- Chemoreceptors in medulla
- Stimulated increase in PaCO2 or decreases in pH
- PaCO2 is normal neuroregulatory control of ventilations
Respiratory Drive
Layers of lungs
- Parietal (Outer)
- Visceral (Inner)
space betwen pluras
potential space, serous fluid 25-50 mL
muscle that helps you inhale and exhale (breathe in and out)
Diaphragm
Lobes of lungs
1/2. Superior lobes (left and right)x2
3. Middle Lobe (Right lung)x1
4/5. Inferior Lobes (left and right)
Between lobes
Fissures
Pressure Changes in lungs during Respiration
Atmospheric: 760 mmHg
Inhalation: 758 mmHg
Exhalation: 762 mmHg
Factors Affecting O2 Concentrations in the blood
- Decreased hemoglobin concentration
- Inadequate alveolar ventilation
- Decreased diffusion across the pulmonary membrane when diffusion distance increases or the pulmonary membrane changes
- Ventilation/perfusion mismatch occurs when a portion of the alveoli collapses
What Happens to CO2 During Hyperventilation?
Hyperventilation lowers CO2 levels due to increased respiratory rates or deeper respirations
Quantity of gas that will dissolve in a liquid depends upon the amount of gas present and its solubility coefficient
Henrys Law
When temperature is constant, the pressure of gas varies inversely with its volume. Lungs function by increasing and decreasing pressure to cause air to either rush on or rush out
Boyle law
Each gas in a mixture of gases exerts its own pressure
- As if all gases were not present
- Partial pressures denoted as “p”
Daltons Law
Ways to compensate with hypoxia
Cardiovascular system delivers more blood to the systems
CO vs O2 in regards to Hemoglobin
CO (200-220 X BETTER THAN O2)
Oxyhemoglobin dissociation curve
The steeper the curve, the higher the pH
CO2 transport methods
- Dissolved in plasma (7-10%)
- Combined with Hb and plasma proteins for easy release at the alveoli (23%) referred to as carbaminohemoglobin
- As bicarbonate (70%)
- Control of respiration
- Located in carotid bodies, arch of the
aorta, and medulla - Stimulated by decreased PaO2,
increased PaCO2, and decreased pH - Cerebrospinal fluid (CSF) pH is
primary control of respiratory centre
Chemoreceptors
provides inhibitory impulses on inspiration and thereby prevents over distension of the lungs and helps to maintain alternately recurrent inspiration and expiration
Pneumotaxic Centre
4 types of hypoxia
- Hypoxic hypoxia
- Hypemic hypoxia
- Stagnant hypoxia
- Histotoxic hypoxia
Explain Inspiration (Active)
Stimulus from respiratory centre of brain (medulla) transmitted via phrenic nerve to diaphragm and to spinal cord/intercostal nerves stimulating the intercostal muscle——–> External intercostal contract- ribs pulled upward and out diaphragm contracts and flattens——–> Thoracic cavity enlarges , lungs expand, decrease in intrapulmonic pressure (758 mmHg)——–>Air flows into airways, alveoli inflate until pressure equalizes
Muscles involved in Forced Inspiration
- Sternocleiodomastoid
- Scales
- Pectoralis minor
- Abdominal Wall
Atmospheric Pressure at Sea Level
760 mmHg
Respiratory Cycle
- Diaphragm contracts (normal inspiration), Accessory muscles contract (Laboured inspiration)
- Thoracic cavity increases and lungs expand
- Alveolar pressure decreases to 758 mmHg
- Diaphragm relaxes (normal respiration), accessory muscles contract (laboured)
- Thoracic cavity decreases in size and lungs recoil
- Alveolar pressure increases to 762 mmHg
Explain Expiration (Passive)
Stretch receptors in lungs signals respiratory centre via vagus nerve to inhibit inspiration (Hering-Breur reflex——->Diaphragm and external intercostals relax——> Thoracic cavity decreases in size——>Elastic lungs recoil——->Intrapulmonic pressure increases to 762 mmHg (760 outside)—–>Air flows out until pressure equalizes
