• When CO2 is high or low in the blood the stimulus triggers the chemoreceptor. 

• In response talk to the brain stem medulla the respiratory center. 

• In response sympathetic or parasympathetic activation

• The trigger change muscle of breathing or airway of breathing to bring back to homeostasis.

• Hyperventilation releases too much CO2. 

• Low CO2 in blood corresponds to PH value. 

• CO2 converts to bicarbonate and hydrogen ion.

• CO2 level high in blood they quickly convert to more bicarbonate turn out high level of hydrogen ion.CO2 level high low level of PH in blood caused more acidic in blood. 

 The body creates a difference between atmospheric and intrapulmonary pressures to facilitate airflow into and out of the lungs through the process of ventilation, which involves the mechanics of breathing. This process is driven by the contraction and relaxation of specific respiratory muscles, leading to changes in the volume and pressure within the thoracic cavity.

### Inhalation (Inspiration)

1. **Muscles Involved**:

   - **Diaphragm**: The primary muscle involved. During inhalation, the diaphragm contracts and flattens, moving downward and increasing the vertical dimension of the thoracic cavity.

   - **External Intercostal Muscles**: These muscles contract, lifting the ribs upward and outward, which increases the lateral and anteroposterior dimensions of the thoracic cavity.

   

2. **Mechanism**:

   - The contraction of the diaphragm and external intercostal muscles expands the thoracic cavity.

   - This expansion decreases the intrapulmonary (alveolar) pressure relative to atmospheric pressure.

   - Air flows into the lungs from the higher-pressure atmosphere to the lower-pressure alveoli.

### Exhalation (Expiration)

1. **Muscles Involved**:

   - **Relaxation of the Diaphragm and External Intercostal Muscles**: During normal, passive exhalation, these muscles relax, causing the diaphragm to move upward and the ribs to move downward and inward.

   - **Internal Intercostal Muscles and Abdominal Muscles**: These muscles can be recruited during forceful exhalation, such as during exercise or coughing, to actively decrease the thoracic cavity volume further.

2. **Mechanism**:

   - The relaxation of the diaphragm and external intercostal muscles decreases the thoracic cavity volume.

   - This increases the intrapulmonary pressure relative to atmospheric pressure.

   - Air flows out of the lungs from the higher-pressure alveoli to the lower-pressure atmosphere.

### Summary of Pressure Changes

- **Inhalation**: The expansion of the thoracic cavity reduces intrapulmonary pressure below atmospheric pressure, causing air to flow into the lungs.

- **Exhalation**: The reduction in thoracic cavity volume increases intrapulmonary pressure above atmospheric pressure, causing air to flow out of the lungs.

### Additional Muscles (during forced breathing)

- **Sternocleidomastoid and Scalenes**: Assist in elevating the rib cage during deep or forced inhalation.

- **Abdominal Muscles (Rectus Abdominis, Transversus Abdominis, Internal and External Obliques)**: Contract to push the diaphragm up more forcefully during forced exhalation.

In summary, the coordination of these muscles and the resulting changes in thoracic cavity volume and pressure facilitate the flow of air into and out of the lungs, ensuring efficient gas exchange.

 Nebulized albuterol and quick-relief inhalers both deliver the medication albuterol, which is a bronchodilator used to treat asthma and other respiratory conditions by relaxing the muscles in the airways and increasing airflow to the lungs. However, they differ in their delivery methods and usage contexts:

1. Nebulized Albuterol:

• Delivery Method: Uses a nebulizer, which is a device that turns liquid albuterol into a fine mist that can be inhaled through a mask or mouthpiece.

• Usage: Typically used in a clinical setting or at home for individuals who have difficulty using inhalers or need higher doses of medication. It requires a power source (electric or battery) and takes about 5-15 minutes to deliver a dose.

• Advantages: Can be easier to use for young children, elderly patients, or those experiencing severe asthma attacks. It ensures the medication reaches deep into the lungs.

2. Quick-Relief Inhaler (Metered-Dose Inhaler - MDI):

• Delivery Method: Delivers albuterol in aerosol form through a small handheld device. The patient inhales the medication directly into the lungs.

• Usage: Commonly used for quick relief of acute asthma symptoms or as a rescue inhaler. It is portable and convenient, making it suitable for on-the-go use.

• Advantages: Fast-acting, easy to carry, and can provide immediate relief. It typically delivers a precise dose with each puff.

Key Differences:

• Administration: Nebulizers require a longer administration time and more setup, whereas inhalers are quick and portable.

• Ease of Use: Nebulizers are easier for those who struggle with the coordination required for inhalers.

• Setting: Nebulizers are often used in more controlled settings (home or clinic), while inhalers are used anywhere due to their portability.

In summary, while both methods effectively deliver albuterol to the lungs, the choice between a nebulizer and an inhaler depends on the patient’s specific needs, abilities, and the context in which the medication is needed.