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Urine System pt. 2
Chapter 24
| Question | Answer |
|---|---|
| How much blood flow through the kidney is pf the resting cardiac output? | 20% to 25% |
| When does filtrate form? | When blood flows through glomerulus |
| What is filtrate composed of? | Water and solutes filtered from blood plasma |
| How does filtrate move through the glomerulus? | Across wall of glomerular capillaries and into capsular space |
| What is tubular fluid? | New name for filtrate when enters Proximal convoluted tubule (PCT) |
| What is the flow order in which tubular fluid goes through? | PCT , Nephron loop , DCT, Enters collecting tubules , Empties into larger collecting ducts |
| What is tubular fluid called when it hits the papillary duct? | Urine |
| Where is the papillary duct located? | Within the renal papilla |
| Where does urine flow within the kidney? | Renal sinus |
| What is the flow order in which urine goes through? | Minor calyx → major calyx → renal pelvis → Ureter → Urinary bladder → Urethra |
| What does the urinary bladder do? | Stores and excretes from body through urethra |
| Urine forms in what 3 processes? | Glomerular filtration, Tubular reabsorption, Tubular secretion |
| Where does glomerular filtration happen? | In glomerular capillaries |
| What does the glomerular filtration do? | Separates some water and dissolved solutes from blood plasma and then the water and solutes enter capsular space of renal corpuscle, due to pressure differences across filtration membrane |
| The separation of water and dissolved solutes is called what? | Filtrate |
| How does Tubular reabsorption move substance? | By diffusion, osmosis, or active transport |
| What is tubular reabsorption? | Movement of components within tubular fluid back into the blood within peritubular capillaries and vasa recta. |
| Where does tubular reabsorption move through? | Move from lumen of tubules and collecting ducts across walls |
| What does tubular reabsorption reabsorb? | Vital solutes and most water |
| What components make up tubular fluid? | Excess solutes, waste products, some water that were not reabsorbed. |
| How does tubular secretion move solutes? | By active transport |
| What does tubular secretion do? | Movement of solutes out of blood within peritubular and vasa recta capillaries into the tubular fluid |
| Where does tubular secretion release into? | Collecting tubules |
| What is the filtration membrane? | A porous, thin, and negatively charged structure formed by glomerulus and visceral layer of glomerular capsule. |
| Why is the filtration membrane composed of 3 layers? | To enter filtrate |
| What are the 3 layers of the filtration membrane? | Endothelium, basement membrane and filtration slits of the visceral layer |
| What substances are filtered by the filtration membrane? | Water, glucose, amino acids, ions, urea, some hormones, vitamins B and C, ketones, very small proteins |
| What are the three categories of substances in blood? | Freely filtered, Not filtered, Limited filtration |
| What are freely filtered substances? | Small substances |
| What are not filtered substances? | Formed elements and large proteins |
| What are not limited substances? | Proteins of intermediate size, due to size or due to negative charge. |
| What is Net filtration pressure (NFP) | Pressures promoting filtration are greater than pressures opposing. |
| What is the Net filtration pressure (NFP) fomrula? | HPg - (OPg + HPc) = NFP |
| HPg | Glomerular hydrostatic pressure |
| HPc | Capsular hydrostatic pressure |
| OPg | Blood colloid osmotic pressure |
| Glomerular filtration rate (GFR) | Is tightly regulated and helps kidney control urine production based on physiologic conditions |
| What is glomerular filtration rate (GFR) influenced by? | Changing luminal diameter of afferent arteriole and altering surface area of filtration membrane. |
| How is GRF maintained? | Renal autoregulation maintains GRF despite changed in systemic blood pressure by decreasing systemic BP and increasing systemic BP. |
| What happens when the Renal autoregulation decreases systemic BP? | Vasodilation of afferent arteriole |
| What happens when the Renal autoregulation increases systemic BP? | Vasoconstriction of afferent arteriole |
| How is GRF decreased? | By the sympathetic division which causes afferent arteriole to vasoconstrict, triggering mesangial cells to CONTRACT and decrease filtration surface area. Urine production will decrease, helping maintain blood volume. |
| How is GRF increase? | By the atrial natriuretic peptide (ANP) which causes afferent arteriole vasodilation, inhibiting renin release , triggering mesangial cells to RELAX and increase filtration surface area. Urine production will increase, decreasing blood volume. |
| How is renal autoregulation controlled? | By intrinsic controls, it maintain constant blood pressure and GFR |
| What two mechanisms help renal autoregulation function? | Myogenic response and tubuloglomerular feedback mechanism |
| Myogenic response with decrease in pressure | -Contraction of smooth muscle of afferent arteriole wall -Decreased blood pressure, less stretch of smooth muscle in arteriole -Causes smooth muscle cells to relax, vessels to dilate -Allows more blood into glomerulus -GFR remains normal |
| Myogenic response with increased pressure | -With increased blood pressure, more stretch of smooth muscle in arteriole -Causes smooth muscle cells to contract -Vessels constrict -Allows less blood into glomerulus -Compensates for greater systemic pressure -GFR remaining normal |
| Tubuloglomerular feedback mechanism | -“Backup” to myogenic mechanism response to increased blood pressure |
| What happened if glomerular blood pressure increased under Tubuloglomerular feedback mechanism? | The amount of NaCl in tubular fluid also increased which is detected by macula densa cells, resulting in further vasoconstriction of afferent arteriole. |
| How does Renal autoregulation maintain GRF through limitations? | By maintaing normal glomerular pressure within certain range |
| What happens when there is a decrease in blood pressure below 80 mm Hg? | Arterioles are at maximum dilation, decreasing glomerular blood pressure and GFR |
| What happens when there is a Increase in blood pressure above 180 mm Hg? | Arterioles at maximum constriction, increasing glomerular blood pressure and GFR |
| How are neural and hormonal substances controlled through the GFR? | By extrinsic controls |
| Neural and hormonal control | Involves physiologic processes to change GFR by decreasing with extensive sympathetic stimulation, increasing atrial natriuretic peptide stimulation, which alters urine production. |
| When is sympathetic stimulation triggered to increase output in the kidneys ? | During exercise or emergency |
| What happens if sympathetic stimulation vasoconstricts too much? | Can reduces blood flow into glomerulus |
| What is atrial natriuretic peptide (ANP)? | A peptide hormone released from cardiac muscle cells |
| When is atrial natriuretic peptide (ANP) triggered? | Distension of heart chambers |
| What does the endothelium of the filtration membrane block? | Formed elements |
| What does the basement membrane of the filtration membrane block? | Blocks large proteins |
| What does the filtration slits of the visceral layer of the filtration membrane block? | Small proteins |
Created by:
Olivve
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