Chapter 25) Urinary System Flashcards
1
Q
Kidney Functions
A
- Regulates total water volume and solute concentration
- Regulates ECF ion concentrations
- Ensured long-term acid base balance
- Removal of metabolic Wastes, toxins and drugs
2
Q
Endocrine Functions of the Kidney
A
- Rennin) Regulation of blood pressure
- Erythopoitein) Regulation of RBC production
3
Q
Kidney Anatomy
A
- Bean shaped organs that lie in a retroperiotneal position (between body wall and dorsal peritonium) in superior lumbar region
- T12-L3
- about 150g (5oz)
- Right kidney lower than left because of liver
- Adrenal (suprarenal) gland atop each kidney
- Convex Lateral Surface and Concave Medial Surface
- Renal Hilum) cleft on mediald surface that leads to internal space called renal sinus.
- Renal Fascia (supporting tissue)
- anchoring layer of dense fibrous connective tissue
- Perirenal Fat Capsule (Supporting tissue)
- Fatty cushion
- Fibrous Capsle (supporting tissue)
- prevents spread of infection of kidneys
4
Q
Internal Kidney Anatomy
A
- Renal Cortex) superficial region
- Renal medulla) cone shaped medullary pyrmaids
- seperated by renal colums
- Papilla) top of renal pyramid
- releases urine into minor calyx
- Lobe) medullary pyrmaid and surrounding cortical tissue
- about 8 per kidney
- Renal Pelvis) Tube continuius with urteter
- Minor calyces) drain pyrmaids at papillae
- Major Clyces)
- collect urine from minor calyces
- empty urine into renal pelvis
- Urine Flow
- Renal Pyrmaid > Minor Calyx > Major Calyx > Renal Pelvis > Ureter
- Pyelonephritis) inflmation/ infection of entire kidney
5
Q
Blood and Nerve Supply of the Kidneys
A
- Kidneys cleasne blood and adjust its composition
- Renal Arteries deliver 1/4 of total cardiac output to kidneys each min
- Arterial and Venous flow use similar paths
- Renal Plexus) networ of autonomic nerve fibers that provide nerve supply to kidneys and ureter
- No segmental veins
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6
Q
Nephrons
A
- Nephrons) Sturctural and Functional units that form the urine
- about 1 million per kidney
- Two main parts
- Renal Corpscule
- Renal Tubule
7
Q
Renal Coruscle (Nephron)
A
- Two Parts
- Glomerulus)
- Tuft of capillaries;
- fenestrated endothelium > Higly porus > allows large ammout or solute rich but protien free fluid to flow into glomular capsule
- Fluid is Filitrat; or the raw material the renal tubes process
- Glomular Capsule (Bowman’s Capsule)
- Cup-shaped, hollow structure surrounding glomerulus
- External Parietal Layer) simple squamous epithelium
- Internal Visceral Layer) conists of podocytes (foot cells) that cling to glomular capillaries
- Fenestrations allow filtrate to pass into capsular space
8
Q
Renal Tubule (nephron)
A
- Proximal Convoluted Tubule
- Proximal > Closest to the renal corpuscle
- Cubodial cells with dense micro villi and large mitochondria
- Functions in reabsorption and secretion
- Nephron Loop)
- descedning and ascending limbs
- Proximal part of descending limb continuious with proximal tububule (same cells)
- Distal descending limb) simple squamous epithlium
- Thick ascening limb) cuboidal cells to columnar cells)
- Distal Convoluted Tubule (DCT)
- Cubodial Cells wit very few microvili
- Function more in secretion than reabsorption
9
Q
Collecting Ducts
A
- Two cell types found in collecting ducts
- Principal Cells
- more numerous
- sparse, short microvilli
- Mantain water and Na+ balance
- Intercalated cells
- Cuboidal cells with abundent microvilli
- two types; A and B
- Help mantian acid-base balance
- Collcting ducts
- recive filtrate from many nephrons
- Run through medullary pyrmids (striped appearence)
- Fuse together to deliver urine through parillae into minor calyces
10
Q
Classes of Nephrons
A
- Cortical Nephrons) 85; almost entirely in cortex
- Juxtamedullary Nephrons)
- long nephron roots indvade medulla
- Ascending limbs have both thick and hting segments
- concentrtates urine
11
Q
Nephron Capillary beds
A
- Glomerulus) Specilized for filtration
- fed and drined by arteriole (affrent arteriole> glomerulus > efferent arteriole)
- Higher blood pressure because affrent arterioles larger than efferent ones (high-resistance vessels)
- Peritubular capillaries
- low pressure, porous capillaries adapted for absorption of water and solutes
- arise from effrent arteioles; empty into venules
- cling to ajacent renal tubules
- Vasa Recta
- Long, thin-walled vessels parallel to long nephron loops of juxtamedullary nephrons
- Form concentrated urine
12
Q
Juxtaglomerular Complex (JGC)
A
- One per nephron
- Distal portion of ascending limb of the nephron loop lies against the afferent arteriole; feeds the glomerulus
- Modified portions of
- distal protion of ascending limb of nephron loop
- Afferent (sometimes efferent) arteriole
- Important in regulation of rate of filtrate formation and blood pressure
- Macula Densa) Dense spot
- tall, closley pact cells of ascending limb
- Chemoreceptors; sense NaCl content of the filtrate
- Granular Cells (juxtaglomerular/ JG cells)
- enlarges smooth muscle cells of arteriole
- release enzyme renin
- mechnoreceptors; sense blood pressure
- Extraglomerular mesangial cells
- Between arteriole and tubule cells
- Interconnected with gap junctions
- May pass signals between macule densa anc granular cells
13
Q
Mechanisms of Urine Formation
A
- Glomerular filtration) dumping into waste container
- takes place in renal capsule
- produces cell and protein free filtrate
- passive proccess
- Tubular resabsoprtion ( reclaiming what the body needs)
- selectivly returns all glucose and amino acids and 99% of water
- moves stuff from filtrate to renal tubules and collecting ducts
- anything not reabsorbed becomes urine
- Tubular Secretion) Selectively adding to the waste container
- selivtively moves substances from blood to filtrate in renal tubes and collectind ducts
- Kidneys filter entire plasma volume 60 times a
14
Q
Filtration Membrane
A
- Membrane between blood and interior of glomerular capsule
- no cells can pass
- three layers
- Fenestrated Endothelium) of glomerular capillaries
- Basement Membrane) lies between the other two layers composed of fused basal laminae
- Foot Processes of Podocytes) filtration slits between foot processes.
- prevent any macromolecules that exit from the basment membrane from traveling farther (slit diaphragms)
- moleciles smaller than 3 nm (water, glucose, amino acids, nitrogonuses wastes) pass from blood into glomelural capsule. `
- Glomular Mesangeal cells) specilized pericytes called glomuerular mesingial cells.
15
Q
Pressures that Affect Filtration
A
- Hydrostatic pressure in glomerular capillaries (Glomerular blood pressure)(outward pressure)
- Chief force pushing water and solutes out of blood
- Quite high compared to other capilalries because of high resistance afferent arteriole
- Colloid Osmotic Pressure in Capsular Space of Glomular Capsule (Outward).
- would pull filtrate into the tubule but is zero because no protein enters
- Hydrostatic pressure in capsular space (HPcs)(Inward)
- Pressure of the filtrate in the capsule
- about 15 mm Hg
- Colloid Osmotic Pressure in capillaries (OPgc)
- Pull of proteins in the blood
- 30 mm Hg
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16
Q
Net Filtration Pressure (NFP)
A
- NFP) Net filtration pressure
- 55 mm Hg forcing out
- 45 mm Hg opposing
- Net force = 10 mm Hg outwatd
- NFP is the main controllable factor that determines glomerular filtration rate (GFR)
- Volume of filtrate formed per minute by both kidneys
- GFR is directly proportional too
- NFP) hydrostatic pressure in glomerous
- Total surface area avaible for filtration
- Filtration membrane permiablility) fenestrated.
17
Q
Regulation of Glomerular Filtration
A
- GFR is tightly regulated to serve two crucial, somtimes apposing needs
- Constant GFR allows kidneys to make filtratre and mantain GFR in kidney (intrensic controls)
- GFR affects systemic blood pressure (extrensic controls)
- Intrensic Controls) act locally to mantaon GFR
- MAP = 80-180 mmHg
- Autoregulation ceases if out of that range
- Extrinsic Controls
- Nervous and endocrine mechanisms
- take predominance if blood pressure is out of MAP
- NFP rises = GFR rises
