Urinary System (Exam 4) Flashcards
What are the functions of the urinary system?
- Regulate: blood volume, composition, pressure, pH, osmolarity
- Produce hormones (erythropoietin)
- Synthesize glucose molecules
- Excrete waste and foreign substances
What 5 things does the urinary system regulate?
Blood volume Composition Pressure pH Osmolarity
What hormone does the urinary system produce?
erythropoietin
What molecule does the urinary system synthesize?
glucose molecules
Where are the kidneys positioned?
Retroperitoneal
Behind all digestive organs at rear of abdominal cavity
What is the purpose of the renal fascia?
To anchor the kidney in place
What are the four main components of the kidney external anatomy?
Renal fascia
Adipose capsule
Renal capsule
Renal hilum
What does the adipose capsule of the kidney do?
Provides padding and support of the kidneys
What does the renal capsule of the kidney do?
Provides padding and shape for the kidneys
What kind of tissue is the renal capsule made of?
Dense irregular connective tissue
What kind of tissue is the renal fascia made of?
Dense irregular connective tissue
What is the renal hilum?
The indent of kidney where renal artery, veins, and ureter meet the kidney
What is the nephron?
structure where filtration of urine occurs
Where are most of the blood vessels in the kidney concentrated at?
renal columns
Where in the kidney are the nephrons and collecting ducts concentrated at?
renal pyramids
What is the blood supply flow of the nephron?
Afferent arterioles > glomerular capillaries > Efferent arterioles > peritubular capillaries
What is contained in the glomerulus?
a network of capillaries
Blood flows into the glomerulus via the…
afferent arterioles
Blood flows out of the glomerulus via the…
efferent arterioles
What is the name of the capsule around the glomerulus?
Bowman’s capsule
What is the name of the tubule closest to the glomerular capsule?
Proximal convoluted tubule
What is the name of the tubule distal to the glomerular capsule?
Distal convoluted tubule
What is the purpose of the Loop of Henle?
to create a concentration gradient in the medulla of the kidney to help concentrate urine for excretion
What are peritubular capillaries?
capillaries outside of the Loop of Henle
How many glomeruli are there per nephron?
One per nephron
How many nephrons are there in the kidneys?
Millions of nephrons
What are the three main stages of urine formation?
glomerular filtration
tubular reabsorption
tubular secretion
Water and most solutes diffuse from glomerulus to glomerulus capsule in what stage of urine formation?
glomerular filtration
99% of water and useful solutes diffuse from the renal tubule to the peritubular capillaries in what stage of urine formation?
Tubular reabsorption
Secretion of wastes, drugs, and excess ions in renal tubule from peritubular capillaries happens in what stage of urine formation?
Tubular secretion
The renal corpuscle refers to what?
The glomerular capsule, the glomerulus, and afferent/efferent arterioles (to a certain degree)
What is the main area of the nephron where action is happening?
the renal tubule
What is the fluid flow in regards to blood and urine formation?
from blood to capsule
In terms of urine formation, the kidneys essentially do what?
They kick everything out and then bring in only the stuff they want
What are podocytes?
Foot cells
Anything that wants to come out during the urinary filtration process must pass through what?
Fenestrations and the filtration slits, collectively known as the filtration membrane
What kidney structures have a filtration membrane?
Podocytes and the glomerulus endothelium
In what three ways are the filtration membrane different than other capillary networks?
Larger surface area
Thinner and leakier
Under higher blood pressure than other capillaries
What are the gaps between podocytes called?
filtration slits
Are ions normal in urine?
Some out is OK, but not all
Is glucose normal in urine?
not normal in urine, but normal as a filtrate
Does your body want urea, uric acid, and creatinine in, out, or a bit of both?
Definitely out
Why are formed elements not normally found in urine or filtrate?
They’re too large to be filtered out
Filtration is highly dependent on…
Blood Pressure
What are the three main types of pressure in filtration formation?
Glomerular Blood Hydrostatic Pressure (GBHP)
Blood Colloid Osmotic Pressure (BCOP)
Capillary Hydrostatic Pressure (CHP)
What is the most important type of pressure for filtration and why?
Glomerular Blood Hydrostatic Pressure, because the blood pressure must be high enough for all other pressures to function properly
At what rate does glomerular filtration occur?
At a fairly constant rate
Glomerular pressure is directly related to what pressure?
Net filtration pressure
What are the two main ways that glomerular filtration is regulated?
Adjusting blood flow into and out of glomerulus
Altering filtration surface area
What is reabsorption in the urinary system?
Process in which most water and many solutes are returned (metabolic wastes less so)
By what mode of transport does reabsorption occur?
Mostly active transport with some ionic diffusion
What is transport maximum and what is it measured in?
Transport maximum is how fast a transporter can work and is measured in mg/min
Obligatory water by osmosis constitutes what percentage of reabsorption?
90%
What is obligatory water by osmosis?
Reabsorption in which water follows solutes
Facultative water by osmosis constitutes what percentage of reabsorption?
10%
What structures are complicit in obligatory water by osmosis?
Proximal convoluted tubule and Loop of Henle
What is facultative water by osmosis?
Reabsorption of water in the kidneys that is under the control of anti diuretic hormone (ADH)
What hormone regulates facultative water by osmosis and what structure is complicit in this process?
Anti diuretic hormone and the collecting ducts
PCT stands for…
Proximal convoluted tubule
What is secretion as it applies to the urinary system?
The process of making tubule fluid from blood
What materials are typically secreted after reabsorption?
H+ K+ NH4+ creatinine some drugs
From what structures does secretion occur after reabsorption in the urinary system?
Proximal convoluted tubule and the collecting ducts
What is an antiporter and what ions are the main antiporters in secretion?
An antiporter is a cell membrane transport mechanism that transports two molecules at once through the membrane in opposite directions
Main antiporters in secretion are H+ and Na+
What system is responsible for the hormonal regulation in the urinary system?
Renin-Angiotensin-Aldosterone System
What triggers the secretion of renin?
Blood pressure decrease
What cells secrete renin after a blood pressure decrease is detected?
juxtaglomerular cells
What is the hormone cascade flow after renin is released?
Angiotensinogen > Angiotensisn I > Angiotensin II
What happens after the the urinary system hormonal regulation cascade?
Vasocontriction occurs
Reabsorption is enhanced via Na+/H+ antiporters
Aldosterone is released which stimulate water retention
What does the release of aldosterone trigger?
Triggers water retention
What does ADH help stimulate?
Helps stimulate facultative water reabsorption
Why is the osmotic gradient needed to excrete concentrated urine?
The Loop of Henle creates a gradient that upon descent allows for water to flow out of the loop which concentrates the solute and upon ascent allows water into the loop which the dilutes the solute without losing more water
What is the normal volume of urine per day?
1 - 2 L
What is the normal color of urine?
yellow, but varies
What is the turbidity of urine?
turbid upon standing
What is the average pH of urine?
6.0
What is the specific gravity of urine?
1.010 - 1.025
What are the normal contents of urine?
Water Electrolytes Urea Creatinine Uric Acid Urobilinogen
What does glucosuria indicate?
Glucose in urine is abnormal and glucosuria indicates diabetes mellitus
What does albuminuria indicate?
Albumin in urine is abnormal and albuminuria indicates:
- increased permeability due to damage;
- increased BP; OR
- irritation
What does hematuria indicate?
RBCs in urine are abnormal and hematuria indicates kidney damage, disease, or tumors
What does ketouria indicate?
Ketone bodies in urine are abnormal and ketouria indicates diabetes mellitus or malnutrition
What are some miscellaneous abnormal constituents of urine?
Bilirubin
Urobilinogen (in high quantities)
Casts
Microbes
What type of epithelium constitutes the mucosa of the bladder?
Transitional epithelium
What is the purpose of rugae in the bladder?
to allow for expansion of the bladder
Is the muscularis of the bladder smooth muscle or skeletal muscle?
smooth muscle
What is the muscularis of the bladder called?
Detrusor muscle
What is the purpose of the trigone?
To send signals to the brain as bladder fills more and more
What is the internal urethral orifice?
proximal external opening of the bladder
Name the two urethral sphincters
Internal urethral sphincter
External urethral sphincter
Is the internal urethral sphincter voluntary or involuntary?
involuntary
Is the external urethral sphincter voluntary or involuntary?
voluntary
What is the Micturition reflex?
reflex in which the urge to pee is triggered
Describe the Micturition reflex
The bladder fills with urine which triggers stretch receptors in the bladder. The stretch receptors send a signal to the spinal cord which sends a signal back from the brain to trigger the contraction of muscles in the bladder. The contraction coupled with the relaxation of the sphincters leads to urination.
At what volume is the Micturition reflex normally triggered?
200 - 400 mL
