1. Introduction and Anatomy of Lungs, Airways and Blood Supply Flashcards
What are the 4 functions of the respiratory system?
- Gas exchange
- Acid base balance
- Protection from infection
- Communication via speech
How is energy produced by gas exchange?
Oxygen is burned and energy is released, producing carbon dioxide as a waste product
What is the respiratory system responsible for?
- Acquiring oxygen
- Removing carbon dioxide
What is the cardiovascular system responsible for?
- Transporting oxygen to tissues
- Transporting carbon dioxide away from tissues
What is external respiration?
Integration of respiratory and cardiovascular systems allowing the movement of gases between the air and the body’s cells
Pulmonary artery
Travels AWAY from the heart
Pulmonary vein
Travels TOWARDS the heart
How does pulmonary circulation differ from systemic circulation?
- Opposite in function
- It delivers carbon dioxide to the lungs and picks up oxygen
What does an increase in energy demand by working muscles lead to?
- Increase in rate and depth of breathing
- Increase in heart rate and force of contraction
What does an increase in rate and depth of breathing speed up?
- Substrate (O2) acquisition
- Waste disposal (CO2)
What does an increase in heart rate and force of contraction speed up?
- Substrate delivery to muscle via blood
- Waste removal via blood
Where does gas exchange occur?
- Lungs
- Systemic capillaries
Describe gas exchange at the lungs.
- O2 moves from inspired air to blood
- CO2 moves from blood to air which is then expired
Describe gas exchange at the systemic capillaries.
- O2 moves from blood to cells
- CO2 moves from cells to blood
How is gas build up in the circulation prevented?
In steady state:
net volume of oxygen exchanged in the lungs per unit time = net volume exchanged in the tissues.
-The same applies for carbon dioxide
What does a gas build up in the circulation result in?
Hampered gas exchange
What are the average volumes of oxygen and carbon dioxide exchanged per minute?
- 250ml oxygen consumed
- 200ml carbon dioxide produced
What are the average breathing rates of adults?
- At rest 10-20 breaths/min
- At maximum exercise 40-45 breaths/min
What physical structures form the respiratory system?
- Nose
- Pharynx
- Epiglottis
- Larynx
- Trachea
- Bronchus
- Lungs
What occurs at the nose in relation to gas exchange?
Air enters the body via the nose where cilia and mucus trap particles and warm and moisten the air
What happens to air after entering the nose?
From the nose, air moves down into the pharynx or throat, which is shared with the digestive system
What does the epiglottis do?
The small flap of tissue folds over the trachea and prevents food from entering it when you swallow
What is the trachea made up of?
Stiff rings of cartilage that support and protect it
Where does air pass through after the pharynx?
Trachea
What does the larynx contain?
Vocal chords which vibrate to produce sound
What is the soft spongy texture of the lungs due to?
The many thousands of tiny hollow sacs that compose them
What happens to air after it passes through the trachea?
It moves into the right and left bronchi which lead inside the lungs
Where does air from the trachea flow to?
Into the left and right bronchi which lead inside the lungs
What are the two components of the respiratory system?
- Upper respiratory system
- Lower respiratory system
What is the upper respiratory system composed of?
- Mouth
- Nasal cavity
- Pharynx
- Larynx
What is the lower respiratory system composed of?
- Trachea
- Bronchi
- Lungs
What is the lower respiratory system enclosed in?
-The thorax, bounded by the ribs, spine and diaphragm
Where are aspirated foreign bodies commonly lodged?
The right bronchi
How is the patency of the airway maintained?
By the C shaped rings of cartilage
What is the point of gas exchange?
Alveoli
How is patency maintained in the bronchioles where there is no cartilage rings?
By physical forces in thorax
How can airway diameter and resistance to airflow be altered?
By activity of bronchial smooth muscle
What does contraction of bronchial smooth muscle result in?
Decrease in diameter = increase in resistance
What does relaxation of bronchial smooth muscle result in?
Increases diameter = Decrease in resistance
Where does most resistance to air flow occur?
Trachea and bronchi
What makes up the respiratory zone?
Bronchioles and Alveoli
What makes up the contraction zone?
Trachea and bronchi
What is each cluster of alveoli surrounded by?
Elastic fibres and a network of capillaries
What are alveoli composed of?
- Type I cells for gas exchange
- Type II cells that synthesise surfactant
What do alveolar macrophages do?
Ingest foreign material that reach the alveoli
Why does gas exchange only occur at the alveoli?
- They have very thin walls
- The walls of the upper airways are too thick
What is air in the airways known as and why?
- Anatomical dead space
- It cannot participate in gas exchange
What feature of the alveoli enhances gas exchange?
Their huge surface area
What lines the respiratory tract?
- Epithelium (pseudo-stratified, ciliated, columnar)
- Glands
- Lymph nodes
- Blood vessels
- Ciliated
- Mucous
Describe the progression from nose to alveoli.
- Epithelium becomes more squamous
- Cilia lost
- Mucous cells lost ( before cilia)
What does the mucous do?
- Moistens air
- Traps particles
- Provides large surface area for cilia to act on
Where do alveoli macrophages escape to?
Pharynx and lymph nodes
Describe Type I pneumocytes.
- 97% alveolar surface
- Simple squamous epithelium
- Gas exchange
Describe type II pneumocytes.
- Produce surfactant
- Phospholipids and protein
- Reduces surface tension at alveolar surface
- Reduces work of breathing
