Tag (respiratory system) Flashcards
Functions of the respiratory system
Gas exchange- O2, CO2
Acid base balance- right balance of acid and basic compounds
Phonation (producing sounds)
Pulmonary defences and metabolisms
Heat and water elimination
Anatomy of the respiratory system
Pharynx
Larynx
Trachea
Bronchi (left and right)
Bronchi
Bronchioles
Alveoli
Right upper and lower lobe
Left upper and lower lobe
Diaphragm
Thoracic cavity
Upper airways of the respiratory system
Nose and mouth- warm, humid, traps foreign bodies, provide mucus.
It is better to breathe in through the nose as it gives the air and change to be warmer and moisturised.
Pharynx- common passageways of food and air for the respiratory and digestive system
Lower airways of the respiratory system
Bronchial tubes
Bronchioles
Alveolar ducts
Alveolar sacs
Diffusion membranes
Alveoli do not regenerate so once we have lost them they are lost forever.
Functional cells in the lungs
Pneumocyte type I: simple squamous epithelium where diffusion takes place. Very thin to reduce gap between blood wall cells and alveoli- reduces diffusion distance.
Pneumocyte type II: secretory cells, secrete mucus. Mucus needed to keep the lungs moist- cannot have gas exchange in a dry medium. It also traps foreign bodies.
Dust cells: macrophages
Alveoli
300 million per lung.
Site of gas exchange.
rich blood supply.
In contact with blood capillaries.
Three types:
- Type 1 alveolar cells: single layer of epithelial cells, make up the wall of alveoli
- Type 2: secrete surfactant, reduce surface tension in alveolar walls, prevent alveolar collapse
- Alveolar macrophages: remove foreign particles from the lungs
Chest wall and pleural sac
Chest wall- houses the lungs and other organs
Pleural sac- two layered membranous sac, found around each lung, attached to the chest, parietal pleura, visceral pleura, intrapleural space contains 15ml of fluid to prevent collapse of the lungs
Ventilation
Inspiration (active)
Expiration (passive)
Pressure changes during breathing
Gases in a closed container follow Boyle’s law (Pressure inversely proportional to Volume). P1V1 = P2V2
Three different pressures are involved in the ventilation.
1- Intrapulmonary pressure
2- Atmospheric pressure
3- Intrapleural pressure (negative)
When a sharp object punctures the intrapleural membranes, air is introduced into the space in-between the visceral and costal membranes (intrapleural pressure = 0)
This leads to end of negative intrapleural pressure, chest wall springs out and the lungs collapse
Muscles involved in ventilation
External intercostal muscles.
Internal intercostal muscles.
Diaphragm.
Inspiration
The external intercostal muscles contract pulling the rib cage upwards and outwards and the diaphragm contracts moving downwards. This increases the volume of the chest cavity. The pressure of the chest cavity decreases which creates a pressure gradient. Air flows into the lungs down the gradient. The alveoli are filled with air containing O2 which diffuses into blood vessels through alveolar walls. At the same time CO2 diffuses from blood vessels into alveoli.
Expiration
The external intercostal muscles relax allowing the rib cage to move downwards and inwards and the diaphragm relates moving upwards. This decreases the chest cavity which increases the pressure. The air flows out of the lungs down the pressure gradient and CO2 is removed.
In forced expiration internal intercostal muscles contract and the abdominal muscles push further decreasing the volume of the thoracic cavity and more air is removed.
Ventilation and respiration
Ventilation- moving air in and out of the lungs
Respiration- gas exchange through coordination of respiratory system and circulatory system
External respiration- exchange of O2 and CO2 between the external environment and tissues
- O2 in: air to lungs to blood to tissues
- CO2 out: tissues to blood to lungs to air
Cellular respiration- metabolism of nutrients in the cells using O2 and releasing waste CO2
Air conduction
Air is conducting from out environment to the lungs as the air is moistened, warmed and filtered as it moves from the nasal passages to the bronchioles (conducting zone).
Then gas exchange between alveoli and blood begins from bronchioles to alveoli (the respiratory zone)
Conducting zone structure
Trachea
Bronchi
Secondary bronchi
3 lobes of right lung
2 lobes of left lung
Tertiary bronchi
Branching
Millions of tubules
Bronchioles
Walls of elastic fibre
Terminal bronchioles
The conducting zone function
Goblet cells- secrete mucus and trap any foreign bodies entering the system.
Ciliated cells- push the mucus up and help in the swallowing process.
The conducting zone is 150ml in volume.
The functions:
- air passageway
- dead space volume
- control air temperature and humidity
Structures of the respiratory zone
Respiratory membrane
Alveoli epithelial cells
Capillary endothelial cells
Methods of respiration
Cellular respiration (internal respiration)
- metabolic processes (inside the mitochondria)
- uses O2 and produces CO2 while making energy
- forms nutrient molecules
External respiration (pulmonary ventilation)
- movement of O2 in and CO2 out of lungs
- exchange (diffusion) O2 and CO2 between the alveoli and blood pulmonary capillaries
- transportation and exchange of O2 and CO2 between the lungs and the tissues
The respiratory membrane
0.2 micrometers thick
Barrier for diffusion
Alveoli (type 1 cells and basement membrane)
Capillaries (endothelial cells basement membrane)
Oxygen transport
External respiration
- exchange of gases between air in alveolus and blood
- exchange of gases between blood and tissues
- partial pressures of gases determine rate and amount
Haemoglobin
- heme- red chromophore bing O2 at Fe
- globin protein- 2 alpha chains and 2 beta chains
Fe bonds
- 4 to heme
- 1 to globin
- 1 weak reversible bond to O2 (if it was irreversible it would not be delivered to cells)
Carbon dioxide transport
3 ways CO2 is transported from the tissue to the lungs
- dissolved in solution (plasma shifted by chloride)
- buffered with water as carbonic acid
- bound to haemoglobin forming carbaminohemoglobin
75% of CO2 is transported in the RBCs and 25% in the plasma.
Pulmonary gas exchange
The rate of gas exchange depends on the partial pressure differences. As ppCO2 is higher in the capillaries than in the alveoli, it diffuses into the alveoli where it is exhaled.
The ventilation/perfusion ratio ensures that alveoli receives the ideal amount of blood gas for efficient gas exchange.
Respiratory control
Respiration is controlled by the brain medullary inspiratory centre which generates nerve impulses which stimulate contraction of the diaphragm and external intercostal muscles.
The inspiratory centre facilitates expiration by stimulating the internal intercostal muscles and abdominal muscles.
The pneumotaxic area inhibits the inspiratory centre preventing inspiratory muscles contraction and protecting the lungs from over-inflating.
The apneustic area stimulates the inspiratory centre and extending the inspiratory muscles contraction.
Lung volume and capacity
Lung volume is measured by the Spirometer. It includes the:
- tidal volume (TV)
- expiratory reserve volume (ERV)
- inspiratory reserve volume (IRV)
Residual volume is the volume of the lung that represents the amount of air left in the lungs after a forced exhalation.
Residual volume cannot be measured but only calculated.
