Respiratory Volumes
How much air some portion of the respiratory system can hold
Tidal Volume
Amount of air inhaled or exhaled with each breath under resting conditions
-500 mL
Inspiratory Reserve Volume (IRV)
Amount of air that can be forcefully inhaled after a normal tidal volume inspiration
-3100 mL (males) or 1900 mL (females)
Expiratory Reserve Volume (ERV)
Amount of air that can be forcefully exhaled after a normal tidal volume expiration
-1200 mL (males) or 700 mL (females)
Residual Volume (RV)
Amount of air remaining in lungs after a forced expiration
-1200 mL (males) or 1100 mL (females)
Respiratory Capacities
The sum of two or more respiratory volumes
Total Lung Capacity (TLC)
Maximum amount of air contained in lungs after a maximum inspiratory effort
-6000 mL (males) or 4200 mL (females)
= TV + IRV + ERV + RV
Vital Capacity (VC)
Maximum amount of air that can be expired after a maximum inspiratory effort
-4800 mL (males) or 3100 mL (females)
= TV + IRV +ERV
Inspiratory Capacity (IC)
Maximum amount of air that can be inspired after a normal tidal volume expiration
-3600 mL (males) or 2400 mL (females)
= TV + IRV
Functional Residual Capacity (FRC)
Volume of air remaining in the lungs after a normal tidal volume expiration
-2400 mL (males) or 1800 mL (females)
= ERV + RV
Spirometer
Instrument for measuring respiratory volumes and capacities
-Can distinguish between: obstructive pulmonary disease and restrictive disorders
Obstructive Pulmonary Disease
Increased airway resistance (bronchitis)
Restrictive Disorder
Reduced TLC due to disease or fibrosis
Forced Vital Capacity (FVC)
Gas forcibly expelled after taking a deep breath
-Measures rate of gas movement
Forced Expiratory Volume (FEV)
Amount of gas expelled during a specific time interval of FVC
-Measures rate of gas movement
Nonrespiratory Air Movements
May modify normal respiratory rhythm
-Most result from reflex action; some voluntary
-ex: coughing, sneezing, crying, laughing, hiccups, and yawns
External Respiration
Diffusion of gases from alveoli to blood across respiratory membrane
-Exchange of O2 and CO2
-Influenced by thickness/surface area of membrane, partial pressure gradients and solubilities, and ventilation-perfusion coupling
Respiratory Membrane
0.5 to 1 um thick
-Large total surface area (40 times that of skin) for gas exchange
-Thicken if lungs become waterlogged and edematous --> gas exchange inadequate
-Reduced surface area in emphysema, tumors, inflammation, mucus
Internal Respiration
Diffusion of gases from blood to body tissues
-Gas exchange in body tissues at capillaries
-Partial pressure of oxygen in tissues is always lower than in arterial blood; CO2 from tissues to blood
Dalton's Law
Law of Partial Pressures:
Total pressure exerted by mixture of gas is equal to the sum of pressures exerted by each gas
Partial Pressure
Pressure exerted by each gas in a mixture
-Directly proportional to its percentage in the mixture
Henry's Law
Gas Mixtures in contact with liquid:
-Each gas dissolves in proportion to its partial pressure
-At equilibrium, partial pressures in two phases will be equal
-Amount of each gas that will dissolve depends on;
--Solubility (CO2 more soluble than O2; N2 not
Alveolar Gas
Composition of ___ ___
Alveoli contain more CO2 and water vapor than atmospheric air
-Gas exchanges in lungs
-Humidification of air
-Mixing of alveolar gas with each breath
Venous Blood
Partial pressure of oxygen is about 40 mmHG
-Drives oxygen flow to blood
Alveolar
Partial pressure of oxygen is about 104 mm Hg
-Drives oxygen flow to blood
Perfusion
Blood flow reaching alveoli
-Changes in partial pressure of oxygen causes a change in diameter of arterioles
-High O2: arterioles dilate
-Low O2: arterioles constrict
-Directs most blood where alveolar oxygen is high
Ventilation
Amount of gas reaching alveoli
-Contributes to efficient gas exchange
Plasma
1.5% of oxygen carried in the blood is dissolved in what?
Hemoglobin
98.5% of oxygen carried in the blood is loosely bound to each Fe of the ___ in RBC's
-4 per molecule
Oxyhemoglobin
Hemoglobin and oxygen combination
Deoxyhemoglobin (reduced hemoglobin)
Hemoglobin that has released O2
Hypoxia
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues
-Causes cyanosis (blue skin)
Anemic Hypoxia
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues due to too few RBCs
-Abnormal or too little hemoglobin
Ischemic Hypoxia
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues due to impaired/blocked circulation
Histotoxic Hypoxia
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues due to cells unable to use O2
-Metabolic poisons (ex: cyanide)
Hypoxemic Hypoxia
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues due to abnormal ventilation
-Pulmonary diseases
Carbon Monoxide Poisoning
Homeostatic Imbalance:
Inadequate delivery of oxygen to tissues due to the greater affinity of CO2 binding to hemoglobin
-Fires
CO2 transport
7-10% is dissolved in plasma
20% is bound to globin of hemoglobin
70% is transported as bicarbonate ions in plasma
Carbonic Acid
CO2 combines with water to form___ ___ (H2CO3), which quickly dissociates
Carbonic Anhydrase
Catalyzes the reaction of CO2 + water --> carbonic acid in RBCs
Carbonic Acid-Bicarbonate Buffer
Resists change in blood pH
-If hydrogen concentration rises --> hydrogen is combined with bicarbonate ions to raise pH
-If hydrogen concentration begins to drop --> carbonic acid dissociates releasing hydrogen ions
Bicarbonate Ion
An alkaline reserve of carbonic acid-bicarbonate system
Rate and Depth
Changes in respiratory __ and __ affect blood pH
Drop in pH
Slow, shallow breathing increases CO2 in the blood which does what to the blood pH
Rise in pH
Rapid, deep breathing decreases CO2 in the blood which does what to blood pH
Metabolic
Changes in ventilation can adjust pH when disturbed by ___ factors
Depth
___ is determined by how actively respiratory center stimulates respiratory muscles
Rate
___ is determined by how long inspiratory center active
Hyperventilation
Increased depth and rate of breathing that exceeds body's need to remove CO2
-Decreased blood CO2 levels (hypocapnia)
Apnea
Breathing cessation; may be due to abnormally low partial pressures of CO2
Hypothalamic Controls
Act through limbic system to modify rate and depth of respiration
-Breath holding that occurs in anger or gasping while in pain
Cortical Controls
Direct signals from cerebral motor cortex that bypass medullary controls
-Voluntary breath holding
Vagal Nerve
Receptors in bronchioles respond to irritants and communicate with respiratory center via the ___________ __________
-Promotes reflexes like coughing or sneezing
Hyperpnea
Increased ventilation in response to metabolic needs
-P(O2), P(CO2), and pH remain constant
Increase
Three neural factors cause ____ in ventilation as exercise begins:
-Psychological stimuli�anticipation of exercise
-Simultaneous cortical motor activation of skeletal muscles and respiratory centers
-Excitatory impulses to respiratory centers from proprio
Lactic Acid
Caused not by poor respiratory function but from insufficient CO or skeletal ability to increase O2 uptake