Life Processes

• Nutrition is the process by which an organism takes food and utilizes it for energy to perform various activities
• Organisms need nutrients to supply energy and raw materials for growth and repair
• Nutrients are materials that provide nutrition to organisms, including carbohydrates, proteins, fats (macronutrients), and minerals, vitamins (micronutrients)
• Modes of Nutrition:

  • Autotrophic Nutrition: Organism prepares its own food (e.g. green plants, blue-green algae)
  • Heterotrophic Nutrition: Organism takes food from another organism (e.g. animals)
• Photosynthesis is the process by which green plants prepare food using sunlight, chlorophyll, CO2, and water
• Raw materials for photosynthesis:

  • Sunlight
  • Chlorophyll
  • CO2
  • Water with dissolved minerals like nitrogen, phosphorous
• Site of Photosynthesis: Chloroplast in the leaf, containing chlorophyll
• Main Events of Photosynthesis:

  • Absorption of light energy by chlorophyll
  • Conversion of light energy into chemical energy
  • Reduction of CO2 to carbohydrates
  • Release of oxygen as a by-product
• Functions of stomata:

  • Exchange of gases (O2, CO2)
  • Transpiration (loses water vapor)
• Significance of Photosynthesis:

  • Main way solar energy is made available for living beings
  • Green plants are main producers of food in the ecosystem
  • Helps maintain balance of carbon dioxide and oxygen in the air
• Heterotrophic Nutrition:

  • Organism takes food from another organism
  • Types: saprophytic, holozoic, parasitic
• Human Digestive System:

  • Composed of alimentary canal (mouth, esophagus, stomach, small intestine, large intestine, rectum, anus) and accessory glands (salivary gland, liver, pancreas)
• Structure of the Human Digestive System:

  • Alimentary Canal: mouth, esophagus, stomach, small intestine, large intestine
  • Associated Glands: salivary gland, gastric glands, liver, pancreas
• Mouth:

  • Contains teeth, tongue, salivary glands
  • Saliva contains salivary amylase for starch digestion
• Oesophagus:

  • Moves food from mouth to stomach through peristaltic movement
• Stomach:

  • Highly muscular walls for churning food
  • Secretes hydrochloric acid, pepsin for protein digestion
• Small Intestine:

  • Highly coiled tube for digestion and absorption
  • Divided into duodenum, jejunum, ileum
• Liver:

  • Produces bile for fat digestion
• Pancreas:

  • Secretes pancreatic juice with digestive enzymes
• Large Intestine:

  • Absorbs water and salts
  • Expels undigested food through the anus
• Nutrition in Amoeba:

  • Holozoic mode of nutrition
  • Steps: Ingestion, Digestion, Absorption, Assimilation, Egestion
• Respiration:

  • The process by which a living being utilizes food to get energy
  • An oxidation reaction
• Respiration is the process by which a living being utilizes food to get energy
• Respiration is an oxidation reaction where carbohydrates are oxidized to produce energy
• Mitochondria is the site of respiration and energy released is stored in the form of ATP (adenosine triphosphate)
• Steps of respiration:

  • Glucose is broken down into pyruvate in the cytoplasm
  • Further breakdown of pyruvic acid takes place in mitochondria
  • Respiration is of two types: aerobic and anaerobic
• Aerobic respiration happens in the presence of oxygen, converting pyruvic acid into carbon dioxide and water

  • Anaerobic respiration happens in the absence of oxygen, converting pyruvic acid into ethyl alcohol or lactic acid
• Pain in leg muscles while running is due to anaerobic respiration in muscles

  • Lactic acid deposition causes the pain, which subsides after rest
• Exchange of gases involves intake of oxygen and release of carbon dioxide

  • Different organisms use various methods for gas exchange, such as diffusion, respiratory systems, gills, spiracles, tracheae, and lungs
• Human respiratory system:

  • Composed of lungs, nostrils, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli
  • Air passes through the system controlled by the diaphragm and intercostal muscles
• Circulatory system in human beings is responsible for transporting substances

  • Composed of heart, arteries, veins, and blood capillaries
  • Blood carries substances throughout the body
• Human heart:

  • Muscular organ with four chambers
  • Functions to pump blood, maintain blood pressure, and circulate oxygen and nutrients
• Types of circulation:

  • Pulmonary circulation carries deoxygenated blood to the lungs and brings back oxygenated blood
  • Systemic circulation pumps oxygenated blood to organs and tissues, returning deoxygenated blood to the heart
  • Coronary circulation supplies oxygenated blood to the heart
• Structure of the human heart:

  • Divided into four chambers: two atria and two ventricles
  • Atria receive blood, ventricles pump blood
  • Right and left regions separated by the septum
  • Blood flow controlled by valves
• Heart chambers:

  • Atria: blood-receiving chambers fed by large veins, thinner walls, smaller than ventricles
  • Ventricles: responsible for pumping and pushing blood out to circulation, larger and more muscular than atria
  • Right ventricle and right atrium are smaller than the left chambers, with fewer muscles compared to the left portion
  • Blood from the right side flows through pulmonary circulation, while blood from the left chambers is pumped throughout the body
• Blood vessels:

  • Veins: supply deoxygenated blood to the heart via inferior and superior vena cava, draining into the right atrium
  • Capillaries: tiny tube-like vessels forming a network between arteries and veins
  • Arteries: muscular-walled tubes supplying oxygenated blood away from the heart to all parts of the body, with the aorta being the largest and branching into smaller arteries
• Valves:

  • Flaps of fibrous tissues located in cardiac chambers between veins
  • Ensure unidirectional blood flow and prevent backward flow
  • Atrioventricular valves: between ventricles and atria (tricuspid valve and mitral valve)
  • Semilunar valves: located between the left ventricle and aorta, and between the pulmonary artery and right ventricle
• Blood:

  • Connective tissue composed of plasma, blood cells, and platelets
  • Blood plasma: pale-colored liquid mostly composed of water, forming the matrix of blood
  • Blood cells: Red Blood Cells (RBCs) and White Blood Cells (WBCs)
  • Platelets: responsible for blood coagulation
• Lymph:

  • Similar to blood but without RBCs
  • Formed from fluid leaking from blood capillaries, collected through lymph vessels and returned to blood capillaries
  • Plays a role in the immune system
  • Lymph contains fewer proteins than blood and assists in transporting and destroying germs
• Double circulation:

  • Blood passes through the heart twice in one cardiac cycle
  • Ensures complete segregation of oxygenated and deoxygenated blood for optimum energy production in warm-blooded animals