Respiratory Anatomy Flashcards
External respiration
Oxygen is absorbed from atmosphere into blood within pulmonary capillaries
Carbon dioxide secreted
Internal respiration
Exchange of gases between blood in systemic capillaries
Cellular respiration
Individual cells gain energy by breaking down molecules in mitochondria, consuming oxygen and generating carbon dioxide
Pulmonary ventilation
Bulk movement of air into and out of lungs
Ventilatory pump
Rib cage + associated muscles + diaphragm
Conducting part of respiratory system
Series of cavities and thick walled tubes which conduct air between the nose and the lungs
Nasal cavities + Pharynx + Larynx + Trachea + Bronchi + Bronchioles
Respiratory part of respiratory system
Tiny thin walled airways where gases are exchanged between air and blood
Respiratory bronchioles + Alveolar ducts + Alveolar sacs + Alveoli
Gas exchange location
Respiratory part of the respiratory system
Surface area of alveoli
75m2 (3/4 tennis court)
Upper respiratory tract
Nasal cavity to larynx
Lower respiratory tract
Trachea to bronchus to bronchioles to alveoli
Filtration location
Vibrissae (nasal hairs)
Mucociliary escalator
Warming location
Capillary network in nasal cavity underneath epithelium
Humidifying location
Nasal cavity covered in mucus membrane
Conchae
Bony projections that increase surface area of the mucus membrane in the nasal cavity and mix and slow down inhaled air
Air pathway from nose to trachea
Nose to nasopharynx Nasopharynx to oropharynx Oropharynx to laryngopharynx Laryngopharynx to glottis Glottis to trachae
Food pathway from mouth to oesophagus
Mouth to soft palate Soft palate closes nasopharynx Soft palate to oropharynx Oropharynx to laryngopharynx Epiglottis closes glottis Oesophagus forced open Laryngopharynx to oesophagus
Number of respiratory generations
28
Conducting zone structures
Trachea Main stem bronchi Lobar bronchi Segmental bronchi Smaller bronchi Bronchioles Terminal bronchioles
Respiratory zone structures
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Lobes in lobar bronchi
3 lobes on the right
2 lobes on the left
Describe the trachea
12cm long tube as thick as a thumb
Supported by incomplete C shaped rings of cartilage
Free ends of cartilage connected by smooth trachealis muscle
Lined with ciliated pseudostratified columnar epithelium
Cilia transport mucus sheet up towards nasopharynx
Anterior to oesophagus
Describe the bronchus wall
Pseudostratified ciliated columnar epithelium and goblet cells lined with mucus Smooth muscle Mucus glands Cartilage plates Alveolus
2 sources of mucus
Goblet cells and mucus glands
Describe the bronchiole wall
Simple ciliated columnar epithelium and club cells lined with watery secretion
Smooth muscle
Alveolus
Role of smooth muscle
Controls air flow by constriction and relaxation
Pathological cause of asthma
Over-constriction of smooth muscle in the bronchi and bronchioles restricting air flow and requiring bronchodilators to relax
Role of cartilage plates
Keep bronchi open - cartilage plates are not prone to collapse
Bronchi more rigid than bronchioles because of presence of cartilage plates
Club cells
Found between epithelial cells in bronchiole walls and secrete a non-mucus watery secretion to keep cells hydrated and air moist
Goblet cells
Found between epithelial cells in bronchus walls and secrete mucus
Cells in alveolar walls
Red blood cells (in pulmonary capillary) Endothelial cells (in pulmonary capillary) Squamous pneumocytes (type I cells) Alveolar macrophages Surfactant cells (type II cells)
Role of surfactant
Liquid lining reduces the work of breathing by reducing surface tension in alveoli and stopping alveoli completely collapsing
Role of surfactant cells
To secrete surfactant
Role of squamous pneumocytes
Very thin trails of cytoplasm in each cell surrounding an area of an alveoli which minimises diffusion distance for gas exchange
Role of alveolar macrophages
Act as normal macrophages to engulf pathogens and foreign particles
Last line of defence if air is contaminated
Describe the diffusion barrier in alveoli
Squamous pneumocyte adjacent to alveolar air space
Capillary endothelium adjacent to blood plasma
Basement membranes of squamous pneumocytes and capillary endothelium fused to reduce diffusion distance
Primary bronchi
Right and left main stem bronchi supplying each lung
Secondary bronchi
Lobar bronchi supplying lobes (3 on the right and 2 on the left)
Tertiary bronchi
Segmental bronchi supplying segments of the lung (10 on the right and 8 on the left)
Each segment has its own air and blood supply
Describe the pleurae
Smooth double layered membrane that covers each lung and lines the thoracic cavity
Two pleurae are continuous at the root of the lung (hilum)
Separated by thin film of fluid that allows pleurae to slide past each other without friction
Fluid also prevents complete separation of the pleurae
Describe movement of the ribs during ventilation
Ribcage movement responsible for 25% air movement into and out of the lungs
Active inspiration requires contraction of external intercostal muscles which run obliquely between ribs
Passive expiration doesn’t require muscular action. The ribcage relaxes back to its resting position
During exercise, both sets of intercostal muscles become active and both inspiration and expiration require muscular action
Describe how the ribs increase the volume of the thorax
Ribs pivot around their joints with the vertebral column. Contraction of the external intercostal muscles lifts the ribs and rotates them around their pivot points. The ribs lift and swing upwards and outwards, increasing the volume of the thorax and allowing air in. The internal intercostal muscles run at right angles to the external intercostal muscles and when they contract they drag the ribs downwards - only for forceful exhalation.
Describe movement of the diaphragm during ventilation
Diaphragmatic muscle contracts which flattens the diaphragm and pulls the central dome down, increasing the volume of the thorax and causing inspiration. Passive relaxation of the muscle lifts the diaphragm back up towards the thorax reducing the volume and causing expiration.
Responsible for 75% of bulk flow of air during quiet breathing.
Describe the diaphragm
The diaphragm is a dome shaped platform that forms the floor of the thorax and the roof of the abdomen. Its central part is a thin sheet of connective tissue (aponeurosis) called the central tendon. The lateral margins are fast acting skeletal muscle innervated by the phrenic nerve.
