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Exercise 40
Anatomy of the Urinary System
Question | Answer |
---|---|
the purpose of the urinary system is | to remove nitrogenous wastes from the body |
this is an ___ function | excretory |
the kidney's maintain | the electrolyte, acid-base, & fluid balances of the blood & is a mj. function of homeostatic organ of the body |
explain the performance functions of the kidneys | (1) act as a blood "filter" (2) a blood "processor"; allows toxins, metabolic wastes & excess ions to leave the body in the urine while simultaneously retaing needed substances & returning them to the blood |
malfunction of the urinary system (kindeys) leads to failure in | homeostasis; can be fatal |
what does the urinary system consist of? | paired kidneys & ureters & the urinary bladder & urethra |
all other organs besides the kidneys provide temporary | storage reservoirs or transportation channels for urine |
the __ kidney is slightly lower than the ___ kidney | right kid is slightly lower than the left kid |
what hold the kidneys in a retroperitoneal position? | fat deposits (adipose capsules) & fibrous renal capsules |
ptosis | when the kidneys are less securely anchored to the body wall due to reduced or rapid weight loss (very thin individuals); may cause kidneys to drop to a lower position |
hilus | present in each kidney; the indented medial region where the renal arteries enter |
urethra | drains the bladder |
trigone | triangular region of the bladder which is delineated by three openings (2 ureteral & 1 urethral orifice) |
name the 3 main regions of the peins | prostatic, membranous & spongy (penile) urethrae |
the urethra of males has a ____ function | dual |
what are they? | (1) it is a urine conduit to the body exterior (2) provides a passageway for the ejaculation of semen |
how long is the urethra in males | approximately 20cm (8 inches) |
how long is the urethra in females | approx. 4cm (1 1/2 inches) |
external urethral orifice | anterior to the vaginal opeing, the external opening |
each kidney contains over a million ___ | nephrons; the anatomical units responsible for forming urine |
name the 2 major structures in each nephron | a glomerulus(capillary knot) & a renal tubule |
the renal tubule in embryologic development begins as a | blind-ended tubule that gradually encloses an adjacent capillary cluster, or glomerulus |
the glomerular (Bowman's) capsule is | the enlarged end of the tubule encasing the glomerulus |
what does the glomerular's inner/visceral wall consist of | podocytes; highly specialized cells |
what structures do podocytes have? | long, branching processes (foot processes) that interdigitate w. those of other podocytes & cling to the endothelial wall of the glomerular capillaries; forms the porous epithelial membrane surrounding the glomerulus |
what is another name for the glomerulus-capsule complex? | renal corpuscle |
name the anatomical areas of the renal tubule in order from the glomerular capsule | the proximal convoluted tubule, loop of Henle (descending & ascending limbs) & the distal convoluted tubule |
what type of tissue is the wall of the renal tubule composed almost entirely of? | cuboidal epithelial cells |
the tissue in the loop of Henle is | simple squamous epithelium |
where are cortical nephrons located? | within the cortex |
as the collecting ducts approach the renal pelvis they fuse to form larger ____, (what do these structures do?) | papillary ducts, they empty the final urinary product into the calyces & pelvis of the kidney |
name the 2 distinct capillary beds that the capillary vascular supply consists of | glomerulus & peritubular capillary bed |
vessels leading to & from the glomerulus, the 1st capillary bed are both __ | arterioles |
the afferent arteriole | feeds the bed |
the efferent arteriole | drains the bed |
the glomerular capillary bed is __-pressure | high |
b.c of this the two major resulting factors are | (1) bed is fed & drained by arterioles (arterioles are high-resistance vessels) (2) the afferent feeder arteriole is larger in diameter than the efferent arteriole draning the bed |
the high hydrostatic pressure | forces out fluid & blood components smaller than proteins from the glumerulus intot he glomerular capsule (forms the filtrate which is processed by the nephron tubule) |
peritubular capillary bed arises from the | efferent arteriole draining the glomerulus (clings intimately tot he renal tubule & empties into the interlobular veins that leave the cortex) |
what type of pressure is the peritubular capillaries | low-pressure |
what does this cause? | cery prous capillaries adapted for absorption rather than filteration & redily take up the solutes & water reabsorbed from the filtrate by the tubule cells |
what are the additional looping vessels that the juxtamedullary nephrons have? what are they parallel to | vasa recta (straight vessels); parallel to the long loops of Henle in the medulla |
the glomerulus produces the ___ & the peritubular capillaries __ most of that filtrate | filtrate, reclaim |
JGA; juxtaglomerular apparatus | plays an important role in filtrate formation |
what does the JGA consist of | (1) juxtaglomerular (JG) cells (2) pressure sensors in the walls of the arterioles near the glomerulus (3) macula densa, a specialized group of columnar cells in the distal convoluted tubule abuting the JG cells |
name the 3 processes that urine results from | filtration, reabsorption & secretion |
filration is the role of the | glomerulus |
what is filtration | a passive process in which a portion of the blood passes from the blomerular bed into the glomerular capsule; filtrate enters the proximal convoluted tubule where tubular reabsorption & secretionb begin |
reabosprption of most substances depends on | active transport processes & is highly selective |
during tubular reabosorption | the filtrate components move through the tubule cells & return to the blood in the peritubular capillaries |
name the substaces that are almost entirely reabsorbed from teh filtrate | water, glucose & amino acids |
most (75%-80%) of tubular rabsorption occurs in the | proximal convoluted tubule |
tubular secretion | the reverse process of tubular reabsorption; important for the disposal of substances not already in the filtrate (drug metabolites) controlling device for blood pH |
name the substances that move either fm the blood of the peritubular capillaries through the tubular cells or from the tubular cells into the filtrate to be disposed of in the urine | hydrogen, potassium ions & creatinine |
urinary bladder | receives urine via the ureters & discharges it via the urethra, stores it temporarily |
voiding is also known as | micturition; urine empties from the bladder |
name the 2 sphinctermuscles/valves that control the outflow of urine from the bladder | internal urethral sphincter (superiorly) & the external urethral sphincter (inferiorly located) |
inferior external sphincter consists of | skeletal muscle & is voluntarily controlled |