BIO 1314- Ch 24 - Fluid, Electrolyte, and Acid-Base Balance
CO2 is constantly produced by
aerobic metabolism
Chemical buffers
bicarbonate, phosphate, and protein
Place the following events in the correct sequence beginning with rising CO2 levels as a result of increased aerobic metabolism.
1. CO2 concentrations rise 2. Carbonic acid levels rise 3. pH falls 4. Peripheral and central chemoreceptors are stimulated 5. The pulmonary ventilation rate increases
ECF (extracellular fluid)
- fluid found outside the cells of the body, constitutes approximately about one third of total body fluid, - transporter of oxygen, nutrients, and waste products - includes: intravascular fluid, interstitial fluid, transcellular fluid
protein buffers
---COOH ___>COO^- + H+ ---NH2 + H+ --> ---NH3+ accounts for 3/4 of all chemical buffering the ability of proteins to buffer is due to certain side groups (R groups) carboxyl groups release H+ amino groups bind H+
Place the following events in the order they would occur after a person breathes in and out deeply and quickly for 30 seconds.
1. CO2 concentrations fall 2. Carbonic acid levels decrease 3. The pH rises 4. Peripheral and central chemoreceptors are stimulated 5. The pulmonary ventilation rate decreases 6. CO2 begins to accumulate 7. PH begins to fall 8. PH returns to normal
ICF pH values
4.5-7.4, avg 7.0
Any substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls is classified as a ______ buffer. Examples include proteins, bicarbonate, and phosphate. Multiple choice question. chemical physiological body
A
Buffers
Any mechanism that resists large changes in pH they maintain homeostasis
The ________ buffer system is the basis for the strong buffering capacity of the respiratory system
Bicarbonate
Bicarbonate buffer
CO2 + Hxo <-->H2CO3 <--> HCO3^- + H+ CO2= carbon dioxide H2O= water H2CO3= carbonic acid HCO3^-= bicarbonate ion H+= hydrogen ion this is a reversible reaction: it can go either direction to maintain pH homeostasis.. HxCO3 is the main area. It can shift to left or right When it shifts to the right, carbonic acid releases H+ into the blood, lowering the pH If it shifts to the left, H+ is bound by HCO3^-k, resulting in less H+ being available in the blood and increasing the pH
Which type of buffer is defined as a substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls?
Chemical
Metabolism depends on _________, which are sensitive to pH
Enzymes
Phosphate buffer
H2PO4^- <--> HPO4^2- + H+ this reaction can proceed to the right and liberate H+ or it can proceed to the left and bind H+ this plays a role in blood plasma and arithosites (blood cells) They are more important in the renal tubules and ICF, where not only are they more concentrated, but the pH is lower and closer to their functional optimum. In the ICF, the constant production of metabolic acids creates pH values ranging from 4.5 to 7.4, probably averaging 7.0.
Phosphates are important in buffering in the ____ and _________ _____________
ICF; renal tubules
Which are true regarding respiratory compensation?
It corrects the pH of body fluids by expelling or retaining CO2. It is effective in correcting for PCO2 imbalances.
Why is it important to maintain the pH of blood and tissue fluids within normal limits? Most enzymes require an acidic pH to function properly. Slight deviations from normal pH can shut down metabolic pathways. The structure and function of macromolecules are pH dependent. Hormones require a blood pH of at least 7.7 to function optimally.
Options 2 & 3
Rising CO2 concentration and falling pH stimulate ________ and _________ _____________, which stimulate and increase in _______ ___________
Peripheral; central; chemoreceptors; pulmonary ventilation
Describe respiratory compensation in response to alkalosis.
Pulmonary ventilation rate decreases
Describe respiratory compensation in response to acidosis.
Pulmonary ventilation rate increases.
peripheral chemoreceptors
Receptors in the carotid arteries and the aorta that monitor blood pH to help regulate ventilation rate.
central chemoreceptors
Receptors in the central nervous system that monitor the pH of cerebrospinal fluid to help regulate ventilation rate.
How can the respiratory system compensate for a drop in blood H+ concentrations?
Reduced pulmonary ventilation allows CO2 to accumulate, lowering the pH back to normal.
physiological buffer systems
Respiratory and Renal (urinary) Systems -Act more slowly than chemical buffer systems -Have more capacity than chemical buffer systems -control body's output of acids, bases, or CO2
Respiratory Buffer
Speeding up or slowing down respirations the lungs can increase or decrease the amount of carbon dioxide in the blood.
Why is it important to maintain the pH of blood and tissue fluids within normal limits?
The structure and function of macromolecules are pH dependent Slight deviations from normal pH can shut down metabolic pathways.
True or False: The renal tubules secrete H+ into the tubular fluid where most of it binds to bicarbonate, ammonia, and phosphate buffers.
True
True or false: slight deviations from the normal pH can shut down metabolic pathways
True
Which system buffers the greatest quantity of acid or base but requires several hours to days to exert an effect?
Urinary
Describe respiratory compensation in response to alkalosis. Pulmonary ventilation rate decreases. The renal tubules increase the rate of H+ secretion. The renal tubules decrease the rate of H+ secretion. Pulmonary ventilation rate increases.
a
Respiratory compensation involves correcting a pH imbalance by which of the following mechanisms? Changing pulmonary ventilation rate Changing the rate of H+ secretion in the renal tubules Changing water and sodium excretion Changing in the rate of urine production
a
Physiological buffers
a system (for example the respiratory or urinary system) that stabilizes pH by controlling the body's output of acids, bases, or CO2.
One of the most important aspects of homeostasis
acids, bases, buffers
Describe respiratory compensation in response to acidosis. Pulmonary ventilation rate decreases. Pulmonary ventilation rate increases. The renal tubules increase the rate of H+ secretion. The renal tubules decrease the rate of H+ secretion.
b
How can the respiratory system compensate for a drop in blood H+ concentrations? Reduced pulmonary ventilation eliminates more CO2 from the body, lowering the pH back to normal. Reduced pulmonary ventilation allows CO2 to accumulate, lowering the pH back to normal. Increased pulmonary ventilation eliminates more CO2 from the body, lowering the pH back to normal. Increased pulmonary ventilation allows CO2 to accumulate, raising the pH back to normal.
b
The addition of CO2 to the body fluids raises H+ concentration and lowers pH, while the removal of CO2 has the opposite effect. This is the basis for the strong buffering capacity of which system? Endocrine Respiratory Urinary Digestive
b
Types of chemical buffers
bicarbonate, phosphate, and protein
Which type of buffer is defined as a substance that binds H+ and removes it from solution as its concentration begins to rise, or releases H+ into solution as its concentration falls? Volatile Physiological Chemical Organic
c
Carbon dioxide, when present in sufficient amounts, will bind with water to form ____________ , which is capable of dissociating into bicarbonate and hydrogen ions.
carbonic acid
Respiratory compensation
changes in pulmonary ventilation correct the pH of the body fluids by expelling or retaining CO2 if there is a CO2 excess (hypercapnia), pulmonary ventilation increases to expel CO2 and bring the blood pH back up to normal if there's a CO2 deficiency (hypocapnia), ventilation is reduced to allow CO2 to accumulate in the blood and lower the pH to normal this is very effective in correcting pH imbalances due to abnormal Pco2
A substance that binds H+ during times of acidity and releases H+ during time of alkalinity is referred to as a ____________ .
chemical buffer
Metabolism depends on _______
enzymes
acid-base balance
equilibrium between acid and base concentrations in the body fluids Normal blood and tissue pH= 7.35-7.45 Even slight deviations from normal pH can cause serious harm Acidosis: pH < 7.35 Alkalosis: pH . 7.45 Below 6.8 or above 8.0 quickly fatal Homeostatic mechanisms to maintain pH Buffers
True or False: A physiological buffer is a system, namely the digestive system, that stabilizes pH by controlling the body's output of acids, bases, or CO2.
false
Slight deviation from normal pH can alter the structure and function of
macromolecules
renal tubule
microscopic tube in the kidney where urine is formed after filtration
pulmonary ventilation
movement of air into and out of the lungs
The carboxyl ends of protein chains are capable of buffering H+ as part of the ____________ .
protein buffer system
Slight deviations from the body's normal _____ range can shut down metabolic pathways as well as alter the structure and function of other macromolecules. Buffer systems help to avoid this.
pH
Enzymes are sensitive to
pH and temperature
The ____________ plays a significant role in the ICF because phosphates are capable of binding and unbinding H+, depending on current conditions of acidity or alkalinity.
phosphate buffer system
A ______ buffer is a system (for example the respiratory or urinary system) that stabilizes pH by controlling the body's output of acids, bases, or CO2. Multiple choice question. physiological phosphate chemical
physiological
A ____________ uses direct elimination of acids, bases, or carbon dioxide from the body in order to adjust systemic acidity.
physiological buffer
ICF (intracellular fluid)
place where the largest quantities of water are found in the body
phosphate buffer system
reacts with acids & bases to form compounds that alter pH; especially effective in renal tubules Phosphates are less concentrated in the ECF than bicarbonates, so they're less important in buffering pH
Which physiological buffer system exerts an effect within a few minutes but cannot alter the pH as much as the urinary system?
respiratory system
The addition of CO2 to the body fluids raises H+ concentration and lowers pH, while the removal of CO2 has the opposite effect. This is the basis for the strong buffering capacity of which system?
the respiratory buffer system
