Chapter 25 - The Urinary System Flashcards
Kidneys
Blood supply comes from the aorta → renal artery → efferent artery (drains blood or returns) → afferent artery (brings blood) → vasa recta → cortical radiate vein → arcuate vein→ interlobar vein →renal vein →inferior vena cava → right artery
Kidneys: Function
- Urine formation; done by filtering fluid from blood allowing toxins, metabolic wastes and excess ions to leave the body as urine, well returning needed substances to the blood.
- Gluconeoginises – process of forming glucose to produce energy (done during prolong fasting).
- Hormones – rennin (maintain blood pressure) and erythropoietin (help produce erythrocytes – red blood cells).
- Metabolize vitamin D to its active form (provitamin D→ 25 dihdroxyl chlocalcifest)
Kidneys: Location
Retro peritoneal position, between the dorsal body wall and the partial peritoneal wall; superior lumbar region, extending from T12 – L3; right is lower than left because of live
Kidneys: Size and Shape
5oz each; 12cm L x 6 cm W x 3 cm T; bean shaped
Kidneys: External Anatomy
Lateral surface is convex, medial surface is concave; each has a space (renal hilum), on top of each is an adrenal gland
- Renal hilum – where vessels and other structures come from (medial surface); contains ureters, lymphatic, renal blood vessels, nerves
- Supporting tissue
a. Fibrous capsule – inner most layer; transparent and prevents infections from spreading to the kidney
b. Perirenal fat capsule – fatty mass; surrounds and cushions the kidney against trauma
c. Renal fascia – outer most layer; dense fibrous connective tissue and it anchors the kidneys and adrenal glands to the surrounding structures
Kidneys: Internal Anatomy
- Renal cortex – contains most of the nephrons (producing urine); long tubules, light in color, granular appearance and most superficial
- Renal medulla – darker region, reddish brown in color, deeper than cortex; it contains cone shaped tissue masses (renal pyramids), the base of the renal pyramid faces the cortex and the apex points internally (papilla of pyramid)
a. Renal pyramids – cone shaped tissue masses
b. Renal columns – inward extensions of cortical tissue and they separate the renal pyramids - Renal pelvis – funnel shaped tube and it’s continuous with the major calyx and the ureters found leaving the hilum
a. Minor calyces – cup shaped areas that enclose the papilla; subdivisions of the major calyces
b. Major calyces – 2 or 3 branching extensions of the renal pelvis
Nephrons
structural and functional unit of kidney (absorption, secretion and re absorption); contains over 1mil of these blood processing units; they carry out the process that form urine
1. Glomerulus – tough of capillaries 2. Renal tubule – portion of the nephron which contains tubuler fluid which gets filtered through the glomerulus 3. Glomerular capsule – aka Boemens capsule; cup shaped part of the renal tubule, its blind ending, and completely surrounds the glomerulus; partial layer is made of simple squamous epithelium 4. Renal corpuscle – glomerular capsule and the enclosed glomerulus 5. Peritubular capillaries – arise from the efferent arteral that’s found draining the glomerular; they cling closely to adjacent renal tubules and they empty into nearby venulous 6. Proximal convoluted tubule – found after the glomerular capsule 7. Loop of Henle – divided up into two parts: thin segment (descending limb) and thick segment (ascending limb) 8. Distal convoluted tubule – found after the loop of henle 9. Collecting ducts – where urine makes its way 10. Justaglomerular apparatus – maintain blood pressure
Ureters
slender tubes and they’re the continuation of the renal pelvis
A. Function – convey urine from the kidneys to the bladder
B. Location – begin at L2 and the descend behind the peritoneum and they run to the posterior lateral wall
Ureters: Internal Anatomy
- Mucosa – closest to the lumen
a. Transitional epithelium – expands and helps hold urine
b. Lamina propria – largest part after the transitional epithelium - Muscularis
a. Longitudinal layer – more internal layer
b. Circular layer – external layer - Adventitia – covers the ureters external layer a (typical fibrous connective tissue)
Urinary Bladder
Smooth, collapsible and muscular sac
A. Function – stores urine temporarily
B. Location – retro peritoneum just posterior to the pubic symphysis
Urinary Bladder: Internal Anatomy
- Trigone – smooth triangular region of bladder base (connects all 3 openings)
a. Uretic orifices – on both sides of the trigone; where the ureters come and pierce the bladder
b. Bladder neck – narrowing of the trigone - Detrusor muscle – muscular layer of the bladder that consists smooth muscle fibers
Urethra
Thin walled muscular tube that’s lined by pseudo stratified columnar epithelia but near the base it contains transition epithelia, near the external surface it contains stratified squamous epithelia
A. Function – drains urine from the bladder and conveys it out of the body
Urethra: Location - Females
Females – 1.5 inches long and tightly bound to the anterior vaginal wall
a. External urethral orifice – external opening, it lies anterior to the vaginal wall, and posterior to the clit
Urethra: Locations - Males
Males – 3 regions and longer
- Prostatic urethra – urethra region that runs in the prostate
- Membranous urethra – runs through the urogenital diaphragm (about 2 cm from the prostate to the beginning of the penis)
- Spongy urethra – passes through the penis and opens at the tip
a. External urethral orifice – opening at the tip of the penis
Urethra: External Anatomy
- Internal urethral sphincter – found at the bladder urethra junction and it’s a thicken of the detrusor smooth muscle
- External urethral sphincter – surrounds the urethra as it passes through the urethra genital diaphragm; formed by skeletal muscle and voluntary controlled
