Respiration Flashcards
Respiration has three meanings:
- ventilation of the lungs (breathing)
- the exchange of gases between the air and blood, and between blood and the tissue fluid
- the use of oxygen in cellular metabolism
Principal Organs of Respiratory System: Upper and Lower Respiratory Tracts
Upper respiratory tract: in head and neck
-nose through larynx
Lower respiratory tract: organs of the thorax
-trachea through lungs
Organs of Respiratory System
nose, pharynx, larynx, trachea, bronchi, lungs
Pharynx (throat)
a muscular funnel extending about 13sm (5in) from the choanae to the larynx
Three regions of the pharynx
nasopharynx: posterior to nasal apertures and above soft palate. receives auditory tubes and contains pharyngeal tonsil.
oropharynx: space between soft palate and epiglottis.contains palatine tonsils.
laryngopharynx: epiglottis to cricoid cartilage. esophagus begins at that point.
Nasopharynx: what passes through it? What is it lined with?
passes only air and is lined by pseudostratified columnar epithelium
Oropharynx and Laryngopharynx: what passes trough? And what is it lined with?
pass air, food, and drink and are lined by stratified squamous epithelium
Larynx-Voice Box: 3 parts
- epiglottis: flap of tissue that closes airway and directs food to the esophagus behind it
- Thyroid cartilage: largest, laryngeal prominence (Adam’s apple) shield-shaped (larger in males)
- Cricoid cartilage: connects larynx to trachea, ringlike
Trachea (windpipe)
a rigid tube about 12cm (4.5 in.) long and 2.5cm (1 in.) in diameter
Found anterior to esophagus
Supported by 16 to 20 C-shaped rings of hyaline cartilage. They reinforce the trachea and keeps it from collapsing when you inhale
Lung Anatomy
Costal surface: pressed against the ribcage
Mediastinal surface: faces medially toward the heart.
-hilum-slit through which the lung receives the main bronchus, blood vessels, lymphatics and nerves
-these structures constitute the root of the lung
Asymmetrical Lungs
Right Lung: shorter that left because the liver rises higher in the right. Has three lobes: superior, middle, and inferior separated by horizontal and oblique fissure
Left Lung: taller and narrower because the heart tilts toward the left and occupies more space on this side of mediastinum. Has indention: cardiac impression. has two lobes: superior and inferior separated by a single oblique fissure
Visceral Pleura
serious membrane that covers lungs
Parietal Pleura
adheres to mediastinum, inner surface of the rib cage, and superior surface of the diaphragm
Pleural Cavity
potential space between pleurae.
Normally no room between membranes, but contains a film of slippery pleural fluid
Functions of Pleurae and Pleural Fluid: 3 functions.
Reduce friction
Create pressure gradient: lower pressure than atmospheric pressure and assists lung inflation
Compartmentalization: prevents spread of infection from one organ in the mediastinum to others
Main (primary) Bronchi
supported by c-shaped hyaline cartilage rings
Lobar (secondary) Bronchi
supported by crescent shaped cartilage plates
- three right lobar (secondary) bronchi: superior, middle, and inferior
- one to each lobe of the right lung
- two It. lobar bronchi: superior and inferior
- one to each lobe of the left lung
Segmental (tertiary) Bronchi
Supported by crescent shaped cartilage plates
Bronchial Tree
All bronchi are lined with ciliated pseudostratified columnar epithelium
- cells grow shorter and the epithelium thinner as we progress distally
- terminal and respiratory bronchioles: final are passages which finally give rise to alveoli
Pulmonary Ventilation (Breathing)
Consists of a repetitive cycle one cycle of inhalation (inhaling) and expiration (exhaling)
Respiratory Cycle
One complete inspiration and expiration
- quiet respiration: while at rest, effortless, and automatic
- forced respiration: deep rapid breathing, such as during exercise
Flow of air in and out of Lungs depends on ?
Pressure difference between air pressure within lungs and outside body
Breathing muscles do what?
Change lung volumes and create differences in pressure relative to the atmosphere
Diaphragm
- prime mover or respiration
- contraction flattens diaphragm and enlarging thoracic cavity and pulling air into lungs
- relaxation allows diaphragm to bulge upward again, compressing the lungs and expelling air
- accounts for two-thirds of airflow
Internal and External Intercostal Muscles
- synergist to diaphragm
- between ribs
- stiffen the thoracic cage during respiration
- prevents it from caving inward when diaphragm descends
- contribute to enlargement and contraction of thoracic cage
- adds about one-third of the air that ventilates the lungs
Scalenes
- synergist to diaphragm
- quiet respiration holds ribs 1 and 2 stationary
Forced Inspiration: muscles involved
- erector spinae, sternocleidomastoid, pectoralis major, pectoralis minor, and serratus anterior muscles and scalenes
- greatly increase thoracic volume
Normal Quiet Expiration
- an energy-saving passive process by the elasticity of the lungs and thoracic cage
- as muscles relax, structures recoil to the original (smaller) size of thoracic cavity, results in air flow out of the lungs
Forced Expiration: muscles involved
- rectus abdominis, internal intercostals, outer lumbar, abdominal, and pelvic muscles
- greatly increased abdominal pressure pushes viscera up against diaphragm increasing thoracic pressure, forcing air out
Valsalva Maneuver
consists of taking a deep breath, holding it by closing the glottis, and then contracting the abdominal muscles to raise abdominal pressure and pushing organ contents out
- normally occurs in: childbirth, urination, defecation, vomiting
- helpful diagnostic tool for evaluating disc herniations/visceral hernias
Neural Control of Breathing: Involuntary
Neurons in medulla oblongata and pons control unconscious breathing
- no autorhythmic pacemaker cells for respiration, as in the heart
- exact mechanism for setting the rhythm of respiration remains unknown
- breathing depends on repetitive stimuli of skeletal muscles from brain
Neural Control of Breathing: Voluntary
Control provided by motor cortex
- inspiratory neurons: fire during inspiration
- expiratory neurons: fire during forced expiration
- innervation: fibers of phrenic nerve supply diaphragm. intercostal nerves supply intercostal muscles
Hyperventilation
Rapid breathing (anxiety)
- Co2 is “blown off” from the body faster than it is produced
- Ph rises
Central Chemoreceptors
Brainstem neurons respond to changes in PH of cerebrospinal fluid
-pH of cerebrospinal fluid reflects the CO2 level in the blood
Peripheral Chemoreceptors
carotid and aortic bodies of the large arteries above the heart
-respond to the O2 and CO2 content and the pH of blood
Stretch Receptors
found in the smooth muscles of bronchi and bronchioles, and in the visceral pleura
- inflation (Hering-Breuer) reflex: triggered by excessive inflation
- protective reflex that inhibits inspiratory neurons stopping inspiration
Irritant Receptors
Nerve endings amid the epithelial cells of the airway
- respond to smoke, dust, pollen, chemical fumes, cld air, and excess mucus
- trigger protective reflexes such as bronchoconstriction, shallower breathing, breath-holding (apnea), or coughing
Inspiration (due to lower intrapulmonary pressure)
- Ribs are lifted by scalenes and associated muscles
- Diaphragm contracts and drops down
- Lung volume and Intrapleural volume increases (decreases inner air pressure)
- Atmospheric air pressure is greater
- Air flows in
Expiration (passive process)
- Relaxed Breathing
- passive process achieved mainly by the elastic recoil of the thoracic cage - forced breathing (Ex: playing a wind instrument)
Airflow
Pressure and resistance determines airflow
The greater the resistance: slower the flow
- Diameter of bronchioles: constriction limits air flow
- Pulmonary compliance (elasticity)
- Presence of surfactant
Alveolar Surface Tension
- thin film of water needed for gas exchange
- pulmonary surfactant produced by the great alveolar cells
- Premature infants that lack surfactant suffer from infant respiratory distress syndrome (IRDS)
Spirometer
a device that recaptures expired breath and records such variables such a rate and depth of breathing, speed of expiration, and rate of oxygen consumption
Tidal Volume
Volume of air inhaled and exhaled in one cycle during quiet breathing (500mL)
Inspiratory Reserve Volume
air in excess of tidal volume that can be inhaled with maximum effort (3000 mL)
Expiratory Reserve Volume
air in excess of tidal volume that can be exhaled with maximum effort (1200 mL)
Residual Volume
air remaining in lungs after maximum expiration (1300 mL)
Vital Capacity
total amount of air that can be inhaled and then exhaled with maximum effort
-important measure of pulmonary health
Inspiratory Capacity
maximum amount of air that can be inhaled after a normal tidal expiration
functional residual capacity
amount of air remaining in lungs after a normal tidal expiration
total lung capacity
maximum amount of air the lungs can contain
spirometry
the measurement of pulmonary function
restrictive disorders
those that reduce pulmonary compliance (black lung, tuberculosis)
obstructive disorders
those that interfere with airflow by narrowing or blocking the airway (asthma, chronic bronchitis)
Emphysema
combines elements of restrictive and obstructive disorders
eupnea
relaxed quiet breathing
apnea
temporary cessation of breathing
hyperpnea
increased rate and depth of breathing in response to exercise, pain, or other conditions
hyperventilation
increased pulmonary ventilation in excess of metabolic demand
hypoventilation
reduced pulmonary ventilation
Kussmaul respiration
deep, rapid breathing often induced by acidosis
orthopnea
dyspnea that occurs when a person is lying down
respiratory arrest
permanent cessation of breathing
tachypnea
accelerated respiration
composition of air
- 6% nitrogen, 20.9% oxygen, 0.04% carbon dioxide, 0-4% water
- vapor depending on temperature and humidity, and minor gases argon, neon, helium, methane, and ozone
Dalton’s Law
the total atmospheric pressure is the sum of the contributions of the individual gases
- partial pressure: the separate contribution of each gas in a mixture
- at sea level 1 atm. of pressure: 760 mmHg
Alveolar Gas Exchange
the back-and-forth traffic of O2 and CO2 across the respiratory membrance
Gases diffuse down their own concentration gradient until?
the partial pressure of each gas in the air is equal to its partial pressure in water
Carbon Dioxide Transport
- 90% of CO2 is hydrated to form carbonic acid
- 5% binds to the amino groups of plasma proteins and hemoglobin to form carbamino compounds - chiefly carbaminohemoglobin (HbCO2)
- 5% is carried in the blood as dissolved gas
Oxygen Transport
- arterial blood carries about 20 mL of O2 per deciliter
- 95% bound to hemoglobin in RBC
- 1.5% dissolved in plasma
Hemoglobin
molecule specialized in oxygen transport
- four protein (globin) portions
- each with a heme group which binds one O2 to the ferrous ion (Fe2+)
- one hemoglobin molecule can carry up to 4 O2
- 100% saturation: Hb with 4 oxygen molecules
oxyhemoglobin
(HbO2): O2 bound to hemoglobin
deoxyhemoglobin
(HHb): hemoglobin with no O2
Carbon Monoxide Poisoning
- Carbon monoxide (CO): competes for the O2 binding sites on the hemoglobin molecule
- colorless, odorless gas in cigarette smoke, engine exhaust, fumes from furnaces and space heaters
Carboxyhemoglobin
CO binds to ferrous ion of hemoglobin
- binds 210 times as tightly as oxygen
- ties up hemoglobin for a long time
- non-smokers: less that 1.5% of hemoglobin occupied by CO
- smokers: 10% in heavy smokers
- atmospheric concentrations of 0.2% CO is quickly lethal
Blood gases and the Respiratory Rhythm
- Most potent stimulus for breathing is pH, followed by CO2, and least significant is O2
- Brainstem respiratory centers receive input from central and peripheral chemoreceptors that monitor the composition of blood and CSF
acidosis
blood pH lower that 7.35
alkalosis
blood pH higher that 7.45
hypocapnia
P CO2 less that 37mm Hg (normal 37-43 mm Hg)
hypercapnia
P CO2 greater that 43 mm Hg
respiratory acidosis and respiratory alkalosis
pH imbalances resulting from a mismatch between the rate of pulmonary ventilation and rate of CO2 production
What is a corrective homeostatic response to acidosis?
hyperventilation
What is a corrective homeostatic response to alkalosis?
hypoventilation
ketoacidosis
acidosis brought about by rapid fat oxidation releasing acidic ketone bodies (diabetes mellitus)
What usually has little effect on respiration?
Po2
chronic hypoxemia
Po2 less than 60mm Hg, can significantly stimulate ventilation
-emphysema, pneumonia
hypoxia
a deficiency of oxygen in tissue or the inability to use oxygen
-consequence of respiratory diseases
hypoxemic hypoxia
state of low arterial PO2
- usually due to inadequate pulmonary gas exchange
- oxygen deficiency at high elevations, impaired ventilation: drowning, aspiration of a foreign body, respiratory arrest, degenerative lung diseases
ischemic hypoxia
inadequate circulation of blood
-congestive heart failure
anemic hypoxia
due to anemia resulting from the inability of the blood to carry adequate oxygen
histotoxic hypoxia
metabolic poisons such as cyanide prevent the tissues from using oxygen delivered to them
cyanosis
blueness of the skin
-sign of hypoxia
Chronic Obstructive Pulmonary Disease
refers to any disorder in which there is a longterm obstruction of airflow and a substantial reduction in pulmonary ventilation
What are two major COPDs?
Chronic Bronchitis and Emphysema
- usually associated with smoking
- other risk factors include air pollution or occupational exposure to airborne irritants
pneumothorax
presence of air in pleural cavity
- thoracic wall is punctured
- inspiration sucks air though the wound into the pleural cavity
- potential space becomes an air filled cavity
- loss of negative intrepleural pressure allows lungs to recoil and collapse
atelectasis
collapse of part or all of a lung
-can also result from airway obstruction
chronic bronchitis
- inflammation and hyperplasia of the bronchial mucosa
- cilia immobilized and reduced in number
- goblet cells enlarge and produce excess mucus
- develop chronic cough to bring up extra mucus with less cilia to move it
- sputum formed (mucus and cellular debris)
- leads to chronic infection and bronchial inflammation
- symptoms include dyspnea, hypoxia, cyanosis, and attacks of coughing
emphysema
- alveolar walls break down
- lungs fibrotic and less elastic
- air passages collapse
- weaken thoracic muscles
What are the effects of COPD?
- reduces pulmonary compliance and vital capacity
- hypoxemia, hypercapnia, respiratory acidosis: hypoxemia stimulates erythropoietin release from kidneys: leads to polycythemia
- cor pulmonale: hypertrophy and potential failure of right heart due to obstruction of pulmonary circulation
Lung Cancer
accounts for more deaths than any other form of cancer
-most important cause is smoking (15 carcinogens)
Squamous-cell carcinoma
Most common lung cancer
- begins with transformation of bronchial epithelium into stratified squamous from ciliated pseudostratified epithelium
- dividing cells invade bronchial wall, cause bleeding lesions
- dense swirls of keratin replace functional respiratory tissue
