Respiration 1 structure Flashcards
Semester 1 year 1
What is internal respiration and what is produced and consumed?
-within the cell
-CO2 produced in glycolysis + Krebs cycle
-O2 consumed in oxidative phosphorylation
What is external respiration?
-ventilation
-exchange + transport of gases around the body
What does respiration rely on?
-diffusion
-O2 diffuses in + CO2 out
-CO2 produced increases intracellular conc. creating a conc. grad
-movement of ventilation maintains diffusion gradients
Describe the movement of gases from entering to leaving the lungs
-gases diffuse out of lungs into capillaries
-blood returns to left side of heart
-oxygenated blood pumped around body (O2 carried by haemoglobin)
-O2 rich blood is close to tissues so there’s a conc. grad
-O2 diffuses out of blood into cell + CO2 diffuses into blood
-CO2 carried in blood back to capillaries next to lung
-CO2 diffuses into lung down conc. grad
What are the 2 zones in the lungs?
-conducting zone
-respiratory zone
What does the conducting zone do?
-no gas exchange takes place
-mechanism to get gases to alveoli
What does the respiratory zone do?
-where gas exchange takes place
-alveolie
Describe the pathway that gases take after passing through the mouth
- trachea
- bronchi
- bronchioles
- alveoli
- alveolar ducts
- alveolar sacs
What structures are in the conducting zone?
-nose
-nasopharynx
-oropharynx (mouth)
-pharynx
-larynx
-trachea
-bronchial tree
What are the functions of the conducting zone?
-filters by removing the large particles
-warms it from atmospheric temp to body temp so gases are more soluble
-humidifies it by saturating it with water vapour so airway doesn’t dry out
Describe the structure of the bronchial wall
-cartilage rings that prevent bronchial from collapsing
-smooth muscle to control airway diameter
-mucous glands produce mucus that traps and removes any stuck particles
-elastic tissue
Describe the respiratory epithelium
-ciliated epithelium
-goblet cells that produce mucus
-sensory nerve endings that pick up chemicals that we breathe in e.g smoke
Describe bronchioles
-less than 1mm diameter
-lack cartilage support so are more prone to collapsing
-lined by respiratory epithelium
-proportionately more smooth muscle compared to bronchi to control airway diameter
Describe the alveoli
-large surface area for optimal gas exchange
-fed from terminal bronchiole
-thin wall for optimal gas exchange
-surrounded by many capillaries
What is the air blood barrier?
-a ‘sandwich’ created by flattened cytoplasm of type I pneumocytes + the capillary wall
-multiple barriers have to be crossed for gas exchange (at least 5)
-membranes brought into very close contact to minimise diffusion distance
-provides a large SA for gas exchange
What are the 2 processes of ventilation and what can they be?
-inspiration or expiration
-can be quiet (at rest) or forced (when active)
During ventilation, how does the movement of air occur?
Down pressure gradients
During inspiration, how is the pressure gradient created?
-atmospheric pressure > alveolar pressure
-air moves into lungs
During expiration, how is the pressure gradient created?
-alveolar pressure > atmospheric pressure
-air moves out of lungs
What muscles are involved in quiet inspiration?
-primary muscles of inspiration
-diaphragm
-external intercostal muscles
What is the effect of muscles in quiet inspiration?
-increase thoracic + lung volume
-increase in volume = reduction in pressure
-air moves into lungs down pressure grad.
-this is Boyle’s law
What muscles are used in forced inspiration?
-accessory (secondary) muscles
-scalenes, sternocleidomastoids, neck + back muscles
-upper respiratory tract muscles - increase airway diameter
Is quiet expiration active or passive?
-passive
-uses elastic recoil
-no primary muscles of expiration
How does quiet expiration occur?
-relaxation of external intercostal muscles
-recoil of lungs due to elastic forces
-diaphragm relaxes
What muscles are used in forced expiration?
-accessory muscles
-internal intercostals
-abdominal muscles
-neck + back muscles
Where are pleura membranes found?
-on outside of lung
-inside of chest wall
What are pleural cavities filled with and where are they?
-in space between membranes
-filled with secretion
What doe the pleural membranes do?
-prevents lungs from sticking to chest wall
-lungs can expand + collapse freely
Why is it important that the elastic forces in lungs and chest are balanced?
-at rest, inward + outward forces balance
-results in pressure in intrapleural space < atmospheric pressure
What is a pneumothorax and what happens as a result?
-collapsed lung
-air gets into intrapleural space due to puncture
-intrapleural space pressure = atmospheric pressure
-elastic nature of lungs takes over + they collapse
