Biology II - Animal Respiratory Systems

Biology II - Session 1: Animal and Human Part

• The session was presented by Dr. Noura Abou Zeinab
• Email address: [email protected]

Respiratory Systems - Outline

• Gas Exchange Surfaces
• Breathing and Transport of Gases
• Respiration and Human Health

Gas Exchange Surfaces

• Respiration involves gas exchange between the body's cells and the environment.
• In terrestrial vertebrates, respiration includes: ventilation (breathing), external respiration (gas exchange between air and blood in lungs), and internal respiration (gas exchange between blood and tissue fluid).
• Effective gas exchange requires moist, thin surfaces with a large surface area relative to body size and vascularization.
• Respiratory pigments like hemoglobin facilitate oxygen delivery to cells.

Overview of Gas Exchange Surfaces

• Gases dissolve in water, but this process happens less efficiently than in air.
• Aquatic animals need to expend more energy for breathing than terrestrial animals due to water's higher density compared to air.

Gas Exchange Surfaces - Specific Examples

• Hydras and planarians: Small animals exchange gases directly with the environment. Larger aquatic animals often have gills.
• Gills of bony fish are finely divided vascularized structures that use a countercurrent exchange system to maximize oxygen transfer from water to blood.
• Arthropods (e.g., insects): Respiratory systems involve branched tracheae that deliver oxygen directly to cells. Oxygen enters through spiracles.

Respiratory Organs

• Different animals have various respiratory organs, including gills, tracheae, and lungs.
• Earthworms exchange gases through their moist skin and vascularized blood vessels.
• Diagrams illustrate variations in respiratory organs between different species.

Anatomy of Gills in Bony Fish

• Water passes over the gills in a direction opposite to blood flow. This maximizes oxygen transfer.

Lungs of Humans

• Air passes through the upper respiratory system, where it's filtered, warmed, and humidified.
• When air reaches the lungs, it is at body temperature and saturated with water.
• The trachea divides into two primary bronchi, which further branch into bronchioles ending in alveoli.
• Air moves into and out of lungs with changes in thoracic cavity pressure through diaphragm and rib cage movement.

Breathing and Transport of Gases - Ventilation

• All terrestrial vertebrates (except birds) utilize a tidal ventilation mechanism.
• Volume of the thoracic cavity and lungs increases with muscle contractions and movement of ribs to create negative pressure. This permits air to flow into the lungs during inhalation.
• Birds have a one-way ventilation mechanism where fresh air never mixes with used air and efficiently facilitates gas exchange.

Breathing and Transport of Gases - Human Modifications

• Adults typically have 12-20 breaths per minute.
• The respiratory center in the medulla oblongata of the brain controls breathing rhythm.
• The center stimulates the diaphragm and intercostal muscles for inhalation, and stops sending signals for expiration occurs.

Breathing and Transport of Gases - Gas Exchange and Transport

• Gas exchange is driven by partial pressure differences.
• Gases diffuse from high to low partial pressure areas.

Breathing and Transport of Gases - Transport of Oxygen and Carbon Dioxide

• External respiration involves oxygen binding to hemoglobin in red blood cells to form oxyhemoglobin.
• Internal respiration involves oxyhemoglobin releasing oxygen into tissues.
• Most carbon dioxide is transported in the blood as bicarbonate ion.

Respiration and Human Health - Disorders of the Upper Respiratory Tract

• Colds are mild viral infections, characterized by sneezing, runny nose, and mild fever.
• Strep throat is an acute pharyngitis caused by bacteria (Streptococcus pyogenes), characterized by sore throat, high fever, and swollen tonsils.

Respiration and Human Health - Disorders of the Lower Respiratory Tract

• Choking occurs due to blockage of the trachea.
• Acute bronchitis and chronic bronchitis are infections of primary and secondary bronchi with inflammation and mucus buildup
• Asthma involves inflammation of the airways with constricting airways.

Respiration and Human Health - Disorders Affecting the Lungs

• Pneumonia involves infection of the lungs with buildup of fluid.
• Tuberculosis is caused by Mycobacterium tuberculosis, resulting in lung damage.
• Pulmonary fibrosis results from the buildup of fibrous tissue in the lungs.
• Emphysema involves damage to alveoli, reducing the surface area for gas exchange.
• Lung cancer begins with thickening of cells in the airways.
• Cystic fibrosis involves mucus accumulation in the lungs, interfering with breathing.

Common Bronchial and Pulmonary Diseases

• Diagrams illustrate anatomical features and causes of different diseases.
• Various respiratory illnesses are visually presented in different diagrams.

Smoking and Lung Disorders

• Diagrams compare healthy lungs with lungs affected by smoking.