Respiratory I Flashcards
The dance of respiratory physiology:
blood and oxygen coming together
Function of respiration
All events involved in gas exchange
gas exchange between external environment and body → obtain O2 and eliminate CO2
Define: Acidotic
can’t get rid of CO2
General Organization of the respiratory system
- an air pump for alveolar ventilation → get air in and out
- a surface for gas exchange → alveoli are exquisitely evolved for efficient gas
- A mechanism to carry oxygen and carbon dioxide in the blood
- a circulatory system
- a mechanism for locally regulating the distribution of air and blood flow
- a mechanism for centrally regulating ventilation → the brain
External Respiration
The exchange of O2 and CO2 between the atmosphere and body tissues
Internal Respiration
Use of O2 in mitochondria to generate ATP by ox-phos
CO2 is waste product
Main purpose of Ventilation
to maintain optimal composition of alveolar gas
Define: alveolus
a buffer compartment between atmosphere and capillary blood
O2 constantly removed by blood
CO2 continuously added from blood
O2 replenished and CO2 removed by ventilation
What are the two phases of ventilaiton?
inspiration and expiration
they provide a stable alveolar environment
Non-respiratory Functions of Respiratory System
- Filter → catches thrombi (clots) and emboli (fat or air)
- metabolic organ → converts Ang I to Ang II, produces surfactant
- Shock-absorber for the heat and enhances venous return
- Alter the pH of blood → blow off CO2
- Route for water loss and heat elimination
- Blood reservoir → 10% of blood volume in pulmonary circulation
- Provide airflow → enables speech, singing, and other vocalizations
Respiratory consists of…
Airways → leading into lungs
Lungs
Structures in thorax → producing movement air through airways
Respiratory Airways: Tubes
carry air between the atmosphere and alveoli
Nasal passages (nose/mouth)
Pharynx
Trachea (windpipe) → air to lungs
Larynx (voice box) → folds vibrate to make sound
Right and Left bronchi
Bronchioles → alveoli (air sacs) clustered at ends of terminal bronchioles
Respiratory Airways: Trachea and Primary Bronchi
- Rings of cartilage prevent collapse during
- negative and positive pressure changes
- a cough (⇡ pressure)
Respiratory Airways: Lobar and Segmental Bronchi
Secondary and Tertiary bronchi
small plates of cartilage
Respiratory Airways: Bronchioles
- No cartilage
- Parenchyma (lung functional tissue) and lung elasticity keep them open
- Airway diameter regulated by
- smooth muscle innervation (ANS)
- circulating hormones and local chemicals
Define: Conducting Zone
- Trachea + first 16 generations of airways
- no alveoli
- no blood gas barrier
- no gas exchange (between blood and lungs)
- anatomic dead space
Define: Respiratory Zone (3L)
- last 7 generations of airways
- the site of gas exchange
- 300 million alveoli
- where the blood-gas barrier is
3 important functions of the Conducting Zone
- Distributes air evenly to deeper parts of lungs
- warms and humidifiers until inspired air is → 37o, saturated with water vapor
- defense → moving staircase of mucus (secreted by goblet cells, cilia push out)
Respiratory Zone: Alveoli
- Large Surface area
- Thin walled → one layer of flattened Type I alveolar cells (93% of wall)
- Total blood-gas barrier is 2 cells across
- alveolar epithelium, interstitial fluid, capillary endothelium
- Type II alveolar cells secrete surfactant
- Alveolar macrophages guard lumen → secrete trypsin
- Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation)
Lungs: Apex
superior tip of the lungs
just deep to clavicle
Lungs: Base
Concave inferior surface resting on diaphragm
Lung Tissue consists of:
airways
alveoli
blood vessels
elastic connective tissue
Thorax: Thoracic Cage
- Ribs and spine
- Chest wall
- Diaphragm
- sealed cavity with 3 membranous bags
- 1 pericardial sac contains the heart
- 2 pleural sacs, each containing 1 lung
Thorax: Thoracic Cage: Ribs and Spine
12 pairs of curved ribs
sternum
thoracic vertebrae
Thorax: Thoracic Cage: Chest wall
muscles in chest cavity
internal and external intercostal muscles connect the 12 rib pairs
sternocleidomastoids and scalenes connect the head and neck to the first 2 ribs
Thorax: Thoracic Cage: Diaphragm
dome-shaped skeletal muscle
separates thoracic cavity from the abdominal cavity
Pleural Sac
- separates each lung from the thoracic wall
- double walled closed sac
- visceral covers surface of lung
- parietal on inside of thorax
- Space within sac contains
- intrapleural fluid (1.5 mL)
- secreted by surfaces of the pleura
- lubricates pleural surfaces
- causes pleural surfaces to adhere together (lung and thorax)
Cohesive forces of intrapleural space: Horizontal
intrapleural fluid creates a slippery surface allowing lungs to slide against thoracic wall
pleural fluid = a lubricant
Cohesive forces of intrapleural space: Vertically
when chest expands → lungs are compelled to follow
Pleural Fluid = lungs and chest expand as a single unit
Define: Atmospheric (barometric) pressure
subject to gravity
pressure exerted by the weight of the air in the atmosphere (760 mm Hg at sea level)
Define: Intrapulmonary (alveolar) pressure
pressure inside the alveoli
when compared to atmospheric pressure it is 0 (B/C they are the same)
Define: Intrapleural pressure
pressure in pleural fluid; normally < intraalveolar pressure
normally less than what is in lungs
Transmural pressure
pressure difference across the lungs
transpulmonary = across lung wall; Palveolar - Pintrapleural
Transmural pressure gradient
important reason lungs follow chest
makes it easier to expand
pushes alveoli out as pressure goes down the gradient
Stretched lungs
tendency to pull in
Compressed thoracic wall
tends to pull out
____ helps keep the lung and chest from pulling away from each other except to the slightest degree
transmural pressure gradient and intrapleural fluid’s cohesiveness
The ever-so slight expansion of the pleural cavity…
creates a vacuum because fluid cannot expand to fill the slightly larger volume
Pip tends to be…
negative during quiet breathing
more negative during deep inspiration
When is Pip positive?
during forced expiration → blowing out
Define: Pneumothorax
air in chest
Symptoms of Pneumothorax
shortness of breath
fatigue
increased HR
chest pain
blue lips/fingers
What causes a pneumothorax?
opening in the chest wall → air enters pleural space → Pip equilibrates with PB → transplum pressure gradient is lost → lungs and thorax separate and assume their natural positions
P
Pressure, tension, or Partial Pressure of gas
V
volume of gas
F
functional concentration of a gas
Q
volume of blood
Cohesive forces of intrapleural space:C
content
A
alveolar
a
arterial
B
barometric
D
dead space
E
expiratory
I
inspiratory
ip
pleural
v
venous
O2
oxygen
CO2
carbon dixoide