Digestion and Respiration in Living Organisms

• Enzymes involved in digestion include Salivary amylase in the mouth, Pepsin in the stomach, Bile juice, and Pancreatic and Intestinal juices in the small intestine

• Salivary amylase breaks down starch

• Pepsin digests proteins and makes food alkaline and digests proteins and fats

• Pancreatic juice and Intestinal juice digests proteins, carbohydrates and fats

• Respiration is the production of bio-energy in the form of ATP in living organisms

• Respiration involves breaking down complex, high-energy food molecules into simple, low-energy molecules like CO₂ and H₂O, while releasing energy

• Respiration is an energy-releasing process associated with all living organisms

• Breathing occurs only in animals, not plants

• Aerobic respiration happens in the presence of oxygen, producing high energy

• In aerobic respiration, glucose is completely broken down by oxidation

• Anaerobic respiration occurs without oxygen, where food substances like glucose aren't completely oxidized, liberating less energy in tissue cells

• Anaerobic respiration occurs in bacteria and yeast cells

• Fermentation, a type of anaerobic respiration, is done by bacteria and yeast cells

• Wine and acetic acid are produced by fermentation

Summary of Types of Respiration:

• Aerobic respiration results in glucose being broken down into carbon dioxide, water, and ATP
• Anaerobic respiration breaks down glucose into lactic acid and ATP
• Fermentation breaks down glucose into ethanol, carbon dioxide, and ATP

Differences Between Aerobic and Anaerobic Respiration:

• Aerobic respiration occurs in all living organisms (plants, animals, microbes)
• Anaerobic respiration occurs only in some bacteria, fungi, germinating seeds, and animal tissues
• Aerobic respiration requires oxygen
• Anaerobic respiration doesn't require oxygen
• Aerobic respiration involves complete oxidation of food (glucose)
• Anaerobic respiration involves incomplete oxidation of food
• Aerobic respiration: one glucose molecule yields CO₂, water, and 38 ATP molecules
• Anaerobic respiration: one glucose molecule yields carbon dioxide, alcohol, and 2 ATP molecules

Animal Respiration Exchange:

• Some animals exchange gases with oxygen and carbon dioxide through their skin like earthworms, aquatic insects, frogs

• Grasshoppers use air tubes (tracheae) that open at the surface of the thorax and abdomen via spiracles

• Gills are filamentous structures found in 4-5 or more pairs of gill pouches of aquatic animals

• Lungs are found in most vertebrates except fish

• Lungs are spongy structures as found in man

The Human Respiratory System:

• Consists of a pair of lungs, the trachea (windpipe) which divides into two bronchi that enter lungs and divide to form bronchioles and alveolar ducts
• Alveoli are tiny, thin-walled, balloon-like structures
• The larynx is a box-like sound-producing organ made of cartilages, producing sound by vibrations of vocal cords
• The epiglottis guards the opening of the windpipe during swallowing
• The pleura is a pair of thin membranes covering the lungs, the pleural cavity contains pleural fluid
• Adam's apple is an anterior elevation on the neck
• The diaphragm is a dome-shaped muscle below the lungs, its contraction and relaxation aid breathing
• Intercostal muscles are externally attached to the ribs, their contraction helps in respiration
• Inspiration is the mechanism by which air enters the lungs
• Expiration is the mechanism by which air leaves the lungs
• Exchange of gases (oxygen and carbon dioxide) occurs between the blood and air in the alveoli
• The exchange of gases occurs due to the diffusion of gases from regions of higher concentration to lower concentration
• Hemoglobin is a respiratory pigment that transports oxygen
• Oxygen combines with hemoglobin to form oxyhemoglobin
• CO₂ is transported from cells to the lungs
• Breathing is involuntary, controlled by the respiratory center in the medulla
• The respiratory system functions in gaseous exchange