Structure and Function of Respiratory Organs

Nasal Cavity:
- Filters, warms, and humidifies air.
- Contains mucous membranes and cilia.
Pharynx:
- Connects nasal cavity to larynx.
- Serves as a passageway for air and food.
Larynx:
- Houses vocal cords.
- Protects the trachea against food aspiration.
Trachea:
- Windpipe that connects larynx to bronchi.
- Reinforced with cartilaginous rings; lined with ciliated mucosa.
Bronchi:
- Two primary bronchi branch from trachea into lungs.
- Further divide into smaller bronchi and bronchioles.
Lungs:
- Main organs of respiration; contain alveoli for gas exchange.
- Right lung has three lobes; left lung has two lobes.
Alveoli:
- Tiny air sacs where gas exchange occurs.
- Surrounded by capillaries; have thin walls to facilitate diffusion.

Gas Exchange:
- Oxygen intake and carbon dioxide expulsion.
Regulation of pH:
- Maintains blood pH through the balance of carbon dioxide levels.
Voice Production:
- Enables phonation through the larynx.
Olfaction:
- Facilitates the sense of smell via olfactory receptors in the nasal cavity.
Protection:
- Filters pathogens and particles; mucous traps contaminants.

Diffusion:
- Movement of gases from areas of higher concentration to lower concentration.
Alveolar Exchange:
- Oxygen diffuses from alveoli into blood; carbon dioxide diffuses from blood into alveoli.
Fick's Law of Diffusion:
- Rate of diffusion is proportional to the surface area, concentration gradient, and inversely proportional to thickness of the membrane.
Role of Hemoglobin:
- Transports oxygen in red blood cells; binds carbon dioxide for transport back to lungs.

Neural Control:
- Controlled by respiratory centers in the brain (medulla oblongata and pons).
Chemoreceptors:
- Monitor levels of carbon dioxide, oxygen, and pH in the blood; influence breathing rate.
Mechanoreceptors:
- Located in lungs; respond to stretch and pressure changes.
Respiratory Cycle:
- Includes inhalation (active process) and exhalation (passive or active).
Influencing Factors:
- Physical activity, emotional state, and environmental changes can alter breathing patterns.

Nasal Cavity: Filters, warms, and humidifies incoming air; contains mucous membranes and cilia for trapping particles.
Pharynx: Connects nasal cavity to larynx; functions as a passageway for both air and food.
Larynx: Houses the vocal cords; prevents food aspiration into the trachea.
Trachea: The windpipe that links the larynx to the bronchi; reinforced by cartilaginous rings and lined with ciliated mucosa for added protection.
Bronchi: Two primary bronchi branch off from the trachea into the lungs, further dividing into smaller bronchi and bronchioles to facilitate airflow.
Lungs: Major organs for respiration containing alveoli; the right lung consists of three lobes, while the left has two lobes to accommodate the heart.
Alveoli: Tiny air sacs where gas exchange occurs; surrounded by capillaries with thin walls allowing efficient diffusion of gases.

Gas Exchange: Responsible for intake of oxygen and expulsion of carbon dioxide; critical for cellular respiration.
Regulation of pH: Maintains blood pH balance by controlling carbon dioxide levels within the bloodstream.
Voice Production: Phonation is enabled by the movement and vibration of the vocal cords in the larynx.
Olfaction: The sense of smell is facilitated by olfactory receptors located in the nasal cavity.
Protection: The respiratory system filters out pathogens and particles with mucus, trapping contaminants and providing a defensive function.

Diffusion: Involves the movement of gases from regions of higher concentration to lower concentration, essential for effective gas exchange.
Alveolar Exchange: Oxygen moves from the alveoli into the bloodstream, while carbon dioxide moves from blood into alveoli for exhalation.
Fick's Law of Diffusion: States that the rate of diffusion is directly proportional to surface area and concentration gradient while inversely proportional to membrane thickness.
Role of Hemoglobin: Efficiently transports oxygen in red blood cells and facilitates carbon dioxide binding for transport back to the lungs.

Neural Control: Regulated by respiratory centers in the brain, specifically medulla oblongata and pons, which control the rhythm of breathing.
Chemoreceptors: Sensitive to levels of carbon dioxide, oxygen, and blood pH, these receptors adjust breathing rates accordingly.
Mechanoreceptors: Found in the lungs; they respond to stretch and pressure changes, providing feedback for respiratory adjustment.
Respiratory Cycle: Comprises inhalation (an active process) and exhalation (which can be passive or active) to facilitate breathing.
Influencing Factors: Breathing patterns can be modified by various factors, such as physical activity, emotional state, and environmental conditions.