Respiratory System 1 Flashcards
Describe the primary functions of the respiratory system
Provides extensive gas exchange surface area between air and circulating blood
Moves air to and from exchange surfaces of lungs
Protects respiratory surfaces from outside environment
Produces sounds
Participates in olfactory sense (sense of smell)
Describe the organisation of the respiratory system
Upper respiratory system = Conducting portion (tubes that conduct down to the respiratory system)
- Nose
- Pharynx
Lower respiratory system = Conducting portion (tubes that conduct down to the respiratory system)
- Larynx (voice box)
- Trachea (windpipe)
- Bronchi → larger bronchioles → terminal bronchioles
Lower respiratory system = Respiratory portion
- Smaller (respiratory bronchioles)
- Alveoli
Understand the importance of respiratory defence mechanisms
Nasal hairs
- Particle filtration system → part of respiratory defence system
Respiratory Epithelium
- Pseudostratified columnar epithelium
- Similar to nasal cavity & nasopharynx
- Mucous cells + mucous glands in lamina propria
- Cilia on epithelial cells
- Mucus layer traps pathogens, preventing them to reach the lungs
Structure and function of Nose
Upper Respiratory Tract
Three main functions
- Warming, moistening and filtering air
- Olfaction
- Modifying speech vibrations
Air enters the respiratory system
- Through nostrils
- Into nasal vestibule
Nasal hairs
- Particle filtration system → part of respiratory defence system
Structure and function of Pharynx
Also referred to as throat
Chamber shared by digestive & respiratory systems (air & food)
Divided into:
Nasopharynx (superior)
- Contains tonsils (has a lot of immune cells, bacteria gets forced to tonsils so cannot travel down to the respiratory system)
- Exchanges air with eustachian tubes
- Equalises air pressure across the eardrum
Oropharynx (middle) (mouth)
- Communicates with oral cavity
Laryngopharynx (inferior)
- Extends from hyoid bone to entrance of larynx and esophagus
Structure and function of Trachea
Lower Respiratory Tract
- Trachea (windpipe)
- Anterior to oesophagus
- C-shaped cartilage rings provide support
- Prevents tracheal wall collapsing during inhalation
- Allows passage of food through oesophagus (soft posterior wall)
- Oesophagus push in the trachea and C-shaped rings to allow to swallow big foods - Extends into mediastinum where it branches into right and left pulmonary bronchi (singular=bronchus)
Structure and function of Bronchi
Lower Respiratory Tract
- Bronchial Tree → 23 generations → progressively smaller
Primary Bronchus
- Branches to form secondary bronchi (lobar bronchi)
One secondary bronchus goes to each lobe
Secondary Bronchi
- Travelling down it will not be C-shaped but will be segmental bronchi
- Branch to form tertiary bronchi, also called the segmental bronchi
- Each segmental bronchus supplies air to a single bronchopulmonary segment (~ 10 per lung)
Structure and function of Bronchioles
Small airways/Dynamic Airways
Trachea & primary bronchi: fairly rigid, nonmuscular tubes
However, bronchioles:
- No cartilage
- But has huge amount of smooth muscle innervated by ANS & stimulated by circulating adrenaline (has receptors)
- More Parasympathetic innovation → bronchoconstriction
- Sympathetic & Adrenaline → bronchial dilation (dilate airways to increase the flow or airways into lungs = increase oxygen) - Sensitive to local chemicals (e.g. O2 & CO2) (Decrease CO2 = constrict) (Increase CO2 = dilate)
- Dynamic → significant capacity to change diameter (affects airflow)
- Important in disease (e.g. asthma)
Structure and function of Alveoli
Cup-shaped pouch
Alveolar Type I cells
- Simple squamous epithelial cells
- Predominant
- Long cytoplasmic extensions
- Site of gas exchange
Alveolar Type II cells
- Cubodial epithelial cells
- Has a lot of Microvilli
- Secrete pulmonary surfactant which reduces surface tension
Alveolar macrophages
- Wandering phagocytes that remove dust and debris
Understand the dynamic nature of the bronchioles
Dynamic Airways
Trachea & primary bronchi: fairly rigid, nonmuscular tubes
However, bronchioles:
- No cartilage
- But has huge amount of smooth muscle innervated by ANS & stimulated by circulating adrenaline (has receptors)
- More Parasympathetic innovation → bronchoconstriction
- Sympathetic & Adrenaline → bronchial dilation (dilate airways to increase the flow or airways into lungs = increase oxygen) - Sensitive to local chemicals (e.g. O2 & CO2) (Decrease CO2 = constrict) (Increase CO2 = dilate)
- Dynamic → significant capacity to change diameter (affects airflow)
- Important in disease (e.g. asthma)
Describe the blood supply to the lung
- Each lobule receives an arteriole and a venule
- Respiratory exchange surfaces receive blood from arteries of pulmonary circuit
- A capillary network surrounds each alveolus (as part of the respiratory membrane)
- Blood from alveolar capillaries
- Passes through pulmonary venules and veins
- Returns to left atrium
Describe the structure of the pleural cavities & membranes
- Pleural membranes help lungs to stay open and inflated and have lungs follow the thoracic cavity
- Mediastinum separates the thoracic cavity into two distinct compartments (right and left compartment)
- Pleural membranes enclose each lung
Parietal pleura
- Outer layer attached to wall of thoracic cavity
Visceral pleura
- Inner layer covering surface of lung
Pleural cavity
- Contains lubricating fluid secreted by membranes
- High cohesive forces
- Covering surface of the lungs
Describe the three processes of respiration
Pulmonary ventilation (breathing) - Physical movement of air into and out of the respiratory tract
External respiration
- Includes all processes involved in exchanging O2 and - - CO2 with the interstitial fluids and external environment
Internal respiration (eg Glygolosis, Krebs cycle)
- Also called cellular respiration
- Involves the uptake of O2 and production of CO2 within individual cells
Role of the C-shaped cartilage in the trachea
C-shaped cartilage rings
- Provide support
- Prevents tracheal wall collapsing during inhalation
- Allows passage of food through oesophagus (soft posterior wall)
- Oesophagus push in the trachea and C-shaped rings to allow to swallow big foods
Roles of the cells of the respiratory zone
Nasal hairs
- Particle filtration system → part of respiratory defence system
Respiratory Epithelium
- Pseudostratified columnar epithelium
- Similar to nasal cavity & nasopharynx
- Mucous cells + mucous glands in lamina propria
- Cilia on epithelial cells
- Mucus layer traps pathogens, preventing them to reach the lungs
