Renal System Normal Function Flashcards
Renal-Relates to the Kidney
Kidney is part of the Urinary System
Two sets of organs
- Urine forming organs (1)
- Organs that store or carry urine out of the body (3)
- Kidneys
- Ureter, Bladder, Urethra
Outline of Topics
- Nephrons and steps in Urine Formation
- Glomerular Filtration - mechanism and _____
- Tubular Reabsorption - importance of ___ reabsorption
- Tubular Secretion - __, ___, role for ______, Organic ____
- Hydration State and varying the concentration of urine
- Medullary osmotic _____
- Anti____ Hormone
- Variable ___ reabsorption at the distal tubule and CD
- Long Term Control of Blood Pressure through the _____ System
- Nephrons and steps in urine formation
- control
- Na+ reabsorption
- H+, K+, Aldosterone, ions
- Hydration state and varying concentration of urine
- gradient
- ADH
- H20
- Long term B control - RAAS system
Parts of the Urinary System
Kidneys: major filtering organ of our body
- Filters _____ by taking blood and filter excess fluid, excess electrolytes to be removed from body
- D____ elimination
Renal Blood Flow: (1) branches off abdominal aorta and supplies blood to kidneys -> kidney filters that blood then leaves through (1) -> drains to (1) back into heart
- waste
- drugs
Renal Artery -> Renal Vein -> Abdominal Vena Cava -> heart
Parts of the Kidney
(1): outer, lighter region
(1): inner darker region
(1): set of tubules where urine collects and drains into renal pelvis
(1): center of kidneys where urine collects and exits through ureter
Renal Cortex
Renal Medulla
Renal Pyramid
Renal Pelvis
Urine is formed in cortex and medulla then drains into renal pelvis
Structure of the Kidneys
Kidneys function as (3) types of organs
Each kidney is composed of about 1 million microscopic functional units called ______:
(2) components
Filtering, Endocrine, Metabolic
Nephrons
Vascular, Tubular Component
Kidney Functions (notes)
We are going to focus on the kidneys filtering function however they also..
Kidneys as Endocrine organs: (1) hormone that acts on bone marrow to stimulate RBC production
Kidneys as Metabolic organs: (1) produces new glucose from substrates such as lactic acid and amino acids (is a main function of liver but kidneys contribute to this)
Erythropoietin (EPO)
Gluconeogenesis
Tubular Components
(1): yellow claw like structure that wraps around the Glomerulus
(1): tuft of capillairies where urine formation _____- plasma within capillaries filters across membrane into bowman’s capsule then down tubules
Flow of Urine
(1): first portion of tubule closest to glomerulus
(1): first down descending arm then up ascending arm
(1)
(1): physically attached to about 9-12 nephrons (located in renal pyramid) -> renal _____ -> _____
Bowman’s Capsule
Glomerulus
Proximal Tubule
Loop of Henle
Distal Tubule
Collecting Duct -> renal pelvis -> ureters
Vascular Components
Flow of Blood
- (1)
- (1): blood moving into Glomerulus
- (1): blood that doesn’t get filtered in glomerulus moves out through this
-
(1): network of capillaries (purple net) that surrounds the nephron
- Exchange of substances back and forth between capillaries and tubules adjusts _____ of urine
- (1): then into vena cava
- Renal Artery
- Afferent Arteriole
- Efferent Arteriole
-
Peritubular Capillaries
- composition
- Renal Vein
Juxtaglomerular Apparatus
**Importance** =
- juxta-glomerular = right ____ to glomerulus
- Portion of ____ tubule sits close and in between (2) -invaginate (form a V) -> regulates ____ of filtration
REGULATES KIDNEY FUNCTION
- next to glomerulus
- distal, sits between afferenta and efferent arteriole -> regulates rate of filtration
Regional Differences Among Nephrons
- All nephrons originate in the _____ of the Kidney
- Differ in location of _____ within cortex
- (1) nephrons: glomeruli where?
- (1) nephrons: glomeruli where?
- Differ in location of _____ within cortex
- cortex
- glomeruli
- (Superficial) Cortical Nephrons: outer cortex
- Juxtamedullary Nephrons: inner cortex
- glomeruli
3 Anatomical Differences of Nephrons
- ____ of glomeruli
- _____ of loop of henle
- Juxtamedullary has ___ ____
Juxtamedullary Nephron
- Glomeruli near ____
- ____ loops of henle
- (1): starts with single vessel that parallels the loop of henle and then exits medulla, peritubular capillaries only really wrap around tubular parts in the cortex
Cortical Nephron
- Glomeruli sit near ____ edge of cortex
- ____ loops of henle
- Peritubular capillaries wrap around _____ tubule
- Location
- Lengths
- Vasa Recta
Juxtamedullary Nephron
- medulla (outer cortex)
- Long
- Vasa Recta
Cortical Nephron
- outer
- Short
- entire
Functional Differences Between Nephrons
Juxtamedullary Nephrons important function =
- High proportion of juxtamedullary nephrons in what type of animals?
- High proportion of cortical nephrons in what type of animals?
Humans: ___% Juxtamedullary, __% Cortical
Important in kidney conservation of water by allowing kidneys at certain times produce very concentrated urine
- dry climates
- wet climates
20% juxta, 80% cortical
Basic Renal Processes
(3)
What percent of plasma that enters glomerulus gets filtered into bowman’s capsule?
Glomerular Filtration (first stage of urine production)
Tubular Reabsorption (tubule -> capillary)
Tubular Secretion (capillary -> tubule)
20%
Glomerular Filtration
Renal Corpuscule =
(3) Layers of Glomerular Membrane
- GF is a completely ______** and nonselective process
Glomerulus + Bowman’s Capsule
- Wall of Glomerular Capillaries
- Basement Membrane
- Inner Layer of Bowman’s Capsule
- passive**
Glomerular Membrane (Notes)
- _____ cells compose the capillary wall
- White outline = ______ membrane
- (1) make up inner membrane of bowman’s capsule is the spaces in between these processes
Function of Glomerular membrane =
- Fluid that enters Bowman’s capsule (filtrate) _____ in composition of plasma minus (2)
- Endothelial cells
- Basement Membrane
- Podocytes: podo meaning feet, foot processes wrap around capillaries
Prevent plasma proteins and cells from getting out of capillaries
- filtrate identical to plasma minus protein and cells
Forces Involved in Glomerular Filtration
(3)
Which forces OPPOSE glomerular filtration?
Net Filtration Pressure =
Capillary Blood Pressure (55) pushing pressure
Plasma Colloid Osmotic Pressure (30) pulling pressure
Bowman’s Capsule Hydrostatic Pressure (15) pushing pressure from bowman’s
Plasma Colloid + Bowman’s Hydrostatic pressures OPPOSE -> only Cap BP promotes GF
10
The Rate of Glomerular Filtration
Depends on (3)
Filtration Coefficient Kf = ___ x ___
GFR = ___ x ___
Net filtration pressure
Surface Area available
Permeability of Glomerular Membrane
SA x Permeability
Kf x net filtration pressure
Rate of Glomerular Filtration (Notes)
- GFR: volume of fluid filtered at glomerulus per ____, measure of renal ___ and ____ of kidneys
- SA = how many functional ____ you have
- Permeability - if membrane gets ____, perm will go down
- Filtration Coefficient Kf should be ____ in a normal healthy person -> if it is then GFR is entirely dependent on (1) AKA capillary blood pressure
- minute, function, health
- nephrons
- injured/scarred
- constant - net filtration pressure
Two Major Mechanisms Control GFR
(2)
Each with Different Goals/Priorities?
Autoregulation
Goal = maintain GFR in the face of normal fluctuations in BP ie. diff positions, stress (intrinsic control, prevents spontaneous changes in GFR whenever arterial BP changes)
Extrinsic Sympathetic Control
Goal = alter GFR in an attempt to control blood volume and BP ie) if BP drops, GFR is going to drop to conserve fluid
Autoregulation
(Goal = maintain GFR in face of normal fluctuations in BP)
- Kidneys maintain steady Glomerular blood flow and a stable GFR by altering the _____ of the _____ _____ by constriction or dilation of ____ ____ lining of the vessels wall
What happens if arterial blood pressure increases?
What happens if arterial blood pressure decreases?
- diameter, afferent arteriole, smooth muscle
Vasoconstriction of Afferent Arteriole to decrease blood flow into glomerulus
Vasodilation of Afferent Arteriole to increase blood flow into glomerulus
What is the Mechanism for Autoregulation?
(1)
Tubuloglomerular Feedback Mechanism Involving the Juxtaglomerular Apparatus
Cells Involved in Autoregulation
(1): located on afferent arteriole and constantly regulates ___
(1): located on distal tubule and constantly regulates ___
BOTH CELLS CAN RELEASE ______ and ______ ONTO AFFERENT ARTERIOLE
Granular Cells - BP
Macula Densa Cells - rate of fluid through distal tubule
VASOCONSTRICTORS, VASODILATORS
Extrinsic (Sympathetic) Control of GFR
(Goal = alter GFR in an attempt to control blood volume and BP)
Sympathetic input can ______ the autoregulatory responses
The smooth muscle cells of the afferent and efferent arterioles contain many (1) receptors that are sensitive to (2)
- Renal nerve releases norepinephrine - ______ arterioles
- Glomerular capillary BP and GFR then ______
Override
alpha adrenergic receptors -> Epinephrine and norepinephrine
- vasoconstricts
- GFR decreases
Through innervation of smooth muscle cells of afferent and efferent arterioles by sympathetic nerves -> releases epi onto alpha adrenergic receptors to cause vasoconstriction -> decrease GFR
Case of Hemorrhage
Example of where Extrinsic Control Kicks in
Tubular Reabsorption and the Importance of Sodum Reabsorption
___% of plasma that enters glomerulus is filtered
- Since GF is a ____ process, a lot filters out that we want to take back, Tubular reabsorption helps us do that
- Tubular Reabsorption: can be a ____ or ____ process depending on the substance but it is always _____
20%
- passive, we want to take alot back
- passive OR active, but always selective
Tubular Reabsorption
__% of water filtered is reabsorbed
___% of sugar filtered is reabsorbed
___% of salt filtered is reabsorbed
Pretty much we reabsorb _____
99%
100%
99.5%
ALOT IS REABSORBED
Spaces that need to be crossed to be Reabsorbed
- Tubular Lumen is made up of (2)
- ______ Membrane
- _____ of Cell
- ______ Membrane
- ______ fluid space
- ______ wall
- epithelial cells and tight junctions
- Luminal
- Interior of Cell
- Basolateral
- Interstitial
- Capillary Wall
Reabsorption of Na+
*Sodium is reabsorbed at any point in the nephron except?*
- Na+ is _____ reabsorbed
- 80% of energy requirement of the kidneys used for Na+ ____ (99.5% of Na+ filtered is reabsorbed)
- Plays important role throughout tubule: not just an end, but also a ____
Descending Loop of Henle
- actively
- Transport
- means (to transport many other substances- is why Na+ reabsorption takes up so many energy)
Reabsorption of Na+
Coupled with what other substances/roles in the
- Proximal Tubule
- Ascending Limb of Loop of Henle
- Distal tubule and Collecting Duct
- Glucose, Amino acids, Water, Urea
- Plays an important role in kidneys ability to concentrate urine and conserve water
- Under hormonal control and plays a role in regulating ECF volume and blood pressure
General Pattern for Sodium Reabsorption
Na+ travels across Luminal membrane either through (2)
Na+ travels across Basolateral membrane through (1)
Passive Channel or Secondary Active Cotransporter
Sodium Potassium ATP pumps (this is what takes a lot of energy)
and remember sodium has a huge driving force to get into cells (so very easy to do just through channels)
Na+ Reabsorption in the Proximal Tubule
In the Luminal Membrane
- __Na+ diffuses through _____ (uses energy) with (3)
In the Basolateral Membrane:
- Na+ diffuses through (1)
- Glucose, Amino Acids, Water soluble vitamins diffuses through (1)
- Cotransporter w glucose, amino acids, water soluble vitamins
- ATP pumps
- Facilitated diffusion
Tubular Maximum
=
- Ex) Glucose is 100% reabsorbed in proximal tubule, but for DM (hyperglycemia) - can start seeing glucose in urine -> therefore there is a ____ to how much glucose can get reabsorbed dt limited ____ cotransporters
Maximal rate of reabsorption limited by available cotransporters
- limit in available cotransporters
Sodium Reabsorption and Glucose (Proximal Tubule)
- Normal (plasma) of glucose are ____/100ml of plasma
- Amount of glucose filtered per min = (plasma) of glucose x ___
- 100mg/100ml x 125ml/min = ___mg/min
- Filtered Load =
- Tubular Maximum (Tm) - point of _____ (is a ___)
- Tm for glucose is ____mg/min
- 100mg/100ml
- GFR
- 125mg/min
- amount of substance filtered by kidneys per minute
-
saturation (is a rate)
- 375mg/min
Sodium Reabsorption and Glucose (Proximal Tubule)
Usually ___% of glucose is reabsorbed in the proximal tubule and returned to the blood stream
If the filtered load for glucose increased beyond 375mg/min, begin to find glucose excreted in ____
Renal Threshold = maximal _____ concentration any of these organic nutrients can reach before it starts to appear in _____
- Renal threshold for glucose =
- RT (1) x GFR (1) = TM (1)
100%
urine
RT = maximal plasma concentration before appears in urine
- 300mg/ml
- 300mg/ml x 125ml/min = 375mg/min
Renal Threshold (Notes)
- If our tubular maximum is 375mg/min, what amount of plasma is needed to reach that maximum? -> this term is called (1)
-
RT = _____/100ml plasma
- Anything above 300 -> glucose will appear in urine -> so you know that when you see glucose in urine their plasma glucose is at least ___ normal
- Renal threshold
-
RT = 300mg
- 3x normal before appearing in urine
Sodium Reabsorption in the Ascending Loop of Henle
Same as in proximal tubule but cotransporter with what substances?
K+, Cl-
Sodium Reabsorption in the Distal Tubule
Same as in proximal tubule and ascending loop but cotransporter with what substances?
Cl-
Sodium Reabsorption in the Collecting Duct
=
Most simple
Na+ through passive channel then ATP pump
Sodium Reabsorption Coupled to Passive Water Reabsorption
Throughout the tubule, water is reabsorbed via _____ which requires (1) provided by ___
80% is reabsorbed in (2) parts of the nephron
Two mechanisms (2)
Osmosis, osmotic gradient, Na+ (water follows sodium)
Proximal tubule and Loop of Henle
1) Paracellular Route (in between epithelial cells)
2) Transcellular Route (through epithelial cells)
Paracellular Route
Explain how this mechanism works?
In certain areas the tight junctions between epithelial cells are leaky (mostly in proximal tubule)
As Na+ gets pumped out of lateral membrane -> clumps in area creating high osmolarity - that moves water into interstitial fluid and to capillary
Transcellular Route
How does water move through this Route? (1)
- Abundance of these channels on _____ membrane
- Luminal Aquaporins only available in what areas?
Osmotic Gradient in transcellular route is created by?
Aquaporins = water channels on both membranes
- abundance on basolateral membrane
- luminal aquaporins only in proximal tubule, descending loop of henle
Created by high osmolarity of Na+ in interstitial space
Water Reabsorption Takeaways (Notes)
Only place where water reabsorption does not occur?
Things needed for water reabsorption
- _____ _____ created by Na+
- Permeability through (2)
Ascending Loop of Henle (super tight junctions and no aquaporins)
- Osmotic Gradient
- Permeability through leaky tight junctions or luminal aquaporins
Sodium Reabsorption Coupled to Passive Chloride Reabsorption Following Water Reabsorption
Passive Reabsorption of Cl, Urea, K
- Once Na and water move out, it increases concentration of everything left ___ (Cl, Urea, K)
- _____ creates a concentration gradient for those substances to also move out through (1)
- behind
- Natural osmotic gradient -> leaky tight junctions
Regulated Reabsorption of PO43- and Ca2+
The reabsorption of some substances helps regulate ____ levels of those substances
(1) for that substance equals normal plasma levels
Our diets are normally rich in _____, it ___ gets filtered
Renal threshold for phosphate reabsorption is set at ____ plasma phosphate, excess is ____ through urine
plasma
Renal threshold = plasma lvls
phosphate, all gets filtered
RT set at normal plasma levels, excess excreted through urine
What does not get reabsorbed?
- ____ products (2) except for ____
- Even though they do get concentrated, like chloride and urea, tubule is ______ to these waste products
We do not reabsorb waste products (phenols, creatinine) except for urea
Tubule is impermeable to waste products
We only reabsorb urea bc helps make amino acids
Summary of Reabsorption
- Proximal Tubule: huge amount of (2) reabsorbed
-
Loop of Henle
- *Descending Loop of Henle:
- *Ascending Loop of Henle
- Distal Tubule and Collecting Duct: Na and Water reabsorption _____ and under _____ control
- huge amount of Na and H20
- Loop of Henle
- Yes H20, No Na+
- Yes Na+, No H20
- variable, hormonal
Tubular Secretion
Selective movement of substances from (1) into (1)
(3) important substances to be secreted
Peritubular Capillaries -> Tubular Lumen
- Hydrogen ions
- Potassium ions
- Organic Cations and Anions (usually foreign to the body-drugs, environmental pollutants)
Hydrogen ion secretion
Plays an important role in ___/___ balance in the body
Occurs primarily in what parts of the nephron (2)…and minor amounts in (1)
acid/base
proximal tubule and collecting duct, ascending loop of henle
Hydrogen Ion Secretion
How does H+ cross the Basolateral membrane?
How does H+ cross the Luminal membrane in the
- Proximal Tubule =
- Collecting Duct and Loop of Henle =
ATPase pump
- Na/H+ antiporter (coupled with Na+ reabsorption)
- Facilitated diffusion
Potassium Secretion
Potassium undergoes both _____ and ______
- In the proximal tubule, potassium is _____ in via passive diffusion is much the same way as ___ and ___ following water reabsorption.
- Potassium is also _____ secreted in the (2) parts of the nephron
- Potassium reabsorption is _____, while potassium secretion is _____
- If plasma (K) is low -> secretion is _____
- If plasma (K) is high -> secretion/excretion is _____
Reabsorption AND Secretion
- reabsorbed, Cl- and Urea
- actively, distal tubule and collecting duct
- unregulated, regulated
- minimal
- enhanced
K reabsorption is passive and unregulated, K secretion is actively secreted and regulated
Mechanism for K+ Secretion
Distal Tubule and Collecting Duct
- K crosses basolateral membrane through (1)
- K crosses luminal membrane through (1)
- Na/K ATP pump
- Passive diffusion
Why isn’t K secreted throughout the tubule when sodium is reabsorbed?
Dt _____ of K+ channels
- In proximal tubule and loop of henle, K+ channels on _____ membrane therefore?
- In distal tubule and collecting duct, K+ channels on _____ membrane therefore?
Location of K+ channels
- basolateral membrane -> cannot enter tubular lumen (just diffuses right back through into interstital space)
- luminal membrane -> allowed to enter tubular lumen
Summarizing Reabsorption Events
- Remember when summarizing reabsorption: Na+ and Cl- ____ in distal tubule and collecting duct through _____ control (1)
Variable
Hormonal control - Aldosterone (mineralcorticoid that controls Na+ reabsorption and K loss) therefore aldosterone simultaneously controls potassium secretion
Aldosterone Control of Sodium Reabsorption and Potassium Secretion
Aldosterone functions (2)
1) Opens Luminal Na+ Channels
2) Increases Na/K ATPase expression
Organic Anion and Cation Secretion
Ways to secrete anion and cations in proximal tubule (2) secretory pathways
- Involve anion and cation _____
- Includes blood born chemical messengers like ______
- Some are foregin compounds like ____ additives, environmental _____, and d___
Reasons there must be a secretory pathway (2)
Organic Anion pathway, Organic Cation pathway
- receptors
- hormones
- food additives, environmental pollutants, drugs
1) Some ions can be bound to plasma proteins and are never filtered by glomeruli
2) Increases speed of elimination
2 pathways both involve the use of energy and coupled with Na reabsorption
Ch 6 Urine Concentration: The Medullary Countercurrent System
- Kidneys can produce urine that ranges in osmolarity (concentration) from ____mOsm to ___mOsm dependent on body’s need to ____ water
- Perfect balance of hydration = _ml/min or _____ urine (___mOsm)
- Overhydrated = __ml/min or ____ urine (___mOsm)
- Dehydrated = __ml/min or _____ urine (___mOsm)
- 100mOsm to 1200mOsm, conserve
- 1ml/min, Isotonic Urine 300mOsm
- 25ml/min, Hypotonic Urine 100mOsm
- 0.3ml/min, Hypertonic Urine 1200mOsm
Obligatory Water Loss
=
Bc of this, the kidneys deal with persistent _____ way better than persistent _____
Minimal water loss bc we can’t eliminate crystals so no matter how dehydrated we are we have to produce and excrete urine
overhydration, dehydration
Medullary Countercurrent System
The medullary osmotic gradient plays a key role in the kidneys ability to produce urine of varied ______
This osmotic gradient is created by a unique _____ arrangement
Medullary Countercurrent System =
concentrations
anatomical
Anatomical parts that create this gradient and the ones that use it to produce urine of varied concentration are collectively called this system
Osmotic Gradient of the Renal Medulla
Cortex = ___tonic
Medulla interstitial space has an osmotic gradient -> _____ as you get closer to the ____ ____
This gradient is what allows us to vary how water is reabsorbed and produce urine of varying _____
Isotonic
increases closer to renal pelvis
concentration
2 Parts of Countercurrent System
1) What part creates the osmotic gradient?
2) What part uses the gradient to vary concentration of urine?
- Long Loops of Henle of Juxtamedullary nephrons
- Collecting ducts of all nephrons
How Long Loops of Henle Create Osmotic Gradient
Descending Loop =
Ascending Loop =
Permeable to water, Impermeable to Na+
Permeable to Na+, Impermeable to water
(ascending loop actively pumps sodium out)
ADH
How does ADH determine how much water is reabsorbed in the distal tubule and collecting duct?
Urine osmolarity that travels up ascending loop of henle gets ____ and exits with an osmolarity of ____mOsm
- 100mOsm = __ water reabsorption in distal tubule and collecting duct
- 1200mOsm = ___ water reabsorption in distal tubule and collecting duct
- 300mOsm = body is ______ hydrated
By determining degree of permeability of tubule/collecting duct
smaller and smaller -> exits with 100mOsm
- NO
- MAXIMAL
- perfectly hydrated -> which means 300 is the mOsm of distal tubule when normal
Vasopressin (ADH)
= Hormone producted by (1) and released by (1)
How do we regulate ADH?
Hypothalamus, Posterior Pituitary
Sensing plasma osmolarity changes in the brain
Vasopressin (ADH) Function
Increases _____ of _____ membrane to H20 by inserting new water ______
- travels through bloodstream and binds to tubular _____ cells -> acts through second messenger system and binds to its _____ -> elevates _____ -> increasing insertion of ______
Keep in mind: ADH just effects water, NOT sodium
Permeability, luminal, channels
- epithelial, receptors, cAMP -> increased insertion of aquaporins
Control of Sodium and Water Excretion: Regulation of Plasma Volume and Osmolarity
- There are two separate but closely ______ control systems that regulate ECF ____ and ECF _____
- ECF volume and ECF Osmolarity have different effects on ______
- Regulation of ECF Volume maintains (1) therefore blood supply to _____
- Regulation of ECF Osmolarity helps maintain (1)
- The _____ play a major role in both of these control systems
- interrelated, volume, osmolarity
- homeostasis
- blood pressure -> blood supply to tissue
-
cell volume
- kidneys
Sodium Balance and ECF Volume
- The body regulates ECF volume by regulating what?
- Sodium is the main ______ constituent of the ECF volume
- ECF osmolarity is tightly maintained so when _____ moves, _____ must move with it - Sodium _____ in the kidney is always followed by water _____ (wherever permeable)
- So any sodium gains or losses in the body are asctd with a corresponding gain or loss in ____
- total body salt content
- osmotic
- sodium moves, water moves -> sodium reabsorption, water reabsorption
- water
Sodium Balance
Balance between gains and losses
What sources
- Gains =
- Losses =
Sodium balance if: ____ NaCl intake = ____ NaCl output + ____ NaCl output
- Ingested Sodium absorbed through GI tract
- Renal Excretion, Nonrenal loss (sweat, feces) usually low except for cases like diarrhea and profuse sweating
Oral = Renal + Nonrenal loss
How are Changes in ECF Volume Sensed?
Body actually monitors_____ volume, not total ECF volume
Changes in plasma volume are sensed by monitoring ___ ____
Specialized sensory receptors called ________
(3)
Unlike the first two =
plasma
blood pressure
baroreceptors
- Aortica Arch baroreceptors
- Carotid Sinus barorecetors
- Renal baroreceptors
Renal Baroreceptors unlike first two do not change by momentary changes in BP, responsible for long term regulation of BP
Renal Baroreceptors
Location =
Renal Baroreceptors ARE the Glomerular Cells in the Glomerular Apparatus
Can sense arterial pressure in afferent arteriole-but DOES NOT adapt
Baroreceptors and RAAS
Decrease in Plasma Volume -> Decrease in Blood Pressure -> Sensed by JGA Granular Cell Baroreceptors stimulates release of enzyme
- (1) into bloodstream and converts peptide prohormone
- (1) found in bloodstream and produced by liver into
- (1) which enters organs like the lungs that have
- (1) which is an enzyme that interacts with it to form active hormone
- (1) : strong hormone that increases plasma volume and BP
- Renin
- Angiotensinogen
- Angiotensin I
- ACE
- Angiotensin II
Actions of Angiotensin II
(5)
Increases Sodium reabsorption (and water reabsorption)
Decreasing GFR
Increased Water consumption and reabsorption
Increase Sodium Reabsorption (and Water Reabsorption)
- Aldosterone Release
- Na/H+ exchanger in proximal tubule
Decreasing GFR
- Direct vasoconstriction of afferent arterioles
- Enhancing Tubuloglomerular feedback system
Increased Water consumption and Reabsorption
- Stimulates thirst and ADH secretion
Angiotensin II Action #1
Angiotensin II acts on (1) to stimulate release of (1) -> that acts on (2) parts of the nephron to increase (1)
Adrenal Cortex -> Aldosterone -> Distal tubule, collecting duct -> sodium reabsorption
Angiotensin II Action #2
Ang II stimulates the (1) in the _____ tubule to increase (1) (water follows sodium)
- Directly stimulates sodium reabsorption through mechanism thats coupled with (1) -> so ang II directly and indirectly through ____
Na/H exchangers -> proximal tubule -> sodium reabsorption
- H+ secretion (so simultaneusly secretes H+) -> so ang II directly and indirectly stimulates sodium reabsorption through aldosterone
Angiotensin II Action #3
(1)
Reduces capillary blood flow and GFR -> limit urine production -> minimize fluid loss
Vasoconstriction of Afferent Arteriole and Systemic Blood Vessels
Angiotensin II Action #4
(1)
Tricks this system into thinking that GFR has gotten too high -> enhances sensitivity and net effect is drop in GFR
Tricks Tubuloglomerular Feedback System -> macula densa cells respond more quickly -> vasoconstrict afferent arteriole -> decrease GFR
Angiotensin II Action #5
(1)
All acts on the hypothalamus to increase the sensation of?
Release of ADH to increase sensation of Thirst
Thirst increases water consumption, ADH increases water reabsorption in distal tubule and collecting ducts
Short Term Plasma/BP Regulation
=
These receptors sense drops in BP when it first happens and then stimulates what?
Aortic Arch and Carotid Sinus Baroreceptors
Increases Sympathetic Actiity to body including kidneys
Increased Sympathetic Nerve Activity Actions
(3)
- Sympathetic Nerve innervates Afferent Arteriole to vasoconstrict and decrease GFR
- Sympathetic Nerve innervates Juxtaglomerular Apparatus to stimulate Granular cells to release Renin
- Stimulates ADH secretion
Summary of Control of Plasma Volume and Total Body Sodium
All in all =
Aortic and Carotid baroreceptors adapt after a few minutes so only a few minutes of sympathetic nerve activity but is enough to get the ball rolling bc renal baroreceptros will take over
Ch 7: Control of Fluid Osmolarity by ADH Thirst System
Water balance and ECF osmolarity
- ECF osmolarity is regulated by maintaining _____ balance
- Total body osmolarity is defined as the ratio of (1):(1)
- Total body osmoles is primarily determined by ECF ____ content
- Water balance depends on equality between total body water ____ and total body water ____
- water
- total body osmoles: total body water
- sodium
- gains, loss
We want to control osmolarity to control cell volume -> hypotonic ECF -> cell swelling -> impaired function/injury to cells
Regulated by maintaining water balance to match whatever concentration of solues we have to make it isotonic
Water Balance
Body water is gained from two primary sources =
Body water is primarily lost through three routes =
Consumed alone or in food or liberated from metabolic processes
Lost through Urine, Feces, Sweat
Water Balance and ECF osmolarity
Two elements that control total body water and therefore osmolarity
- the ____ control water excretion
- the _____ mechanism that controls oral intake of water
Both effector mechanisms are part of a _____ feedback loop that starts in the _____ of the brain
Regulation of ECF osmolarity involves the detection of ____ osmolarity
- kidneys
- thirst
negative feedback loop, hypothalamus
plasma
Central Osmoreceptors
=
(2)
Increased plasma osmolarity sensed by these and stimulate _____ -> ______ -> _______
Circumventricular Organs that sense changes in osmolarity of plasma
SFO
OVLT
Hypothalamus -> Posterior Pituitary -> release of ADH
Sensitivity of ADH release
OVC’s very ____
In healthy individuals, plasma osmolarity is about 290mOsm
- The threshold for AVP (arginine vasopressin) release is actually a bit lower about _____ mOsm
- Increases by as little as _% in plasma osmolarity can produce a large increase in plasma ___
- ADH then acts on the (2) to increase water reabsorption
sensitive
- 280
- 1%, ADH
- distal tubule and collecting duct
Central Osmoreceptors: Functions of SFO/OVLT
When SFO and OVLT sense increased osmolarity and release ADH, also stimulates what?
Thirst
Where does the system that controls plasma osmolarity intersect with the system that controls plasma volume?
Ang II receptors on SFO and OLVT -> stimulate thirst and hypothalmic release of vasopressin
Part of brainstem that controls SNS activity also stimulates thirst and hypothalmic release of vasopressin + ang II also stimulates SFO/OVLT to sitmulate thirst
Thirst and ADH release stimulated under conditions where plasma osmolarity rises OR when plasma volume and BP drop -> goals are both fluid consumption and water retention
Other Factors Affecting Plasma (ADH) and Plasma Osmolarity
and how?
- Rate of ADH _____ by _____
- P___, F___, and T____
- A_____
- ADH breakdown by Liver
- liver impairment -> decreased breakdown -> increased plasma
- Pain, Fear, Trauma
- increased sympathetic activation increases plasma ADH (ie post surgical SIADH, temporary)
- Alcohol
- Alcohol suppreses ADH secretion -> inappropriate water loss (why we pee so much when we’re drunk) -> more vulnerable to dehydration
