Overview of the Urinary System Flashcards
the kidneys control blood composition and volume by
removing wastes and regulating water levels
the kidneys regulate osmolarity of body fluids by
controlling solutes and water levels
the kidneys regulate blood pH by
excreting hydrogen ions
the kidneys regulate blood pressure by
activating reninangiotensin pathway
the kidneys control oxygen-carrying capacity of blood by
secreting erythropoietin
the kidneys contribute to metabolism by
synthesizing glucose during periods of starvation
“waste” refers to
any substance that is not useful to the body
metabolic wastes are
substances produced by the body
nitrogenous wastes
metabolic wastes that result from breakdown of proteins
amino groups removed from amino acids combine with
hydrogen ions to form ammonia, which is highly toxic and must be diluted with huge quantities of water
ammonia
gets converted to less toxic urea by liver and this uses much less water
uric acid
results from breakdown of nucleic acids
creatinine
results from use of creatine phosphate during muscle metabolism
the amount of nitrogenous waste in blood is expressed as
blood urea nitrogen (BUN)
- normal levels are 10-20 mg/mL
azotemia
elevated BUN is azotemia
- it indicates renal insufficiency
if azotemia is left untreated it can lead to
uremia
uremia
elevated BUN
- can cause diarrhea, vomitting, dyspnea, cardiac arrhythmia, convulsions, coma, and even death
excretion
the process of discharging waste materials across cell membranes
skin- excretions and glands
sudoriferous glands in skin eliminate excess heat and excrete water and small amounts of salts and urea during perspiration
lungs
excrete large quantities of carbon dioxide and small amounts of water vapor
liver
extracts bilirubin from erythrocytes and excretes it as bile by adding it to feces
kidneys
excrete nitrogenous wastes and other substances by adding them to urine
description of kidneys
reddish brown organs that extend from T-12 to L-3 behind parietal peritoneum against posterior abdominal wall
right kidney
slightly lower because of the liver
adult kidney
larger- about 150 grams
lateral surface of each kidney
is convex and the medial surface is concave
- blood vessels, lymphatic vessels, nerves, ureter attach to renal hilum
renal capsule
a smooth, transparent membrane that each kidney is enclosed within
adipose capsule
fatty adipose capsule cushions kidney from trauma and holds it in place
renal fascia
fibrous renal fascia anchors kidney to abdominal wall
frontal section through kidney
shows c-shaped parenchyma with two distinct zones
renal cortex
superficial reddish zone
renal medulla
deep brownish zone
renal parenchyma
glandular tissue that forms urine
portions of the renal cortex extend into the renal medulla to form
renal columns
renal pyramids
striated, cone-shaped renal pyramids are loacted within renal medulla
apex of each renal pyramid
forms renal papilla that faces hilum
the papilla of each renal pyramid is enclosed within a
minor calyx that collects urine
major calyx
urine from 2 or 3 minor calyces is delivered to major calyx
renal pelvis
2 or 3 major calyces empty urine into renal pelvis
each kidney contains over one million
nephrons, which carry out the kidney’s functions
renal corpuscle
consists of a glomerulus, which is a ball of capillaries that is enclosed within a two-layered Bowman’s capsule
outer parietal layer of renal corpuscle is composed of
simple squamous epithelium
inner visceral layer of renal corpuscle consists of
podocytes that wrap around capillaries
renal tubule
extends about 3 cm from Bowman’s capsule to the tip of a renal pyramid
proximal convoluted tubule
PCT- arises from Bowman’s capsule
- it is the longest segment and contains simple cuboidal epithelium with numerous microvilli.
microvilli
form a ‘brush border’ to increase surface area
nephron loop of Henle
extends from PCT into renal medulla
descending limb
a thin segment of simple squamous epithelium
- very permeable to water
ascending limb
a thick segment of simple cuboidal epithelium
- involved in salt transport
distal convoluted tubule
DCT- begins when loop of Henle returns to renal cortex
macula densa
cluster of epithelial cells at beginning of DCT
collecting duct
terminal structure of renal tubule
several nephrons and collecting ducts
several nephrons empty urine into a single collecting duct
- it joins with other collecting ducts to transfer urine into a papillary duct
cortical nephrons
short nephron loops that barely dip into the renal medulla
juxtamedullary nephrons
have very long nephron loops that extend deep into the renal medulla
the kidneys are richly supplied with
blood vessels and as much as 25% of the circulating blood supply can be in the kidneys at any moment
blood enters a kidney from the aorta by way of
a renal artery that branches many times until it gives rise to a series of afferenet arterioles
juxtaglomerular cells
located in wall of an afferent arterioles are modified smooth muscle juxtaglomerular (JG) cells
juxtaglomerular apparatus
JG cells combine with macula densa cells to form a juxtaglomerular apparatus
at the end of each afferent arteriole
is the collection of glomerular capillaries
the blood that supplies a nephron passes through
two capillary beds
glomerular capillaries reunite to form
efferent arteriole that drains them after they produce filtrate
efferent arteriole divides to form
peritubular capillaries that surround each cortical nephron
- reclaim most filtrate
efferent arterioles divides to form _______ _____ that surround each juxtamedullary nephron
vasa recta
blood exits these capillaries and enters
venules, which form a series of veins that eventually merge to form the renal vein that delivers blood to the inferior vena cava
