Respiratory System Flashcards
What is respiration external?
Exchange of O2 + CO2 between an organism + external environment
What is respiration internal?
Utilisation of O2 by cells in metabolism
What is the pathway of breathing?
Nasal cavities –> pharynx –> trachea –> bronchi –> bronchioles –> alveoli –> O2 + CO2 exchange
What is part of the upper respiratory tract?
Nasal + nose sinuses
Nasopharynx
Pharynx
Larynx
What is part of the lower respiratory tract?
Trachea
Bronchi
Bronchioles
Lungs
What is the function of respiratory system?
Gaseous exchange Olfaction Speech Homeostasis Protection
Why olfaction?
Nerve endings in nasal cavity + transmitted to brain via 1st cranial nerve
Why speech?
Vocal cords in larynx
Why homeostasis?
Via O2 + CO2 exchange
Why protection?
Via immune system + mucus production
Describe structure of the nose
Lined with cilia
What is the function of cilia in the nose?
Filter the air
Epithelial cells secrete mucus to trap dust + bacteria
Describe structure of nasopharynx
Back = adenoids
Eustachian tubes
What is function of adenoids in nasopharynx?
Made up of dense lymphoid tissue = fight infections
What is the function of eustachian tubes in
nasopharynx?
Connect nasopharynx to ear = equalise pressure in ear
What is the pharynx?
Muscular tube behind mouth, between nasopharynx + larynx
What is the function of pharynx?
Air + food passage
What are the tonsils made up of?
Dense lymphoid tissue
What are the problem with tonsils?
During infection can cause air-flow resistance
What is the larynx?
Short passage - connects pharynx to trachea
Walls contain vocal cords
What is the opening from pharynx to larynx?
Glottis
What happens to the glottis when swallowing?
Covered by epiglottis to prevent choking
What is the trachea?
Tube from larynx to upper chest
What is the structure of trachea?
20 “C” shaped rings of cartilage + smooth muscle
What is the importance of mucus in the bronchi?
Trap solid particles + cilia move them outwards = expelled in coughing
What is the bronchi?
Trachea divides to form bronchi
What is the structure of bronchi?
Similar to trachea
Lined with cilia, which secrete mucus + saline
What does the cartilage rings allow in the trachea?
Expansion of oesophagus = bolus food swallowed
Describe saline secretion by airway epithelial cells
NKCC brings Cl- into epithelial cell from ECF
Apical anion channels allow Cl- to enter lumen
Na+ goes from ECF to lumen by paracellular, drawn by electrochemical gradient
NaCl movement from ECF to lumen creates conc gradient = H2O flows into lumen
Describe the cause of cystic fibrosis
CFTR channel malfunction Reduction of saline layer production Cilia become trapped in mucus Bacteria colonise epithelium Recurrent chronic lung infections
What is the structure of the bronchioles?
Cartilage absent from terminal bronchioles = more smooth muscle
What are the bronchi + bronchioles innervated by?
Autonomic nervous system = contain muscarinic cholinergic + β2 adreno receptors
Why do they contain muscarinic cholinergic receptors?
Cause broncho-constriction
Why do they contain β2 adreno receptors?
Mediate broncho-dilation
Do the 1st 16 generations of bronchioles play a role in gas exchange?
NO
What are the 1st 16 bronchioles knows as?
Conducting airways
Which bronchioles play a role in gas exchange?
Remaining 7 generations
What is the structure of alveoli?
Type I + II epithelium
Blood vessels
What does type I epithelium do in alveoli?
Primary site for gas exchange
Very thin to allow rapid diffusion
What does type II epithelium do in alveoli?
Synthesis chemical known as surfactant
= reduce surface tension
= reduce resistance in inhalation + exhalation
Why are blood vessels important in alveoli?
Rapid gas exchange
= close to alveolar air
What is the structure of 1 lung?
Bronchus with bronchioles + alveoli
Thin protective membrane over entire organ
Describe gas exchange
O2 enters blood at alveolar-capillary interface
O2 transported in blood dissolved in plasma or bound to haemoglobin
O2 diffuses into cells
CO2 diffuses out of cells
CO2 transported dissolved, bound to haemoglobin
CO2 enters alveoli
How many O molecules can 1 haemoglobin bind?
4
When can haemoglobin bind O2?
When in Fe2+ (ferrous) state
Why is the blood red?
Interaction of Fe2+ with O2 = complex to have red colour when fully saturated with O2
What happens when there is a decreased P50 (increased affinity)?
- temp
- pCO2
+ pH
What happens when there is a increased P50 (decreased affinity)?
+ temp
+ pCO2
- pH
What effect does a drop in pO2 have on Hb saturation?
Minimal effect
What happens when a large amount of O2 is released from Hb?
Only small change in pO2, which facilitates release + diffusion of O2 into tissue
What is CO2 + pH effect have?
Enhance O2 uptake in lung + delivery to tissues
What is temperature effect have?
Increase during exercise, decrease in cold weather
What is 2,3 DPG effect?
Increase in hypoxia, decrease in stored blood samples
What is 2,3 DPG?
Di phospho glycerate
Bind to Hb = allosteric inhibitor
What is CO2 transport?
Dissolved CO2 from cellular respiration (7%)
RBCs (23%)
Plasma (70%)
What are the respiratory muscles?
Diaphragm
External intercostal
Internal intercostal
Accessory muscles
What do the external intercostal muscles do?
Lift lungs upwards + outwards as contract
What do the internal intercostal muscles do?
Pull ribs down in opposition to external
Describe diaphragm
Diaphragm forms continuous sheet - separates thorax + abdomen
Describe diaphragm at rest
Dome like shape
Describe diaphragm contracting (inspiration)
Crown of diaphragm descends = increases vol of chest
Describe diaphragm relaxing (expiration)
Elastic recoils of chest wall = passive expiration
Describe what happens in exercise
Chest wall lifted upwards + outwards by external
Diaphragm contracts more strongly
= chest vol increased
Internal contract = reduce chest vol = expiration
What happens in severe exercise?
Accessory muscles lift chest wall further
What is the tidal vol?
The vol of air moves during single inspiration or expiration
What is the inspiratory reserve vol?
Additional vol you inspire before tidal vol
What is the expiratory reserve vol?
Amount of air forcefully exhaled after end of normal expiration
What is the residual vol?
At end of max expiration, lungs still contain vol air that cannot be expelled
What is the vital capacity?
Sum of inspiration reserve vol, expiratory reserve vol + tidal vol
What is the total lung capacity?
Sum of vital capacity + residual vol
What is the functional residual capacity?
Sum of expiratory reserve vol + residual vol
What is the inspiratory capacity?
Sum of tidal vol + inspiratory reserve vol