Respiration and Cellular Respiration

1.3 Respiration Definition: Respiration is the process in which oxygen enters into the cells and oxidizes various food substances like carbohydrates, fats and proteins present in them is called as respiration. Cellular Respiration   Transformation of chemical energy in food into chemical energy cells can use: ATP These reactions proceed the same way in plants and animals and the process is called cellular respiration. Overall Reaction: – C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy (Sugar) There are two types of respiration:   Aerobic, which requires oxygen and releases lots of energy Anaerobic, which does not require oxygen but releases much less energy per mole of starting material. Aerobic Respiration:         When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration. Occurs in the presence of oxygen in all living cells of higher plants. Oxygen is required. The substrate is completely oxidized to CO2 , H2O and energy. Energy liberated during oxidation of 1 glucose molecule is 38 ATP. Steps involved – Glycolysis (Glucose is converted into 2 molecules of pyruvic acid) (Takes place in the cytoplasm) Aerobic oxidation of pyruvic acid into CO2 and H2O ( Takes place in the mitochondria) Anaerobic Respiration:              Food can also be broken down, without using oxygen. This is called anaerobic respiration. Breakdown of food releases energy. Occurs in bacteria, certain fungi, germinating seeds and fleshy fruits. Oxygen is not required. The end products are alcohols or acids and CO2. Energy liberated during oxidation of 1 glucose molecule is 2 ATP. All reactions take place in the cytoplasm. Anaerobic respiration in humans may be summarized by the word equation: Glucose lactic acid + energy In yeast anaerobic respiration may be summarized by: Glucose ethanol + carbon dioxide + energy During glycolysis, glucose molecules (six-carbon molecules) are split into two pyruvates (three-carbon molecules) during a sequence of enzyme-controlled reactions. Without oxygen, pyruvate is converted to lactic acid in animals or ethanol in plants and yeast. It produces only about 10% of the energy released in the complete oxidation of glucose. Anaerobic respiration in humans takes place when muscle undergoes extreme contraction as in vigorous exercise. 1.3.2 Types of respiratory surfaces: General body surface: Cell membrane - ex. Amoeba.   Amoeba, being a unicellular organism, don't have specialized respiratory apparatus-like lungs or gills. Instead, it relies on a simple and efficient process called diffusion for gas exchange through its body surface. Respiration in amoeba:    Dissolved Oxygen: Oxygen needed for cellular respiration is dissolved in the water environment where amoeba lives. Cell Membrane: The thin and permeable cell membrane of the amoeba acts as the surface for gas exchange. Passive Diffusion: Due to the difference in concentration, oxygen constantly diffuses from the surrounding water (higher concentration) into the cytoplasm of the amoeba (lower concentration), it does not require energy from the amoeba, hence this process is called as passive transport.   Cellular Respiration: The absorbed oxygen is then used within the amoeba's cells for cellular respiration, the process by which they convert glucose and other nutrients into energy (ATP). Carbon Dioxide Release: Carbon dioxide, a waste product of cellular respiration, diffuses out of the amoeba's cell membrane back into the surrounding water. Advantages of Diffusion for Amoeba:   Simple and Efficient: Due to its small size and high surface area to volume ratio, diffusion allows amoeba to meet its oxygen needs effectively without complex respiratory organs. Low Energy Requirement. Limitations of Diffusion:   Diffusion becomes less efficient as the organism grows larger. In larger organisms, diffusion alone would not be sufficient to meet their oxygen needs. Skin - ex. Earthworm and Frog Earthworm:      An earthworm is a terrestrial invertebrate that lives on the earth surface. They help in keeping the soil porous and suitable for agriculture. They can breathe through their skin. Respirationis done with the help of thin permeable skin. An earthworm’s body is divided into several segments, which are segmented by multiple septa and contain nephridia, which aid in exhalation. Respiratory Apparatus an Earthworm     Earthworms lack specialized respiratory organs. Except for the first three anterior segments and the last posterior segment, all body segments include nephridia. They use nephridia, coiled tubular duct-like organs that filter and eliminate waste from their bodies, made of apertures that extend to the skin. Each segment can expel waste gases through these openings in the earthworm’s skin. Respiration through skin: Frog    Frogs come under the amphibian species. It means that these species can live on both land and water. Unlike fish with gills or insects with tracheal systems, frogs utilize a combination of three different surfaces for gas exchange. Lungs:     These are the primary organs for respiration on land, like those found in mammals. Frog lungs are sac-like organs located in the frog's chest cavity. They are not as complex or efficient as mammalian lungs, but they suffice for gas exchange on land. During respiration on land, air enters and leaves the lungs through nostrils and a single trachea that splits into two bronchi, each supplying air to a lung. Skin:     The thin and moist skin of a frog plays a crucial role in gas exchange, especially when submerged in water. A frog's skin is thin, moist, and highly vascularized, meaning it contains a network of blood vessels close to the surface. This allows for the diffusion of oxygen from the water directly into the blood and the release of carbon dioxide from the blood into the surrounding water. Mucus glands in the skin keep the frog's skin moist, which is essential for efficient gas exchange through the skin. Buccal Cavity Lining:   The moist lining of the mouth cavity can also absorb some oxygen dissolved in water, especially when a frog stays underwater for a long time. However, the contribution of the buccal cavity to gas exchange is minimal compared to the lungs and skin.  Respiratory System in Cockroach: Trachea and spiracles:  A cockroach is an insect that lives in damp places.     It is omnivorous, eating small insects, grains, cereals, other plants, and animal products; as a result, it consumes all organic materials. Cockroaches have a unique respiratory system, which is called the tracheal system. The trachea, often known as the windpipe, is a tubular structure that helps to transmit air. The tracheal system is a network of tracheal tubes that insects, especially cockroaches, use to extract oxygen from the air around them. The respiratory system of a cockroach is segmented into three different parts: Spiracles –      These are tiny holes seen on the main body’s lateral surface. These are similar to human noses in that they are open to the air and have apertures. As a result, the air is inhaled through spiracles, and it goes through the tracheal tube. Muscle sphincters control the opening of the spiracles. When the sphincters open, air enters the holes; when they close, air does not pass anymore Trachea –  This portion transports oxygen from the air (received through spiracles) to other body parts through tube-like structures that open through spiracles Tracheoles –   These are trachea portions that have been subdivided into thinner tube-like structures. Tracheoles have a fluid network (hemolymph), and they are the places where gaseous exchange occurs by diffusion. Respiratory Apparatus in Fishes: Gills of fish     The gills are the main organ by which gases are exchanged between the fish and the surrounding water. Through the gills, fish are able to absorb oxygen and give off carbon dioxide. Like the lungs, the gills have a large area for gaseous exchange.  Some species have altered gills and other organs so that they can take atmospheric air and extract the oxygen like skin, air bladder etc. Structure of fish gill       Gills are located on either side of the head, behind and below the mouth. The region between the buccal cavity (mouth) and the oesophagus is called the pharynx. They are covered by a protective bony plate called the operculum in bony fish (teleosts) or by a fold of skin in sharks and rays. These slits are called the gill slits. The gill slits are separated by a tissue called the gill arch or the branchial arch. Gill filaments are feathery structures containing numerous thin, flattened plates called lamellae. Gas Exchange in Gills: 1. Water Flow: Fish take in water through their mouths. Muscular contractions help draw water in or force it out over the gills. 2. Counter current Flow: An important adaptation is the counter current flow mechanism. Water flows in the opposite direction to the blood flow in the gill filaments. This creates a concentration gradient that facilitates the efficient diffusion of gases. 3. Oxygen Uptake: Oxygen dissolved in the water diffuses across the thin membranes of the lamellae into the bloodstream within the gill filaments. 4. Carbon Dioxide Release: Conversely, carbon dioxide, a waste product of cellular respiration in the fish's body, diffuses from the blood into the water flowing over the lamellae. 5. Water Expulsion: The water laden with carbon dioxide is then expelled through gill openings or slits on the sides of the body. Lungs of Human   The mammalian respiratory system is a well-developed machine designed to efficiently extract oxygen from inhaled air and eliminate carbon dioxide, a waste product of cellular respiration. Here is a breakdown of the key components and their functions Main Organs: Lungs:   These are the powerhouse organs of the respiratory system, located within the chest cavity. They are spongy, air-filled organs with a massive surface area for gas exchange. Trachea (Windpipe): This tube connects the nasal cavity to the bronchi, acting as a passage for air to enter and exit the lungs. Bronchi: These are two branching tubes that emerge from the trachea and lead to each lung. Bronchioles: The bronchi further divide into smaller tubes called bronchioles, which penetrate deep within the lungs. Alveoli: Bronchioles terminate in clusters of tiny, sac-like structures called alveoli. These are the sites where gas exchange between air and blood takes place. Process of Respiration: 1. Inhalation: We take in air through our nostrils. The nasal cavity filters dust, warms, and humidifies the air. 2. Trachea and Bronchi: The filtered air travels down the trachea and into the bronchi. Rings of cartilage in the trachea and bronchi help keep them open during inhalation. 3. Gas Exchange in Alveoli: Within the alveoli, oxygen from the inhaled air diffuses across the thin alveolar walls and into the bloodstream. Simultaneously, carbon dioxide diffuses from the blood into the alveoli. 4. Exhalation: The blood now rich in oxygen and depleted of carbon dioxide travels throughout the body. We exhale the air containing excess carbon dioxide back out through the bronchi, trachea, and nasal cavity. The Role of the Diaphragm:     The diaphragm, a dome-shaped muscle below the lungs, plays a crucial role in respiration. During inhalation, the diaphragm contracts and flattens, enlarging the chest cavity. This creates a negative pressure that draws air into the lungs. Exhalation is a more passive process, where the diaphragm relaxes, and the chest cavity recoils, pushing air out of the lungs. Accessory Organs and Functions: Larynx (Voice Box): Located at the top of the trachea, the larynx contains vocal cords that vibrate to produce sound during speech. Pharynx: This muscular passage connects the nasal cavity and mouth to the trachea and esophagus. It plays a role in swallowing and the passage of air.