pressure in GLOM,           GCBP and           GFR
Definition
Constriction of the efferent arteriole, increase back pressure in GLOM, increasing GCBP and increasing GFR
Term
Angiotensin II causes posterior pituitary to release    , increasing       reabsorption at the level of the collecting duct and the                         ,         blood volume, BP, GCBP, and     .
Definition
Angiotensin II causes posterior pituitary to release ADH, increasing water reabsorption at the level of the collecting duct and the distal convoluted tubule, increasing blood volume, Blood pressure, glomerulular capillary blood pressure, and glomerulular filtration rate
Term
Angiotensin II causes                to release             increasing     reabsorption,            water reabsorption at the colecting duct and distal convoluted tubule,          blood volume, BP, GCBP, and GFR.
Definition
Angiotensin II causes adrenal cortex to release aldosterone, increasing water reabsorption, at the collecting duct and distal convoluted tubule, increasing blood volume, blood pressure, glomerulular capillary blood pressure, glomerulular filtration rate.
Term

1. What is another name for tubular cells?

2. What do tubular cells do?

Definition

1. macula densa

2. sense the rate of NaCl flow

Term
If rate of NaCl flow is high, the tubular cells release              
Definition
if rate of NaCl flow is high the tubular cells release endothelin
Term
What happens after the release of endothelin cause by high rate of NaCl flow?
Definition
afferent arteriole constricts, decreasing blood flow to the GLOM, decreasing GCBP, and decreasing GFR
Term
If NaCl flow rate is low (GFR IS NEGATIVE), the tubular cells release                   
Definition
If rate is low (GFR IS NEGATIVE), the tubular cells release Brady Kinin
Term
What happens after Brady Kinin is released due to a low rate of NaCl flow?
Definition
Afferent arteriole dilates, increasing blood flow to GLOM, increasing GCBP, increasing GFR
Term
What is reabsorption?
Definition
movement of valuable substances out of the filtrate within tubules and into the blood of the peritubular capillaries
Term

- What is Na+ reabsorption?

- Process is driven by a    /                . The        is located on the              surface of the tubule epithelial cells

Definition

-80% of the ATP needed by the kidneys is used for actively reabsorbing Na+

- the process is driven by a Na+/K+ ATPase pump. The pump is located on the BASOLATERAL surface of the tubule epithelial cells

Term

Na+ reabsorption

(picture)

Definition
[image]
Term
What role do Cl- and HCO3 play in reabsorption?
Definition

Cl- and HCO3 are reabsorbed following electrical gradients

- they maintain electrical neutrality in plasma and filtrate

Term
What happens to the non-reabsorbed substances?
Definition
there is a high concentration of non-reabsorbed substances in the urine, which are either too large to be reabsorbed or don't have the specific carrier proteins
Term
What are the specific carrier proteins?
Definition
urea, creatine, and uric acid
Term
What are the specific TUBUlar regions of reabsorption?
Definition
Proximal convoluted tube, loop of henle, distal convoluted tube, collecting duct
Term
What is reabsorbed in PCT?
Definition

Proximal Convoluted Tube

-all glucose and amino acids

-a majority of H2O, Na+, HCO3-, Cl-, K+

Term
What is reabsorbed in Loop of Henle?
Definition

some Na+, Cl-, and K+ at ascending loop of henle (salts)

some H2O at descending loop of Henle

Term

- What does reabsorption in the distal convoluted tubule and collecting duct depend on?

- what does it target tissues for?

Definition

- what the body needs and circulating hormone levels

- ADH and Aldosterone

Term

Distal Covoluted tubule, and Collecting Duct

(picture)

Definition
Term
What is secretion?
Definition
movement of substances (not needed) from the blood in the peritubular capillaries and into the filtrate in the tubular lumen
Term

Secretion of    is important in maintaining pH.

Where does secretion of this occur?

What does the secretion of this depend on?

Definition

Secretion of H+ is important in maintaining pH.

- it occurs at proximal convoluted tubule, distal convoluted tubule and collecting duct

- it depends on the acidity of BODY FLUIDS

Term

if the body fluids are:

too acidic =            secretion of H+

too basic =             secretion of H+

Definition

too acidic = increase secretion of H+

too basic = decrease secretion of H+

Term

K+

- where it is secreted from?

- what it does?

Definition

- active secretion in distal convoluted tubule and collecting duct

- coupled to Na+ reabsorption via the Na+/K+ ATPase pump at the basolateral surface of the tubule epithelial cells

Term
How is K+ used?
Definition

coupled to Na+ reabsorption via the Na+/K+ ATPase pump at the basolateral surface of the tubule epithelial cells

 

Term
What effect does aldosterone have on K+ reabsorption?
Definition

Aldosterone alters the rate of K+ secretion at the same time it alters the rate of Ha+ reabsorption

 

INCREASE in ALDOSTERONE = INCREASE in Na+

reabsorption = increase in K+ secretion

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