CH. 27 Urinary System Flashcards
What are the organs of the urinary system?
kidneys, ureters, urinary bladder, and urethra
What are the functions of the urinary system?
1) storage of urine
2) excretion of urine
3) regulation of blood volume
4) regulation of erythrocyte production
5) regulation of ion levels
6) regulation of acid-base balance
Where do vessels, nerves, and the ureter enter and/or exit the kidney?
the hilum
What are the tissue layers of the kidneys?
1) Fibrous capsule: directly adheres to the outer surface of the kidney and is composed of dense irregular CT
2) Perinephric fat: external to the fibrous capsule and contains adipose CT that varies in thickness
3) Renal fascia: composed of dense irregular CT that anchors kidney to the posterior abdominal wall and peritoneum
4) Paranephric fat: outermost layer surrounding the kidney; composed of adipose CT
What are the two types of capillary networks that efferent arterioles branch into?
Peritublar capillaries: associated with the convoluted tubules and primarily reside in the cortex of the kidney
Vasa recta: associated with the nephron loop and primarily reside in the medulla of the kidney
What is the nephron?
functional filtration unit in the kidney; consists of the a renal corpuscle, a proximal convoluted tubule, a nephron loop, and a distal convoluted tubule
What makes up the renal tubule?
proximal convoluted tubule, nephron loop, and distal convoluted tubule
What are the two types of nephrons?
1) cortical nephrons: resides solely in the cortex, and their relatively short nephron loops just barely penetrate the medulla
2) juxtamedullary nephrons: renal corpuscles lie close to the corticomedullary junction, and their long nephron loops extend deep into the medulla
In what 3 processes is urine formed?
1) Glomerular filtration
2) Tubular reabsorption
3) Tubular secretion
What two structures make up the renal corpuscle?
1) glomerulus
2) glomerular capsule
What 3 layers of the “filter” must substances in the blood pass through to become filtrate?
1) Endothelium of glomerulus
2) Basement membrane of glomerulus
3) Visceral layer of glomerular capsule
What is the primary function of the nephron loop?
to facilitate reabsorption of water and solutes from the tubular fluid
What are the 3 concentric tunics of the wall of the ureter?
1) mucosa: formed from transitional epitheliuml both distensible and impermeable to the passage of urine
2) muscularis: consists of two smooth muscle layers: an inner longitudional layer and an outer circular layer; produce peristalitc waves that propel the urine through the ureters into the urinary bladder
3) adventitia: formed from areolar CT
What are the three layers of smooth muscle of the muscularis of the bladder collectively called?
detrusor muscle
What are the steps of the micturition reflex?
1) when the bladder fills with urine and becomes distended, stretch receptors in the bladder wall are activated, and they signal the micturition reflex center
2) impulses within the parasympathetic division of the autonomic nervous system travel to both the internal urethral sphincter and the detrusor muscle
3) the smooth muscle in the internal urethral sphincter relaxes, and the smooth muscle in the detrusor muscle contracts
4) the person’s conscious decision to urinate causes relaxation of the external urethral sphincter
5) in addition to the squeezing action of the detrusor muscle on the volume of the urinary bladder, expulsion of urine is facilitated by contraction of the abdominal wall muscles
6) upon emptying of the urinary bladder, the detrusor muscle relaxes, and the neurons of the micturition reflex center are inactivated
