Respiration Flashcards
Define external respiration
Exchange of O2 and CO2 between organisms and external environment
Define breathing
Muscle contraction and relaxation to move air in and out of the lungs
What is ventilation?
Air going from outside to inside of the body for gas exchange
What are the 3 types of breathing and where do they come from?
- Automatic: Brainstem
- Voluntary: Motor cortex
- Emotional: Limbic system
What are the 3 respiratory centres?
- Protective reflexes
- Chemo-receptors
- Pulmonary stretch receptors
What are alveoli?
- air sacs
- surface of alveoli is moist
- pulmonary surfactant lowers surface tension
- surface tension resists stretching
What is pulmonary surfactant and what secrets it?
It is made of phospholipids and protein and makes it easier for the lungs to expand. It is secreted by Type II alveolar cells.
What are the 2 protective reflexes
- Cough
- Sneeze
What causes a cough?
Receptors on epithelial cells
What causes a sneeze?
Receptors in upper airways
What are the 3 parts of rhythmic breathing?
1) Inspiration - active
2) Post-inspiration - active
3) Expiration - passive
What is the diaphram?
- most important inspiratory muscle
- has a phrenic nerve
- asymmetrically innervated
- 70% of tidal volume
What is the thorax?
A closed compartment which contains fluid to allow pleura to slide over one another, it has a thin membrane
What are the 3 types of membrane in the thorax?
- Costal parietal
- Mediastinal parietal
- Diaphragmatic
Define transpulmonary pressure and what it should be
The difference in pressure between the inside and the outside of the lungs in the thorax, it should be 4mm/Hg
What does the tongue do for respiration?
The contraction supports the airway as well as reducing resistance during respiration
What is O2 in the blood transported on?
Haemoglobin
Where is >98% of the haemoglobin?
In erythrocytes
What is the Bohr effect?
CO2 shifts the haemoglobin saturation to the right and causes it to release more O2
Why is it so common to have carbon monoxide poisoning?
- 210x more affinity for CO than O2
- CO displaces O2 to make carboxyhaemoglobin
- no reflex to increase ventilation as no O2 in blood
Where is the larynx?
Upper respiratory tract
What is airway resistance in the conducting zone determined by?
Cross sectional area
What is the conducting zone?
- provides a low resistance pathway for airflow
- warm or cool and moistens the air
- defends against microbes and foreign matter
What are the 4 levels of defence?
- Cilia
- Mucus
- Macrophages
- Constriction of the bronchioles via smooth muscle
