Resp. Physiology Flashcards
4 main functions of the respiratory system
Gas exchange, acid base balance, protection from infection via goblet cells and lymphoid tissues, and communication via speech
Oxygen is required for:
aerobic respiration, produce CO2 as a waste product
Deoxygenated blood:
returns to heart via the venous system, goes through right side of the heart through pulmonary artery
Pulmonary circulation
takes blood form heart to lungs
Pulmonary veins
carry oxygenated blood from lungs to the heart
In a steady state, what is the net volume of gas exchanged in the lungs per unit time
250ml/min O2
200ml/min CO2
What is:
normal respiration rate
max respiration rate
12-18
40-45
How many lobes does:
right lung have
left lung have
3
2
Describe the respiratory tree
Trachea - which bifurcates at sternal angle into
2 primary bronchi (left and right)
Primary bronchi then split twice on the left and thrice on the right (supplying each lobe) giving rise to secondary bronchi
Secondary bronchi keep dividing till they become bronchioles
Bronchioles end in alveoli
Alveoli - site of gas exchange
Name structures of the upper respiratory tract
Nasal cavity Tongue Pharynx Vocal cords oesophagus Larynx
Name structures of the lower respiratory tract
Trachea
Right lung, right bronchus
Left lung, left bronchus
Diaphragm
What is the clinical significance of the right bronchus
Slightly more vertical trajectory - aspirated foreign bodies get commonly lodged into right bronchus
What maintains the patency of the airway in primary, secondary and tertiary bronchi
C-shaped cartilage
What maintains the patency of bronchioles
physical force in thorax
Bronchial smooth muscle activity…
…can affect airway diameter, thus resistance to airflow
Contraction of bronchial smooth muscle
decreases diameter and increases resistance
Relaxation of bronchial smooth muscle
increases diameter, decreases resistance
Which type of cells make up the bulk of the alveoli?
Type 1 cells
Which cell types produces surfactant
Type 2 cells
What are 3 functions of mucous?
Moistens air
Traps particles
Provides large S.A for cilia to act on
What are the functions of elastic fibres?
They cover surface of alveoli, allowing them to stretch during inspiration and use elastic energy to recoil during expiration
What is Boyle’s law?
Pressure exerted by a gas is inversely proportional to its volume
What kind of muscle is the diaphragm?
Skeletal muscle - it separates thoracic cavity from abdominal cavity
Name the layers of the pleura and what they line
Visceral pleura - attached to outer surface of lungs
Parietal pleura - attached to the inner surface of thoracic cavity
both are continuous with one another
thin layer of intrapleural fluid is found between the two layers
Name 2 functions of pleural fluid
- Allows membranes to slide across each other (providing frictionless movement)
- Holds membranes together i.e. provides cohesive force. This holds the lungs against the ribs and the diaphragm
What is pleurisy?
Inflammation of pleura
Gasses always move..
from high pressure to low pressure
Muscles of inspiration:
External intercostal muscles
Diaphragm
Sternocleidomastoid
Scalenes
Muscles of expiration
Passive process but in severe respiratory load use internal intercostal muscles and abdominal muscles
Describe mechanics of breathing in relation to diaphragm, volume and pressure
Diaphragm contracts and flattens increasing the dimensions of the thoracic cavity superiorly and inferiorly
This decreases pressure - air moves in from high pressure to low pressure
Breathing out - diaphragm relaxes - decreasing thoracic volume
What is the function of intercostal muscles in relation to breathing? What do they act on?
Act on ribs and sternum
elevate ribs, increasing lateral dimensions of thoracic cavity thus increasing volume and decreasing pressure
increase anterior/posterior dimensions
Asthma
Increased resistance due to over-reactive constriction of bronchial smooth muscle
Mainly affect expiration
What is intra-thoracic alveolar pressure? P(A)
Pressure inside lungs
Can be positive or negative compared to atmospheric pressure
What is intra-pleural pressure? P(ip)
Pressure inside pleural cavity - always negative (in healthy lungs)
What is trans-pulmonary pressure? P(T)
Difference between alveolar and intra-pleural pressure
Always positive
What are the P(A) pressure changes during normal breathing cycle:
- No air movement
- Inspiration
- Expiration
- P(A) = 0 (same as atmospheric pressure)
- P(A) = negative
3, P(A) = postive
How does intra-pleural pressure change in breathing cycle?
Always negative
More negative during inspiration
Less negative during expiration
