- Slides: 14
Human Respiratory System
Parts of respiratory system Nostrils • Opening called external nares. • Inner linings lined by mucus secreting cells • Hairs present to filter dust in inhaled air and also to warm air. • Nasal cavity divided into two by intranasal septum.
Parts of respiratory system Pharynx • Common passage for food and air lies behind the nasal cavity.
Parts of respiratory system Bronchus • Plural - Bronchi • Divisions of trachea before entering into the lungs. • Divide further into thinner bronchioles and finally into capillaries, which end into the alveoli.
Parts of respiratory system Alveolus • Plural-alveoli • Millions in each lung • Total surface area for gaseous exchange -90 m sq. • Alveolus surrounded by dense capillary network for exchange of gases by diffusion.
Breathing • Exchange of gases between breathing organs (Lungs) and the surroundings. • Physical process • Involves expenditure of energy. • No enzymes needed • Occurs outside cells. • Single step process.
Mechanism of breathing Inhalation- intake of air from surroundings into the breathing organ. • Intercostal muscles pull the rib cage upwards and outwards. • Diaphragm flattens • Thoracic volume increases • Air pressure inside thoracic cavity decreases, below atmospheric air pressure. • Air enters inside the lungs and ventilates it
Mechanism of breathing Exhalation- breathing out of air to the surroundings from the breathing organ. • Intercostal muscles pull the rib cage backwards and downwards. • Diaphragm becomes dome shaped. • Thoracic volume decreases • Air pressure inside thoracic cavity increases, above atmospheric air pressure. • Air moves out from the lungs.
Respiration Bio-oxidation of food to produce energy. • Cellular process • Bio-chemical process • Enzymes are needed • Energy produced is much more than used • Catabolic process • Multi-step process.
Types of respiration Aerobic • Takes place in abundant supply of oxygen. • Products formed are CO 2, water and 38 ATPs • Takes place in cytoplasm and mitochondria. • Takes place in animals and plants.
Types of respiration Anaerobic • In the absence of air • Products formed are Ethanol • Very less energy (2 ATPs) produced • Takes place in Bacteria. • Takes place in the cytoplasm. • Also called Fermentation.
Types of respiration Inadequate supply of oxygen • Forms lactic acid due to partial oxidation of glucose. • Causes muscular fatigue or cramps
Respiration in Unicellular organisms • By diffusion