Exam 3- Chapter 16 Flashcards
What 3 things does respiration include?
- Ventilation (breathing)
- Gas exchange between blood and lungs and between blood and tissues
- Oxygen utilization by tissues to make ATP
What is external respiration?
Ventilation and gas exchange in lungs
What is internal respiration?
Oxygen utilization and gas exchange in tissues
What are the two divisions of the respiratory system?
- Respiratory Zone
2. Conduction Zone
What is the GENERAL function of the respiratory zone division of the respiratory system?
site of gas exchange
What is the GENERAL function of the conduction zone division of the respiratory system?
gets air to the respiratory zone
Describe the conduction route of the conduction zone (10 steps).
- Air travels down the nasal cavity
- Pharynx
- Larynx
- Trachea
- Right and left primary bronchi
- Secondary bronchi
- Tertiary bronchi —> (more branching)
- Terminal bronchioles
- Respiratory zone (respiratory bronchioles)
- Terminal alveolar sacs
What are the 3 specific functions of the conduction zone division of the respiratory system?
- Transports air to the lungs
- Warms, humidifies, filters, and cleans the air
(Mucus traps small particles, and cilia move it away from the lungs) - Voice production in the larynx as air passes over the vocal folds
In the conduction zone, how are small particles moved away from the lungs?
Mucus traps small particles, and cilia move it away from the lungs
What are alveoli? Function?
Air sacs in the lungs where gas exchange occurs
How many alveoli are there?
300 million of them
How are alveoli and surface area related?
Provide large surface area (760 square feet) to increase diffusion rate
What is within the central mediastinum of the thoracic cavity? What fills the rest of the thoracic cavity?
- Heart
- Trachea
- Esophagus
- Thymus
- Lungs
What lines the thoracic wall?
parietal pleura
What covers the lungs?
visceral pleura
The parietal and visceral pleura are normally pushed together, with a potential space between called the what?
intrapleural space
Gas exchange in the lungs occurs via what?
diffusion
Describe how O2 is diffused into the blood.
O2 concentration is higher in the lungs than in the blood, so O2 diffuses into blood.
Describe how C02 is diffused out of the blood (into the lungs).
CO2 concentration in the blood is higher than in the lungs, so CO2 diffuses out of blood.
When talking about ventilation, in what way does air move?
Air moves from higher to lower pressure.
What are 3 important physical properties of the lungs?
- Compliance
- Elasticity
- Surface Tension
Pressure differences between the two ends of the conducting zone occur due to changing what?
lung volumes
What is atmospheric pressure?
pressure of air outside the body
What is Intrapulmonary pressure?
pressure in the lungs
What is Intrapleural pressure?
pressure within the intrapleural space (between parietal and visceral pleura)
During inhalation, is intrapulmonary pressure or atmospheric pressure lower?
Intrapulmonary pressure is lower than atmospheric pressure
What is pressure below that of the atmosphere called?
subatmospheric or negative pressure
During exhalation, is intrapulmonary pressure or atmospheric pressure lower?
Intrapulmonary pressure is greater than atmospheric pressure.
During inhalation/exhalation, how does the Intrapleural pressure relate to the intrapulmonary and atmospheric pressure?
Lower than intrapulmonary and atmospheric pressure in both inhalation and exhalation
The difference between intrapulmonary and intrapleural pressure is called what?
transpulmonary pressure
How does the Intrapleural pressure physically affect the lungs?
Keeps the lungs against the thoracic wall
What does boyles law state?
States that the pressure of a gas is inversely proportional to its volume
During inhalation, lung volume increases. What happens next?
An increase in lung volume during inspiration decreases intrapulmonary pressure to subatmospheric levels. Air goes in.
During inhalation does the lung volume increase or decrease?
Increase
During exhalation does the lung volume increase or decrease?
Decrease
During exhalation , lung volume decreases. What happens next?
A decrease in lung volume during exhalation increases intrapulmonary pressure above atmospheric levels. Air goes out.
Can lungs expand when stretched? What is this referred to?
Yes. Lung compliance.
What is lung compliance defined as?
Defined as the change in lung volume per change in transpulmonary pressure (ΔV/ΔP)
What disease decreases lung compliance and how?
Reduced by infiltration of connective tissue proteins in pulmonary fibrosis
Summarize what lung elasticity is.
Lungs return to initial size after being stretched.
Do lungs have a low or high amount of elastin fiber?
Lungs have lots of elastin fibers.
The lungs are always under elastic tension because?
Because the lungs are stuck to the thoracic wall, they are always under elastic tension
Surface tension allows the lungs to resist what?
distension
What is surface tension exerted by?
Exerted by fluid secreted in the alveoli
Surface tension raises the pressure of the alveolar air as it acts to ____ __ ____.
collapse the alveolus
What does the law of laplace state?
Pressure is directly proportional to surface tension and inversely proportional to radius of alveolus.
Would smaller or larger alveoli be at greater risk of collapse without surfactant?
Small alveoli would be at greater risk of collapse without surfactant
What is surfactant secreted by?
type II alveolar cells
What is surfactant composed of?
Consists of hydrophobic protein and phospholipids
What is the function of surfactant?
- Reduces surface tension between water molecules
2. Prevents collapse
Is surfactant more concentrated in smaller or larger alveoli?
More concentrated in smaller alveoli
When does production of surfactant begin?
Production begins late in fetal life
Since production of surfactant begins in fetal life, what are premature babies at risk of?
premature babies may be born with a high risk for alveolar collapse called respiratory distress syndrome (RDS)
What is respiratory distress syndrome (RDS)
premature babies may be born with a high risk for alveolar collapse due to insufficient concentrations of surfactant called respiratory distress syndrome (RDS)
What is another name for breathing?
pulmonary ventilation
What are the two types of breathing/pulmonary ventilation and describe what they do.
- Inspiration: breathe in
2. Expiration: breathe out
How is breathing/pulmonary ventilation accomplished?
Accomplished by changing thoracic cavity/ lung volume
During inspiration, how does the volume of the thoracic cavity (and lungs) increase when the diaphragm contracts (flattens)?
Volume of thoracic cavity (and lungs) increases vertically when diaphragm contracts (flattens)
During inspiration, how does the volume of the thoracic cavity (and lungs) increase when parasternal and external intercostals raise the ribs?
Volume of thoracic cavity (and lungs) increases horizontally when parasternal and external intercostals raise the ribs
During expiration, how does the volume of the thoracic cavity (and lungs) decrease when the diaphragm relaxes (dome)?
Volume of thoracic cavity (and lungs) decreases vertically when the diaphragm relaxes (dome)
During expiration, how does the volume of the thoracic cavity (and lungs) decrease when internal intercostals lower the ribs in forced expiration?
Volume of thoracic cavity (and lungs) decreases horizontally when internal intercostals lower the ribs in forced expiration
What is an example of a Pulmonary Function Test?
Spirometry
How is a spirometry conducted?
Subject breathes into and out of a device that records volume and frequency of air movement on a spirogram.
What type of graph does a spirometry produce?
spirogram
What is a spirometry measuring?
Measures lung volumes and capacities
What can a spirometry diagnose?
Can diagnose restrictive and disruptive lung disorders
Lung Capacity Measurements:
What is vital capacity?
maximum amount of air that can be forcefully exhaled after a maximum inhalation
Lung Capacity Measurements:
What is total lung capacity?
amount of gas in the lungs after a maximum inspiration
Lung Capacity Measurements:
What is inspiratory capacity?
amount of gas that can be inspired after a normal expiration
Lung Capacity Measurements:
What is functional residual capacity?
amount of gas left in lungs after a normal expiration
Lung Capacity Measurements:
What is tidal volume?
amount of air expired or inspired in quiet breathing
Lung Capacity Measurements:
What is expiratory reserve volume?
amount of air that can be forced out after tidal volume
Lung Capacity Measurements:
What is inspiratory reserve volume?
amount of air that can be forced in after tidal volume
Lung Capacity Measurements:
What is residual volume?
amount of air left in lungs after maximum expiration
In a restrictive lung disorder, describe the:
- Lung tissue
- Vital capacity
- Forced Expiration
- Lung tissue is damaged
- Vital capacity is reduced
- Forced expiration is normal
In a obstructive lung disorder, describe the:
- Lung tissue
- Vital capacity
- Forced Expiration
- Lung tissue is normal
- Vital capacity is normal
- Forced expiration is reduced
What are 2 examples of a restrictive lung disorder?
- Pulmonary Fibrosis
2. Emphysema
What is an example of an obstructive lung disorder?
Asthma
How are obstructive lung disorders usually diagnosed?
by doing forced expiratory volume tests (FEV test)
What are the symptoms of asthma?
dyspnea (shortness of breath) and wheezing
What is dyspnea?
shortness of breath
What are 3 things asthma is caused by?
Caused by inflammation, mucus secretion, and constriction of bronchioles
What is another name for asthma?
airway hyperresponsiveness
What is allergic asthma triggered by?
- Allergens stimulating T lymphocytes to secrete cytokines and recruit eosinophils and mast cells, which contribute to inflammation
- Cold or Dry Air
Is allergic asthma reversible?
YES
What is allergic asthma reversible with? (give an example)
bronchodilator (albuterol)
What symptoms are characterized by Chronic Obstructive Pulmonary Disease (COPD)?
- Chronic inflammation
- excessive mucus production
- narrowing of the airways
- Alveolar destruction
What two other diseases are included with COPD?
emphysema and chronic obstructive bronchiolitis
In an FEV test, a patient with COPD would show what?
Accelerated decline in FEV
Inflammation from COPD is due to/involved what?
- Macrophages
- Neutrophils
- Cytotoxic T cells
With COPD, what can smoking trigger?
Excessive mucus production and inflammation
Is COPD common to people who do or do not smoke?
Most people with COPD smoke
Is there a cure for COPD?
NO
What is the 5th leading cause of death?
COPD
In addition to the excessive mucus production and inflammation that smoking triggers in COPD, what else does it trigger?
Smoking also promotes the infiltration of obstructing fibrous tissue and muscle in the airways and remodeling of blood vessels in the lungs, leading to pulmonary hypertension
What is emphysema?
Destruction of alveoli
How does emphysema affect surface area for gas exchange?
Reduces surface area for gas exchange
How does the destruction of alveoli in emphysema physically affect the bronchioles during expiration?
With fewer alveoli to put pressure on bronchioles, they collapse during expiration.
What is the most common cause of emphysema? What does this cause trigger?
Smoking is the most common cause. It triggers inflammation and destruction of alveoli by immune cells
What is pulmonary fibrosis?
accumulation of fibrous tissues in the lungs when alveoli are damaged.
What may pulmonary fibrosis be due to?
inhalation of small particles
What is an example of pulmonary fibrosis?
black lung in miners
What does dalton’s law state?
The total pressure of a gas mixture is equal to the sum of the pressures of each gas in it.
What is partial pressure?
the pressure of an individual gas
How can partial pressure be measured?
can be measured by multiplying the % of that gas by the total pressure
In the alveoli does the percentage of oxygen increase or decrease during gas exchange? CO2? How does this affect the partial pressure of each?
In the alveoli, the percentage of oxygen decreases and CO2 increases, changing the partial pressure of each.
What does the partial pressure of oxygen change with?
Altitude and location
What does the blood gas measurement measure?
Only measures oxygen dissolved in the blood plasma. It will NOT measure oxygen in red blood cells
Does the blood gas measurement provide a good measurement of lung function?
It does provide a good measurement of lung function
If partial pressure oxygen in blood is more than _____ below that of lungs, gas exchange is impaired.
5 mmHg
The rate of blood flow through the lungs is equal to what?
that through the systemic circuit (5.5 L/minute cardiac output)
What is the pressure difference between the left atrium, and the pulmonary artery?
only 10 mmHg.
For pulmonary circulation, must vascular resistance be very low or very high?
Very low
For pulmonary circulation vascular resistance must be very low. Why? What does this reduce the possibility of?
- Low pressure/low resistance pathway
2. Reduces possibility of pulmonary edema
Pulmonary arterioles constrict when alveolar partial pressure O2 is___ , and dilate when partial pressure O2 is ___.
- Low
2. High
Blood flow to alveoli is _____ when they are full of oxygen and _____ when not.
- increased
2. decreased
The constriction/dilation of of the pulmonary arterioles are opposite of that of the what?
systemic arterioles
Systemic arterioles constrict when partial pressure O2 in tissues is ____, and dilate when the partial pressure O2 in tissues is _____.
- High
2. Low
- Pulmonary arterioles constrict when alveolar partial pressure O2 is low, and dilate when partial pressure O2 is high.
BY CONTRAST - Systemic arterioles constrict when partial pressure O2 in tissues is high, and dilate when the partial pressure O2 in tissues is low.
What does this ensure?
This ensures that only tissues that need oxygen are sent blood.
Ventilation/Perfusion Ratios:
The response of pulmonary arterioles to low oxygen levels makes sure that ___________ matches _________.
- ventilation (O2 into lungs)
- perfusion (blood flow)
What is an example of a group of people that experience disorders caused by high partial pressure of gases?
deep-sea divers
What are 3 disorders that deep-sea divers experience due to high partial pressure of gases?
- Oxygen Toxicity
- Nitrogen Narcosis
- Decompression sickness
Disorders Caused by High Partial Pressure of Gases (Deep Sea Divers):
What is oxygen toxicity? Why is this true?
- 100% oxygen is dangerous at 2.5 atmospheres.
2. Due to oxidation of enzymes
Disorders Caused by High Partial Pressure of Gases (Deep Sea Divers):
How does nitrogen narcosis occur? What does it result in?
- Occurs if nitrogen is inhaled under pressure
2. Results in dizziness and drowsiness
Disorders Caused by High Partial Pressure of Gases (Deep Sea Divers):
How is decompression sickness caused?
When a diver comes to the surface too fast, nitrogen bubbles can form in the blood and block small vessels.
Besides deep sea diving, what is another scenario in which decompression sickness can be initiated?
Can also happen if an airplane suddenly loses pressure
Where is the rhythmicity center located?
Medulla Oblongata
How many types of neurons are located within the rhythmicity center?
four types of neurons identified for different stages of breathing
What are the two main groups of the rhythmicity center?
- Dorsal respiratory group
2. Ventral respiratory group
What is the dorsal respiratory group made up of? What nerve does it stimulate?
- Made up of inspiratory neurons
2. Phrenic nerve
What is the ventral respiratory group made up of? What types of neurons does it stimulate?
- Made up of inspiratory neurons
2. stimulate spinal respiratory neurons and expiratory neurons that INHIBIT the phrenic nerve
What structure influences the medulla activity?
Pons
What are the two divisions of the pons involved in respiration?
- Apneustic center
2. Pneumotaxic center
What does the apneustic center of the pons do?
Promotes inspiration
What does the pneumotaxic center of the pons do?
Inhibits inspiration
Automatic control of breathing is influenced by feedback from ______.
chemoreceptors
Chemoreceptors involved in respiration monitor what 4 things?
- pH of fluids in the brain
- pH of the blood
- PCO2 of the blood
- PO2 of the blood
Where are the central chemoreceptors located?
Medulla
Where are the peripheral chemoreceptors located?
Carotid and aorta arteries
When ventilation is inadequate, CO2 levels ___ and pH ____.
- Rise
2. Falls
carbon dioxide + water = ________
carbonic acid
In hyperventilation, CO2 levels ___ and pH ____.
- Falls
2. Rises
Why do oxygen levels not change as rapidly?
because of oxygen reserves in hemoglobin
Why are O2 levels not a good index for control of breathing?
Because oxygen levels do not change as rapidly because of oxygen reserves in hemoglobin
Ventilation is controlled to maintain _____ levels of CO2 in the blood. Oxygen levels _____ ___.
- constant
2. naturally follow
When increased CO2 in the fluids of the brain decrease pH, this is sensed by chemoreceptors in the medulla, and ventilation is _____.
increased
What do chemoreceptors in the medulla (central chemoreceptors) respond to?
increased CO2 in the fluids of the brain which decrease pH
When increased CO2 in the fluids of the brain decrease pH, this is sensed by chemoreceptors in the medulla, and ventilation is increased. This takes longer, but is responsible for how much % of increased ventilation?
70-80%
What do peripheral chemoreceptors in the aorta, and carotid bodies respond to?
rise in H+ due to increased CO2 levels
Which respond quicker, central or peripheral chemoreceptors.
Peripheral chemoreceptors respond much quicker, but are not responsible for as much of the increased ventilation of the lungs.
How does the pressure of O2 in row blood effect ventilation?
Indirectly affects ventilation by affecting chemoreceptor sensitivity to PCO2 (Low blood O2 makes the carotid bodies more sensitive to CO2)
Pulmonary Receptors and Ventilation: What are Unmyelinated C fibers affected by? What do they produce, when a person breathes pepper spray?
- Capsaicin
2. Produce rapid shallow breathing when a person breathes in pepper spray
Pulmonary Receptors and Ventilation: What are two receptors that stimulate coughing?
- Irritant Receptors
2. Rapidly Adapting Receptors
Pulmonary Receptors and Ventilation: Where are irritant receptors located? What do they respond to? What is the response?
- In the wall of the larynx
- Respond to smoke, particulates, etc.
- Coughing
Pulmonary Receptors and Ventilation: Where are rapidly adapting receptors located? What do they respond to? What is the response?
- In the Lungs
- Respond to excess fluid
- Coughing
Pulmonary Receptors and Ventilation: What is the Hering-Breuer reflex stimulated by? What does it inhibit? What is it’s purpose?
- Stimulated by pulmonary stretch receptors
- Inhibits respiratory centers as inhalation proceeds
- Makes sure you do not inhale too deeply
Most of the oxygen in blood is bound to what?
Hemoglobin
What is the structure of hemoglobin?
4 polypeptide globins and 4 iron-containing hemes
How many molecules of O2 can each hemoglobin carry?
Each hemoglobin can carry 4 molecules O2
How many hemoglobin per RBC?
248 million hemoglobin/RBC
Wha are the 3 different forms of hemoglobin?
- Oxyhemoglobin/reduced hemoglobin
- Methemoglobin
- Carboxyhemoglobin
Oxyhemoglobin/reduced hemoglobin:
How is the iron structured? Can it bind with O2?
- Iron is in reduced form (Fe2+)
2. YES
Methemoglobin hemoglobin:
How is the iron structured? Can it bind with O2? Is this normal? What can cause this?
- Oxidized iron (Fe3+)
- NO
- NO
- Some drugs can cause this
Carboxyhemoglobin:
What is hemoglobin bound to?
Hemoglobin is bound with carbon monoxide
% Oxyhemoglobin Saturation= what?
% oxyhemoglobin to total hemoglobin
What does % Oxyhemoglobin Saturation measure?
Measured to assess how well lungs have oxygenated the blood
What is the normal % Oxyhemoglobin Saturation?
97%
What is % Oxyhemoglobin Saturation measured with?
Measured with a pulse oximeter or blood– gas machine
Oxygen-carrying capacity of blood is measured by its what?
hemoglobin concentration
What is anemia?
below-normal hemoglobin levels
What is polycythemia? What may it occur from?
above-normal hemoglobin levels; may occur due to high altitudes
_______ made in the kidneys stimulates hemoglobin/RBC production when O2 levels are low.
Erythropoietin
What is loading?
when hemoglobin binds to oxygen in the lungs
What is unloading?
when oxyhemoglobin drops off oxygen in the tissues
What chemical equation represents loading and unloading?
deoxyhemoglobin + O2 oxyhemoglobin
The direction of the loading/unloading reaction depends on what?
depends on PO2 of the environment and affinity for O2
Does high PO2 favor loading or unloading?
loading
Systemic arteries have a PO2 of what?
100 mmHg
Oxygen Unloading: Systemic arteries have a PO2 of 100 mmHg. This makes enough oxygen bind to get what % oxyhemoglobin?
This makes enough oxygen bind to get 97% oxyhemoglobin (20 ml O2/100 ml blood)
Systemic veins have a PO2 of what?
40 mmHg
Oxygen Unloading: Systemic veins have a PO2 of 40 mmHg. This makes enough oxygen bind to get what % oxyhemoglobin
75% (15.5 ml O2/100 ml blood)
What % of oxygen is unloaded in tissues?
22% oxygen is unloaded in tissues
Oxygen Dissociation Curve: Oxygen remaining in veins serves as a what?
oxygen reserve
Is oxygen unloading during exercise greater or smaller?
greater
What is the % of oxygen unloaded in tissues:
- At rest
- Light exercise
- Heavy exercise
- 22% at rest
- 39% light exercise
- 80% heavy exercise
How does pH and Temperature effect Oxygen Transport?
pH and temperature change the affinity of hemoglobin for O2.
pH and temperature change the affinity of hemoglobin for O2. What does this ensure?
This ensures that muscles get more O2 when exercising
Affinity _____ at lower pH and ___ at higher pH
- decreases
2. increases
Affinity decreases at lower pH and increases at higher pH = ___ ___
Bohr effect
More unloading occurs at ____ pH.
lower
Increased metabolism = ____ CO2 = ___ pH
- more
2. lower
Hemoglobin affinity for O2 is decreased at _____ temperatures. What does this further enhance?
- Increased
2. This further enhances the amount of O2 unloaded to muscles during exercise.
Effect of 2,3-DPG on Oxygen Transport: RBCs obtain energy from the anaerobic metabolism of ____.
Glucose
Effect of 2,3-DPG on Oxygen Transport: RBCs obtain energy from the anaerobic metabolism of glucose. During this process what is made? What is this inhibited by?
- 2,3 diphosphoglyceric acid (2,3-DPG) is made
2. Inhibited by oxyhemoglobin
When is 2,3-DPG produced? What does this increase?
2,3-DPG is produced if a person is anemic or at high altitude. This increases oxygen unloading.
Can adult hemoglobin (hemoglobin A) bind to 2,3-DPG? Fetal hemoglobin (hemoglobin F)?
Adult hemoglobin (hemoglobin A) can bind to 2,3-DPG, but fetal hemoglobin (hemoglobin F) cannot
Since fetal hemoglobin (hemoglobin F) cannot cannot bind to 2,3-DPG what does this mean?
Fetal hemoglobin therefore has a higher affinity for O2 than the mother, so oxygen is transferred to the fetus
What are two types of inherited hemoglobin defects?
- Sickle-cell anemia
2. Thalassemia
Sickle-cell anemia is found in what % of african americans?
found in 8−11% of African Americans
The affected person with sickle-cell anemia has hemoglobin __ with a ____ amino acid difference.
- S
2. Single
Sickle-cell anemia: Deoxygenated hemoglobin S polymerizes into what? What does this hinder?
- long fibers, creating a sickle-shaped RBC
2. This hinders flexibility and the ability to pass through small vessels
What race is Thalassemia mainly found in?
found mainly in people of Mediterranean heritage
What is going wrong with thalassemia?
Production of either alpha or beta chains is defective.
What are the symptoms of thalassemia?
Symptoms are similar to sickle-cell anemia
Both inherited hemoglobin defects (sickle-celll anemia, and thalassemia) carry resistance to what?
malaria
What is myoglobin?
Red pigment found in skeletal and cardiac muscles
What is myoglobin similar to?
Similar to hemoglobin
What is different about myoglobin and hemoglobin?
Has 1 heme (vs 4 in hemoglobin) so can only carry 1 oxygen molecule
What is myoglobins affinity to oxygen? When is oxygen released?
Higher affinity to oxygen; oxygen is only released when PO2 is very low
What is the function of myoglobin?
Stores oxygen and serves as go-between in transferring oxygen from blood to mitochondria
What are the 3 forms in which CO2 is carried in the blood?
- Dissolved in plasma
- As carbaminohemoglobin attached to an amino acid in hemoglobin
- As bicarbonate ions
What is Carbonic Anhydrase?
Enzyme that combines water with CO2 to form carbonic acid at high PCO2
Where do the actions of carbonic anhydrase occur?
Occurs within RBCs in the capillaries of systemic circulation
What must the PCO2 be in order for carbonic anhydrase to work?
High PCO2
What is the chemical equation for the effects of carbonic anhydrase?
H2O + CO2———> H2CO3
How is bicarbonate and H+ formed?
Increases in carbonic acid favor dissociation into bicarbonate and hydrogen ions
What is the chemical equation for the formation of bicarbonate and H+?
H2CO3———> H+ + HCO3−
What is a chloride shift?
- H+ in RBCs attach to hemoglobin and attract Cl−.
- The exchange of bicarbonate out of and Cl− into RBCs is called the chloride shift
H+ in RBCs attach to hemoglobin and attract Cl−. The exchange of bicarbonate out of and Cl− into RBCs is called the what?
chloride shift
Describe the Bohr Effect.
- Bonding of H+ to hemoglobin lowers the affinity for O2 and helps with unloading
- This allows more H+ to bind, which helps the blood carry more carbon dioxide
Reverse Chloride Shift:
- In pulmonary capillaries, increased PO2 favors the production of _____.
- This makes H+ dissociate from hemoglobin and recombine with bicarbonate to form ____ ___.
- oxyhemoglobin
2. carbonic acid
What is the chemical equation for a reverse chloride shift?
H+ + HCO3− ———> H2CO3
In low PCO2 what happens with a reverse chloride shift? What is the chemical equation for that? What is the result?
- In low PCO2, carbonic anhydrase converts carbonic acid back into CO2 + H2O
- H2CO3 ———-> CO2 + H2O
- CO2 is exhaled
How is the acid-base balance maintained?
Maintained within a constant range by the actions of the lungs and kidneys
Acid-Base Balance: what is the range that the pH is maintained at?
pH ranges from 7.35 to 7.45.
Why is carbonic acid considered a volatile acid?
Because it can be converted into a gas and exhaled
What are examples of nonvolatile acids?
lactic, fatty, ketones
What are nonvolatile acids buffered by?
bicarbonate
Bicarbonate as a buffer: can bicarbonate always/continuously buffer? How do the kidneys help this situation?
- Buffering cannot continue forever because bicarbonate will run out.
- Kidneys help by releasing H+ in the urine
Acidosis: When does this occur?
when blood pH falls below 7.35
What are two types of acidosis?
- Respiratory acidosis
2. Metabolic acidosis
What does respiratory acidosis result from?
hypoventilation
What does metabolic acidosis result from?
excessive production of acids, loss of bicarbonate (diarrhea)
What is alkalosis?
when blood pH rises above 7.45
What are two types of alkalosis?
- Respiratory alkalosis
2. Metabolic alkalosis
What does respiratory alkalosis result from?
hyperventilation
What does metabolic acidosis alkalosis from?
inadequate production of acids or overproduction of bicarbonates, loss of digestive acids from vomiting
What is the respiratory component of blood pH measured by?
Respiratory component of blood pH measured by plasma CO2
What is the metabolic component of blood pH measured by?
Metabolic component measured by bicarbonate
What control the respiratory component of acid-base balance?
Ventilation controls the respiratory component of acid-base balance
How does Hypoventilation effect the acid-base balance? What occurs?
1.
- Ventilation is insufficient to “blow off” CO2
- PCO2 is high
- carbonic acid is high
2. Respiratory acidosis occurs
How does Hyperventilation effect the acid-base balance? What occurs?
1.
- Rate of ventilation is faster than CO2 production.
- Less carbonic acid forms
- PCO2 is low
2. Respiratory alkalosis occurs
What can compensate for the metabolic component of acid-base balance?
Ventilation can compensate for the metabolic component.
Ventilation can compensate for the metabolic component.:
- A person with metabolic acidosis will ______.
- A person with metabolic alkalosis will ______.
- hyperventilate
2. hypoventilate
Hyperpnea
Occurs when exercise produces deeper, faster breathing to match oxygen utilization and CO2 production
What control hyperpnea?
Neurogenic and humoral mechanisms control this.
Lactate Threshold: Ventilation does not deliver enough O2 at the beginning of exercise. What two things happen next. If heavy exercise continues what will be used again?
- Anaerobic respiration occurs at this time.
- After a few minutes, muscles receive enough oxygen.
- If heavy exercise continues, lactic acid fermentation will be used again
Define lactate threshold.
The lactate threshold is the maximum rate of oxygen consumption attained before lactic acid levels rise
Lactate threshold occurs when how much % of the maximum oxygen uptake is reached? What is this due to?
- Occurs when 50−70% maximum oxygen uptake is reached
- Due to aerobic limitations of the muscles, not the cardiovascular system
- Endurance exercise training increases mitochondria and Krebs cycle enzymes in the muscles
What increases mitochondria and Krebs cycle enzymes in the muscles?
Endurance exercise training
Why must adjustments in high altitude be made?
Adjustments must be made to compensate for lower atmospheric PO2
In high altitude, what adjustments must be made to compensate for lower atmospheric PO2?
- Changes in ventilation
- Hemoglobin affinity for oxygen
- Total hemoglobin concentration
What is the function of the Hypoxic ventilatory response?
Decreases in PO2 stimulate the carotid bodies to increase ventilation.
Hypoxic ventilatory response:
1. Hyperventilation does what to PCO2, and what does this cause?
- What do the kidneys do to compensate?
- Chronically apoxic people produce what in the lungs? What is this/What does it do?
- Hyperventilation lowers PCO2, causing respiratory alkalosis
- Kidneys increase urinary excretion of bicarbonate to compensate
- Chronically apoxic people produce NO in the lungs, a vasodilator that increases blood flow.
Affinity of Hemoglobin for Oxygen: Oxygen affinity decreases. How does this affect the proportion of oxygen unloaded? What does this occur due to? At extremely high altitudes, what will override this, and what will that cause?
- Oxygen affinity decreases, so a higher proportion of oxygen is unloaded.
- Occurs due to increased production of 2,3-DPG
- At extreme high altitudes, effects of alkalosis will override this, and affinity for oxygen will increase.
Increased Hemoglobin Production:
1. Kidney cells sense decreased PO2 and produce what?
- What does this stimulate
- What can increased RBC’s lead to.. which produces what?
- Erythropoietin
- This stimulates bone marrow to produce more hemoglobin and RBCs.
- Increased RBCs can lead to polycythemia, which can produce pulmonary hypertension
