urinary system Flashcards
(22 cards)
describe the general functions of the urinary system
3 major functions:
- excretion (removal of organic wastes from body fluids)
- elimination (getting wastes out of body and into environment)
- homeostatic regulation (of blood volume, and in tandem blood pressure, and solute concentration of blood)
describe the structure of the kidneys (superficial anatomy included)
external anatomy: smooth convex outer surface with an indent in the middle called the renal hilum where blood vessels, nerves and the ureters enter/exit. adrenal glands sit on top of the kidneys.
internal anatomy: divided into three regions
- renal cortex
= contains the most nephrons
- renal medulla
= contains renal pyramids, papilla, and columns with collecting ducts and some loops of henle
- renal pelvis
= collects urine from major and minor calyces and is surrounded by the renal sinus
describe the function and location of the kidneys
function: to filter blood, remove waste, and produce urine
location: either side of vertebral column (between T12 and L3)
structure of the filtration membrane. how does the structure relate to its function
made up of three components:
- fenestrated capillaries of glomerulus
- basement membrane (between capillaries and podocytes)
- filtration slits between podocytes of glomerular capsule
function: the narrow spaces ensure that only small molecules (like ions, water, and glucose) pass into the bowman’s space, while larger molecules like proteins and blood cells are retained in the bloodstream.
structure, function, and histology of a nephron?
structure: comprised of many components.
- renal corpsucle (glomerulus and glomerular capsule)
- PCT
- loop of henle (descending and ascending limbs)
- DCT
- collecting duct
- vasa recta
function: filtration (glomerulus), reabsorption (PCT mainly), secretion (DCT mainly), concentration of urine (collecting duct and loop of henle)
histology:
- tubules are made up of simple cuboidal epithelium.
- glomerulus is made up of simple squamous epithelium
differentiate between cortical nephrons and juxtamedullary nephrons
cortical nephrons:
- ~85% of nephrons
- short loop of henle
- surrounded by peritubular capillaries
juxtamedullary nephrons:
- ~15% of nephrons
- longer loop of henle that dips into medulla
- surrounded by vasa recta
both empty into collecting duct, renal papillae, and minor calyces
structure, function, and location of the ureters
structure: muscular tube approx. 30 cm long. made up of an outer layer of CT, middle smooth muscle, lamina propria, then transitional epithelium.
function: transports urine from kidney to urinary bladder
location: runs along back and pelvic region, from kidneys to bladder
structure, function, and location of urinary bladder
structure:
- made up of 2 layers.. inner mucosa (with transitional epithelium and lamina propria) and muscularis (3 layers of smooth muscle called the detrusor muscle)
function: temporary storage of urine (500-800 mL)
location: inferior to peritoneum, posterior to pubic symphysis
structure and function of urethra male and female
structure:
males=18-20cm, made up of 3 portions (prostatic urethra, membranous urethra, spongy/penile urethra)
females=3-5cm long
both sexes have an internal and external urethral sphincter
function: carries urine from the bladder to outside the body
compare and contrast male urethra and female urethra, and describe the significance of this with respect to UTI’s and kidney stones
Length: male urethra is much longer (18-20 cm) while females is much shorter (3-5 cm)
Location: female urethra is much closer to the anus than the male urethra.
UTI’s: females are much more likely to develop a UTI because the close proximity of their urethra to the anus increases chances of contamination by bacteria from the digestive tract/feces. in addition, the short urethra means a UTI is more likely to progress to the bladder, causing cystitis.
Kidney stones: If a male develops kidney stones and a stone must “pass,” it will have to travel from the kidney down the ureter to the bladder, and then all along the much longer urethra.
describe the voluntary and involuntary control of urination, including a brief description of the micturition reflex.
involuntary portion: when urine accumulates in the bladder, it causes distension of the bladder which activates stretch receptors. the stretch receptors send signals to the CNS (specifically the spinal cord and brainstem) indicating that the bladder is becoming full. in response, the detrusor muscle contracts, causing the internal urethral sphincter to relax.
voluntary portion: if convenient, you can voluntarily relax the external sphincter and allow urination to occur. if not, the reflex can be temporarily suppressed consciously, postponing urination.
