An Overview and The Upper Respiratory Tract Flashcards
What is the role of the respiratory system?
Connected organs and structure that function to conduct clean, warm and moist air in close proximity with the circulatory system’s blood for gas exchange
What does the respiratory system need to be effective?
- A surface for gas exchange
- blood and air brought close together but separated - A path or air to flow to reach the gas exchange surface in optimal condition
- Ability to draw breath in and out (repetitively)
- Plus: sound production and olfaction (smell)
What are the main components of the respiratory system?
- upper respiratory tract (URT) (nose to pharynx)
- lower respiratory tract (LRT) (larynx to alveoli)
- plus:
- thoracic cavity
- joints
- respiratory muscles
What are the zones of the upper respiratory system?
Respiratory zone:
- Bronchioles to alveoli
- Sites for gas exchange
Conducting zone:
- nose to brachioles
- ensure air is warm, clean and moist
Conducting zone branches into two sections, the nasal cavity (olfaction - only air passes through here) and the oral cavity (food and air)
Describe the epithelia in the respiratory system
Tract lined with mucosa (mucous producing layer): epithelium attached via basement membrane to lamina propria (the underlying layer of connective tissue that holds the basement membrane down).
Epithelium changes along length of tract to reflect function.
- Most of the conducting region:
- Respiratory epithelium
- Where air and food travel:
- stratified squamous
- Site of gas exchange:
- simple squamous
- Olfaction:
- olfactory mucosa
Describe a brief overview of the histological structures
Most body organs are lined with mucosa:
- epithelia
- attached via a basement membrane
- to the lamina propria
- connective tissue
- may contain glands
Below this is usually a submucosal layer
- more connective tissue
- depending on the region, may contain many glands
Describe the respiratory epithelium
Actual name is Pseudostratified ciliated columnar epithelium (with goblet cells).
- found in the nasal cavity, part of pharynx, larynx, trachea and bronchi
- Is produced by stem cells called basal cells as they need to be regenerated. They are also directly attached to the basement membrane.
Goblet cells produce mucus - traps debris, moistens air
Ciliated cells - patterned movement pushes mucus towards the pharynx
- swallowed and digested by stomach acid
What are the components and functions of the URT?
- nose and nasal cavity
- paranasal sinuses (more of an accessory structure)
- pharynx
- nasopharynx
- orophrynx- laryngopharynx
Functions:
Conducting passage
- prepares air for respiratory membrane (gas exchange)
- warm, clean, moist
- paranasal sinuses - resonating chambers for speech
- olfaction - sensory receptors for smell
Describe the nose
- primary passageway for air
- cartilages
- soft, flexible
- maintain patent (unobstructed) airway
- nostrils
- external nares
- vestibule (passageway) lined with skin
- has sebaceous and sweat glands, hair follicles
- vibrissae (hairs) filter inhaled air
Note: patent means always open
Describe the bones of the nasal cavity
- nasal septum in midline
- anterior - cartilage
- posterior - bone
- internal nares open into nasal pharynx
- roof of cavity formed by two types of bones
- floor of cavity formed by hard and soft palates
- conchae on lateral walls
Describe the conchae
- three projections
- superior, middle and inferior conchae (turbinates - called this because they spin air around so it can be cleansed)
- covered by respiratory epithelium
- swirl inspired air
- particles stick to mucosa
- more time for warming and humidifying or air, plus olfactory detection
Describe the nasal epithelium
- Nasal cavity
- mostly respiratory epithelium
- plus, specialised area of olfactory epithelium
- area on roof of nasal cavity, contains smell (olfactory) receptors
Note: nasal epithelium and respiratory epithelium are NOT the same
Describe nasal mucosa
- Epithelium sits on lamina propria
- Thin-walled vascular plexus
- Helps warm incoming air
- When air temp drops, plexus dilates = greater heat transfer
- nose bleeds normally originate from damage here as capillaries are very close to the surface
Describe paranasal sinuses as well as their functions
- Sinus = cavity within a bone (normally air filled)
- paranasal = surrounding the nose
- found within four types of bones
- lined with respiratory mucosa
- drain into pharynx
Functions:
- lighten skull (by balancing air pressure in head and outside)
- increased surface area to clean, warm and moisten air
- sound resonance
- infected mucus can block drainage = blocked sinuses
Describe the pharynx
- commonly called the throat
- muscular funnel-shaped tube shared by respirator and digestive system
- three regions
- nasopharynx (air passage ONLY)
- oropharnynx
- laryngopharynx
