BIO 132 – Anatomy and
Physiology II
Study Outline
20.1. Overview of Renal Physiology:
a. The three basic processes performed by the nephron and collecting ducts are _____________________________, _______________________________, and ________________________________________.
b. The first step in urine production is ________________________________ involving the transfer of water and solutes from plasma to ____________________________________________.
c. As filtered fluid and solutes pass along the nephron, most of this material is returned to _______________________ or ____________________________ in a process called ______________________________________.
d. In addition, as fluid moves along the nephron, materials can be added to tubular fluid in a process called ____________________________________.
e. The excretion rate for any substance is equal to the _____________________ rate minus the _________________________________ rate plus the _____________________________ rate.
20.2. Glomerular Filtration:
a. Glomerular capillaries are specialized for filtration by __________________________________ than most capillaries, and are subject to higher __________________________________ than most capillaries
b. The filtration barrier excludes substances on the basis of __________________________ and ____________________________.
c. In general small molecules like water, ions, glucose and amino acids freely pass the filtration barrier so that their concentration in plasma is __________________________ to their concentration in the glomerular filtrate. By contrast, most _____________________________ are excluded from the filtrate and their presence in urine indicates a problem in glomerular filtration.
20.3. Net Filtration Pressure:
a. Glomerular filtration depends on three of the four _____________________ forces. Only _____________________________ is essentially zero because negligible amounts of protein are found in the capsular space (=space of Bowman’s capsule).
b. The glomerular hydrostatic pressure (GHP) is relatively ________________________ compared to other capillaries because of the series arrangement of glomerular capillaries between two high resistance arterioles. A typical value of GHP is ____________________________ compared to ______________________________ in most capillaries. Also unlike most capillaries, the GHP does not vary along the capillary length.
c. The hydrostatic pressure within the __________________________________ tends to oppose GHP, and so is called the ____________________________ (CHP). CHP is on the order of ___________________________________.
d. Like other capillaries filtration is opposed in glomerular capillaries by the ________________________________ (COP), attributable to the osmotic pressures exerted by plasma proteins
e. The net filtration pressure (NFP) can be calculated by subtracting the ____________________________________________ from the _________________________________________. Specifically the NFP is equal to _________________________ minus _________________________ minus _______________________________. Under typical conditions, NFP is positive on the order of _________________________ favoring filtration.
20.4. Glomerular Filtration Rate:
a. The glomerular filtration rate (GFR) is the amount of filtrate formed in all renal corpuscles of both kidneys per unit time. A typical GFR is on the order of _____________________________ L/day or when expressed per minute, ___________________________________.
b. It is important that GFR be maintained at a relatively constant value because if GFR were to become too high, certain substances would pass through the nephron _____________________ and thus be _______________________. Conversely, if GFR were to become too low, nearly all the filtrate might be ____________________________________ and so waste products will be _____________________________________.
c. GFR depends on _______________________________________________, ______________________________, and ____________________________. With respect to the net filtration pressure, an increase in blood pressure will __________________________________ GFR whereas a decrease in blood pressure will _____________________________ GFR.
20.5. Regulation of GFR:
a. There are three basic mechanisms which help maintain constant GFR: ______________________________, _______________________________, and _______________________________.
b. ____________________________ refers to the kidney’s ability to maintain a constant renal blood flow and GFR despite changes in systemic arterial pressure. Renal autoregulation takes the form of two distinct mechanisms called _____________________________ and ________________________.
c. As a result of the myogenic mechanism, an increase in blood pressure within the afferent arteriole will cause this vessel to __________________________ which in turn will cause GFR to ____________________________________. Conversely a fall in blood pressure will result in _______________________ of the smooth muscle of this vessel so that GFR _______________________.
d. As a result of tubuloglomerular feedback, an increase in GFR will result in a _______________________________ of the afferent arteriole so that GFR is reduced. The sensory input to this reflex involves increase flow of water and NaCl past the ______________________________ which in turn leads to the release of a ________________________________ substance.
e. GFR is also subject to extrinsic regulation in the form of _________________ regulation and _____________________ regulation.
f. At moderate levels of sympathetic stimulation, the afferent and efferent arterioles constrict to about the same extent so that GFR _________________. With higher levels of sympathetic stimulation, the afferent arteriole constricts ____________________ than the efferent so that GFR __________________.
g. Sympathetic input to JG cells results in an increase in ___________________ release.
h. The two hormones which affect GFR are ____________________________ and ____________________________. Angiotensin II causes both arterioles to _______________________ which results in a ____________________ in GFR. By contrast, ANP causes GFR to ____________________________ by acting on ______________________ cells causing them to relax and thereby increasing the capillary surface area available for filtration.