Renal sinus
Обяснение
The renal sinus is the shallow C-shaped space that contains and receives the renal pelvis and calyces. The cortex and pyramids are tissue regions, not the collecting space.
Cortex
Обяснение
The cortex is the outer reddish-brown region and contains mainly convoluted proximal and distal tubules. The medulla is the inner paler region formed by pyramids and straight ducts.
Filtering blood to form the initial filtrate
Обяснение
The renal corpuscle is the nephron’s filtration unit, where blood is filtered to form the initial filtrate. The other options describe functions of different structures or hormones.
Podocyte filtration slits
Обяснение
Podocyte filtration slits are the third layer of the barrier and are about 25 nm wide. The fenestrated endothelium has much larger pores, and mesangial cells are contractile support cells.
Linking the glomerulus to signals about renal blood flow and regulating filtration
Обяснение
The juxtaglomerular apparatus links the glomerulus to renal blood flow signals and helps regulate filtration. It is not the site of urine concentration or glucose storage.
Tubular reabsorption
Обяснение
Tubular reabsorption moves useful substances from tubular fluid back into the blood. Tubular secretion does the opposite, moving substances from blood into the tubule.
Blood flow equals capillary pressure divided by flow resistance
Обяснение
Renal blood flow is described as capillary pressure divided by flow resistance. The other choices mix unrelated filtration or clearance concepts.
80–180 mmHg
Обяснение
The kidney maintains relatively constant renal blood flow and GFR across about 80–180 mmHg. Outside this range, autoregulation becomes less effective.
Glomerular filtration, tubular reabsorption, and tubular secretion
Обяснение
Urine formation relies on glomerular filtration, tubular reabsorption, and tubular secretion. The other choices are not the core renal processes.
About 65%
Обяснение
About 65% of sodium and water reabsorption occurs in the proximal tubule. This is why the proximal tubule is described as the site of bulk isosmotic reclaim.
60 mmHg hydrostatic minus 25 mmHg oncotic minus 10 mmHg tissue resistance
Обяснение
The course gives net filtration pressure as 60 minus 25 minus 10, which equals 25 mmHg. This reflects hydrostatic pressure opposed by oncotic and tissue resistance forces.
Hemorrhage causing decreased capillary blood pressure
Обяснение
Hemorrhage lowers capillary blood pressure and therefore decreases GFR. Increased renal blood flow or lower plasma protein concentration would tend to raise filtration.
Tubuloglomerular feedback
Обяснение
Tubuloglomerular feedback is the salt-sensing mechanism in which the macula densa adjusts arteriolar tone to stabilize GFR. The other choices refer to different renal functions.
Vasoconstriction that helps conserve blood volume or redirect flow
Обяснение
Sympathetic stimulation can constrict renal vessels during hemorrhage or exercise to conserve blood volume or redirect blood flow. It does not primarily produce renal vasodilation.
Movement down an electrochemical or concentration gradient without direct ATP use
Обяснение
Passive transport is movement down a gradient without direct ATP use. Active carrier-mediated uphill movement is the opposite process.
Transcellular transport
Обяснение
Transcellular transport goes through cells using membrane transporters or channels. Paracellular transport goes between cells through intercellular spaces.
Clearance equals urine concentration times urine flow rate divided by plasma concentration
Обяснение
Clearance is calculated as U × V / P, using urine concentration, urine flow rate, and plasma concentration. This quantifies the plasma volume cleared of a substance per minute.
Because PAH is cleared efficiently by the kidneys
Обяснение
PAH is handled so efficiently that its clearance is used to estimate renal plasma flow. In contrast, inulin is used for GFR because it is freely filtered with no net reabsorption or secretion.
Tubular reabsorption adjusts in proportion to filtered load
Обяснение
Glomerulotubular balance means tubular reabsorption rises in proportion to filtered load delivered to the tubules. This helps keep tubular fluid composition relatively stable when GFR changes.
Loop of Henle anatomy, vasa recta, and ADH
Обяснение
Counter-current concentration depends on the loop of Henle, vasa recta, and ADH. Together they create and preserve the medullary osmotic gradient needed for concentrating urine.
Limits changes in hydrogen ion concentration
Обяснение
Buffering resists changes in H+ concentration rather than removing the added acid or base. It is the first-line defense for acid-base stability.
Macula densa
Обяснение
The macula densa senses Na+ in the tubular filtrate and communicates with the juxtaglomerular apparatus. Podocytes and mesangial cells belong to the glomerulus rather than the distal tubule.
Diabetes insipidus
Обяснение
Diabetes insipidus results from reduced ADH, which impairs water conservation and causes high urine output. The other choices describe bladder disorders or a diagnostic graph.
About 3 years
Обяснение
Complete voluntary control is achieved at about 3 years when cortical control takes over micturition. Before that, voiding is largely reflexive.
Запомнете отговорите с 24 флашкарти по Kidney Structure and Function Fundamentals.
Kidney regions — main zones?
Cortex and medulla.
Renal sinus — role?
Receives renal pelvis and calyces.
Hilus — function?
Entry/exit point for vessels and ducts.
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