Respiration 1 Flashcards
What is cellular respiration?
Intracellular- mitochondrial
uses O2 and produces CO2 and energy.
What is external respiration?
Gas exchange (O2 in and CO2 out) between the external environment and the cells.
What are the 4 steps to external respiration?
- Ventilation or gas exchange between the atmosphere and air sacs (alveoli) in the lungs
- Exchange of O2 and CO2 between air in the alveoli and the blood in the pulmonary capillaries
- Transport of O2 and CO2 by the blood between the lungs and the tissues
- Exchange of O2 and CO2 between the blood in the systemic capillaries and the tissue cells
Describe the main properties of lungs
What do we need for effective external respiration?
properties:
- A 75m2 sheet of single- and multiple-layer epithelial cells (Surface area)
- Can fit into 3 litres (Volume)
- High SA:VOL
what the lungs need:
- Connect it to the outside
- Keep it hydrated
- Structures protect it from inhaled damage (muscociliary escalator) and external trauma (ribcage)
- Control how it operates
(controlled by autonomic nervous system and skeletal muscles)
Non-respiratory functions: defend and maintain
- Alveolar macrophages and the mucociliary escalator►defence against inhaled particles
- Inspired air must be warmed and humidified ► lungs are a route for water loss and heat elimination
- Pressure differential in the chest vein ►enhances venous return
- Pulmonary ventilation rate responds to H+ (via CO2) in the blood ►helps maintain normal acid–base balance by increaseing ventilation which brings in more O2 and takes away excess CO2
- Control of the vocal cords in respiratory tract►enables speech, singing, and other vocalisation
What are the airway’s defences?
- The bronchi help to defend the airways►Bronchial epithelial cells produce anti-microbial peptides
- The mucociliary escalator lines the bronchi and it consists of:
- Goblet cells which produce sticky mucus to trap bacteria
- Ciliated epithelial cells which beat the mucus to the pharynx
Cilia beating generate the
mucociliary escalator:
Cell surface- epithelial cells which line the bronhi protruding from it are cilia
Fluid in this environment that allows cilia to move backwards and forward
Directly above are goblet cells which produce sticky mucus (glycoproteins)
Allows bacteria, viruses, pollen and dust be be trapped
What is the mucociliary escalator made of?
Sticky mucus, made of glycoproteins, traps inhaled particles and bacteria
Describe the mucociliary escalator
Cilia project into the periciliary fluid- a liquid layer secreted by epithelial cells
What does the action of the ciliary beating do?
The action of the cilia beating then moves the mucus raft to the back of the throat
What action is taken by the mucociliary escalator when you inhale things like bacteria or dust?
- Epithelial cells increase fluid secretion (pericilliary fluid)
- Goblet cells produce mucus
- bacteria/dust gets stuck
- This can either be ingested (cilia beat the material down into the stomach to be destroyed by stomach acid) or cilia move it up and you spit it out
What does healthy airway epithelium look like?
What does CF airway epithelium look like?
Individuals do not secure enough fluid to keep the muscus flowing.
Genetic mutation- issues with chloride pump disrupts osmotic balance so mucus does not have enough water
Mucus (consists of glycoproteins) builds up and aggregates (purple area in the diagram)
Allows bacteria to proliferate leading to fatal lung infections
Why is smoking bad for your lungs?
Compare the alveoli in a smokers lung compared to that of a non smokers lung
- Cigarette smoke paralyses the cilia (for up to 4 hours)
- Mucus hypersecretion blocks the airways
- Alveolar macrophages can’t defend you
- Lungs are irreversibly damaged
- In a healthy persons lung the alveoli are separated by a thin wall which allows efficient transfer of oxygen to their neighbours
- The alveoli in a smokers lung appears larger and have large borders between them gas exchange becomes immensely restricted
What does the respiratory system consist of?
the airways, lungs and muscles
What are the structures that comprise the airways?
–Pharynx and Larynx
–Trachea
–Primary bronchi
— Nasal cavities
Does gas exchange occur in the airways?
NO
The lungs are responsible for gas exchange
What structures are resposible for gas exchange?
–Respiratory bronchioles
–Alveolar ducts
–Alveolar sacs
–Alveoli
How do muscles contribute to gas exchange?
Responsible for moving air in and out of the airways and lungs
What are the main muscles involved in gas exchanhge?
Mucles of the abdomen are very important for gas exchange
Does branching increase surface area?
What is the structure from the upper to lower part of respiratory tract?
yes
From upper to lower part of respiratory tract:
structures become smaller: (trachea►bronchi►bronchioles►terminal brochioles►respiratory bronchioles►alveolar ducts►alveolar sacs
surface area to volume ratio increases
Explain the properties of alveoli and how they are important to their function
- Alveoli are thin-walled, inflatable air sacs encircled by pulmonary capillaries.
- Alveoli are the units of gas exchange.
- Alveoli walls consist of a single layer of flattened Type I (90%) alveolar cells (pneumocytes).
- Type II (5%) alveolar cells secrete pulmonary surfactant.
- Alveolar macrophages are found in the lumen.
approx 300 million alveoli in each lung
Describe the functional features of alveloli?
- Large space in the middle (alveolus) which allows gas exchange
- Capillaries and blood vessels surrounding it
- Monocytes which mature into macrophage to eat any nasty material inhaled
What are alveoli surrounded by?
An almost continuous sheet of blood maximises gas exchange to get the oxygen to metabolically active tissue cells