Respiratory system III Flashcards
1
Q
Ventilation
A
- Air to the alveoli for gases to
exchange
2
Q
Perfusion
A
- The circulatory system needs to ensure blood gets to the
alveolar
3
Q
Gas Exchange
A
- Respiratory membranes are between air and blood
- Respiratory bronchioles and alveolar ducts and alveoli
- Perfusion for those that have emphysema
4
Q
Gas exchange
Thickness of membrane
A
- O2 exchange affected before CO2
- O2 diffuses through the respiratory membrane less easily than does CO2
5
Q
Gas exchange
Total surface area of the respiratory membrane
A
- Less surface area reduces gas exchange
6
Q
Gas exchange
Partial pressure of gases across the membrane
A
- Pressure exerted by a specific gas in a mixture of gases PO2, PCO2
- Gases in the air dissolve in the liquid
- Until partial pressure in liquid = to the partial pressure in air
- Gases in liquid and air diffuse from areas of higher partial pressure toward areas of lower partial pressure until equal
7
Q
step 1
Process of gas exchange
tissues to alveoli
A
- Blood from tissues has a lower Po2 and a higher Pco2 compared to alveolar air
- O2 diffuses from the alveoli into the pulmonary capillaries
- CO2 diffuses from pulmonary capillaries into the alveoli
8
Q
Step 2
Process of gas exchange
venous end of capillaries
A
- Pressures equal because of diffusion
- The blood carries O2 away by bulk flow
to the tissues where O2 is required - Mixing with deoxygenated blood =
lower PO2 than in capilaries
9
Q
Step 3
Process of gas exchange
Diffusion to cells
A
- Oxygen diffuses out of the blood and
into the interstitial fluid then into cells - Carbon dioxide diffuses from cells into
the interstitial fluid and from the interstitial fluid into the blood and equalibrium is reached
10
Q
How is oxygen stored in the body
A
- As a gas in the lungs
- Dissolved in tissue fluids
- As oxyhaemoglobin in blood
- As oxymyoglobin in muscle
11
Q
Oxyhaemoglobin
Dissociation Curve
A
- Hemoglobin to bind to O2
depends on the Po2 - High Po2, haemoglobin binds to
O2 - Low Po2, hemoglobin releases
O2 - In the lungs the ppO2 is usually high heam holds most O2
- At tissues the ppO2 is usually low heam relases the O2
12
Q
Factors that effect Oxyhaemoglobin
Dissociation Curve
A
- Low Po2,
*high Pco2
*low pH
*high temperature
*Physical Exercise
13
Q
Transport of Carbon Dioxide
A
- Transported as CO2 dissolved in the plasma
- Transported bound to blood proteins, primarily haemoglobin
- As bicarbonate ions
14
Q
Gas exchange in Tissues
A
- CO2 diffuses into plasma and
RBC - Forms carbonic acid catalysed by carbonic anhydrase found inside RBC and on capillary
epithelium - Increase uptake of CO2 by red blood cells
15
Q
Gas exchange in tissues
A
- Capillaries of the lung CO2 diffuses from RBC to alveoli
- HCO3 dissociates to produce H2CO3
- Carbonic anhydrase catalyses formation
of CO2 and H20 from H2CO3 - The CO2 diffuses into the alveoli and is
expired
16
Q
pH importance of carbon dioxide
A
- CO2 levels increase, the blood pH decreases
because CO2 reacts with H2O to form H2CO3 - H+ that results from the dissociation of H2CO3 is responsible for the decrease in pH
- Blood levels of CO2 decline, the blood pH increases
17
Q
Regulation of pH
A
- Chemical acid base buffer system
- The respiratory centre - lungs
- Kidney which takes hours
18
Q
Control of Respiration
A
- Rate of breathing dependant on number of times repiratory muscles are stimulated
- Spontaneously initiated within the central nervous system
- Increase in the depth of breathing is dependant on more stimulation and stronger contractions of muscle fibre
19
Q
Rhythmic breathing
Starting inspiration
A
- Neurons are continually active stimulating the repiratory centre caused by blood gas lavels muscle movement
- When threashold is reached somatic nervous system neurons stimulate respiratory muscles and inspiration starts
20
Q
Rhythmic breathing
Increasing inspiration
A
- Increase in neurone activation therefore stonger stimulation of respiratory muscles which last 2s
21
Q
Rhythmic breathing
Stopping inspiration
A
- Neurones that stimulate inspiratory muscles also stimulate medullary neurones that stop inspiration
- Receive input from the pontine respiratory neurons stretch receptors in the lungs
- When inputs exceed threashold levels it causes neurone respiratory muscles to be inhibited
- Leads to relaxation and expiration
22
Q
Key functions of Respiration
A
- Maintainance through involantary controls through regular rhythmic breathing
- Tidal volume and breathing frequency so that ventilation is mantained for gas exchange
- Adjust breathing pattern depending on activity
23
Q
Pons
A
- Pontine respiratory group
- Controls switches between inspiration
and expiration
24
Q
Medulla Dorsal respiratory group
A
Diaphragm
25
Q
Medulla Ventral respiratory group
A
- Intercostals
- Abdominals
- Inspiratory and expiratory
26
Q
Hering- Breuer reflex
A
- Limits the extent of inspiration
- As the muscles of inspiration contract the lungs fill with air
- Sensory stretch receptors located in the lungs are stimulated
- Action potentials sent to the medulla oblongata
- Inhibition of respiratory centres causes expiration
27
Q
Chemical control of breathing
A
- Increase of CO2 in the blood urgue to breath increases with CO2
28
Q
3 Control pathways
A
- PCO2 is the principle pathway, controlling the rate and depth of breathing on a breath-by-breath basis
- Acclimatization to altitude, the PO2 pathway can override the PCO2 pathway
- Allows talking, swallowing and coughing to break through the normal pattern of breathing and try to match breathing to the expected voluntary or behavioural activity
29
Q
Central chemoreceptors
A
- PaCO2 rises causing a rapid increase in H+ ions
- Causes the pH level to fall
- Causes the central chemoreceptors to transmit a signal to increase ventilation
- PaCO2 and CO2 decrease and when balance is
restored, ventilation will decrease
30
Q
Types of chemoreceptors
A
- Central Medulla oblongata
- Peripherally Carotid bodies and Aortic bodies
31
Q
Controlling the breathing rate
A
- CO2 levels of the blood decrease causing the pH to increase - Medullary chemoreceptors signal decrease inbreathing rate keeps CO2 in the blood
- Increase CO2 in the blood causes H+ levels to increase and blood pH decreases
32
Q
Globullar innervation
Airways
A
- Innervated by the vagus nerve –
Parasympathetic causing bronchoconstriction
33
Q
Respiratory muscle innervation
A
- Intercostal (motor) nerves
- Phrenic nerve innervates the diaphragm
34
Q
Parasympathetic nervous system
A
- Acetylcholine is the effector neurotransmitter
- The muscarinic M1 to M5
- Most important receptor M3 for airways
35
Q
Muscarinic receptors
A
- Stimulation causes the contraction of bronchial smooth muscle
- Muscarinic receptors located in many glands help to stimulate secretion
36
Q
Sympathetic nervous system
A
- Noradrenaline effector with adrenergic receptors
- Beta1 receptors – Heart Stimulation increases rate and force
- Beta2 receptor smooth muscle of bronchioles stimulation (Agonist) causes relaxation
