renal 1

Question 1

name the 5 functions of kidneys

Answer 1

1- maintains normal fluid volume in the body via regulating the loss of water in the urine

2- controls the concentrations of ions in the ECF by regulating how much is reabsorbed from the urine (Na, Cl, K..)

3- helps regulate ECF acid-base balance (pH) through reabsorption vs. secretion of H+ and HCO3-

4- eliminates nitrogenous metabolic end-products (urea, ammonia, uric acid) in the urine

5- eliminates drugs & foreign chemicals from body (which makes urinalysis such a powerful detection tool)

Question 2

all the functions of the kidney function through 3 basic mechanisms:

Answer 2

1- filtration: passive formation of the primary/raw urine

2- reabsorption: the active & passive conservation of substances from that primary urine back into body

3- secretion- the active transport of naturally occurring and foreign substances from the blood into the urine

Question 3

basic structure of the kidney: in longitudinal sections, has ___ layer and ___ layer

Answer 3

outer layer (renal cortex)
inner layer (renal medulla)

Question 4

what is the basic anatomical unit of the kidney? what does it consist of and how many?

Answer 4

nephron- about 1 million nephrons per kidney

nephron consists of glomerulus & tubular system

Question 5

___ is the filter of the kidney, it is a structure composed of ____ and is housed in a structure called ___

Answer 5

glomerulus
50 capillaries
Bowman’s capsule

Question 6

kidney is fed blood by the ___, which breaks down into smaller and smaller arteries, the ___ feeds blood into glomerulus

after blood is filtered, it leaves glomerulus by way of the ___, which breaks into second capillary bed called ____ that surround the rest of the nephron –> they reform into venules and veins that take blood away from kidney

Answer 6

renal artery
afferent arteriole

efferent arteriole
paratubular capillaries

Question 7

glomerulus acts as a filter, and like other capillary beds, filtration depends on interaction of a number of diff pressures…

Answer 7

pressure drives filtration of blood from capillary blood into Bowman’s capsule

Question 8

the driving force of glomerulus filtration is ___, and selectivity is done by ____

Answer 8

pressure
permeability of the glomerular membrane and the cells that surround it (based on the size of the pores that blood gets filtered into)

Question 9

glomerulus is like a strainer with fine mesh, it allows small things through, big proteins get excluded- want to get rid of ___, but the filtrate contains both that and a lot more of the substances that are necessary for normal physiological processes that body needs to conserve (_____), rest of nephron involved in processing this filtrate primary urine and reabsorbing the physiologically valuable components while allowing nitrogen wastes to be excreted

Answer 9

nitrogenous wastes
water, salts, glucose, amino acids

Question 10

describe the pathway of the complete nephron

Answer 10

blood filtered in glomerulus, bowman’s capsule –> primary urine filtrate passes thru proximal convoluted tubule –> Loop of henle (descending –> ascending) –> distal convoluted tubule –> empties into common collecting duct (multiple nephrons can empty into a single collecting duct)

Question 11

what is the functional unit of kidney

Answer 11

nephron + collecting duct

Question 12

efferent arteriole leaves glomerulus and breaks into capillary bed which forms a network of capillaries that surround the nephron and collecting duct, goes back into blood through ___…

Answer 12

paratubular network (vasa recta part of it)

Question 13

collecting ducts are arranged together in ____, all collecting ducts dump their fluids into ___, which dumps its fluid into the ___, which terminates into the ___ –> final urine then goes into ___ –> ___, then released from body through ___

Answer 13

renal pyramids (triangular shape)
minor calyx
major calyx
renal pelvis
ureter
bladder
urethra

Question 14

name the 2 types of nephrons

Answer 14

cortical nephron
juxtamedullary nephron

Question 15

cortical nephron: mostly found in the ___ of the kidney
name its 3 primary features

Answer 15

renal cortex
- short loop of Henle that protrudes slightly into renal medulla
- makes up 85% of nephrons of the kidney
- function primarily in bulk reabsorption of water and solutes (does the major lifting)

Question 16

juxtamedullary nephron is found where?
name its 3 primary features

Answer 16

glomerulus & tubule system are on the inside 1/3 of the cortex
- long loop of Henle that protrudes very deeply into the renal medulla (follows the collecting duct almost all the way down to renal pelvis)
- make up 15% of total nephrons
- main function is water reabsorption (concentrating urine to allow max water reabsorption)

Question 17

glomerulus functions as a filter (runs on pressure & selectivity is based on size), in order for fluid to get from glomerulus to Bowman’s capsule, it has to get through the filtration barrier:

Answer 17

3 layers
1- single endothelial layer of the capillaries (fenestrated capillaries- big pores, very permeable)
2- basal membrane (very permeable, there to just hold things together)
3- cellular layer of Bowman’s capsule made of a special cell type called podocyte (single layer of podocyte cell, has junctions called foot processes that project inward toward the fluid in Bowman’s capsule, the spaces in b/w foot processes are called filtration slits/pores, where a lot of the fluid just passes thru, whether the pores are/aren’t open depends on conformation of a protein complex in the pore)

Question 18

glomerular filtration runs on pressure…blood entering afferent arteriole produces some type of ___ pressure which drives filtration (__mmHg), lots of protein which established ___ pressure which pulls pressure back to ___mmHg –> now another pressure, Bowman’s capsule itself is filled with fluid…., this is the ___ pressure of Bowman’s capsule __mmHg –> net pressure is ____, this is the filtration pressure that drives fluid and small molecules across capillary beds into glomerulus

Answer 18

arterial hydrostatic pressure, 55mmHg
colloid osmotic pressure, 30 mmHg

there is back pressure on that fluid pushing on the capillaries which is the hydrostatic pressure of Bow, 15mmHg pushing back

net is 10 mmHg

Question 19

glomerular filtration is the _____ (about ___)

Answer 19

volume of blood filtered per unit time (180 L/day)
GFR is commonly measured parameter to check on health of kidneys

Question 20

name 3 markers used to measure kidney health

Answer 20

1- creatinine, produced by normal skeletal muscle metabolism- gets filtered by kidney, if it’s too high, something wrong with kidney (but creatinine not steady, changes with variables)

2- serum albumin- measured in urine, usually albumin is not filtered, so presence of it in the urine shows kidney/glomerular damage

3- Cystatin C- newer marker, much more stable compound, produced at steady rate and does not change with variables

Question 21

regulation of GFR, glomerular filtration occurs at ___ and ___

GFR is tightly regulated by 2 basic mechanisms:

Answer 21

low pressure, but high volume

intrinsic regulation & extrinsic regulation

Question 22

GFR intrinsic regulation has 3 subregulations:

Answer 22

myogenic regulation

tuboglomerular regulation

mesangial cell regulation

Question 23

intrinsic regulation of GFR, myogenic regulation: afferent arteriole is lined with ___, which is sensitive to the degree of ___ that occurs when incoming blood pressure changes (normally pressure in glomerulus is 55mmHg, if that goes up, ___ expands, sensed thru….

Answer 23

smooth muscle
stretch
smooth muscle expands, sensed thru stretch-activated calcium channels, calcium current crosses muscle and causes it to contract, that constricts diameter of arteriole, reduces pressure, and brings GFR back down to normal

constant adjustment of pressure to maintain constant GFR

Question 24

intrinsic regulation of GFR, tuboglomerular feedback involves new groups of cells in nephron, ___ cells are sensory cells that sense the concentration of ___ and ___ in the tubula fluid

Answer 24

macula densa cells
sodium & chloride

Question 25

intrinsic regulation of GFR, tuboglomerular feedback

macula densa cells belong to the ____, they sense concentration of Na & Cl in the fluid as it comes up from the ____, if concentrations reflect normal GFR, nothing happens –> if GFR increases due to increased BP –> filtration goes up…

Answer 25

juxtaglomerular complex
ascending loop of Henle

filter more Na & Cl, so conc is greater than normal –> sensed by macula densa cells and they secrete paracrines (ATP and adenosine) –> they act on the afferent arteriole to adjust vascular tone to bring BP back down to normal (low GFR results in vasodilation of afferent arterioles; high GFR results in vasoconsriction)

Question 26

intrinsic regulation of GFR, mesangial cell regulation

mesangial cell is like a ___, it wraps around the capillaries, they do what to the capillary?

Answer 26

modified smooth muscle
they can constrict a capillary or allow it to dialate (another way to control flow & pressure)

if GFR goes up b/c of pressure, mesangial cells detect it and squeeze down, cut off flow to capillaries and reduce GFR back down to normal