Introduction and Anatomy Flashcards
Explain the functions of the respiratory system
Gas exchange
Acid base balance
Protection from infection (URT has lymphatic tissue which scans for pathogens and can initiate a response. Cilia and mucous prevent pathogens getting into LRT)
Communication via speech (air moves across vocal cords - learn to control on expiration as develop)
Explain the importance of gas exchange
Cellular respiration: burn O2 to release energy and acquire CO2 (toxic waste product).
Explain how the cardiovascular and respiratory systems are both involved in gas exchange
The respiratory system acquires O2 and removes CO2 via gas exchange.
The cardiovascular system transports oxygen to tissues from the lungs and transports CO2 away from tissues to the lungs.
This process is called external respiration.
What is external respiration?
The movement of gases between the air and body cells
Explain the process of external respiration
Gas exchange occurs in the lungs.
O2 moves from inspired air to the blood in the lungs
CO2 moves from the blood to air which is expired.
The pulmonary artery travels AWAY from the heart to the lungs and carries deoxygenated blood to the lungs containing CO2.
The pulmonary vein travels from the lungs TOWARDS the heart and carries oxygenated blood away from the lungs.
Oxygen is then taken around the body via systemic circulation.
Via systemic capillaries, O2 is taken up by cells and CO2 is removed from cells.
Explain how the cardiovascular and respiratory systems are integrated in terms of increased energy demand by working muscle.
Increased energy demand by working muscle leads to: RESPIRATORY: Increased rate of depth of breathing Substrate (O2) acquisition Waste (CO2) disposal
CARDIOVASCULAR:
Increased heart rate and contraction force
Substrate delivery to muscle via blood
Waste removal via blood
In a steady state, how is the net volume of oxygen in the lungs exchanged per unit time proportional to to net volume exchanged in tissues?
Equal.
Same applies for CO2.
Why is it important that in a steady state, the net volume of a specific gas exchanges per unit time is equal to the net volume exchanged in tissues?
Prevents build up of CO2 or O2 in circulation which would inhibit gas exchange.
Ensures demand = supply.
State the average volumes of gas exchanged per minute.
250ml of oxygen is consumed
200ml of carbon dioxide is produced
What is the average breathing rate at rest?
10-20 breaths per minute
What is the breathing rate at maximum exercise in adults?
40-45 breaths per minute
Describe the function of the mouth and nose.
Air enters the URT via the mouth and nose.
The nose has a bigger surface area to volume ratio than the mouth so air dries out less easily.
The nose starts off the process of making air SATURATED and MOIST (this is needed for gas exchange to occur). (This process id continued by the respiratory tree).
The nose also scans the air with lymphoid tissue and mucus and cilia prevent pathogens going further down the respiratory tree.
Describe the function of the pharynx
Where air travels after the nose.
Pharynx is shared with GI tract
Briefly describe the structure and function of the larynx
Contains vocal cords that vibrate to produce sound
Describe the structure and function of the trachea
Transports air from larynx to bronchi.
Supported by incomplete rings of cartilage.
Bifurcates into bronchi at sternal notch.
List the organs of the URT
Nasal cavity
Mouth
Pharynx
Layrnx
List the organs of the LRT
Trachea
Bronchi
Lungs
Describe the structure of the right lung in terms of lobes, fissures and secondary bronchi
3 LOBES: superior, middle and inferior
FISSURES: superior and middle lobes separated by horizontal fissure, middle and inferior lobes separated by oblique fissure
3 SECONDARY BRONCHI: one for each lobe
Describe the structure of the left lung in terms of lobes, fissures and bronchi
2 LOBES - superior and inferior
FISSURES: lobes separated by horizontal fissure
2 SECONDARY BRONCHI
Describe the difference in structure between the right and left bronchi and its clinical consequences
The RIGHT main bronchus is more vertical than the LEFT.
This means aspirated foreign bodies commonly lodge here
Describe the branching of the respiratory tree
Trachea 2 primary bronchi (1 per lung) Secondary bronchi (3 in right lung, 2 in left lung) Bronchioles Alveoli
State how patency is maintained in the trachea
Potency maintained by C shaped rings of cartilage
State how patency is maintained in the primary and secondary bronchioles
Cartilage rings
State how patency is maintained in the bronchioles
Physical forces in the thorax
State the function of the alveoli
Gas exchange
After the trachea branches into bronchi, how many more times do the bronchi branch until the alveoli are reached?
22 times
State the relationship between airway diameter and branching
As branching increases, airway diameter decreases.
Describe the relationship between airway diameter and resistance to airflow
As diameter increases, resistance to airflow decreases.
HOWEVER, most resistance to airflow occurs in the UPPER airways because there are many bronchioles, meaning that the surface area of the bronchioles is much greater than that of the trachea. Therefore there is much more congestion of air in the trachea, as many small molecules are feeding into one large airway, whereas in the bronchioles, a few small molecules are feeding into many small airways.
Describe the structure of alveoli
Alveoli are contained in lung lobules
Each alveoli is surrounded by elastic fibres and a capillary network
Thin walls
Macrophages (gather residual dirt and escape to pharynx or lymph nodes)
Describe the two types of cells (pneumocytes) in alveoli
Type 1 cells:
gas exchange (always directed abutted to capillaries)
97% of alveolar surface
Simple squamous epithelium
Type 2 cells:
surfactant production
Why do elastic fibres never separate an alveolus from its capillaries?
So there is no barrier for gas exchange
Describe the function of the elastic fibres surrounding each alveolus.
When elastic fibres recoil, the alveoli contract. This is a passive process as no energy is needed since the energy has been invested in stretching the elastic on inspiration.
Why can gas exchange no take place further up the respiratory tree?
What is this space called and what is its function?
The walls are too thick - only alveoli have thin enough walls.
The upper airways are referred to as the anatomical dead space. Function: air conduction only.
List the components of the lining of the respiratory tract
Epithelium Glands Lymph nodes NUTRITIVE blood vessels Cilia Mucous producing goblet cells
What happens to the epithelium as you move down the respiratory tree?
Becomes more squamous
Mucous cells lost (before cilia)
Cilia lost
State where mucous is produced and its function.
Produced in sub epithelial glands and goblet cells.
Function: moistens air and traps particles, providing a large surface area for cilia to act on.
