Respiration
Process of exchanging gases between the atmosphere and body cells. Consists of gas exchange, regulation of blood ph, voice production, olfaction
Respiratory zone
Actual site of gas exchange, the respiratory bronchioles, alveoli, and alveolar ducts
Conducting zone
All respiratory passageways leading to and including the terminal bronchioles, serve as passageway allowing air to reach respiratory zone, also cleanse, humidify, warm incoming air
Upper Respiratory tract: Nasal Cavity
Functions: airway for reparation, moistens and warms air, filters and cleans air, resonating chamber for speech, olfactory receptors. Includes Paranasal sinuses, conchae, vestibule, nares(nostrils), hard and soft palates
Mucous in Respiratory Tract
Cilia move mucus and trapped particles from the nasal cavity to the pharynx
Paranasal sinuses
Nasal cavity is surrounded by Paranasal sinuses within the frontal, maxillary, sphenoid, and ethmoid bones that serve to lighten the skull, warm, and moisten air and produce mucus. ,Sinusitis-inflamed sinuses
Pharynx
Nasopharynx- serves only as air passageway co rains pharyngeal tonsil which traps and destroys airborne pathogens
Oropharynx-air and food passageway that extends from soft palate to epiglottis and house palatine and lingual tonsils
Laryngooharynx-air and food passageway, posterior to epiglottis, extends to the larynx, and is continuous inferior with the esophagus
Larynx
Air passageway, switch-send food and air in correct passageway, voice production.
Houses vocal ligaments. Voice box-made of 9 cartilages, all hyaline except epiglottis (elastic). Vocal folds and the medial space between them are called the glottis, larynx can act as a sphincter preventing air passage
Epiglottis
Designed to close off the larynx during swallowing to prevent food or liquids from entering the airways
Lower Rest-Trachea
Descends from the larynx through the next into the mediastinum, where it terminates at the primary bronchi, lined with ciliated pseudostratified epithelium, designed to propel mucus upward through toward the pharynx
Layers of tracheal wall
- Mucosa-pseudostratified columnar epithelium with goblet cells and cilia
- Submucosa- connective tissues with mucous glands
- Hyaline cartilage-16 to 20 rings provide flexibility and support
- Adventitia-connective tissue
Lower Resp. Tract Bronchi
Trachea branches into R and L primary bronchi, they branch into three R and two L secondary bronchi, then into tertiary bronchi, then into bronchioles and terminal bronchioles
As they become smaller, supportive cartilage not present, smooth muscle in the walls increases allowing less resistance in airflow
Alveoli
Thin-walled, gas-filled balls (300 million/lung), provide huge surface area for gas exchange
Lung root
Blood vessels and bronchi connect lung to heart/trachea
Hilum
Indentation of lung where blood vessels, bronchi, lymph vessels, nerves enter lungs
Parietal pleura
Lines thoracic cavity
Visceral pleura
Covers lungs
Pleural fluid
In pleural cavity, reduce friction
Breathing mechanism
Breathing or ventilation is the movement of air from outside the body into the bronchial tree and alveoli, air movements of inspiration and expiration, changes in size of thoracic cavity due to changes in pressure
Intrapulmonary pressure (Ppul)
Pressure in the alveoli, decrease during inspiration, increase during expiration, always equalize with atmospheric pressure
Intrapleural pressure (Pip)
Pressure in the pleural cavity, always negative relative to intrapulmonary pressure, more negative as thoracic cavity volume increases during inspiration
Transpulmonary pressure
Ppul-Pip, determines size of lungs at a given time
Pulmonary ventilation: Boyles law
Volume decrease, pressure increase. Volume increase, pressure decrease
Mechanics of breathing-Inspiration
- Inspiratory muscles (external intercostals and diaphragm) contract, diaphragm down, rib cage up and out
- Thoracic cavity volume increase, intrapleural pressure drops
- Lungs are stretched, intrapulmonary volume rises
- Intrapulmonary pressure drops
- Air flows into lungs: down its pressure gradient until intrapulmonary pressure=atmospheric pressure
Mechanics of breathing-expiration
- Inspiratory muscles (external intercostal and diaphragm) relax, diaphragm up, rib cage down and in
- Thoracic cavity volume decreases, intrapleural pressure rises
- Elastic lungs recoil passively, intrapulmonary volume drops
- Intrapulmonary pressure rises
- Air flows out of lungs, down its pressure gradient until intrapulmonary pressure = atmospheric pressure
Gas exchange
Occurs between lungs and blood as well as blood and tissues, external = blood and lungs, internal= blood and tissues, both are subject to basic properties of gases and composition of alveolar gas
Dalton’s law of partial pressure
Total pressure exerted by mixture of gases is equal to sum of pressures exerted by each gas, gas exchange at pulmonary and systemic capillaries is via passive diffusion of O2 and CO2 due to PPG (occurs when PP of gas differs across a membrane), gas from higher PP to lower PP
External respiration- partial pressure gradients and gas solubilities
PP gradient for O2 exists between blood and lungs. Venous blood PO2= 40mmHg, and Alveolar PO2=104mmHg. Drives O2 flow into blood, equilibrium reached. CO2 less step, venous blood = 45mmHg and alveolar = 40 mmHg. Still diffuses equal amounts with O2
O2 Transport
- 1.5% dissolved in plasma
- 99% bound to Hb
Most bound to Hb to form oxyhemoglobin that releases O2 to body cells, though much is still bound to Hb in venous blood
O2 Hb dissociation curve
Each Hb binds 4 O2, affinity= easier after 1st O2 is bound, 100mmHg= lungs, 40 mmHg=resting tissues, 20 mmHg= exercising tissues
CO2 transport
Dissolved in plasma, combined with Hb, in the form of bicarbonate ions. 10% dissolved in plasma, 20% bound to Hb (carbaminohemoglobin- Hb + bound CO2), 70% as bicarbonate ions from CO2 reaction
Hyperventilation
Exceeds metabolic needs, Respiratory alkalosis (blood too basic)
Hypoventilation
Not meeting metabolic needs (blood is acidic)
Neural control of respiration - medulla
Dorsal Respiratory Group (DRG)- integrate input from peripheral stretch and chemoreceptors -> relay to VRG
Ventral Respiratory Group (VRG)- control rhythm of respiration, inspiration= impulses via Phoenician nerve to diaphragm and intercostal nerves to external intercostal, expiration: stop impulses
Respiratory center in Pons
Pontine Respiratory Group, transmits impulses to VRG to fine tune breathing rhythms
Pneumonia
Inflammation of and fluid in alveoli, reduces gas exchange and may have fluid buildup in serous membranes
Asthma
Inflammation of airways
COPD- chronic obstructive pulmonary disease
Difficulty breathing, hypoventilation, pulmonary infections
Chronic bronchitis
Excessive mucous production, inflammation of airways, produce more mucous, impedes ventilation and gas exchange
Emphysema
Destruction of alveoli, reduce surface area fro gas exchange and lungs lose elasticity