What is a Renal Tubule?
Part of a Nephron, that begins as a cup-shaped glomerular (Bowman's) capsule, surrounding the glomerulus.
What is the function of a Fenestrated glomerular capillaries?
Allows filtrate to pass from plasma into the glomerular capsule.
What are the Renal Tubules?
Proximal Convoluted Tubule, Loop of Henle, and Distal Convoluted Tubule.
What is the Proximal Convoluted Tubule?
PCT - Functions in reabsorption and secretion. Confined to the cortex.
What is the Loop of Henle?
Thin segment ususally within the descending limb. Freely permeable to water. Thick segment of ascending limb.
What is the Distal Convoluted Tubule?
DCT - Functions more in secretion than reabsorption. Confied to the cortex.
What are Collecting ducts?
Receive filtrate from many nephrons. Fuse together to deliver urine through papillae into minor calyces.
Why is blood pressure high in Glomerulus?
Afferent arterioles are large in diameter than efferent arterioles. Arterioles are high-resistance vessels.
What is the Vasa Recta?
Rect = Straight, Vasa = Vessels. Long vessels parallel to long loops of Henle.
What are the Mechanisms of Urine Formation?
Glomerular filtration, Tubular Reabsorption, and Tubular Secretion.
What is Tubular Reabsorption?
Tubules to blood. Returns all glucose and amino acids, 99% of water, salt, and other components to the blood.
What are the Intrinsic controls of Glomerular Filtration?
Renal Autoregulation - Acts locally wihin the kidney.
What are the Extrinsic Controls of Glomerular Filtration?
Nervous and endocrine mechanisms that maintain blood pressure, but affect kidney function.
What is the function of the Proximal Convoluted Tubule?
Site of most reabsorption. 65% of Na+ and water. All nutrients. Ions. Small proteins.
What is the function of the Distal Convoluted Tubule and Collecting Duct?
Reabsoprtion is hormonally regulated - Ca2+ (PTH), Water (ADH), and Na+ (Adosterone and ANP).
What is Facultative Water Reabsorption?
Water reabsorption that depends on the pressence of ADH. In the presence of ADH 99% of H20 in filtrate is reabsorbed.
What are the risk factors of Kidney stones?
May be due to chronic bacterial infection, urine retention, elevated Ca2+ in blood, higher pH of urine.
What is a Trigone?
Smooth trigangular area outlined by the openings for the ureters and the urethra. Infections tend to persist in this region.
What are the layers of the bladder wall?
Transitional epithelial mucosa, thick detrusor muscle (three layers of smooth muscle), and fibrous adventitia (peritoneum of superior surface only).
What does the Urinary Bladder Expand?
During filling, also rises superiorly without significant rise in internal pressure.
What is the Internal Urethral Sphincter?
Involuntary (smooth muscle) at bladder-urethra junction. Contracts to open.
What is the External Urethral Sphincter?
Voluntary (skeletal) muscle surrounding the urethra as it passes through the pelvic floor.
What is the location of the external urethral orfice in the Female?
Anterior to the vaginal opening, posterior to the clitoris.
What does the female urethra have an increased chance of?
Urinary Tract Infections due to shortness.
What are the three regions of the Urethra of the Male?
Prostatic Urethra, Membranous Urethra, and Spongy Urethra.
What is the Spongy Urethra?
15 cm - passes through the penis and opens via the external urethral orifice.
What are the three simultaenous events in Micturition?
Contraction of detruster muscle by ANS, Opening of internal urethral sphincter by ANS, opening of external urethral sphincter by somatic nervous system.
What is Reflexive Urination?
Urination in infants. DIstension of bladder activates stretch receptors. Excitation of parasympahtetic neurons in reflex center in sacral region of Spinal Cord. Contractor of the detruster muscle. Contraction (opening) of internal sphincter. Inhibition of somatic pathways to external sphincter, allowing its relaxation (opening).
Why is incontinence normal in infants?
Control of the voluntary urethral sphincter develops with the nervous system.