Introduction and Anatomy of Lungs Airways and Blood Supply Flashcards
What are the functions of the respiratory system?
Gas exchange Acid base balance - regulation of body pH (7.4 average pH) Protection of infection Communication via speech
Why is gas exchange essential?
Oxygen is essential for releasing energy Removing carbon dioxide, the waste product.
What is the cardiovascular system responsible for?
Transporting oxygen to tissues Transporting carbon dioxide away from tissue
What is meant by external respiration?
Movement of gases between the air and the bodies cells
Where does the pulmonary artery take blood? (Only artery that takes deoxygenated blood)
Away from the heart
Where does the pulmonary vein take blood? (Only vein that takes oxygenated blood)
Towards the heart
How does pulmonary circulation differ from systemic circulation?
Opposite in function - It delivers CO2 to the lungs and picks up O2
What changes occur in the respiratory system and cardiovascular system when E demand increases by working muscle?
Respiratory - Rate & Depth of Breathing.
Speeds up: - Substrate (O2) acquisition - Waste disposal (CO2) Cardiovascular- Heart Rate & Force of Contraction.
Speeds up: - Substrate delivery to muscle via blood - Waste removal via blood
What is the movement of O2 during gas exchange?
O2 moves from inspired air to blood (at lungs) O2 moves from blood to cells (at the systemic capillaries)
What is the movement of CO2 during gas exchange?
CO2 moves from blood to air which is then expired (at Lungs) CO2 moves from cells to blood (at the systemic capillaries)
What is the relationship between the volume of oxygen exchanged in the lungs per unit time and that of the net volume exchanged in the tissues
EQUAL Same applies for carbon dioxide
What is the purpose of this equal exchange between the lungs and the tissues?
This prevents gas build up in the circulation which would hamper gas exchange. Helps to ensure supply = demand
What are the average volumes exchanged per minute?
250 ml oxygen exchanged (consumed) 200 ml carbon dioxide exchanged (produced)
What are breathing rates at rest? And maximum breathing rate?
Breathing rate is 10-20 breaths/min at rest, 40 - 45 at maximum exercise in adults
What portion of the respiratory system is shared with the digestive system?
The pharynx - From your nose, oxygen moves into the pharynx or throat
What helpful roles does the nose have in the respiratory system?
Air enters the body through nose. Cilia and mucus trap particles Warms and moistens air
What is the function of trachea?
Transports oxygen from the pharynx to the lungs
What protective structural component exists in the trachea?
Stiff rings of cartilage - supports and protects
What are lungs spongy?
Lots of hollow sacs that compose them
What is the function of the epiglottis?
Small flap where tissue folds over the trachea and prevents food from entering it when you swallow It is mostly open, closes on swallowing
What is the function of the larynx?
Contains vocal cords - vibrate to produce sound
What is the bronchus?
Where the trachea bifurcates (at sternal angle), air moves from trachea to bronchus which lead to the inside of the lung.
Where is the lower respiratory system enclosed?
In the thorax, bounded by the ribs, spine and the diaphram
What body structures are found in the upper respiratory system?
Pharynx, Vocal Cords, Esophagus, Nasal Cavity, Tongue, Larynx
What body structures are found in the lower respiratory system?
Right lung, Left lung, Left brochus and right bronchus, diaphragm
Where do the lungs sit?
In the pleural cavity - contains 3 ml of fluid
How much does each bronchi branch?
22 times, before finally terminating in a cluster of alveoli
Which primary bronchi is wider?
The right primary bronchi - more aspirated foreign bodies lodge here
What maintains patency (open) in the airways?
C - shaped rings of cartilage
What doesn’t contain C - shaped rings of cartilage?
Bronchioles
What maintains patency in the bronchioles?
Physical forces in the thorax
What happens to airway diameter as you go down the respiratory tree?
Decreases
Where does greatest resistance to air flow occur?
Upper respiratory tract (conducting zone), contains lots more molecules Branching increases surface area
What is the effect of contraction on resistance?
Contraction decreases diameter = increases resistance Relaxation increases diameter = decreases resistance
What controls airway diameter, and therefore resistance to airflow?
Activity of bronchial smooth muscle
What is each cluster of alveoli surrounded by?
Elastic fibres and a network of capillaries
What are the functions of the elastic fibers?
Stretch during inspiration, they release this stretch energy on exhalation (contraction)
What type of cells exist in the alveoli?
Type 1 cells - gas exchange Type 2 cells - produce surfactant Capillaries exist between the alveoli - direct contact with type one cells - minimises distance Alveolar macrophages ingest foreign material that reaches alveolli
Where is gas exchange possible?
Only at the alveoli - very thin walls
What is the function of conducting airways?
The walls of the upper airways are too thick to allow gases to cross and their function is purely conduction of air to and from the alveoli (the air in these airways is known as anatomical dead space because it cannot participate in gas exchange).
What is the function of huge surface area of the alveoli?
The huge surface area of the alveoli further enhances their gas exchange function.
What lines the respiratory tract?
Epithelium (psuedo-stratified, ciliated, columnar) Glands Lymph nodes Blood vessels (nutritive) Ciliated Mucous
What is the progression from the nose to alveoli?
Epithelium becomes more squamous Cilia lost Mucous cells lost (before cilia) Goblet cells lost before cilia, cilia are the last thing to be lost
What is the function of mucous?
Moistens air Traps particles Provides large surface area for cilia to act on
What cells are associated with mucous?
Goblet cells Subepithelial glands
What is the movement of macrophages from the alveoli?
Macrophages escape to pharynx/lymph nodes
What is another word for
Pneumocytes - rich capillary network
Describe type 1 Pneumocytes
Pneumocytes - 97% alveolar surface Simple squamous epithelium Gas exchange
Describe type 2 Pneumocytes
Surfactant production Phospholipids and protein Reduces surface tension at alveolar surface Reduces work of breathing
