Term
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Definition
| Absorbs most of filtered water and nonwaste plasma solutes. Also major site of solute secretion (not K+) |
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Term
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Definition
| Reabsorbs large amounts of major ions and small amounts of water |
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Term
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Definition
| Fine-tunes for most substances, determines final amount of excreted substances and adjusts the rate of reabsorption. |
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Term
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Definition
| Filtration of plasma from glomerular capillaries from the Bowman's space to form urine. Glomerular filtrate is cell and protein free. Contains ultrafiltrate in same concentration as in the plasma. |
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Term
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Definition
| Proteins kept out because of molecular weight and charge repulsion from corpuscle membranes. Exceptions include Ca2+ and fatty acids that are bound to the plasma proteins and are not filtrated. |
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Term
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Definition
| Determine filtrations through hydrostatic pressure that favors filtration,, protein concentration difference that creates an osmotic force that opposes filtration. Plasma protein concentration and osmotic force increase from beginning to the end of the glomerular capillaries. |
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Term
| Glomerular capillary hydrostatic pressure (Pgc) |
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Definition
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Term
| Bowman's space hydrostatic pressure (Pbs) |
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Definition
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Term
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Definition
| Opposes filtration from the presence of protein in the glomerular capillary plasma. No protein in filtrate in Bowman's space. |
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Term
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Definition
| Virtually zero because there is no protein. |
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Term
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Definition
| Movement from tubular lumen to peritubular capillary plasma. Glucose is 100% reabsorbed. |
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Term
| Pathway of Tubular reabsorption |
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Definition
1. Filtered loads are larger than amount of substance in body
2. Reabsorption of waste is incomplete
3. Reabsorption of most useful plasma components i.e. water, inorganic and organic nutrients & glucose
4. Occurs by diffusion across tight junctions connecting tubular epithelial cells and by mediated transport by tubular cells.
5. Final steps of reabsorption moves substance from interstitial fluid into peritubular capillaries by diffusion or bulk flow. |
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Term
| Reabsorption by diffusion |
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Definition
| Urea is reabsorbed by proximal tubule by diffusion. The movement of water changes movement of urea. If water removal is increased then urea concentration is increased by tubular fluid so that it diffuses into peritubular capillary and reabsorbed. |
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Term
| Reabsorption by mediated transport |
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Definition
| Substance must cross the luminal membrane then diffuse through the cytosol of cell and across basolateral membrane at tight junctions of plasma membrane. |
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Term
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Definition
| Limit to the amount of material that can transport per unit of time due to binding sites on membrane transport proteins, which become saturated when concentration of transported substance increases to a certain level. |
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Term
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Definition
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Term
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Definition
| Hyperglycemia in which the plasma glucose concentration exceeds the threshold value of 200mg/100mL so filtered load exceeds ability of nephron to reabsorb. |
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Term
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Definition
| Filtered load of glucose can lead to significant disruption of normal renal function. |
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Term
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Definition
| Movement into tubular lumen to be excreted out of body. Toxins should be fully excreted. |
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Term
| Steps of Tubular Secretion |
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Definition
1. Occurs by diffusion or mediated transport
2. H+ and K+ are most important secreted substances
3. Active secretion requires active transport from blood into cell or out of cell.
4. Usually coupled to Na+ reabsorption
5. Secretion from interstitial space into tubular fluid draws substances from peritubular capillaries and increases rate of secretion and filtration. |
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Term
| Metabolism by tubular cells |
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Definition
| Important for some substances to remove them from the blood or filtrate. The body can also produce substances to add to blood or tubular fluid. |
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Term
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Definition
| Cells of the renal tubules make glucose and add it to the blood. Can catabolize organic substances such as peptides in order to eliminate them from body. |
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Term
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Definition
| Filtered amount + Secreted amount - Reabsorbed amount |
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Term
| Regulation of membrane channels and transporters |
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Definition
| Hormones and paracrine or autocrine factors. Genetic mutations can lead to abornality in the Na+ glucose cotransporter leading to reabsorption of glucose in the proximal tubule. |
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Term
| Net Glomerular filtration pressure |
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Definition
| Normally positive and initiates urine formation by forcing protein-free filtrate of plasma out of the glomerulus and into the Bowman's space and then down the tubule into the renal pelvis. |
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Term
| Net Glomerular Filtration Pressure equation |
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Definition
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Term
| Glomerular Filtration Rate |
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Definition
| Determined by net filtration pressure and permeability of corpuscular membranes and the surface area available for filtration. |
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Term
| Constriction of afferent or dilation of efferent arterioles |
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Definition
| Decreases GFP and therefore decreases the GFR |
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Term
| Dilation of afferent or constriction of efferent |
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Definition
| Increases GFP and therefore increase the GFR. |
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Term
| Simultaneous constriction or dilation of both sets of arteriles |
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Definition
| Leaves pGC unchanged because of their opposing effect. |
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Term
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Definition
| Measure of total amount of nonprotein or non-protein bound substances filtered into Bowman's capsule by multiplying the GFR by the plasma concentration of the substance. It can be compared to substance excreted and indicate if the substance undergoes net tubular reabsorption or net secretion. |
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Term
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Definition
| Volume of plasma from which that substance is completely removed by the kidneys per unit of time. Cs= Us x V/ Ps |
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Term
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Definition
Biologically inert polysaccharide, can be used to estimate the glomerular filtration rate since it is filtered, but not reabsorbed or secreted.
Present in some of the vegetables and fruits that we eat. If it were injected into us, the amount of ____ entering the nephrons from the plasma would equal the amount excreted and none would be reabsorbed or secreted. |
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Term
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Definition
| Commonly used to approximate the GFR because it doesn't undergo reabsorption, and undergoes a small amount of secretion. It slightly overestimates GFR but is close enough to be highly useful in most clinical situations. It is assumed that _____ production by the body is constant and similar between individuals. Increase in _____ production in blood indicates decrease in GFR, a hallmark of kidney disease. |
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Term
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Definition
All plasma that enters the kidney per unit of time is cleared of its X.
When the clearance of a filterable substance is less than the GFR, that substance must undergo reabsorption. |
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Term
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Definition
1. Contraction of the detrusor muscle causes urination. Innervated by parasympathetic neurons. When it's relaxed the IUS is closed. When it contracts it opens the IUS.
2. Internal urethral sphincter : Contains sympathetic innervation
3. External urethral sphincter is a ring of skeletal muscles. Contraction can prevent urination even when the detrusor contracts strongly.
4. During filing, little parasympathetic input to detrusor and strong sympathetic input to internal urethral sphincter and strong input by somatic neurons to relax detrusor and close sphincters.
5. As it fills, pressure increases and stimulates stretch receptors in bladder wall. Stimulate parasympathetic neurons to contract detrusor and inhibit sympathetic neurons to the internal urethral sphincter and contributes to its opening. Also inhibits somatic motor neurons to the external sphincter causing it to relax and open.
6. Incontinence is the voluntary release of urine. |
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Term
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Definition
| Voluntary release of urine. |
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Term
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Definition
| Most common due to sneezing, coughing, or excercise. |
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Term
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Definition
| May be caused by any irritation to the bladder or urethra. |
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Term
| Internal urethral sphincter |
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Definition
| Contains sympathetic innervation |
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Term
| External urethral sphincter |
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Definition
| Ring of skeletal muscles. Contraction can prevent urination even when the detrusor contracts strongly. Innervated by somatic motor neurons. |
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Term
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Definition
| Has a parasympathetic input in micturition. |
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Term
| Two sources of body water gain |
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Definition
| Water from oxidation of organic nutrients and water ingested in liquids and food |
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Term
| Four sites of water lose to external environment |
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Definition
1. Skin evaporation in a continuous process called insensible water loss. Person is unaware of it occuring.
2. Respiratory airways
3. GI tract during diarrhea and vomiting
4. Urinary tract |
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Term
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Definition
| Active process occurring in tubular segments except the descending limb of the loop of Henle. |
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Term
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Definition
| Osmosis and dependent upon Na+ reabsorption |
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Term
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Definition
| High water reabsorption and low urine volume |
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Term
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Definition
| Large urine flow from increased urine and low vasopressin |
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Term
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Definition
| Increase in urine flow because increase of solute excretion. |
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Term
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Definition
| Vasopressin malfunctions from posterior pituitary malfunction or inability of kidneys to respond to vasopressin. |
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Term
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Definition
| High concentrated urine relative to plasma (high vasopressin) |
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Term
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Definition
| Minimal volume of water in which mass of solute can be dissolved. This loss contributes to dehydration when water intake is 0. |
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Term
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Definition
| Regulates collecting ducts water retention |
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Term
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Definition
| Steroid that acts slowly by inducing change in gene expression and protein synthesis. Induces synthesis of channels and pumps in cortical collecting duct. Stimulates Na+ absorption from lumen of large intestine and ducts carrying fluid from sweat and salivary glands. |
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Term
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Definition
| Secreted by juxtaglomerular cells of apparatus in kidney. Contributes to control of arterial pressure. |
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Term
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Definition
| Stimulate secretion of aldosterone and vasoconstriction of arterioles. High during salt depletion and low with high salt. |
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