A + P Urinary System Flashcards
urinary system function
main: rid the body of nitrogenous products and other wastes
regulate the amount of water and ions present in the body fluids
kidneys function
main organ for removal of wastes and in osmotic regulation of the body fluids
nitrogenous wastes
- AAs
- AAs can be
AAs construct proteins and other nitrogen-containing molecules for use by certain cells in the body
AAs can be oxidized for energy or converted to fats or carbohydrates
when AAs are oxidized or converted to other kinds of molecules…
the amino (NH2) group must be removed the nitrogen containing compounds produced as a result of protein and AA breakdown are toxic and must be removed from the body
nitrogenous wastes are excreted in the form of
ammonia (NH3)
urea
uric acid
ammonia
formed immediately after the amino group is removed from an AA, often in the intestines during digestion
this process requires very little energy
urea
humans excrete nitrogenous wastes in the form of urea because it is less toxic than NH3 and can be moderately concentrated to conserve H2O
urea is produced in the liver by a process that requires more energy than NH3 production, but it reduces the toxicity of the waste
uric acid
the end product of specific protein digestion
neither very toxic nor very soluble in water
high levels in the blood can lead to gouty arthritis or the formation of kidney stones
uric acid is excreted along with urea
urinary system anatomy
kidneys
ureters
urinary bladder
urethra
kidney function
primary filtration organs
kidney structure
cortex medulla calyx renal pelvis nephrons
cortex
outer portion
where blood is filtered via the glomeruli
medulla
- divided into
- what happens there?
inner portion
divided into several pyramids/lobes
this is where the amount of Na+ and H2O in your urine is regulated (e.g. how concentrated the urine will be) via the loops of Henle
calyx
- function
- drains to
urine repository from each medullar pyramid
each calyx drains into the renal pelvis
renal pelvis
-function
central urine repository within the kidney before excretion through the ureter
nephrons
microscopic (about 1 million/kidney), partially housed in both the cortex and medulla
nephron composition
glomerulus Bowman's Cpasule proximal convoluted tubule (PCT) Loop of Henle distal convoluted tubule (DCT) collecting duct
glomerulus
- function
- fluid composition
- what stays in the blood vessels
- where are they housed?
network of capillaries from which fluid “leaks” out of the circulatory system (ultra filtration)
the fluid (ultra filtrate) is mostly water, urea, salts, minerals, and nutrients
RBC, WBC, and platelets stay in the blood vessels
the glomeruli are housed within the cortex of the kidney
Bowman’s Capsule
- visual
- function
- location
a funnel-like structure that surrounds and collects ultra filtrate from the glomerulus
housed within the cortex of the kidney
proximal convoluted tubule
- function
- location
reabsorbs water and nutrients, such as glucose and AAs, that leaked out of the glomerulus
housed within the cortex of the kidney
Loop of Henle
- location
- includes
- as ultra filtrate…
- function of structure
extends from PCT in cortex into medulla
-includes a hairpin bend, which creates a concentration gradient for Na+ in the medulla
as ultra filtrate passed down the loop into a salty medulla, H2O is lost to the medulla and recollected in peritubular capillaries
as ultra filtrate moves back up the loop it loses Na+
the entire structure is designed to concentrate the urine for excretion
distal convoluted tubule
- function
- location
passes by glomerulus and is responsible for mineral balance (save Na+ at expense of K+ or vice versa, and sometimes expel extra H+ here)
housed within the cortex of the kidney
collecting duct
- location
- function
extends from cortex through medulla into calyx
delivers urine to the renal pelvis
blood flow through the kidney
- enters through
- blood contains
blood enters the kidney through a branch of the aorta called the renal artery
-blood contains glucose and O2 (because the kidney works hard to produce urine) and urea (which must be removed from the blood
blood in the renal artery
- must have
- may have
- kidney removes
must have sufficient pressure or the kidney will not be able to filter the blood
blood may have too much Na+ or too much H2O
kidney removes whichever is in excess to maintain adequate blood volume and ion balance
renal artery branches
branches into interlobular arteries, which further divide into afferent arterioles
afferent arteriole
- leads to
- fluid leaks
leads to a network of capillaries called a glomerulus
fluid leaks out of the capillaries of the glomerulus, but large molecules and cells do not fit through the pores (ultra filtration)
blood leaves the capillaries of the glomerulus via
efferent arteriole
blood from efferent arterioles enter
peritubular capillaries
peritubular capillaries
-function
collect much of the water that was lost through the glomerulus
interlobular veins
- from
- lead to
from the peritubular capillaries
lead to a renal vein, which exits the kidney and returns blood to the inferior vena cava
renal vein
-blood has
had all of its urea removed and should have exactly the right amount of H2O and Na+
ureters
-function
pathways for urine that extend from each renal pelvis to the urinary bladder
urinary bladder
-function
“holding tank” for urine awaiting excretion
urethra
pathway for external urine excretion
urine production (diuresis)
- glomerulus
- -blood enters
- -blood leaves
- -ultra filtrate
blood enters the glomerulus via an afferent arteriole where blood pressure forces H2O and small molecules (ultra filtrate), such as urea out through the pores in the glomerular capillaries into the surrouding Bowman’s capsule
blood leaves the glomerulus via the efferent arteriole
ultra filtrate collects in Bowman’s capsule and drains into the PCT - this is the foundation of what will become urine
Glomerular Filtration Rate
volume of fluid filtered from the glomerulus into Bowman’s capsule per unit time
calculating GFR is important for assessment of the excretory function of the kidneys
proximal convoluted tubule
-cells have
cells have numerous microvilli and mitochondria, which provide surface area for reabsorption and energy
PCT
-selective reabsorption
occurs from the PCT
water, glucose, vitamins, important ions and most AAS are reabsorbed from the PCT back into adjacent peritubular capillaries via active transport
a substance is no longer absorbed by the PCT when…
- what happens to it?
- reason
- helps regulate
the concentration in the blood reaches a certain level
-remains in the urine
prevents the composition of the blood from fluctuating
-process helps regulate the levels of glucose and inorganic ions such as Na+, K+, HCO3-, PO43-, and Cl-
Loop of Henle
due to…
concentration gradients established in the medulla, the Loop of Henle is able to conserve H2O and further concentrate urine
Descending Loop
- has low…
- consequently
- removal of Na+
has low permeability for ions and urea, but high permeability for H2O
consequently, H2O moves out of the descending loop as it passes through the area of high Na+ concentration produced by the ascending loop
this removal of Na+ concentrates the urine while conserving H2O for the body
Ascending Loop
- has low
- Na+
- -results
- removal of H2O
has low permeability for H2O and ions, but high permeability for Na+
Na+ is actively pumped out in the ascending loop and H2O cannot re-enter
-results in a higher concentration of Na+ in the medulla, which supports H2O removal in the descending loop
this removal of H2O further concentrates the urine
countercurrent multiplier
- high Na+
- movement of Na+
- H2O loss
- urea
high Na+ in the medulla acts to help remove H2O in the descending loop
-called counter current multiplier
movement of Na+ out of the ascending loop and into the medulla results in H2O loss and concentrated urine in the descending loop
H2O loss and increased Na+ concentration that occurs in the descending loop further enhances the ability of the ascending loop to pump more Na+ out into the medulla
urea remains concentrated in the fluid for excretion
distal convoluted tubule (DCT)
- functions
- what is secreted
most of the minerals and salts from the ultra filtrate are reabsorbed
some wastes are actively secreted into the urine
-include H+, K+, toxic and foreign substances (drugs, penicillin, uric acid, creatine, creatinine)
collecting duct
- what drains into it
- what do they do
DCT from several nephrons drain into a common collecting duct
collecting ducts pass through the concentration gradient that was established by the Loops of Henle
-as fluid passes through the collecting ducts, additional H2O leaves the collecting duct due to osmosis, which is the final step in the conservation of H2O and concentration of urine
urination (micturition)
- bladder filling
- cerebral cortex
- decision to urinate
- immersiton duresis
as the bladder fills with urine, mechanoreceptors send APs to the spinal cord (via the pelvic nerves) and then to the pons and cerebrum of the brain
cerebral cortex can override the urge to urinate, although this is a learned voluntary response
when the decision to urinate occurs, the pons initiates motor nerve impulses that cause the bladder to contract and the internal and external sphincters of the urethra to open
theory that you can induce urination through the immersion of the hand in water
regulation of blood pH
breathing
kidneys
breathing
- adjustment
- rapid breathing
- slow breathing
adjustment of the breathing rate can make quick, but slight, alterations in the pH of the blood by reducing the amount of CO2 in the blood
- rapid breathing results in more CO2 given off during ventilation, which moves the equation below to the left and increases the blood pH
- slow breathing results in less CO2 given off during ventilation and the equation moves to the right, which decreases the pH
breathing equation
CO2 + H2O –> H2CO3 HCO3- + H+
kidneys
- kidneys
- blood pH is low
- blood pH is high
the kidneys provide a slower, but more powerful means of regulate pH
-excrete or absorb hydrogen ions and bicarbonate ions as necessary for adjusting pH (happens at the DCT)
when blood pH is low, H+ is excreted into the DCT and HCO3- from the ultra filtrate/urine is reabsorbed into the blood
when the pH is too high, less H+ is excreted into the DCT and less Na+ and HCO3- are reabsorbed into the blood
hormones of the urinary system
Anti-Diuretic Hormone (ADH)
aldosterone
Atrial Natriuretic Hormone (ANH)
Andi-Diuretic Hormone (ADH)
- function
- osmotic pressure of blood increases
- osmotic pressure of blood decreases
increases the permeability of the collecting ducts
- if the osmotic pressure of blood increases (too much Na+, not enough H2O), the hypothalamus stimulates the posterior pituitary gland to release ADH and the permeability of the collecting ducts will increase, which facilitates removal of H2O from the urine and absorption into the blood
- if the osmotic pressure of blood decreases, the posterior pituitary does not release ADH, the permeability of the collecting duct remains low, and additional H2O is excreted in urine
ADH
-alcohol and diuretic drugs
alcohol and diruetic drugs inhibit the secretion of ADH and thus increase H2O loss (and consequently lower blood pressure)
aldosterone
- function
- low osmotic pressure
- increased osmotic pressure
acts primarily on the DCT to promote Na+ absorption into the blood to regulate blood volume and blood pressure
- when osmotic pressure is low, the afferent arteriole cells secrete renin
- renin initiates a series of chemical reactions that ultimately stimulate the adrenal cortex to release aldosterone
- increased osmotic pressure associated with increased Na+ contributes to the reabsorption of H2O from the DCT into the blood, which increases blood volume and blood pressure
- in the absence of aldosterone, more Na+ is excreted and less H2O is reabsorbed from the DCT, which decreases blood volume and lowers blood pressure
Atrial Natruiretec Hormone (ANH)
- function
- loss of H2O
- presence of too much blood
inhibits the release of aldosterone and ADH, which causes the kidneys to excrete excess H2O
- loss of H2O and Na+ contribute to lowered blood volume and blood pressure
- presence of too much blood in the circulatory system stimulates the atria in the heart to secrete ANH
homeostatic imbalance of the urinary system
kidney stones urinary incontinence urinary tract infection (UTI) nephrotic syndrome chronic kidney disease (CKD)
kidney stones
renal calculus
sometimes the salts and minerals (typically calcium and phosphate) in the urine crystallize in the pelvis and form a solid mass or “pebble” (usually less than 5 mm in diameter), which prevents urine from draining out of the pelvis into the ureter
-can be passed (1-4 weeks) or surgically removed (10-20% of stones) for analysis of the stone composition
urinary incontinence
any involuntary leakage of urine, which usually can be attributed to underlying medical conditions, such as
- uncontolled diabetes
- enlarged prostate
- multiple sclerosis
- Parkinson’s disease
urinary tract infection (UNI)
common bacterial infection that affects part of the urinary tract
consequently, there may be pain during urination and either frequent urination or urges to urinate (or both)
nephrotic syndrome
group of symptoms that include protein in the urine, low blood protein levels, high cholesterol and triglyceride levels, and swelling
syndrome is caused by different disorders that damage the kidneys, including glomerulonephritis, diabetes, cancer, immune disorders, various infections, and use of certain drugs
chronic kidney disease (CKD)
the slow loss of kidney function over time
symptoms are often absent until kidney function is severely reduced
the final stage of CKD is know as end-stage renal disease (ESRD), at which point the kidneys are no longer able to remove enough wastes and excess fluids from the body
many causes of CKD, but the two most common are diabetes and high blood pressure
