Urinary System Flashcards
What are the three basic steps to urine formation?
filtration, reabsorption, secretion
filtration, reabsorption, secretion
What is filtration?
- blood in the glomerulus is filtered through to the Bowman’s capsule. Filtration is across a highly selective filtration membrane
What is the filtration membrane made of?
endothelium of the glomerulus and epithelium of the Bowman’s capsule, it does not allow the passage of blood cells or large proteins
What is the filtration membrane made of?
What does it not allow the passage of?
- endothelium of the glomerulus and epithelium of the Bowman’s capsule,
- it does not allow the passage of blood cells or large proteins
What is reabsorption?
valuable substances are reclaimed from the filtrate and returned to the general circulation via the peritubular capillaries/vasa recta
Where does reabsorption mostly occur?
in the proximal convoluted tubule
What is prevented from being lost as waste?
water, glucose, salt, an amino acids
What is secretion?
the movement of substances from the blood (in peritubular capillaries/vasa recta) into the filtrate in the tubular lumen
Where does secretion mostly occur?
occurs mostly at the DISTAL convoluted tubule and the COLLECTING DUCT
What does secretion allow for?
allows for the elimination of substances from the blood that wasn’t filtered through the glomerulus
What three pressures affect the filtering process?
glomerular capillary blood pressure,
plasma colloid osmotic pressure,
bowman’s capsular hydrostatic pressure
What is Glomerular capillary blood pressure (GCBP)?
fluid pressure exerted by the blood within the glomerulus, pushes fluid and solutes across the filtration membrane
The GCBP is ___a_____ pressure that ____b_____ filtration ( 55Hg)
a. POSITIVE
b. FAVORS
What is Plasma Colloid Osmotic Pressure?
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
PCOP hinders the movement of __a______ into the _______b______ and exerts a _______c________ pressure ( 30 mmHg)
a. FILTRATE
b. BOWMAN’S CAPSULE
c. NEGATIVE
What is Bowman’s Capsular Hydrostatic pressure?
caused by the turbulence of filtrate into the Bowman’s capsule
BCHP interferes with ___a___ moving into the __b___ and exerts a ___c___ pressure ( 15 mmHg)
a. FLUID
b. BOWMAN’S CAPSULE
c. NEGATIVE
Adding the pressures together yields the __________ , which defines the G—– F —- R—-
net filtration rate which defines the Glomerulular Filtration Rate
GCBP + PCOP + BCHP = mmHg =
(+55 GCBP) + (-30 PCOP) + (-15 BCHP) = +10 mmHg = Net Filtration Pressure (NFP)
a - Which numbers of Net Filtration Pressure calculation contribute to filtration?
b. which ones hinder filtration?
c. As long as the value of NFP is the process of filtration is .
a-positive ones contribute to filtration
b-negative ones hinder filtration
c- as long as the value of NFP is positive, the process of filtration is favored
The __a___ filtrate you have the __b___ urine you will have and vice verssa
a. MORE
b. MORE
Any__a___ in any of the pressures will cause a corresponding __b___ in GFR and vice versa
a. INCREASE
b. INCREASE
What are the two mechanisms for regulation of Glomulular Filtration Rate?
- Renal Autoregulation/myogenic,
2. tubulo-glomerular feedback mechanism
What happens during Renal Autoregulation of the GFR?
- vascular smooth muscle reflexively contracts after it has been stretched
- if blood is flowing through the afferent arteriole at a high rate/ high volume, the afferent arteriole will be stretched, then reflexively contract
The decrease in flow rate/volume in the afferent arteriole causes….
it to dilute.
What is tubulo-glomerular feedback mechanism?
involves a structure in the nephron called the juxtaglomerular apparatus
What type of cells is the Juxtaglomerular apparatus made of?
vascular cells
and
tubular cells
What is another name for vascular cells? why?
granular cells because they contain renin granules
How is the RENIN in the vascular cells in the juxtaglomerular apparatus used?
Renin is released when the cells sense a decrease in GFR; caused presumably by a decrease in systemic blood pressure
Angiotensin II causes:
- constriction of the Efferent arteriole
- posterior pituitary to release ADH
- adrenal cortex to release aldosterone
Constriction of the __a___ arteriole, __b___ back pressure in GLOM,__c___ GCBP and__d___ GFR
a. efferent
b. increase
c. increasing
d. increasing
Angiotensin II causes posterior pituitary to release ___a___ , increasing __b___ reabsorption at the level of the collecting duct and the __c___ , __d___ blood volume, BP, GCBP, and .
a. ADH,
b. water
c.
d. increasing
Angiotensin II causes a to release b increasing c. reabsorption, d water reabsorption at the collecting duct and distal convoluted tubule, e blood volume, BP, GCBP, and GFR.
a. adrenal cortex
b. aldosterone,
c. water reabsorption,
d. increasing
- What is another name for tubular cells?
- macula densa
- What do tubular cells do?
of NaCl flow
If rate of NaCl flow is high, the tubular cells release
endothelin
What happens after the release of endothelin cause by high rate of NaCl flow?
afferent arteriole constricts, decreasing blood flow to the GLOM, decreasing GCBP, and decreasing GFR
If rate is low (GFR IS NEGATIVE), the tubular cells release
Brady Kinin
What happens after Brady Kinin is released due to a low rate of NaCl flow?
Afferent arteriole dilates, increasing blood flow to GLOM, increasing GCBP, increasing GFR
What is reabsorption?
movement of valuable substances out of the filtrate within tubules and into the blood of the peritubular capillaries
What is Na+ reabsorption?
-80% of the ATP needed by the kidneys is used for actively reabsorbing Na+
- Process is driven by a / . The is located on the surface of the tubule epithelial cells
Na+/K+ ATPase pump.
pump
BASOLATERAL
What role do Cl- and HCO3 play in reabsorption?
Cl- and HCO3 are reabsorbed following electrical gradients
- they maintain electrical neutrality in plasma and filtrate
What happens to the non-reabsorbed substances?
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
What are the specific carrier proteins?
urea, creatine, and uric acid
What are the specific TUBUlar regions of reabsorption?
Proximal convoluted tube, loop of henle, distal convoluted tube, collecting duct
What is reabsorbed in PCT?
Proximal Convoluted Tube
What is reabsorbed in Loop of Henle?
some Na+, Cl-, and K+ at ascending loop of henle (salts)
some H2O at descending loop of Henle
- What does reabsorption in the distal convoluted tubule and collecting duct depend on?
- what does it target tissues for?
- ADH and Aldosterone
Distal Covoluted tubule, and Collecting Duct
What is secretion?
movement of substances (not needed) from the blood in the peritubular capillaries and into the filtrate in the tubular lumen . Secretion of is important in maintaining pH
Where does secretion of this occur?
What does the secretion of this depend on?
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 if the body fluids are: too acidic = secretion of H+ too basic = secretion of H+ too acidic = increase secretion of H+ too basic = decrease secretion of H+
K+
a- where it is secreted from?
b- what it does?
a- active secretion in distal convoluted tubule and collecting duct
b- coupled to Na+ reabsorption via the Na+/K+ ATPase pump at the basolateral surface of the tubule epithelial cells
How is K+ used?
coupled to Na+ reabsorption via the Na+/K+ ATPase pump at the basolateral surface of the tubule epithelial cells
What effect does aldosterone have on K+ reabsorption?
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
