Lecture 20 - The Urinary System Flashcards
what is the main function of the urinary system?
the ensure optimal properties of the blood (homeostasis) by removing metabolic wastes generated by body cells
true or false: the purpose of the urinary system is to produce urine
false, the purpose is to ensure that you have good blood, urine is a byproduct
what are the six other functions of the urinary system?
1) regulates blood ionic composition
2) regulates blood pH
3) regulates blood volume and pressure
4) produces hormones
5) helps liver detoxify poisons and regulate glucose levels
6) conserve valuable nutrients and eliminates waste
are the kidneys intraperitoneal or retroperitoneal?
retroperitoneal, posterior to the abdominal wall
where are the kidneys located in reference to the ribs?
the left kidney runs from T12-L2, the right kidney runs from L1-L3
why is the left kidney higher than the right kidney?
the liver pushes the right kidney down during development
what is located on the superior-medial surface of each kidney?
the adrenal glands
list the layers of connective tissues that surround the kidneys
- perirenal fat
- renal fascia
- pararenal fat
connective tissue that surrounds the perirenal fat
renal fascia
a layer of fat that is beside the kidneys and behind the parietal peritoneum
pararenal fat
tubes that drain into the renal pelvis
minor calyx and major calyx
a very tight connective tissue that wraps around the kidneys
the fibrous capsule
like the lungs, the kidneys also has a _____ for vessels to enter and exit
hilum
contains one renal pyramid, and half a renal column on either side, and reaches up to the capsule
renal lobe
the apex of the renal pyramid
renal papilla
the renal pyramid is made of:
medulla
what is the path that urine follows through the kidneys?
renal pyramid –> renal papilla –> minor calyx –> major calyx –> renal pelvis
how many minor calyces form a major calyx?
2-3
what is the path of blood flow through the kidneys?
renal artery –> segmental artery –> interlobar arteries –> arcuate arteries –> interlobular arteries –> afferent arterioles –> nephrons –> efferent arterioles –> peritubular capillaries/vasa recta —> interlobular veins –> arcuate veins –> interlobar veins –> segmental veins –> renal vein
peritubular capillaries are located in the
cortex of the kidneys
the vasa recta are located in the
medulla of the kidneys
the basic functional unit of the kidney
the nephron
how many nephrons are in each kidney
~1 million
what are the two basic components of the nephron
the corpuscle and long simple epithelial renal tubule
blood is filtered in the:
renal corpuscle
which components of blood are retained after filtration?
blood cells and large proteins
which components of blood are filtered into the nephron?
low molecular weight proteins, ions, metabolites, dissolved wastes, etc.
which substances are reabsorbed into the bloodstream in the renal tubule?
water, ions, and useful substances
initial dilated part of the nephron with capillary loops, located in the cortex, and produces filtrate
renal corpuscle
which blood vessel marks the separation between the cortex and medulla?
arcuate artery
the long, convoluted part of the nephron with the short, straight part going into the medulla but is mostly located into the cortex, and is the site of reabsorption
proximal convoluted tubule
located in the medulla and responsible for the recovery of water and sodium from the urine
thick and thin descending limbs, thin and thick ascending limbs
long convoluted part of the nephron which is closely associated with the renal corpuscle, and is located in the cortex
distal convoluted tubule
short and links nephron to the collecting ducts (has a hormonal effect in the medulla)
connecting tubule
collects urine and leaves the kidneys
collecting ducts
what are the two types of nephrons? which is more abundant?
cortical nephrons (85% - most abundant) and juxtamedullary nephrons (15%)
type of nephron responsible for most reabsorption and secretions
cortical nephron
type of nephron with the necessary conditions to concentrate the urine
juxtamedullary nephron
efferent arterioles form peritubular capillary beds around tubules in the:
cortex
what is the function of the peritubular capillaries?
reabsorption of water, organic molecules, and salt by osmosis
what is the function of the vasa recta?
retrieve water in the descending limb by maintaining the salt concentration of the medulla
list the major parts of the renal corpuscle
- glomerulus
- Bowman’s capsule
- Bowman’s space
- mesangial cells
- podocytes
- arterioles (efferent and afferent)
Bowman’s capsule is made of what type of epithelial tissue?
simple squamous epithelium
the proximal convoluted tubule is made of what type of epithelial tissue?
simple cuboidal epithelium
which is thicker and contains more smooth muscle at the renal corpuscle, the afferent arterioles or efferent arterioles?
the afferent arterioles (regulates blood pressure)
- physical support of capillaries
- adjusted contractions in response to blood pressure changes
- phagocytosis
- secretions important for immune defense and repair in the glomerulus
these are all chracteristics of:
mesangial cells
what is a brush border?
simple cuboidal epithelium with microvilli
what are the functions of the proximal convoluted tubule?
reabsorption of organic nutrients, proteins, ions, water, and electrolytes
what is the function of the renal corpuscle?
produces filtrate
adjusts salt content of the filtrate; the medulla stays “salty” and tries to retrieve as much water as possible in the vasa recta
nephron loop (loop of Henle)
the thin limb of the nephron loop is made of:
simple squamous epithelium
what parts of the thin limb of the nephron loop make it optimal for water reabsorption?
aquaporins on the basal and apical surfaces (permeable to water)
the thick limb of the nephron loop is made of:
simple cuboidal epithelium
is the thick limb of the nephron loop permeable to water?
nope (reabsorbs Na+ and Cl-)
what are the functions of the distal convoluted tubule?
- variable reabsorption of ions and electrolytes
- allow excretion of acids, toxins, and urea
- regulates blood flow to keep filtrate constant despite the individual’s blood pressure
sodium reabsoption is regulated by:
aldosterone
the distal convoluted tubule is made of:
simple cuboidal epithelium (until the macula densa where cells are more columnar)
where are juxtaglomerular cells located?
outside the glomerulus; between the afferent and efferent arterioles and the macula densa
what are the functions of juxtaglomerular apparatus?
- secretes renin (increases blood pressure)
- constricts smooth muscle in efferent and afferent arterioles
- increased blood pressure in the glomerulus = increased filtration rate
the juxtaglomerular apparatus is a feedback mechanism which regulates ______ and keeps ______ constant
blood pressure, rate of filtration
what is the function of the macula densa?
monitors electrolyte concentration
what is the function of the collecting tubules and ducts?
variable reabsorption of water and ions
the collecting tubules and ducts is made of:
simple cuboidal epithelium to columnar
posterior pituitary hormone which is released when dehydrated and makes the collecting ducts more permeable to water (concentrates filtrate by activating aquaporins)
antidiuretic hormone (ADH)
what is the function of the papillary duct?
delivery of urine to the minor calyces
the papillary duct is made of:
simple columnar epithelium
what is the effect of low ADH secretion on the urine?
there is a large volume of dilute urine
what is the effect of high ADH secretion on the urine?
there is a small volume of concentrated urine
the part of the urinary tract which transports urine
ureter
the part of the urinary tract which eliminates urine
urethra
the part of the urinary tract which stores urine
The urinary bladder
what type of epithelium is found in the urinary tract?
transitional epithelium (review lecture 2)
are the ureters intraperitoneal or retroperitoneal?
retroperitoneal
- made of ‘stretchy’ transitional epithelium
- impermeable
- lots of immune cells present
- contains lots of smooth muscle
these are all characteristics of:
ureters
smooth muscle in the ureters moves urine by:
peristalsis
the ureters enter the urinary bladder via the:
uretic orfices (posteriorly)
what are the points where kidney stones get stuck?
the points of ureteric constriction
list the three sites of ureteric constriction
1) ureteropelvic junction: exiting the kidney and crossing the renal fascia (T10-L1)
2) crossing of the common iliac vessels at the pelvic brims (T11-L2)
3) ureterovesical junction: entering the urinary bladder posteriorly (L1-L2)
where is the reffered pain for the urinary system felt?
T10-L2 (loin to groin)
like the stomach, the interior of the urinary bladder is lined with:
rugae
the urinary bladder is made primarily of:
detrusor muscle (thick smooth muscle)
what is the trigone muscle?
a very smooth muscle (no folds/rugae) which lies between the ureteric openings and the urethra
how many urethral sphincters are there and what are their names?
2; the internal urethral sphincter and the external urethral sphincter
which urethral sphincter is under voluntary control?
the external urethral sphincter
name the 4 main layers of the urinary bladder
- mucosa (transitional epithelium and lamina proporia)
- submucosa
- detrusor muscle
- serosa (parietal peritoneum)
the lamina proporia of the urinary bladder contains lots of:
immune cells
how many layers of smooth muscle are in the detrusor muscle?
three
the transitional epithelium of the urinary bladder allows for a:
change in shape
which spinal nerves provide sympathetic innervation to the urinary bladder?
T10-L1
what is the effect of sympathetic stimulation on the urinary bladder?
- stimulates contraction of the internal urethral sphincter
- inhibits detrusor muscle contraction
- prevents voiding
which spinal nerves provide parasympathetic innervation to the urinary bladder?
S2-S4
what is the effect of parasympathetic stimulation on the urinary bladder?
- relaxation of the internal urethral sphincter
- stimulates detrusor contraction
- voids bladder
which nerves provide somatic innervation to the urinary bladder?
pudenal nerve from lumbosacral plexus
what is the effect of somatic motor control on the urinary bladder?
control of the external urethral sphincter (skeletal muscle)
what 3 parts of the urethra are present in biological males that are not present in biological females?
- prostatic urethra
- membranous urethra
- penile (spongy) urethra
how long is the urethra in biological males?
~18-20cm
how long is the urethra in biological females?
~3-5cm
