Respiration

Oxygen Supply: Provides the body with O2 necessary for metabolic processes.
Carbon Dioxide Outlet: Eliminates CO2, a byproduct of metabolism.
pH Regulation: Helps regulate blood acidity levels, maintaining a stable pH balance.
Interdependent functions: These tasks are closely linked to each other and work in concert with the circulatory system.

Cyclic Activity: Characterized by regular cycling between inhalation (inspiration) and exhalation (expiration).
- Preparation of Air: The upper respiratory system filters, warms, and moisturizes the air before it reaches the lungs.
- Airpathway: The lower respiratory tract (trachea, bronchial tubes) directs air into the lungs.

Inspiration:
- Caused by the activity of external intercostal muscles and the diaphragm.
- Increases thoracic cavity volume, causing lower lung pressure and allowing air to flow in.
Expiration:
- Involves relaxation of respiratory muscles and potential engagement of the internal intercostal and abdominal muscles for forced breathing.
- Reduces thoracic cavity volume, creating higher lung pressure, pushing air out.

Oxygen Diffusion: O2 from inhaled air diffuses into blood via pulmonary capillaries and binds to hemoglobin for transportation throughout the body.
Carbon Dioxide Transport: CO2 is carried in three forms:
- Bound to hemoglobin (like O2).
- Dissolved in blood plasma.
- Buffered with water as H+ and bicarbonate, contributing to pH balance.
CO2 Diffusion: Higher CO2 concentration in blood than in lung air enables CO2 to diffuse from blood into lungs for exhalation.

Control of Respiratory Activity: Regulated by neurons in the medulla and pons, based on chemical signals and sensory information.
- Chemoreceptors: Respond primarily to CO2 and H+ concentrations, rather than O2.
- Normal Rate: Average resting rate is 12-14 breaths per minute, with a tidal volume of 400-500 ml in healthy adults.
Inspiratory Duty Cycle: The ratio of inspiration time to total respiratory cycle time is approximately 0.4.

Hyperventilation: Increased depth/rate of breathing leads to reduced H+ and resultant alkalosis (pH>7.45).
Hypoventilation: Decreased breathing leads to CO2 accumulation, causing acidosis (pH<7.35).
Measurement of Respiration:
- Pneumograph transducer measures chest movement to track respiration rates.
- For precise tidal volume and breath composition analysis, spirometry and breath gas analysis are utilized.

Breathing and Emotions: Breathing patterns are influenced by psychological states (speech, anxiety, etc.) and social interactions.
Voluntary Control of Breathing: Humans can consciously control breathing, impacting physiological states (meditation, panic attacks).
Physiological Feedback: Changes in respiration can affect heart rate and other variables (e.g., respiratory sinus arrhythmia), showing the interconnectedness of bodily systems.