Urinary System / Portage Learning A&P2, Module 7

Urinary System / Portage Learning A&P2, Module 7 urinary system organs 2 kidneys 2 ureters 1 urinary bladder 1 urethra kidney (shape, weight, location) bean shaped / size of soup can, about 5oz / located between T12-L3 vertebrae and are protected by the rib cage / right is slightly lower than the left b/c of the liver above it 00:0401:08 adrenal glands a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress. renal hilus (hilum) a notch located near center of medial concave side of the kidney / the passageway to renal sinus for vessels and ureter 3 layers of kidney tissue (outermost to innermost) renal fascia (outer, fibrous connective tissue, keeps kidney in place), adipose capsule (middle, fatty layer protects kidney from trauma), renal capsule (inner layer of protective tissue projects kidney from injury + infection) 3 regions of kidney (outermost to innermost) cortex, medulla, renal pelvis renal pelvis (of kidney) central collecting region in the kidney, extensions of the pelvis (calyces) collect urine and drain continuously into pelvis and then into ureter kidney blood supply chain Abdominal aorta - renal artery - segmental artery - lobar artery - interlobar artery - arcuate artery - interlobular artery - afferent arteriole - glomerular capillaries / filtration / efferent arteriole - peritubular capillaries (deoxygenated) or vasa recta - interlobular vein - arcuate vein -interlobar vein - renal vein which exits kidney Input from the _______ adjusts the diameter of the renal arteries thereby regulating renal blood flow. sympathetic nervous system Ureters Thin muscular tubes that carry urine from the kidneys to the bladder. ureterovesical valves sphincters located where the ureters enter the bladder, prevent urine from flowing back toward the kidney trigone of bladder triangular region at the base of the urinary bladder between the openings of the two ureters and the urethra urinary bladder (location) the male bladder lies in front of the rectrum + just behind the pubic symphysis / the female bladder sits below uterus, in front of vagina ureteral orifices The opening of a ureter into the urinary bladder 3 layers of ureter wall (outermost to innermost) outer fibrous connective tissue layer / middle muscular layer, uses peristaltic waves to carry urine to bladder / inner layer made of transitional epithelium, continuous with kidney's lining 3 layers of bladder wall (outermost to innermost) outer fibrous connective tissue layer / middle detrusor muscle layer / inner mucosal layer made of transitional epithelium specialized to enable cellular expansion to absorb fluid Describe the bladder when it is full and when it is empty. When filled with urine, the bladder swells and becomes pear-shaped, raising in the abdominal cavity / It collapses into a pyramid shape when empty 2 sphincters of the bladder Internal Urethral Sphincter (involuntary controlled) + External Urethral Sphincter (voluntary controlled) transitional epithelium location lines the ureters, bladder, and part of the urethra, specialized to enable cellular expansion to absorb fluid Differences between male and female urethra: Female is shorter and only carries urine. Male is longer and carries urine and semen 3 regions of male urethra prostatic urethra, membranous urethra, spongy (penile) urethra nephron Functional and structural unit of the kidney, function of the nephron is to control the concentration of water and soluble materials by filtering the blood, reabsorbing needed materials and excreting the rest as urine. nephron (functions) filtration of the blood, reabsorption of needed materials, excretion of waste as urine renal tubule consists of proximal convoluted tubule, loop of henle, distal convoluted tubule glomerulus A ball of capillaries surrounded by Bowman's capsule in the nephron glomerulus capsule (renal corpuscle) composed of the glomerulus, a network of tiny blood capillaries surrounded by the glomerular (Bowman's) capsule, a double-walled simple squamous epithelial cup What causes water and solutes to leave the glomerulus? The afferent arteriole, which is fed by the interlobular artery, is much larger in diameter than the efferent arteriole. The difference in diameter causes an extremely high blood pressure in the glomerular capillaries, forcing water and solutes out of the blood, thus making filtration possible. Water and solutes leave the glomerulus, enter the glomerular capsule, and subsequently flow into the renal tubule. filtrate water and solutes that have been filtered through the glomerulus and entered the glomerular capsule (Bowman's capsule) ________are found in the cortex region of the kidney, except for a portion of their loop of Henle which extends into the medulla. ______pass deeply into the medulla because of their location and their longer loops of Henle. Cortical nephrons / Juxtamedullary nephrons proximal convuluted tubule (PCT) first coiled section of the renal tubule, specialized to reabsorb water and many solutes from the glomerular filtrate and secrete unwanted substances Loop of Henle second section of renal tubule, initial descending limb that allows water loss followed by ascending limb that allows salt loss distal convuluted tubule (DCT) last coiled section of renal tubule, allows for hormonal controlled reabsorption of water and solutes, mostly responsible for secretion of unwanted substances Filtrate is considered urine once it: reaches the renal pelvis What are the three types of capillaries associated with nephrons and their function? Glomerular Capillaries, highly coiled capillary beds formed from afferent arteriole, leaving as efferent arteriole, specialized for filtration because of porosity and high pressure / Peritubular capillaries, closely follow renal tubules and drain into interlobular vein, adapted for reabsorption because of porosity and low pressure / Vasa Recta, follows loop of Henle in juxtamedullary nephrons of the medulla micturition urination, the act of emptying the bladder incontinence inability to control urination urine retention inability to empty the bladder How many times a day does the kidney filter through the blood plasma? 60 times each day, using 25% of the resting body energy to excrete waste as urine About how many gallons are filtered vs. excreted as urine? About 47 gallons of glomerular filtrate containing the water, nutrients, and essential ions are removed daily from the blood plasma. By the time filtrate enters the collecting ducts, it contains about only 0.5 gallons of urine, with the other 99% being returned to the blood. 3 steps of urine formation 1. glomerular filtration 2. tubular reabsorption 3. tubular secretion What is Blood hydrostatic pressure (HP)? the amount of pressure found inside the blood in the capillaries, driving fluids out of the glomerular capillary (rises with BP) What is Colloid osmotic pressure (COP)? aka oncotic pressure, the movement of fluid from the interstitial fluid back into the capillaries dependent on the amount of proteins in the plasma (normal range 25-32mmHg Capsular Pressure (CP) It also opposes blood hydrostatic pressure and drives fluid back into the glomerular capillaries. Net Filtration Pressure (NFP) the difference between net hydrostatic pressure and net osmotic pressure when entering the PCT (difference between outgoing forces and incoming forces at the glomerulus) What prevents blood cells from leaving the glomerular capillaries? The size of the capillary fenestrations prevents passage of blood cells and most blood proteins from leaving across the filter. Glomerular Filtration Rate (GFR) the amount of blood filtered by the glomerulus over time (normal GFR is 120-125mL/min or 180 L/day) What causes an increase in the GFR? a decrease? GFR is increased by arterial blood pressure in the kidneys. Decreased by an increase in glomerular osmotic pressure most often caused by dehydration. What happens if the GFR is too slow? too fast? If flow is too slow, nearly all the filtrate is reabsorbed, including most of the wastes that should be exerted. If flow is too fast, the needed substances cannot be adequately reabsorbed. What are the three mechanisms that regulate renal flow? Renal Autoregulation / Nervous System Controls / Renin-Angiotensin-Aldosterone (RAA) Renal Autoregulation of GFR Under normal circulstances, the kidneys themselves regulate GFR by controlling the diameter of the afferent and efferent arterioles. Nervous System Control of the GFR Nervous system takes over regulation by narrowing afferent arteriole diameter, the adrenal glands secrete epinephrine which decreases renal blood flow and therefore decreases GFR renin-angiotensin-aldosterone system (RAA) Decreased blood pressure causes the juxtaglomerular cells of kidneys to secrete renin which converts angiotensinogen (inactive) to angiotensin I (active) which is then converted into angiotensin II by angiotensin-converting enzyme (ACE) / Angiotensin II stimulates the adrenal cortex to secrete aldosterone which causes renal tubules to reabsorb more sodium ions and increased blood pressure/ Once blood pressure is restored, there is a decreased drive to stimulate renin release Angiotensinogen a pre-enzyme produced by the liver and freely circulates in the blood (is converted to angiotensin 1 and then angiotensin 2 to trigger thirst mechanism during RAA) When blood pressure drops, the enzyme ____ is released by the juxtaglomerular (JG) cells of the nephron. renin In the ____, angiotensin I is converted to ____. (during RAA) lungs, angiotensin II Once circulating angiotensin II reaches the adrenal cortex, it causes the release of the hormone ____. (during RAA) aldosterone Tubular reabsorption process of reclaiming water and solutes from the filtrate and returning them to the blood, and may be a passive or active process True or false: all reabsorption occurs in the renal tubules by diffusion. False: Some ions require active transport. Where does the greatest amount of renal tubular reabsorption occur?