Flashcards in Lecture #15: Micturition and Glomerular Filtration Deck (56)
What are the 2 different conduction paths of sensory signals from bladder stretch receptors?
1) conducted to sacral region of spinal cord via pelvic nerves.
2) conducted reflexively back to bladder via parasympathetic nerves.
As the bladder continues to fill, micturition reflexes occur more often and are more powerful. Once the micturition reflex is powerful enough, it causes a second reflex. What is the second reflex and what does it do?
The second reflex passes through the pudendal nerves to inhibit the external sphincter.
The nephrons function to get rid of waste materials. What are the 4 waste products secreted?
How does the nephrons function to regulate arterial pressure long term?
By excreting variable amounts of sodium ion and water.
How does nephrons function to regulate arterial pressure short term?
Secrete hormones and vasoactive factors such as renin.
What do all of the many functions of nephrons regulate within the body?
> Get rid of waste materials
- urea, creatinine, uric acid, bilirubin
> Regulate water and electrolyte balance
> Regulate body fluid osmolarity
>Regulate arterial pressure
- Long Term
*excrete variable amounts of sodium ion and water
- Short Term
* Secrete hormones and vasoactive factors such as renin
>Regulate acid-base balance
- excrete acids and regulate body fluid buffer stores
- eliminate sulfuric and phosphoric acids
>Secretion, Metabolism, and Excretion of Hormones
- active form of vitamin D
What is the formula to calculate urinary excretion rate?
Filtration Rate - Reabsorption Rate + Secretion Rate
What is the first step in urine formation?
What components make up the glomerular filtrate?
What formula is used to calculate filtration fraction?
Filtration Fraction = GFR/Renal Plasma Flow
* fraction of renal plasma flow that is filtered = 0.2
(i.e., 20% of plasma flowing through kidney is filtered).
True or False:
The concentration of most substances except for proteins is the same in the filtrate and the plasma.
What forms the slit filtration barrier?
* with negative charges
True or False:
The endothelium and basement membrane layers of the filtration barrier have a negative charge and the podocytes of the filtration barrier have a neutral charge.
False - The endothelium, basement membrane, and podocytes of the filtration barrier all have a negative charge.
Albumin is smaller in size then the slit pores made by the podocytes, but why does it not freely pass through?
Because of the negative charge.
In which portion of the filtration barrier are fenestre found?
Does the endothelium, basement membrane, or podocytes of the filtration barrier have the strongest negative charge?
What determines the glomerular filtration rate (GFR)?
> the balance of hydrostatic and colloid osmotic forces acting across the capillary membrane
> capillary filtration coefficient
- product of permeability and filtering surface area of capillaries
What are 2 diseases that can lower glomerular capillary filtration coefficient?
> Chronic un-controlled hypertension
> Diabetes mellitus
What is the definition of minimal change nephropathy?
When the basement membrane losses negative charges.
What is hydronephrosis?
Distension and Dilation of Renal Pelvis and Calyces.
True or False:
Reflex contractions relax spontaneously when the bladder is only partially filled.
How do you calculate glomerular filtration rate (GFR)?
GFR = (K1) x (Net Filtration Pressure)
*Net Filtration Pressure is the Starling Forces
(Pg - Pb - PIEg + PIEb)
(60 - 18 - 32 + 0) = 10 mmHg
K1 = GFR/Net filtration pressure
= 125 ml/min / 10 mmHg = 12.5 mmHg
What effect does increase the K1 have on GFR?
It raises GFR
What effect does lowering K1 have on the GFR?
It reduces GFR
True of False:
Some low-molecular weight substances are not freely filtered because they are partially bound to proteins.
What is the K1?
K1 = capillary filtration coefficient
*product of permeability and filtering surface area of capillaries.
What are 2 factors that influence glomerular capillary colloid osmotic pressure?
1) arterial plasma colloid osmotic pressure
2) filtration fraction
What is a factor that increase glomerular colloid osmotic pressure?
Increasing Filtration Fraction
What effect does increasing arterial pressure have on glomerular hydrostatic pressure and thus, GFR?
An increase in arterial pressure will increase the Pg (glomerular hydrostatic pressure), and thus, will increase the GFR.