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POWERPOINT® LECTURE SLIDE PRESENTATIONby LYNN CIALDELLA, MA, MBA, The University of Texas at AustinAdditional Text by J Padilla exclusively for physiology at ECC
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
HUMAN PHYSIOLOGYAN INTEGRATED APPROACH FOURTH EDITION
DEE UNGLAUB SILVERTHORN
UNIT 3UNIT 3
20 Integrative Physiology II: Fluid and Electrolyte Balance
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Mass Balance in the Body Homeostasis requires that amounts
gained must be equal to that lost. Ion concentration- need proper
amounts of Na+, Cl-, K+, and Ca2+: nervous, cardiac& muscle function-
imbalances cause problems with membranes of cells that are excitable.
Primarily replaced with thirst & appetite and excreted in urine, sweat, & feces
pH balance- cells functions within a pH range that is maintained by H+, CO2, & HCO3–
Fluid- water levels need to be maintained, ingestion and urine formation have largest impact.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Key factors for Homeostasis
Na+ & H2O= affect ECF Osmolarity: amounts of solutes dissolved in solution, concentration and permeability influence direction of osmosis which changes the size of cells
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5-29
Osmosis and Osmotic PressureOsmolarity describes
the number of particles of solution in a quantity of osmoles OsM per liter
Osmolarity is influence by fluid, ion, & protein levels. Compensation occurs via renal, behavioral, repiratory, and CV responses
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-2
Water Balance in the Body Water makes up 50-60% of total body weight.
Main entry way is through food, most lost in urine unless there is excessive sweating or diarrhea
Homeostasis maintains water balance unless there is pathology or an abnormal ingestion of water.
Men have more water than women
Water makes up 50-60% of total body weight.
Main entry way is through food, most lost in urine unless there is excessive sweating or diarrhea
Homeostasis maintains water balance unless there is pathology or an abnormal ingestion of water.
Men have more water than women
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-3
Water Balance
A model of the role of the kidneys in water balance
Kidneys cannot add water, only preserve it or get rid of excess amounts. Renal filtration will stop if there is a major loss causing extremely low blood pressure and blood volume
Kidneys cannot add water, only preserve it or get rid of excess amounts. Renal filtration will stop if there is a major loss causing extremely low blood pressure and blood volume
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Fluid and Electrolyte HomeostasisThe body’s
integrated response to changes in blood volume and blood pressure incorporate many systems
Decreased blood volume will result in mechanisms that increase blood pressure and volume, and reduce water loss
Figure 20-1a
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-1b
Fluid and Electrolyte Homeostasis
Increased blood volume results in the excretion of salt and water which eventually reduces blood pressure and ECF/ICF volumes.
Increased blood volume results in the excretion of salt and water which eventually reduces blood pressure and ECF/ICF volumes.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-4
Urine Concentration
Osmolarity changes as filtrate flows through the nephron. Reabsorption is controlled by kidney tissue concentrations as water permeability and diffusion of solutes changes as needed. Water and sodium reabsorption alter urine concentration. Diuresis is the removal of excess water.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-5a
Water Reabsorption
Vasopression or antidiuretic hormone causes a graded effect of forming water pores on collecting duct cells. Thus permeability is increased and more water is retained making urine more concentrated.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-5b
Water Reabsorption
If vasopressin is absent water will not move out through water pores (aquaporins)and the urine will be dilute.
If vasopressin is absent water will not move out through water pores (aquaporins)and the urine will be dilute.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-6, steps 1–2
Water Reabsorption
Collecting duct lumen
Filtrate300 mOsm
Cross-section ofkidney tubule
Collecting duct cell
Secondmessengersignal
cAMP
Medullaryinterstitial
fluid
Vasopressin receptor
Vasarecta
Vasopressin
Vasopressin binds to mem-brane receptor.
Receptor activates cAMP second messenger system.
1 2
1
2
600 mOsM
600 mOsM
700 mOsM
The mechanism of vasopressin action on tubular cells of the nephronThe mechanism of vasopressin action on tubular cells of the nephron
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-6, steps 1–3
Water Reabsorption
Collecting duct lumen
Filtrate300 mOsm
Exocytosisof vesicles
Cross-section ofkidney tubule
Collecting duct cell
Secondmessengersignal
cAMP
Storage vesicles
Aquaporin-2water pores
Medullaryinterstitial
fluid
Vasopressin receptor
Vasarecta
Vasopressin
Vasopressin binds to mem-brane receptor.
Receptor activates cAMP second messenger system.
Cell inserts AQP2 water pores into apical membrane.
1 2 3
1
2
3
600 mOsM
600 mOsM
700 mOsM
Apical membrane water permeability increases exponentially with water pores are added
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-6, steps 1–4
Water Reabsorption
Collecting duct lumen
Filtrate300 mOsm
H2O
Exocytosisof vesicles
Cross-section ofkidney tubule
Collecting duct cell
Secondmessengersignal
H2O
cAMP
Storage vesicles
Aquaporin-2water pores
600 mOsM
H2O
Medullaryinterstitial
fluid
Vasopressin receptor
600 mOsM
Vasarecta
H2O
700 mOsM
Vasopressin
Vasopressin binds to mem-brane receptor.
Receptor activates cAMP second messenger system.
Cell inserts AQP2 water pores into apical membrane.
Water is absorbed by osmosis into the blood.
1 2 3 4
1
2
3
4
Vassopressin is also called antidiuretic hormone- it causes reabsortion of water (in turn increasing urine concentration and decreasing volume).
Vassopressin is also called antidiuretic hormone- it causes reabsortion of water (in turn increasing urine concentration and decreasing volume).
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-7
Factors Affecting Vasopressin Release
Three stimuli control vasopressin but the most potent is blood osmolarity above 280mOsM. The higher the osmolarity, the more vasopressin released by posterior pituitary. Osmoreceptors also trigger thrist centers in hypothalamus
Three stimuli control vasopressin but the most potent is blood osmolarity above 280mOsM. The higher the osmolarity, the more vasopressin released by posterior pituitary. Osmoreceptors also trigger thrist centers in hypothalamus
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-10
Water BalanceCountercurrent exchange in the medulla of the kidney. Descending limb is permeable to water while the ascendig limb is permeable to ions. 25% of all Na+ and K+ reabsorption happens in ascending limb; resulting in dilute urine. Water amounts can be changed again at distal tubule and collecting duct.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Fluid and Electrolyte Balance Vasa recta removes water- blood
runs in opposite direction as filtrate, water moves in according to the concentration gradient Close anatomical association of the
loop of Henle and the vasa recta- this allows for water to move out of the tubule and into the blood without dilution the interstitial fluid in the medulla.
Urea increase the osmolarity of the medullary interstitium- transporter proteins move urea into the medulla to increase osmolarity of the interstitial fluid creating a gradient to move water out without affecting the movement of other ions (Na+ & K+)
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-12
Sodium BalanceHomeostatic responses to salt ingestion show the integrated effects on sodium, water, and blood pressure. Without salt appetite [salt] would increase and tissue cells would shrink. Thus vasopressin and thirst is activated.
..
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-13, steps 1–2
Sodium Balance
Interstitialfluid
Blood
Aldosterone
Aldosteronereceptor
P cell of distal nephron
Lumen of distal
tubule
Aldosterone combines with a cytoplasmic receptor.
Hormone-receptor complex initiates transcription in the nucleus.
1
2
12Transcription
mRNA
Aldosterone action in principle cells- targets cells of the distal convoluted tubule and collecting duct.
Aldosterone action in principle cells- targets cells of the distal convoluted tubule and collecting duct.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-13, steps 1–4
Sodium Balance
Interstitialfluid
Blood
Aldosterone
ATP
Aldosteronereceptor
P cell of distal nephron
Translation andprotein synthesis
ATP
Lumen of distal
tubule
Aldosterone combines with a cytoplasmic receptor.
Hormone-receptor complex initiates transcription in the nucleus.
New protein channelsand pumps are made.
Aldosterone-induced proteins modify existing proteins.
1
2
3
4
12
3
4
Transcription
mRNA
Newchannels
Proteins modulateexisting channels and pumps.
New pumps
Existing channels are called the leak proteins that allow for a rapid movement of ionsExisting channels are called the leak proteins that allow for a rapid movement of ions
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-13, steps 1–5
Sodium Balance
Interstitialfluid
Blood
Aldosterone
ATP
Aldosteronereceptor
P cell of distal nephron
Translation andprotein synthesis
K+
Na+
K+ K+
Na+
Na+
ATP
K+
secreted
Na+
reabsorbed
Lumen of distal
tubule
Aldosterone combines with a cytoplasmic receptor.
Hormone-receptor complex initiates transcription in the nucleus.
New protein channelsand pumps are made.
Aldosterone-induced proteins modify existing proteins.
Result is increased Na+ reabsorptionand K+ secretion.
1
2
3
4
5
12
3
4
5
Transcription
mRNA
Newchannels
Proteins modulateexisting channels and pumps.
New pumps
Aldosterone causes K+ secretion and sodium reabsorption. A secondary effect is that water follows sodium.Aldosterone causes K+ secretion and sodium reabsorption. A secondary effect is that water follows sodium.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-15
Sodium Balance
Decreased blood pressure stimulates renin secretion. Granular cells can be activated to release renin by three factors: drop in blood pressure, a signal from the kidneys, or increased sympathetic activity.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-14
Sodium Balance
The renin-angiotensin-aldosterone pathway- (RAAS). Renin is an enzyme that assist in ANG II formation. ANGII activates several mechanisms that ultimately increase blood pressure and volume
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-16
Sodium Balance
Action of natriuretic peptides- cause sodium loss through urine (natriuresis) and act as RAAS antagonist. They are released when myocardial cells stretch too much or during heart failure
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Potassium Balance Regulatory mechanisms keep plasma potassium in narrow range
(3.5-5meq/L) Aldosterone is released in response to excess levels, it increases
permeability at distal nephron so K is moved into the urine while sodium is reabsorbed
Hypokalemia (K+ levels below 3) In ECF levels are low, K+ leaves the cell, and resting membrane
potential is more negative (hyperpolaized)= stronger stimulus Muscle weakness and failure of respiratory muscles and the heart due
to hyperpolarized neurons.
Hyperkalemia (K+ levels above 6) In ECF levels are high, more K+ enters the cell, thus depolarizing it
but then less able to repolarize thus LESS excitable Can lead to cardiac arrhythmias
K+ irregularities include kidney disease, diarrhea, and diuretics
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Behavioral Mechanisms
Drinking water and eating salt is the only way the body obtains these substances, therefore individuals who cannot do this must be assisted.
Drinking replaces fluid loss – when body osmolarity raises above 280mOsM hypothalmic osomreceptors trigger thrist. Oropharynx receptors are stimulated by cold drink and signal thirst quench
Low sodium stimulates salt appetite – the hypothalamus also has centers for salt appetite which trigger a response when osmolarity is low.
Avoidance behaviors help prevent dehydration
Desert animals avoid the heat
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Disturbances in Volume and Osmolarity
Figure 20-17
In each situation compensantion mechanism aim to bring conditions to normal, in some cases there is incomplete compenstation. Notice how most imbalances are due to what is ingested or loss in excess amounts
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Severe Dehydration Compensation
Condition: low ECF volume, low blood pressure, high osmolarity
Compensation Mechanisms Cardiovascular Responses- increase cardiac output &
vasoconstriction to increase blood pressure. Vasoconstriction reduces GFR activating granular cells to release renin
Angiotensin II- produce after renin release that activates RAAS pathway to trigger thirst, vasopressin release, and vasoconstrion. (aldosterone is not release as it would increase osmolarity)
Vassopressin- increase water reabsorption to reduce loss in urine
Thrist/ IV-replacement of loss fluids and lowering of osmolarity
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Acid-Base Balance Normal plasma pH is 7.38–7.42- also resembles the pH inside
cells, its optimum for proper protein & enzyme function H+ concentration is closely regulated- slight pH changes indicate
a 10-fold increase/decrease in [H+] which can have damaging effects on protein structure & function.
Abnormal pH affects the nervous system- H+ imbalances cause K+ imbalances because transporter protein in kidneys moves H+ and K+ in antiport fashion Acidosis: neurons become less excitable and CNS depression
patients can fall into a coma or have respiratory failure Alkalosis: hyperexcitable- numbness, tingling, muscle twitches,
severe cases lead to paralysis of respiratory muscles
pH disturbances- induced by an imbalance of H+ input/output Compensation by buffers, ventilation, or renal regulation Greatest source is CO2 level changes induced by metabolic or
respiratory factors
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-19
Acid-Base Balance
Hydrogen balance in the body is quickly compensated by ventilation and slowly compensated by renal regulation.
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Acid and Base InputAcid
Organic acids – acids produced by the body during metabolism or ingested molecules that realease H+ (acidic fruits, amino acids, fatty acids)
Under extraordinary conditions – produce more H+ than the body can normally get rid off and cause pathological effects
Metabolic organic acid production can increase Ketoacids – strong acids produced when fats & proteins are metabolized
Diabetes – metabolism disorder causes ketoacid formation
Accumulation of CO2 - can occur as a result of anaerobic respiration, increased metabolism, or decreased ventilation
Acid production - CO2 combines with water rapidly to make an acid and drop pH. Respiratory system gets rid of 75% of a
Base
Few dietary sources of bases- conditions of alkalosis rarely encountered
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-20
pH DisturbancesThe reflex pathway for respiratory compensation of metabolic acidosis responds to shifts in H+ & CO2 based on the law of mass action.
CO2 + H2O == H2CO3 == H+ HCO3 .
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
pH Homeostasis Buffers moderate changes in pH- cannot prevent changes,
they absorb/release H+ Cellular proteins, phosphate ions, and hemoglobin- serve
as intracellular buffers Ventilation
Rapid- quickly gets rid of CO2 by increasing breathing rate 75% of disturbances- are cleared by ventilation thanks to
the central and peripheral chemoreceptors that sense changes in [H+]
Renal regulation- uses ammonia and phosphate buffers in addition to Directly excreting or reabsorbing H+
Indirectly by change in the rate at which HCO3– buffer is
reabsorbed or excreted
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-21
pH Disturbances
Overview of renal compensation for acidosis. The nephron takes care of the 25% of compensation the lungs can’t handle. They excrete H+ by trapping it in ammonia and phosphate ions. They also make HCO3
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 20-23
Intercalated CellsRole of intercalated cells in acidosis and alkalosis – these are located in
between principal cells of the distal tubule and have high amounts of carbonic anhydrase. Movement occurs via H+-ATPase and H+-K+-ATPase
Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings
Acid-Base BalanceRespiratory system increases CO2 during hypoventilation and decreases it during hyperventilation. When metabolism causes a disturbance respiratory keeps CO2 levels normal but pH changes because buffer levels drop.
Mass balance shifts equation to left or right
Respiratory system increases CO2 during hypoventilation and decreases it during hyperventilation. When metabolism causes a disturbance respiratory keeps CO2 levels normal but pH changes because buffer levels drop.
Mass balance shifts equation to left or right
CO2 + H2O == H2CO3 == H+ HCO3 .