Anatomy_Key Terms_Ch24 Flashcards
hilum
vertical cleft where vessels, ureters, and nerves enter and leave the kidney
fibrous capsule
“thin, tough layer of dense connective tissue adheres directly to the kidney’s surface, maintaining its shape and forming a barrier that can inhibit the spread of infection from the surrounding regions”
perirenal fat capsule
”"”raround the kidney””, just external to the renal capsule is the _, and external to that is an enverlope of renal fascia”
renal fascia
contains an external layer of fat, the pararenal fat (near the kidney), cushions the kidney aginst blows and helps hold the kidneys in place
renal cortex
more superficial region of the kidney, light in color and has a granular appearance
renal medulla
consists of cone-shaped masses called renal pyramids
renal pyramids
broad base of each abuts the cortex, whereas its apex or papilla points internally, exhibit striations because they contain roughly parallel bendles of tiny urine-collecting tubules
renal columns
inward extensions of the renal cortex, separate adjacent pyramids
renal pelvis
(pelvis=basin), flat funnel-shaped tube, simply the expanded superior part of the ureter
major calices
(singular, calyx), branching extensions of the renal pelvis form two or three _ each of which divides to form several minor calices
minor calices
(calyx=cup), cup-shaped tubes that enclose the paillae of the pyramids, collect urine draining from the papillae and empty it into the renal pelvis
segmental arteries
as each renal artery eapproaches a kidney, it divides into five _ that enter the hilum
interlobar arteries
each segmental artery divides into _ which lie in the renal columns between the renal pyramids
arcuate arteries
”"”shaped like a bow””, at the medulla-cortex hunction, the interlobar arteries branch into _ which arch over the bases of the renal pyramids”
cortical radiate arteries
radiating outward from the arcuate arteries and supplying the cortical tissue are small _
glomeurular arterioles
cortical radiate arteries give rise to _, which feed into the peritubular capillaries surrounding the tubules in the kidney
cortical radiate, arcuate, interlobar, and renal veins
blood leaving the renal cortex drains sequentially into the _, _, _, and _
nephron
”"”kidney””, main structural and functional unit of the kidney, composed of the renal corpuscle and a renal tuble (proximal tubule, nephorn lop/loop of Henle, distal tubule, collecting tudct) and lined by a simple epithelium”
filtration
a filtrate of the blood leaves the kidney capillaries and enters the renal tubule, contains all the small molecules of blood plasma, processed into urin by the mechanisms of resorption and secretion
resportion
most of the nutrients, water, and essential ions are recovered from the filtrate and returned to the blood of capillaries in the surrounding connective tissue (99% of renal filtrate volume), unnedded substances and wastes contribute to the urine that ultimately leaves the body
secretion
active process which moves additional undersirable molecules into the tubule from the blood of surrounding capillaries
renal corpuscle
“spherical, occur strictly in the cortex, consist of a tuft of capillaries called a glomerulus surrounded by a cup-shaped, hollow glomerular capsule (Bowman’s capsule)”
glomerulus
”"”ball of yarn””, tuft of capillaries supplied by an afferent arteriole and drained by an efferent arteriole, epithelium is fenestrated (has pores) and thus the capilllaries are highly porous”
capsular space
hollow interior of the glomerular capsule into which large quantities of fluid and small molecules pass from the capillary blood (20%)
parietal layer
simple squamous epithelium, contributes to the structure of the capsule but plays no part in the formation of filtrate
visceral layer
clings to the glomerulus and consists of unusual, branching epithelial cells called podocytes
podocytes
”"”foot cells””, octopus-like, branches end in foot processes”
foot processes
“or pedicels (““little feet””), interdigitate with one another as they surround the glomerular capillaries”
filtration slits
thin clefts between the foot processes through which the filtrate passes into the capsular space
filtration membrane
the actual filter that lies between the blood in the glomerulus and the capsular space, consists of three layers
proximal convoluted tubule
confined entirely to the renal cortex, most active in resorption and secretion. walls are formed by cuboidal epithelial cells whose apical (exposed) surfaces have long microvilli that increase the surface area of these cells tremendously, maximizing their capacity for resorbing water, ions, and solutes from the filtrate. the plasma membrane on their basal and lateral cell surfaces is highly infolded and contains many ion-pumping enzymes responsible for resorbing molecules from the filtrate. the cells contain many mitochondria, which provide the energy for resorption.
nephron loop
(loop of Henle), U-shaped, consists of a discending limb and an ascending limb. the first part of the descending limb is continuous with the proximal tubule and has a similar structure; the rest of the descending limb is the descending thin limb (DTL), the narrowest part of the nephron, with walls consisting of a permeable simple squamous epithelium. the nephron loop continues into the ascending thin limb (ATL) joining the thick ascending limb (TAL). the thick ascending limb joins the distal convoluted tubule in the cortex. the cell structure of this thick segment resembles that of the distal convoluted tubule.
distal convoluted tubule
like the proximal convoluted tubule is confined to the renal cortex. it has walls of simple cuboidal epithelium and is specialized for the selective secretion and resorption of ions. it is less active in resorption that the proximal tuble, and its cells do not have an abundance of absorptive microvilli. the cells of the distal tubule do have many mitochondria and infoldings of the basolateral membrane, features that are typical of all ion-pumping cells in the body
collecting ducts
receive urine from several nephrons and run straight through the cortex into the deep medulla
papillary ducts
at the papilla of the pyramid, adjacent collecting ducts join to form larger _ which empty into the minor calices
cortical nephrons
represent 85% of all nephrons, are located almost entirely within the cortex, with their nephron loops dipping only a short distance into the medulla
juxtamedullary nehprons
”"”near the medulla””, 15% of nephrons, their renal corpuscles lie near the cortex-medulla junction and nephron loops deeply invade the medulla, thin segments are much longer than those of cortical nephrons”
afferent glomeruler arteriole
foods the glomeruli, arise from the cortical radiate arteries that run through the renal cortex
efferent glomeruler arteriole
drains the glomeruli
peritubular capillaries
arise from the efferent arterioles draning the cortical glomeruli, lie in the interstitial connective tissue of the renal cortex, a loose areolar connective tissue that surrounds the renal tubules, adapted for absorption: low-pressure, prous, readily absorb solutes and water from the tubule cells after these substances are serorbed from the filtrate
vasa recta
”"”straight vessels””, hairpin loops that descend into the medulla running alongside the nephron loops, part of the kidney’s urine-concentrating mechanism”
juxtaglomerular complex
”"”near the glomerulus””, structure that functions in the regulation of blood pressure”
granular cells
“modified smooth muscle cells with secretory granuales containing a hormone called renin (““kidney hormone””), mechanoreceptors that secrete renin in response to falling blood pressure in the afferent arteriole”
macula densa
”"”dense spot””, terminal portion of the nephron loop adjacent to the granular cells, conssists of tall closely packed epithelial cells that act as chemoreceptors for monitoring sodium concentrations in the filtrate”
extraglomerular mesangial cells
interact with cells of the macula densa and granular cells to regulate glomerular blood flow
ureters
slender tubes about 25 cm long that carry urine from the kidneys to the bladder
mucosa (ureters)
composed of a transitional epithelium taht stretches when the ureters fill with urine and a lamina propria composed of a stretch, fibroelastic connective tissue containing rare patches of lymphoid tissue
muscularis (ureters)
consists of two layers: an inner longitudinal layer and an outer circular layer of smooth muscle, a third layer of muscularis, an external longitudinal layer, appears in the inferior third of the ureter
adventitia (ureters)
ureter wall, typical connective tissue
urinary bladder
collapsible, muscular sac that stores and expels urine, lies inferior to the peritoneal cavity on the pulvic floor just posterior the pubic symphysis
urachus
”"”urinary canal of the fetus””, fibrous band, the closed remnant of an embryonic tube called the allantois”
trigone
”"”triangle””, defined by the openings for both ureters and the urethra”
detrusor
”"”to thrust out””, consists of highly intermingled smooth lmuscle fibers arranged in inner and outer longitudinal layers and a middle circular layer”
urethra
thin-walled tube that drains urine from the bladder and conveys it out of the body
internal urethral sphincter
thickening of the detrusor at the bladder-urethra junction, involuntary sphincter of smooth muscle that keeps the urethra closed when urine is not being passed and prevents dribbling of urine between voidings
external urethral sphincter (urinary system)
surrounds the urethra with the sheet of muscle called the urogenital diaphragm, skeletal uscle, used to to inhibit urination voluntarily until the proper time
external urethral orifice
small, often difficult-to-locate opening that lies anterior to the vaginal opening and posterior to the clitoris
prostatic urethra
about 2.5 cm long and runs in the prostate
itermediate part of the urethra
or membranous urethra, which runs for about 2.5 cm through the membranelike urogenital diaphragm
spongy urethra
about 15 cm long, passes through the entire penis, and opens at the tip of the penis via the external eruthral orifice
micturition
“aka voiding or urination, act of emptying the bladder, brought about by the contraction of the bladder’s detrusor muscle, assisted by the muscles of the abdominal wall, which contract to raise intrabdominal pressure”
urinary tract infections
most occur in sexually active young women, intercourse drives bacteria from the vagina and the external genital region (and anus) through the nearby opening of the short urethra and toward the bladder
