Lab Exam 3 Flashcards
The urinary system is composed of the
kidneys, ureters, urinary bladder, and the urethra.
The urinary system is constantly working to maintain the
purity and health of the body’s fluids by removing unwanted substances and recycling others.
The kidneys contribute to homeostasis by
regulating plasma composition through the elimination of metabolic wastes, toxins, excess ions, and water.
Three main metabolic waste products
(nitrogenous compounds), urea, uric acid, creatinine
urea
is formed by the breakdown of amino acids
Uric acid
is formed by the byproduct of breakdown of nucleic acids
Creatinine
is formed from the breakdown of a molecule known as creatine phosphate
Kidney function 1
Regulation of the volume, composition, and pH of the body fluids
Kidney function 2
Regulation of acid-base homeostasis (via the production of ammonia)
Kidney function 3
Regulation of energy metabolism via gluconeogenesis during fasting conditions
Kidney function 4
Regulation of plasma osmolarity through the control of aquaporin receptors within the collecting duct
Kidney function 5
Detoxification of metabolic wastes through excretory mechanisms
Kidney function 6
Conversion of vitamin D3 into its active form
Kidney function 7
Synthesis and conversion of important hormones such as erythropoietin and renin.
Kidneys are located in the
retroperitoneal space just behind the peritoneum of the abdominal cavity
Right and left kidney will be located on the
upper abdominal quadrant of the retroperitoneal space
Right kidney is located
a little slightly lower compared to our left kidney
Kidney maintains its shape and structure through its
fibrous capsule that’s located along the outside of the organ itself
Renal cortex is below
fibrous capsule. Lighter pink outer region and is where urine production can occur.
renal medulla or renal pyramid
Small, triangular-shaped, darker pink shapes found inside the kidney
Renal cortex and renal medulla will make up the
renal lobe
Renal papillae
Apex of the pyramid or point of the pyramid, at the very bottom of the pyramid
Renal columns
Between each renal medulla and renal pyramid, lighter pink regions. Maintain the integrity and shape or structure of the kidneys
Minor calyx
is where urine formation that found in the medulla will travel down into this minor calyx.
Major calyx
where urine travels to after the minor calyx, three major calyxes, will form together to form the regional pelvis
Hilus
indentation found on an organ that can contain blood supply and contain neural innervation. Will include the renal pelvis, renal artery, renal vein, and the renal plexus for innervation
Urine will travel through the
renal pelvis, down into the ureter, into the urinary bladder and then finally through the urethra
in renal blood flow, the
First five arteries will be our last five veins, but they’ll be inverted with each other
Renal blood flow
Renal artery -> Segmental artery -> Interlobar artery -> Arcuate artery -> Interlobular artery -> Afferent arteriole -> Glomerulus -> Efferent arteriole -> Peritubular capillaries -> Vasa recta -> Interlobular vein -> Arcuate vein -> Interlobar vein ->Segmental vein -> renal vein
Renal artery
branch off of the abdominal aorta and it’s going to be providing deoxygenated blood to the kidneys. Will travel through the hilum
Interlobar arteries travel through the
lobes of the medulla
Arcuate artery
form arches along the outside of the cortex
Interlobular arteries
form these small tree-branch like structures off of the arcuate arteries
Afferent arteriole
provides blood supply to the glomerulus
Efferent arteriole
exiting the glomerulus
Peritubular capillaries
surrounding the tubules, specifically the portions of the proximal convoluted tubule and the distal convoluted tubule
Vasa recta
will provide a blood capillary system that surrounds the loop of Henle
Interlobar veins
between lobes and medulla
Renal vein
enter into the inferior vena cava
The Nephron
The main functional unit of the kidney responsible for urine formation, Smallest functioning unit of the kidneys
Cortical nephron
found in the cortex, Shorter loops of Henle, About 80-85% of nephrons in humans
Shorter loops of Henle
produce more diluted urine
Juxtamedullary nephron
located adjacent to the medulla or next to the medulla, Longer loops of Henle that extend down the renal medulla, Only 15-20% of nephrons in humans
Longer loops of Henle that extend down the renal medulla
allow for more water reabsorption, will be able to produce much more concentrated urine
The nephron is composed of
Renal corpuscle = Bowman’s capsule + glomerulus. Renal tubule
Renal tubule with three distinct parts
Proximal Convoluted Tubule, Loop of Henle, Distal Convoluted Tubule
The nephron produces urine through three/four main interaction mechanisms:
Filtration, Reabsorption, Secretion, Excretion
Filtration
A filtrate of the blood leaves the kidney capillaries and enters the renal tubule. Will only occur at the glomerulus to produce an ultrafiltrate product
Filtration definition
the movement of water and plasma solutes through the glomerular capillary walls into the urinary space of the Bowman’s capsule.
Reabsorption
Most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood. Most reabsorption will occur at the proximal convoluted tubule
Reabsorption definition
when a substance is transported from the filtrate, through the tubular cell membrane walls, and eventually into systemic circulation
Secretion
Certain substances are secreted from the blood into the filtrate product to be eliminated. Can occur in the proximal convoluted tubule.
Secretion definition
a substance is transported from peritubular blood vessels into the filtrate product, which will ultimately form urine
Excretion
Process of eliminating or expelling waste matter through the final excretory product, urine
Glomerular filtration is where we see
podocytes, forming our internal wall of the glomerulus and this is what helps make it a more structured area to not allow certain products to move out and for only smaller substances to move out the area or out of the bloodstream
When podocytes are formed, there are extensions called
pedicles. Pedicles will form filtration slits in the area which will allow filtrate to leave the capillaries and actually enter into Bowman’s capsule
The endothelium of these capillaries are
very porous
The endothelium of these capillaries allow
fluid, waste products, ions, glucose, and amino acids to pass from the blood into the capsule.
Glomerular Filtration blocks out
bigger molecules like blood cells and proteins so they stay in the blood and exit through the vasa recta.
hematuria
red blood cells being present in the urine
albuminuria
albumin being present in the urine
Glomerular Filtration Rate (GFR)
volume of filtrate produced by both kidneys per minute. Physiological indicator of renal function
Glomerular filtration is determined by
Starling’s pressures
Proximal Convoluted Tubule (PCT) cell walls are made up of
cuboidal epithelial cells containing mitochondria to power pumps that pull sodium ions from the filtrate using active transport
the microvilli in Proximal Convoluted Tubule (PCT)
increase surface area to help reabsorb as much of the “good stuff” as possible
The vast majority of renal reabsorption occurs in the
proximal convoluted tubule
renal reabsorption is approximately
67% of sodium and 67% of water
The coupled sodium and water reabsorption is
proportional to each other (isosmotic). This mechanism is essential for the maintenance of the chemical integrity of the extracellular fluid composition and general homeostasis
In a healthy individual there will be
~100% reabsorption of glucose
When plasma glucose is below 200 mg/dL
most if not all filtered glucose is reabsorbed
Renal threshold for glucose
200 mg/dL
In diabetes mellitus, if its left untreated,
individuals can present with ketonuria or ketones being present in the urine due to the breakdown of fatty acids for energy
If the blood glucose concentration is higher than 200 mg/dL but lower than 350 mg/dL, what can be said regarding reabsorption and excretion?
There is some reabsorption occurring and there’s also some excretion of glucose so they will present with glycosuria
If the blood glucose concentration is higher than 400 mg/dL what can be said regarding reabsorption and excretion?
The reabsorption process has reached its maximum rate. That suggests that all glucose transporters are full with glucose. They’re no longer able to reabsorb glucose back into the bloodstream. We should see mainly excretion. No more reabsorption can occur, and excretion will be the predominant source
Loop of Henle
Starts in the cortex, dips down in the medulla, comes back into the cortex
Loop of henle contains
thin descending, thin ascending, thick ascending
Thin descending
is only permeable to water and is through passive transport that water will be reabsorbed back into our blood capillary system. Higher concentration of urine as more water leaves
Thin ascending
is impermeable to water and we have active transport of sodium outward so into the interstitial fluid of the medulla and chloride ions will follow passively. This will create a very hypertonic area in that interstitial fluid.
a very hypertonic area in that interstitial fluid will help
drive in the descending limb that passive movement of water out of the descending limb of the loop of Henle and into the capillaries
Interstitial fluid is hypertonic to the
filtrate