Define respiration.
the entire process of exchanging gases between the atmosphere and body cells
What is external respiration?
exchange of gases between the air in the lungs and the blood
What is internal respiration?
exchange of gases between the blood and body cells
What is cellular respiration?
the use of O2 and production of CO2 by cells of the body
What is another term for ventilation?
breathing
Why (chemically speaking) do we need oxygen?
oxygen is needed to burn the fuel [sugars and fatty acids] in our cells to produce energy
What are the parts of the upper respiratory tract?
nose, nasal cavity, sinuses, pharynx
What are the parts of the lower respiratory tract?
larynx, trachea, bronchial tree, lungs
For the nose, identify: bridge, dorsum nasi, apex, external nares, alae.
check it out in a picture
What type of cartilage is found in the nose area?
primarily composed of HYALINE CARTILAGE, which is densely packed with collagen, a structural protein
What bones form the nasal cavity?
the paired nasal, maxilla, palatine and lacrimal bones, as well as the unpaired ethmoid, sphenoid, frontal and vomer bones
What are the structures of the nasal cavity, and how do they help to warm, moisten and filter the air we breathe?
- nasal conchae (superior, middle, inferior)
- nasal meatus (groove inferior to each nasal conchae)
- lamina propia (mucus/serous glands; secretes watery mucus and lysozyme),
What are vibrissae, and what are they good for?
stiff hairs act as filters that become coated with mucus, they catch particles
What is another function of the nasal cavity?
- warm, moisten and purify inspired air
- olfaction
- resonance
What are the three divisions of the pharynx?
nasophraynx, oropharynx, laryngopharynx
What types of epithelium do we find in each of these regions, and how does that relate to the function of each section?
nasopharynx - pseudo-stratified ciliated columnar epithelium (good for respiration)
oropharynx/laryngopharynx - nonkeratinized stratified squamous epithelium (digestion and respiration)
What are the functions of the larynx?
passage of air in/out of lungs, prevents foreign objects entering trachea, contains vocal cord for speech
What are the nine cartilages which make up the larynx?
all are HYALINE CARTILAGE
- thyroid cartilage w/ laryngeal prominence
- ring-shaped cricoid cartilage (end of larynx)
- epiglottis (ELASTIC CARTILAGE)
- paired arytenoid, cuneiform, corniculate
What is the function of the “false vocal cords”?
plays a major role as a barrier to the entry of food or large foreign objects into the respiratory tract
How do the true vocal cords differ from the false?
- true vocal folds are the more inferior and are where sound is actually produced
- false vocal folds are a pair of thick folds of mucous membrane that protect and sit slightly superior to the more delicate true folds
How does the larynx of a male differ from that of a female?
“Adam’s Apple”
- female: more rounded, shorter from front to back, shorter vocal cords
- male: more “V” shaped, longer from front to back, longer vocal folds
How do we speak?
- true vocal folds produce sound when air is forced across them
- pitch changed by amount of tension
What is Valsalva’s maneuver? What does it do for the body?
“closing of the glottis and contraction of the abdominal muscles”
- increases intrathoracic and intra-abdominal pressure
- aids in defecation
- stabilizes trunk during heavy lifting
- increases vagal activity
- slows return of blood to the heart
Describe the trachea. Where is it in relationship to the esophagus, and how do they fit together?
“windpipe”
- extends from larynx to primary bronchi (T5)
- 20 “C” shaped rings of hyaline cartilage
- open end of C posterior to allow esophagus to expand in
- the ridge (carina) => most sensitive areas for triggering cough reflex
What muscle is found in the trachea? What type of epithelium lines it, and what does it do?
- smooth muscle (trachealis muscle)
- lined with pseudo-stratified ciliated columnar epithelium
- contracts during coughing to expel mucus
What is the carina?
CARINA => the ridge of trachea most sensitive areas for triggering cough reflex
How do the right and left primary bronchi differ? If you inhaled a foreign object, where would it probably end up?
- right primary bronchus is more vertical, shorter, wider
- foreign object would end up in right bronchus
Describe the branching of the bronchi.
bronchi begin when the trachea divides to form the right and left main bronchi (the pleural of bronchus)
Describe the branching of the bronchi and bronchioles.
- deeper into the lungs, each bronchus is further divided into FIVE smaller, SECONDARY bronchi, which provide air to the lobes of the lungs
- the secondary bronchi continue to branch off to form the TERTIARY bronchi, which are further divided into TERMINAL BRONCHIOLES
- the smallest passageways, called BRONCHIOLES, lead to tiny air sacs (alveoli)
How do you tell the difference between a bronchus and bronchiole?
- the bronchi (or bronchus) are the air passages into the lungs that begin at the end of the trachea
- the bronchioles are the passageways by which air passes to the alveoli (air sacs) of the lungs
What effect does the autonomic nervous system have on bronchioles?
walls contain SMOOTH muscle
SYMPATHETIC => dilate
PARASYMPATHETIC => constrict
What are the membranes surrounding the lungs?
pleural membranes
How do the right and left lung differ and why?
RIGHT => 3 lobes, two fissures, shorter
LEFT => 2 lobes, one fissure, cardiac notch
Name the lobes and fissures of each lung.
(from superior to inferior)
RIGHT => superior lobe, horizontal fissure, middle lobe, oblique fissure, inferior lobe
LEFT => superior lobe, oblique fissure, inferior lobe
What is a bronchopulmonary segment?
a portion of lung supplied by a specific segmental bronchus and arteries
How does the presence of the mediastinum protect lung function?
mediastinum isolates the left and right lung from each other so that they function as two separate chest cavities
What two circulations supply the lungs? Are they totally separate?
the lungs receive blood from two SEPARATE systems: the BRONCHIAL circulation and the PULMONARY circulation
What three types of cells would you find in an alveoli, and what does each do?
- Type I alveolar cells: simple squamous epithelium
- Type II alveolar cells: secrete alveolar fluid (contains surfactant)
- alveolar macrophages: “dust cells”
What is respiratory distress syndrome of the newborn, and what can be done to help? What should NOT be done and why?
“retrolental fibroplasia”
- monitor arterial oxygen > 100 mm Hg
DO: administer surfactant, positive pressure respirator
DON’T: supplemental oxygen, ventilator
Describe the alveolar-capillary or respiratory membrane. How is it suited to diffusion?
two basement membranes and two laters of cells
- 1/16 the thickness of a RBC
- lots of surface area (70-80 square meters)
GASES DIFFUSE (remember!)
Describe the muscles involved in inspiration. Which one is the most important?
- diaphragm, external intercostals = normal muscles of inspiration
- DIAPHRAGM is most important bc it moves ~75% of air
- pectoralis minor, sternocleidomastoid = accessory muscles of inspiration
How does inspiration occur? How does Boyle’s law explain what is happening?
- air moves depending on a pressure gradient
- before inspiration, pressure in lungs = pressure of atmosphere = 760 mm Hg
- inspiration increases the size of the thoracic cavity and decreases pressure
- BOYLE’S LAW => at a constant temp, the pressure of a gas varies inversely with its volume P1V1 = P2V2
- gases always fill their container
How does expiration occur?
- diaphragm and external intercostals relax
- elastic recoil of stretched elastic fibers and surface tension of the liquid in lungs decreases the lung volume and increases the pressure, forcing air out of the lungs
What additional muscles are involved in forced inhalation and in forced exhalation?
FORCED INHALATION => the sternocleidomastoid, scalene muscles to lift the upper rib cage even more than in normal breathing
FORCED EXHALATION => contraction of INTERNAL intercostal and ABDOMINAL muscles (mostly obliques, transversus)
What is the primary factor which determines the resistance in the lungs? Why is this normally insignificant?
PRIMARY FACTOR => friction in respiratory passages
- greater airway diameter = lower resistance of air flow and vice versa
- normal, healthy lung, airway = resistance is insignificant because the airway diameters are huge
What is lung compliance? What factors affect it?
LUNG COMPLIANCE => distensibility (stretchiness) of lung tissue
- factors: elasticity of the lung tissue and surface tensions at air water interfaces (also: deformities of thorax, ossification of costal cartilages, paralysis of intercostal muscles)
What is eupnea? Apnea? Dyspnea?
EUPNEA => normal, quiet breathing
APNEA => temporary cessation of breathing
DYSPNEA => sensation of painful/labored breathing
Define tidal volume.
air moved in and out by one respiration, about 500 ml
Define inspiratory reserve volume.
additional air taken in during maximal inhalation
Define expiratory reserve volume.
additional air expired during forced exhalation
Define residual volume.
amount of air left in alveoli after forced expiration that keeps them inflated
Define inspiratory capacity.
tidal volume (TV) + inspiratory reserve volume (IRV) = inspiratory capacity
Define expiratory capacity.
no one ever talks about this one but... tidal volume (TV) + expiratory reserve volume (ERV) = expiratory capacity
Define vital capacity.
tidal volume (TV) + inspiratory reserve volume (IRV) + expiratory reserve volume (ERV) = vital capacity (VC)
Define total lung capacity.
tidal volume (TV) + inspiratory reserve volume (IRV) + expiratory reserve volume (ERV) + residual volume (RV) = total lung capacity (TLC)
What is the anatomic dead space?
due to conducting parts of system (nose, pharynx, larynx, trachea, etc.)
How could you estimate a person’s anatomic dead space volume?
about equal to ideal weight in pounds expressed in milliliters
Be able to calculate minute volume of respiration and the alveolar ventilation rate.
minute volume of respiration = tidal volume (TV) * breaths per minute
alveolar ventilation rate = [tidal volume (TV) - dead space] * breaths per minute
What is meant by Forced Vital Capacity and Forced Expiratory Volume? How would they change in obstructive and restrictive pulmonary disease?
Forced Vital Capacity => deep breath expelled rapidly
Forced Expiratory Volume => amount of air expelled during a specific time of FVC
OBSTRUCTIVE => exhale much less
RESTRICTIVE => exhale 80% or more
What is the medullary rhythmicity center, and what does it control?
two groups of neurons in the reticular formation within the medulla oblongata involved in establishing or modifying the pattern for breathing
Which of the two groups of neurons found in the medullary rhythmicity center controls the normal rate of breathing?
the ventral respiratory group (VRG)
How is the medullary rhythmicity center influenced by the pontine respiratory center (pneumotaxic area of the pons)?
pontine respiratory center interacts with medullary respiratory centers to smooth the respiratory pattern and coordinates transition between inspiration and expiration
What is the normal rate of breathing?
12-15 breaths per minutes
What influences the central chemoreceptors, and how do they respond? The peripheral chemoreceptors?
CENTRAL => influenced by concentration of carbon dioxide, oxygen, hydrogen, and pH (increase carbon dioxide and hydrogen)
PERIPHERAL => lower oxygen, increase carbon dioxide, and increase breathing
What is hyperventilation and how does it affect blood pH? Why?
HYPERVENTILATION => an increase in the rate and depth of breathing that exceeds the body’s need to remove carbon dioxide
- LOSS of carbon dioxide from the body = the pH of blood INCREASES and become more ALKALINE
How do temperature and pain affect the breathing rate?
high temp = increases breathing rate
low temp = decreases breathing rate
sudden pain = decreases breathing rate
prolonged pain = increases breathing rate
What is the normal atmospheric pressure at sea level?
760 mm Hg
What do we mean by a partial pressure?
the pressure that would be exerted by one of the gases in a mixture if it occupied the same volume on its own
What is Dalton’s Law? Henry’s Law?
DALTON’S LAW => in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases
HENRY’S LAW => the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid
How does the partial pressure of a gas influence its diffusion?
- a gas will diffuse from a higher pressure to a lower pressure down the gradient
- partial pressure of oxygen is greater in the external environment than in the capillaries, so oxygen diffuses into the capillaries
- CO2 is much more soluble than O2 in water
What happens during external respiration? During internal respiration?
EXTERNAL => exchange between air in alveoli and blood
INTERNAL => process of diffusing oxygen from the blood, into the interstitial fluid and into the cells
How does the response of the arterioles in the lungs to low oxygen content of the alveoli differ from the response of arterioles elsewhere in the body?
under low oxygen content, pulmonary arterioles constrict
How does the concentration of CO2 affect the bronchioles?
high carbon dioxide levels dilate the bronchioles
How is oxygen transported in the blood (be specific).
98% of oxygen is bound to the iron in hemoglobin as oxyhemoglobin (rest is dissolved in plasma)
How does the binding or the loss of one or more oxygen molecules to hemoglobin affect subsequent bindings or losses?
after the first oxygen molecule binds to iron, the hemoglobin changes shape to readily take more oxygen
- 1 hemoglobin molecule can hold up to 4 molecules of oxygen
- amount of oxygen on hemoglobin is determined by the partial pressure of oxygen
What other factors can influence hemoglobin saturation?
increased temperature, carbon dioxide, acid, and BPG all cause hemoglobin to release more oxygen (this is why muscle cells receive more oxygen during exercise)
What is the Bohr effect?
HbO2 bond weakens and causes oxygen to unload where it is most needed
Why is carbon monoxide dangerous?
CO binds to iron in hemoglobin more tightly than oxygen
What three ways does the blood transport carbon dioxide?
- 7% is dissolved in plasma
- 23% combines with amino groups of hemoglobin forming carbaminohemoglobin
- 70% is converted into bicarbonate ions
How is MOST of the carbon dioxide transported?
conversion of CO2 into bicarbonate ions
What is the Haldane effect?
the amount of CO2 transported is affected by the partial pressure of oxygen
Define functional residual capacity.
expiratory reserve volume (ERV) + residual volume (RV) = functional residual capacity (FRC)
