Science: The Respiratory System

The Respiratory System

• Comprises organs and tissues for the exchange of oxygen and carbon dioxide.
• Nose: Visible part with two openings known as external nares or nostrils.
• Nasal Cavity: Divided by nasal septum, serves as a passageway for air.
• Pharynx: Five-inch muscular tube for transporting food and air.
• Larynx: Involved in speech production, constructed of cartilages.
• Epiglottis: Ensures food does not enter the trachea during swallowing.
• Trachea: Four-inch tube that extends from the larynx; lined with cilia.
• Bronchi: Split into right and left primary bronchi leading to the lungs.
• Bronchioles: Smaller branches that connect bronchi to alveoli (air sacs).
• Lungs: Located in the thoracic cavity with apex (upper) and base (lower resting on diaphragm).

The Circulatory System

• Transports materials throughout the body, essential for life.
• Heart: Cone-shaped organ weighing less than a pound, with outer parietal and inner visceral pericardium.
• Heart walls include three layers: epicardium (outer), myocardium (middle), endocardium (inner).
• Features four chambers: right atrium, left atrium, right ventricle, left ventricle.
• Contains four valves: two atrioventricular (AV) and two semilunar valves.
• Blood vessels: Medium for circulation in the cardiovascular system.
• Blood: Vital fluid composed of erythrocytes (carry oxygen), leukocytes (immune defense), plasma (nutrients), and thrombocytes (clotting).

Cells in Blood

• Erythrocytes (RBC): Anucleate, biconcave, responsible for oxygen transportation.
• Leukocytes (WBC): Nucleated, mobile, provide immune defense, including granulocytes and agranulocytes.
• Plasma Composition: 92% water, 7% proteins, 1% solutes.
• Antigens: Determine blood type; Group O is universal donor, Group AB is universal recipient.

Respiratory Diseases

• Disorders: Groups of symptoms disrupting normal functions without known causes.
• Diseases: Medical conditions with identifiable causes.
• Common respiratory diseases include:
  • Common Cold: Contagious upper respiratory infection.
  • Asthma: Chronic lung disease affecting multiple age groups.
  • Tuberculosis: Infectious disease usually targeting lungs.
  • Emphysema: Deterioration of lung alveoli.
  • Chronic Bronchitis: Inflammation of large airways.
  • Influenza: Viral infection involving nose, throat, and lungs.
  • Lung Cancer: Malignancy forming in lung tissues.

Cardiovascular Disorders

• Aneurysm: Swelling in blood vessel wall.
• Cardiac Arrhythmia: Abnormal heartbeat.
• Atherosclerosis: Thickening of arterial walls.
• Coronary Heart Disease: Insufficient oxygen-rich blood supply to the heart.
• Hypertension: High blood vessel pressure.
• Anemia: Insufficient hemoglobin in blood.
• Leukemia: Cancer of blood cells.

Genetics

• Genetics: Study of gene inheritance through generations.
• Genes: Related to Greek genos, meaning "offspring."
• DNA: Long chain of nucleotides encoding genetic information.
• Traits: Characteristic features of individuals.
• Alleles: Different versions of a gene.
• Dominance: Traits expressed through dominant alleles (e.g., TT for tall).
• Recessive: Traits requiring two copies to express (e.g., short trait).

Mendelian Inheritance Patterns

• Homozygous: Same alleles (e.g., TT or tt).
• Heterozygous: Different alleles (e.g., Tt).
• Gregor Mendel: Conducted pea plant experiments, known as "father of genetics."
• Chromosomes: Structures composed of DNA, with autosomes (22 pairs) and sex chromosomes (23rd pair).
• Laws of Inheritance:
  • Law of Unit Characters: Traits occur in pairs.
  • Law of Dominance: One allele can mask another.
  • Law of Segregation: Alleles separate during gamete formation.
  • Law of Independent Assortment: Alleles assort independently during gamete formation.

Genetic Variability

• Genetic Variability: Diversity in genotype due to genetic and environmental factors.
• Homologous Recombination: Changes in chromosome structure leading to varied traits.
• Hybridization: Breeding between different species.
• Migration: Movement of individuals or populations.
• Polyploidy: Presence of more than two homologous chromosome sets.
• Genetic Mutation: Changes in DNA sequence during cell division.

Sex Chromosomes

• Comprise X and Y chromosomes determining sex.
• Females have XX, males have XY.
• Autosomes: 22 pairs of chromosomes; carry inherited traits.

Patterns of Inheritance

• Non-Mendelian Patterns: Include incomplete dominance, multiple alleles, polygenic traits, and sex-linked traits.
• Examples: Hemophilia (blood clotting disorder), color blindness (color perception deficiency).

Biodiversity and Environmental Impact

• Evolution: Changes in species traits over generations.
• Extinction: Complete loss of organisms.
• Deforestation: Habitat loss through forest clearing and burning.
• Overexploitation: Removal of species faster than natural population growth.
• Pollution: Environmental contamination through various factors.

Photosynthesis

• Process converting light energy into chemical energy in plants.
• Occurs in chloroplasts, involving two phases:
  • Light-dependent Reactions: Convert light to ATP in thylakoids.
  • Light-independent Reactions: Use ATP and NADPH to synthesize glucose in stroma.