Respiratory System Flashcards
(23 cards)
What happens during inspiration
- Dome shaped muscle of the diaphragm flattens
- Inter costal muscles pull the rib cage upwards and outwards
- This increases volume of the chest cavity
- Air is drawn into the lungs
What is breathing
The mechanical process that moves air into and out of the lungs
What happens during expiration
- The diaphragm relaxes and resumes its dome shape
- The inter costal muscles relax and the rib cage falls inwards and downwards
- This reduces the volume of the chest cavity
- Air is forced out of the lungs
4 mechanisms of respiration
- Breathing: entry & exit of air into and out of lungs
- External respiration: exchange of gases (O2 and CO2) between air and blood
- Internal respiration: exchange of gases between blood and tissue
- Cellular respiration: production of ATP in cells
Describe the passage of air in the upper respiratory tract
- Air enters through nostrils
- Air passes through the nasal cavities into the pharynx (throat)
- The trachea brings the air to the lungs
Where does the trachea extend from and to
Extends from the larynx (voice box) and branches into the two primary bronchi
Describe the passage of air through the lower respiratory tract
- The air travels through the right and left bronchi which branch into bronchioles
- The bronchioles deliver air to the alveolar ducts
How are the alveoli specialised fro gaseous exhange (4)
- Alveoli walls are extremely thin
- They have a large surface area in relation to volume
- They are fluid lined enabling gases to dissolve
- Surrounded by numerous capillaries
What is the test for lung funcion
Spirometry, it measures breathing capacity and how much air you can breathe out
Spirometry: Tidal volume
When relaxed small amounts of air move in and out. It is the lung volume representing the normal volume of air displaced between normal inhalation and exhalation when extra effort is not applied
Spirometry: Vital Capacity
Maximum amount of air a person can expel from the lungs after a maximum inspiration
What can vital capacity help to diagnose
Underlying lung disease (3-5L normal adult)
Spirometry: Residual Volume
Air that remains in lungs
Spirometry: Dead Air Space
Inhaled air that remains in lungs (around 1000ml)
What does respiration include (2)
- Exchange of gases in lungs
- Exchange of gases in tissues
What is external respiration
The exchange of gases between air in alveoli and blood in the pulmonary capillaries
The steps of external respiration
O2:
* Alveolar air (air coming into the lungs) contains a higher partial pressure of O2 (pO2)
* Blood entering the pulmonary capillaries is low in O2
* O2 diffuses into plasma and into rbcs (oxyhaemoglobin)
CO2: Reverse pattern
* Blood entering pulmonary capillaries (after it has circulated the body) Has a higher partial pressure of CO2 (pCO2) than atmospheric air
* CO2 diffuses out of blood into the lungs
What is internal respiration
Refers to the exchange of gases between systemic capillaries and the tissue fluid
Describe steps of internal respiration
- Oxyhaemoglobin gives up O2 which diffuses out of blood into tissue due to pO2 of tissue fluid is lower than in blood
- CO2 diffuses into the blood from the tissues
- Small amount of CO2 binds with Hb to form carboxyhaemoglobin
What is most CO2 carried in the blood as
Bicarbonate (HCO3-)
What affets the ability of Hb to bind to O2
Temperature and pH
How does temp affect ability of Hb to bind to O2
- Increased temp decreases the affinity of Hb for O2.
- As Hb exposed to higher temps in the metabolising tissues, affinity decreases and Hb unloads O2
What conditions favour the uptake of O2 by Hb
Lower temp and higher pH in lungs is favourable for uptake of O2 by Hb
