Test 2: Lecture 18: Urinary Flashcards
what do the kidneys and associated urinary passages do?
- Filter blood
- Recover useful metabolites
- Remove wastes
- Transport fluid wastes
kidneys regulate
•Regulate fluid volume
Regulate acid/base balance
Regulate electrolyte composition
kidneys secrete which two hormones
renin and erythropoietic factor
kidneys play a role in metabolism of ___
calcium
the kidney removes waste specifically ___ and other metabolic wastes
nitrogenous
the kidney regulates contributes to the regulation of ___(Na+, Cl-, Ca2+, and PO43-, etc.),
electrolyte composition
renin is secreted by the kidney and is __
a molecule which contributes to the regulation of blood volume and pressure
the kidney secretes erythropoietic factor which ___
which stimulates RBC production
The kidney activates ___ that play a role in calcium regulation
vitamin D
stages of development of the kidney
pronephros, mesonephros, metanephros
Metanephros has two origins:
•Metanephric duct gives rise to the collecting ducts, the calyces, the pelvis and the ureters
•Metanephric blastema (aka metanephrogenic mesenchyme) gives rise to the nephrons
___ gives rise to the collecting ducts, the calyces, the pelvis and the ureters
•Metanephric duct
___ (aka metanephrogenic mesenchyme) gives rise to the nephrons
•Metanephric blastema
•Urogenital sinus and the allantoic stalk give rise to the ___ (and other structures)
urinary bladder
•The reproductive system’s development is closely associated with the
urinary system.
the ___ is the definitive kidney in frogs
mesonephros
mammalian kidneys can be ___ or ___
unilobed (carnivores, horses, small ruminants)
multilobed (swine, large ruminants)
The outer part of the kidney is called the ___
cortex
the center of the kidney where urine is collected is called the ___
renal pelvis
Kidneys receive about ___ of the cardiac output per minute.
20 to 25%
About 90% of the blood in the kidney is found in the ___
cortex
The cortex contains the ___ (glomeruli and Bowman’s capsules), the proximal convolutes tubules, the ___convolutes tubules and parts of both the Loops of __ and collecting ducts.
renal corpuscles
distal
Henle
The medulla of the kidney contains parts of both the ___ and the collecting ducts.
Loops of Henle
what is found in the medulla of the kidney
- contains parts of both the Loops of Henle and the collecting ducts.
what is found in the cortex of the kidney
the renal corpuscles (glomeruli and Bowman’s capsules)
the proximal convolutes tubules
the distal convolutes tubules
parts of both the Loops of Henle and collecting ducts.
a kidney has a ___ layered capsule made of :
three
connective tissue (fibrous)
adipose
connective tissue (fibrous)
The kidneys have compound tubular gland composed of ___ tubules
uriniferous
Cortex of the kidney contains the __ (cortical labyrinth) and the __ (medullary rays)
pars convoluta
pars radiata
The medulla has cone shaped ___whose broad base contacts the cortex. One or more pyramids join to form a ___ whose rounded, apical portion projects into the ___
pyramids
papilla
calyx.
___ (when present) are continuous with the pelvis which is continuous with the ureter.
calyces (calyx)
branches before the renal pelvis, only in multilobar kidneys
another name for cortical labyrinth
(pars convoluta)
another name for pars radiata
medullary rays
part of the cortex between the pyramids of the medulla in the kidney
columns
pathway of blood in kidney
label the arteries
blood vessels of the kidney
- The blood supply to the kidney is as follows. Blood enters the kidney at its hilum via the renal arteries. The renal arteries branch to form segmental arteries, which branch to form the lobar/interlobar arteries. At the corticomedullary junction, the interlobar arteries branch to form the arcuate arteries (which run in the same direction as the junction). The arcuates branch into the interlobular arteries. The interlobular arteries branch to form the many afferent arterioles. These enter the capillary bed of the glomerulus. The capillary bed leads to the efferent arterioles which branch into the peritubular capillaries or the vasa recta. Venous drainage is via companion vessels. There are also lymph vessels which drain the capsule and the medulla.
blood flow in kidney from interlobular artery to interlobular vein
interlobular artery
afferent arteriole
glomerulus
efferent arteriole
peritubular capillary or vasa recta
interlobular vein
vasa recta
glomerulus→ efferent arteriole→
capillary bed when closer to the cortical-medullary junction (in the medulla)
if closer to the capsule of the kidney will go into the peritubular capillary instead (in the cortex)
glomerulus has ___ capillaries
fenestrated
blood of the kidney will go into the pertitubular capillary when it it closer to the ___
capsule of the kidney
oxygen and carbon dioxide exchange occurs where in the kidney
peritubular capillary
vasa recta
nephron is made of:
cortex:
•Renal Corpuscle (Glomerulus and Bowman’s Capsule)
•Proximal Convoluted Tubule
part of the Loop of Henle
medulla
most of the loop of Henle
•Distal Convoluted Tubule
multiple distal convoluted tubules form together to make the ___
collecting tubule (duct)
what is special about the blood flow of the kidney
arteriole → capillaries → arteriole → capillaries → venule
usually arteriole → capillary → venules
parietal layer of the bowmans capsule is what cell type
simple squamous
(outer layer)
the visceral layer of the bowmans capsule is what cell type
inner layer of bowmans capsule: surrounds glomerulus
podocytes extends false foot and connects to capillary bed (glomerulus)
the proximal convoluted tubule is made of what type of cells?
7 times longer then distal convoluted
cuboidal epithelium
but look columnar due to microvilli, pink
microvilli→ increases surface area = absorption
loop of henle is made of
simple squamous(descending) into simple cuboidal (ascending)
descending limb and ascending limb (dips from cortex past the arcuate vessels into the medulla, then back up into the cortex)
why does the loop of henle have different cell types in the descending vs ascending limbs?
simple squamous(descending) → simple diffusion
into simple cuboidal (ascending) → active transport
distal convoluted tubule has what type of cells
cuboidal
shorted then proximal convoluted tubules, smaller microvilli, less pink
very circular tubes
in the cortex of the kidney
the distal convoluted tubule is found in the __
cortex
will sandwich between the afferent and efferent arteriole of the glomerulus in the vascular pole
___ are composed of glomeruli and Bowman’s capsules
Renal corpuscles
The metanephric kidney is a compound ___ gland
tubular
- The ___include the proximal convoluted tubules, the Loops of Henle, and the distal convoluted tubules.
secretory tubules
the peritubular capillary wraps around the ___ in the ___
proximal and distal convoluted tubules
cortex of the kidney
the vasa recti wrap around the ___ in the ___
loops of henle
medulla of the kidney
The ___ is a circular structure surrounding the glomeruli
Bowman’s capsule
3 parts of the bowmans capsule
the podocytes are the visceral layer (closest to the capillaries and very difficult/impossible to see with a light microscope),
the urinary space
the simple squamous cells of the parietal (peripheral) layer.
The ___ tubule is the longest (7x longer than the average distal convoluted tubule dct), widest, most developed part of the tubule.
proximal convoluted
The distal convoluted tubule, the glomeruli and Bowman’s capsules are found in the ___ of the cortex
pars convoluta
The cells of the dct are more cuboidal and less acidophilic than the pct cells. less acidophilic = __
less pink
The collecting duct can be seen in the ___ of the cortex and in the medulla.
pars radiata
the cells of the collecting duct are
tall cubes and this lumen tends to be larger than the rest.
The very beginning of the distal convoluted is looped back and is positioned at the ___ between the afferent and efferent arterioles.
vascular pole
The macula densa is located where?
at the vascular pole between the afferent and efferent arterioles
The glomerulus of a __ nephron is closer to the capsule and the loop of Henle is much shorter as compared to the __ nephrons
cortical
medullary
- In some classes of vertebrates like aves, the cortical and medullary nephrons’ glomeruli are ___ in size, and the ___ nephrons basically lack a loop of Henle entirely.
very different
cortical
___ nephrons have very long loops of henle and the glomerulus is closer to the cortex-medulla junction
juxtamedullary nephron
filtration in the glomerulus happens by ___
pressure and size, anything smaller than albumin
three processes of the kidney
filtration
reabsorption
secretion
filtration in the kidney
pressure and size
anything smaller then albumin gets pushed from the blood into the tubules
occurs in the glomerular capillary bed
reabsorption of the kidney
returns 99% of substances back into interstitial fluid → into blood
happens in the renal tubules, proximal convoluted tubules, loop of henle, distal convoluted tubules and collecting ducts
active and passive transport
essential molecules are taken back
secretion of the kidney
selective process whereby toxic substances and waste products (that were too large to be filtered by the glomerular capillaries) are moved from the blood into the filtrate
happens in renal tubules and collecting ducts
hormonally controlled
glomerular filtration has a __ part barrier
3 part filtration barrier
non specific, pressure and size
If a molecule is small enough, and either neutral or positively charged, it can enter the filtrate.
Blood leaves the vascular side (pole) of the glomerulus via the ___ arteriole
efferent
Bowman’s capsule
•The parietal layer, a simple squamous epithelium, associated with the connective tissue stroma (1)
A urinary space between (2)
Glomerulus (3)
Proximal convoluted tubule (1)
Distal convoluted tubule (2)
Duct in Pars Radiata of Cortex
Thick Descending Loop of Henle (1)
Thick Ascending Loop of Henle (2)
Collecting Duct (3)
medulla of kidney
Thick Descending Loop of Henle (1)
Thick Ascending Loop of Henle (2)
Collecting Duct (3)
vasa recta (4)
3 layers of filtration barrier in kidney
arterioles have fenestrations (capillary endothelium)
protein layer (basement membrane)
podocytes have filtration slits
why monitor albumin levels in urine
albumin should not be filtered, should not fit out
if it is filtered body does not have a way to reabsorb it and the albumin is lost in urine
this can happen by Glomerular nephritis tends to cause the fenestrations to stretch/enlarge
Glomerular ___ tends to cause the fenestrations to stretch/enlarge
nephritis
albumin leaves in urine
Glomerular sclerosis
has multiple causes (it can even be genetic). It promotes a hardening of the basement membrane. This will reduce filtration and can lead to death.
what is secreted in the PCT
what is reabsorbed in the loop of henle descending loop
h2O
what is reabsorbed by the ascending loop of henle
Na
K
Cl
What is reabsorbed by the DCT
Na
Cl
HCO3
H20
calcium
what is secreted by the DCT/ collecting duct
H+
K+ (potassium)
NH4
what is reabsorbed by the collecting tube?
water and urea
hormone regulated
reabsorption of __ in the ascending branch will create higher concentrations in the blood, this will cause __ to leave the decending loop of henle by __ to even out the concentration
NaCl (salt)
water
osmosis (passive)
(body doesn’t like high salt will try to add water to balance it out)
cells are taller in the ascending limb of the loop of henle because
they actively transport NaCl out of substrate back into blood
(need bigger cell for rER, golgi and ATP)
increased pressure in the glomerular capillary =
decreased pressure =
filter faster (too fast can not reabsorb essential things)
filter slower (too slow things build up in blood, toxic)
NFP= ___ -___
net filtration pressure= Pressure that promotes filtration – opposing pressures
= (HP blood glom caps) – (HP capsule + OP blood glom caps)
it is the ___ within the glomerular capillaries that promotes filtration. Control the blood pressure in the capillaries to control the GFR
blood pressure
two ways of renal autoregulation of GFR
- Myogenic mechanism
- Tubulo-glomerular feedback
the wall of the ___ arteriole is thicker then the wall of the ___ arteriole in the glomerulus
afferent (granular cells that can contract)
efferent
when blood pressure is too high in the body the afferent arteriole will ___
close, tighten making the pressure in the capillary bed of the glomerulus lower (normal pressure)
acute increased body BP will not cause damage to the capillary bed, long term increased BP may cause damage, diabetes= less working nephrons
the distal convoluted tubules have a line of cells closest to the glomerulus that sense sodium. These cells are called ___
macula densa
macula densa will determine sodium concentration
too much sodium =
too little sodium=
filter too fast, can’t reabsorb
filter too slow, sodium still in blood instead of leaving into nephrons (not cleaning/balancing)
the ___ which sense NaCl will communicate with the ___ to change speed of filtration in the golmerulus
macula densa
afferent arteriole
hormone EPO
made in the kidney
target organ: red bone marrow
effect: make more RBCs
Body wide effect: increased hematocrit
angiotensin II
kidney’s renin involved in its formation
made in liver (angiotensinogen)
target organ: tunica media of arterioles
effect: muscle contracts (vasoconstriction)
Body wide effect: increased blood pressure
aldosterone
kidney’s renin encourages its release
made in adrenal cortex
target organ: kidney
effect: reabsorb salt which encourages the reabsorption of water= do not urinate a lot
Body wide effect: increased blood pressure
ADH (vasopressin)
made in hypothalamus
target organ: kidney
effect: reabsorb water= do not urinate a lot
Body wide effect: increased blood pressure
- A solute being reabsorbed can take one of two routes:
paracellular (between the lining cells)
transcellular (through the lining cells).
Solvent (water) reabsorption can be ___ (about 90% of the water in the filtrate is absorbed in this manner; the water must follow the ___) or ___ (about 10% of the water in the filtrate is absorbed under the influence of __).
obligatory(passive) - solutes
facultative- ADH
what is reabsorbed and secreted in the proximal convoluted tubules
-
Reabsorption
- 65% of the filtrate volume is reabsorbed
- Na+, HCO3-, and other ions
- Glucose, amino acids, some vitamins, and other nutrients
-
Secretion
- H+ and NH4+ ions
- Some drugs
what is reabsorbed and secreted in the loop of Henle
- Reabsorption
- Na+ (also K+ and Cl-) in the ascending loop
- H2O in the descending loop
no secretion
what is reabsorbed and secreted in the distal convoluted tubule
- Reabsorption
- Na+ regulated by aldosterone (Cl- follows)
- Ca+2 regulated by PTH (parathyroid hormone)
- Secretion
- K+ regulated by aldosterone
what is reabsorbed and secreted in the collecting duct
- Reabsorption
- H2O regulated by ADH (Antidiuretic hormone)
- Na+ regulated by aldosterone (Cl- follows)
- Urea increased by ADH
- Secretion
- K+ regulated by aldosterone
The filtrate within the loop of henle is ___ as it flows through the descending limb of the loop, and then becomes more ___ as it flows through the ascending limb
concentrated
dilute
Myogenic Mechanism
granular cells in afferent arterioles contract or expand to control pressure into the glomerulus
contract = less pressure into capillary
This mechanism prevents an increase in the systemic blood pressure from increasing the hydrostatic pressure within the glomerulus which would have raised the GFR.
The Tubuloglomerular Feedback Mechanism
The macula densa cells of the distal convoluted tubule have apical receptors for sodium ions. tell granular cells of the afferent arteriole to contract or open
too much sodium= too fast= too much pressure= can not reabsorb
too little sodium= too slow= low pressure= toxins stay in blood instead of being pushed out
juxtaglomerular cells
granular cells (contract or open to control GFR and secrete hormones)
hormone that causes blood pressure to increase
angiotensin II
When blood pressure decrease, the walls of the afferent arterioles are stretched less and the granular cells (juxtaglomerular cells) secrete renin. It encourages the formation of angiotensin I from angiotensinogen (a plasma protein produced by the liver). Angiotensin I is converted to its active form, angiotensin II (by angiotensin converting enzyme). It causes arteriole constriction which raises blood pressure.
how does angiotensin work?
low blood pressure causes granular cells to secrete renin, which causes angiotensinogen to form angiotensin I. Angiotensin I + angiotensin converting enzyme= angiotensin II which raises blood pressure by causing arterioles to contract
what hormone helps with water retention in the collecting ducts
antidiuretic Hormone (ADH)
which hormone tells the kidney to reabsorb salt?
aldosterone
what hormone increases the number of circulating blood cells?
erythropoietin (EPO)
path of urine
The urine released at the openings of the papillary ducts flows from the calices and the pelvis into the ureters and then to the urinary bladder. Peristaltic waves force the urine toward the bladder.
___ force the urine toward the bladder.
Peristaltic waves
The walls of the ureter and the urinary bladder contain folds (___)
rugae
The calices, pelvis, ureter and urinary bladder are lined by ___
transitional epithelium.
The epithelium, and lamina propria are surrounded by combined ___ of smooth muscle.
spiral and longitudinal layers
At the neck of the bladder, the muscle fibers form a ___
three-layered sphincter.
The urethra of the male has 3 components;
prostatic (transitional epithelium)
membraneous
penile (pseudostratified epithelium).
The female urethra begins as a ___ which changes to ___ toward its meatus.
transitional epithelium
stratified squamous
urinary bladder
ureter
___ have very long loops of henle and produce a very ___urine
desert mammals
concentrated
___ have short loops of henle and produce ___ urine
mammals in fresh water
dilute
___ have cortical nephrons and produce an ___ urine that is concentrated in the cloaca
reptiles
isotonic
___ have nephrons with cilia to sweep away large volumes of urine
freshwater fish
___ waste is correlated to Phylogeny and Habitat
Nitrogenous
___ is excreted by most aquatic animals, especially those living in fresh water. It is soluble but toxic in high concentrations
ammonia
___ is excreted by most mammals and most adult amphibians
urea
___ is less than ammonia / can concentrate it. It is produced in liver during metabolic cycles. Some is retained by kidney for ___
urea
osmoregulation
___ is excreted by insects, birds and reptiles
uric acid
__ is less soluble than ammonia and is pastelike. It is better than the other urea or ammonia, if embryo develops in a shell
uric acid
The calyces are actually lined on one side by the ___, and on the other by ___.
renal papillae
transitional epithelium
pars radiata
straighter sections where loops of henle and collecting ducts start
pars convoluta
part of kidney that is all “squigily” where the PCT and DCT are
medulla of kidney
- thick ascending loop of henle (cubodial round nucleus)
- thin loops of henle (descending) (thin cells, round buldging nucleus)
- vasa recta (should be next to loop of henle) thin cells, flat nucleus- squamous
