Gaseous exchange powerpoint.pdf

Y SYSTEMS THE BOD GASEOUS EXCHANGE  DIFFERENCE BETWEEN CELLULAR RESPIRATION, BREATHING AND GAS EXCHANGE Cellular respiration – a Breathing– the physical Gas exchange – The chemical process occurring process whereby air moves excha...

Y SYSTEMS THE BOD GASEOUS EXCHANGE  DIFFERENCE BETWEEN CELLULAR RESPIRATION, BREATHING AND GAS EXCHANGE Cellular respiration – a Breathing– the physical Gas exchange – The chemical process occurring process whereby air moves exchange of oxygen (O2) and inside cells in which food in and out of the lungs carbon dioxide (CO2) across molecules such as glucose a gaseous exchange surface. are broken down to release energy REQUIREMENTS OF EFFICIENT GAS EXCHANGE ORGANS  REQUIREMENTS OF EFFICIENT GAS EXCHANGE ORGANS The gas exchange surface must be large – to provide sufficient oxygen and to get rid of sufficient carbon dioxide The gas exchange surface must be thin – to ensure rapid diffusion of gases The gas exchange surface should be moist – to prevent cells from drying out and to ensure that gases (oxygen and carbon dioxide) can diffuse in a dissolved sate. The gas exchange organs must be well-ventilated – to ensure fresh supplies of air containing oxygen from the external environment and to remove air containing carbon dioxide. The gas exchange surface must be well protected – to prevent drying out and damage The gas exchange surface must have a transport system – for efficient transport of gases between gas exchange organs and body cells  HUMAN GAS EXCHANGE- STRUCTURE, LOCATION, FUNCTIONS AND ADAPTATIONS OF THE VENTILATION SYSTEM 01 Nose and Nasal Cavity 02 Mouth and Oral Cavity RESPIRATORY SYSTEM The nose and nasal cavity are They serve as an alternative responsible for filtering, entry point for air as they 01 warming, and moistening the allow you to breathe through air you breathe in. your mouth. 02 03 Pharynx (Throat) 04 Larynx (Voice Box) 03 04 Pharynx is a common passage The larynx contains the vocal for both air and food. It cords, which vibrate to connects the nasal cavity and produce sound during speech. mouth to the larynx. 05 05 Trachea (Windpipe) 06 Bronchi and Bronchioles The trachea is a tube that The bronchi branch off from carries air from the larynx to the trachea and lead to the the bronchi. It is lined with lungs. They further divide into cilia. smaller bronchioles. 06 07 07 Alveoli 08 Diaphragm Alveoli are tiny air sacs at the The diaphragm is a dome- end of the bronchioles. They shaped muscle that play a crucial role in gas separates the chest cavity exchange during breathing. from the abdominal cavity. 08  NASAL CAVITIES The two external nostrils lead to two nasal cavities that are separated by a septum Small hairs in the nasal cavities filter large particles from the inhaled air Each nasal cavity is divided into three passages by three curved turbinate bones. The nasal cavities are lined with a mucous membrane that consists of ciliated columnar epithelial cells The epithelial cells are richly supplied with blood capillaries that warms the incoming air Goblet cells in the epithelium secrete mucus that moistens the incoming air, traps dust and germs and is antiseptic. Cilia on the epithelial cells perform sweeping movements in a direction away from the lungs to expel dust – carrying mucus to the outside.  X (THROAT) PHARYN The nasal cavities open into the pharynx. The pharynx leads to two openings i.e. the opening known as the glottis which leads to the trachea and the opening that leads to the oesophagus  TRACHEA The trachea is a long, tubular structure located at the front of the oesophagus The larynx (voice box) with the vocal chords is located at the top of the trachea The epiglottis is at the top of the larynx and consists of cartilage The epiglottis closes the glottis during the swallowing process and prevents food from entering the trachea The walls of the trachea are supported and kept open by C-shaped cartilage rings. The trachea is lined with ciliated columnar epithelium with goblet cells that secrete mucus. The mucus moistens the incoming air and trap dust particles Mucus with trapped foreign particles are moved to the pharynx through the sweeping actions of the cilia  BRONCHI The trachea branches into two bronchi that enters the right and left lung The bronchi are also lined with a mucous membrane and are held open by O-shaped cartilage rings The bronchi divide into smaller branches inside the lungs and form the bronchioles  BRONCHIOLES The bronchioles do not have cartilage rings and their walls consist of smooth muscle that can contract and relax to alter air flow. Each bronchiole ends in an infundibulum which consists of groups of alveoli.  ALVIOLI The millions of alveoli increase the gaseous exchange surface The walls of the alveoli are thin and consists of a single layer of squamous epithelium. These thin walls allow for efficient gaseous exchange A thin layer of tissue fluid lines the inside surface of the alveoli and keep the surface of the alveoli moist, preventing the cells from drying out. The alveoli are surrounded by a network of capillaries. Capillaries transport oxygen to the tissues and carbon dioxide to the lungs The walls of the capillaries are thin and consist of a single layer of squamous epithelium to allow for efficient gaseous exchange.  LUNGS The two lungs are located in the chest and are protected by 12 pairs of ribs. The lungs are spongy and elastic and can expand and contract during breathing The right lung has three lobes and the left lung has two lobes Each lung is surrounded by a double membrane, the pleura The fluid between the pleura prevents friction when the lung expands or shrinks  ADAPTIONS OF THE LUNGS AND THEIR FUNCTIONS ADAPTION FUNCTION The lungs are spongy and elastic. can expand and contract easily during breathing Lungs are surrounded by a double membrane, with intrapleural prevents friction during breathing fluid between the two membranes Bronchioli eventually end in millions of alveoli increase the gaseous exchange surface Wall of an alveolus consists of a single layer of squamous thin surface for efficient gaseous exchange epithelium Alveoli are surrounded by a network of blood capillaries. transport of O2 to the tissues and COz to the lungs Walls of the blood capillaries consist of a single layer of thin surface for efficient gaseous exchange endothelium.  RESPIRATORY MUSCLES AND THE RIBS Diaphragm The diaphragm is a dome-shaped muscle plate which separates the chest and the abdomen The diaphragm contracts and flattens altering the volume of the chest cavity and is important in breathing. Intercostal muscles The intercostal muscles are located between consecutive ribs and consists of the external and internal intercostal muscles. The intercostal muscles contract and relax during inhalation and exhalation altering the volume of air in the chest (thoracic cavity) Ribs The ribs are on either side of the sternum, protect the lungs from injury VENTILATION OF THE LUNGS INHALATION EXHALATION  INHALATION/ INSPIRATION EXHALATION/ EXPIRATION This is the active phase of breathing This is the passive phase of breathing The external intercostal muscles contract The external intercostal muscles relax Causing the ribs to move upward and outwards Causing the ribs to move downwards and inwards The diaphragm contracts and becomes flatter The diaphragm relaxes and become dome-shaped The volume of the thoracic cavity increases The volume of the thoracic cavity is decreased The abdominal muscles relax so that the abdominal cavity can The abdominal muscles contract and force the abdominal content accommodate all the internal organs upwards against the diaphragm The pressure in the thoracic cavity and lungs decrease The pressure in the thoracic cavity and lungs increase The elastic lungs expand The elastic lungs are compressed Atmospheric pressure is higher than the pressure of air in the Air pressure in the lungs is higher than in the atmosphere lungs Air rich with oxygen(O2) flows into the lungs Air rich with carbon dioxide (CO2) flows out of the lungs  MODEL OF BREATHING https://www.youtube.com/watch?v=fybV8zIGyu8  GASEOUS EXCHANGE  GASEOUS EXCHANGE AT THE ALVEOLI SURFACE The inhaled air in the alveoli has a higher oxygen concentration than the blood in the surrounding blood capillaries The oxygen dissolves in the thin layer of moisture that lines the alveoli and diffuses through the thin walls of the squamous epithelium of the alveoli and endothelial walls of the capillaries into the blood. The blood that reaches the alveoli from the tissues has a higher concentration of carbon dioxide than the air in the alveoli Carbon dioxide diffuses from the blood in the capillaries through the endothelial walls of the capillaries and the thin squamous epithelial walls of the alveoli into the air in the alveoli.  GASEOUS EXCHANGE BETWEEN THE BLOOD AND TISSUES Oxygenated blood reaches the tissues The blood in the capillaries has a higher oxygen concentration than the cells of the tissues Oxygen diffuses through the endothelial walls of the capillaries into the tissue fluid that surrounds the cells and then into the cells The cells have a higher carbon dioxide concentration than the blood in the capillaries Carbon dioxide diffuses from the cells into the tissue fluid and then diffuses into the blood in the capillaries. TRANSPORT OF GASES IN THE BLOOD  TRANSPORT OF GASES IN THE BLOOD Transport of oxygen: Most of the oxygen that diffuses from the air in the alveoli to the blood in the capillaries combines with haemoglobin in the red blood cells (erythrocytes) to form oxyhaemoglobin. A small portion of oxygen dissolves in the blood plasma and is transported in solution. Transport of carbon dioxide: Most of the carbon dioxide that diffuses from the cells into the blood in the capillaries is transported as bicarbonate ions. Carbon dioxide combines with water to form carbonic acid. The carbonic acid dissociates and is forms bicarbonate ions. Some of the carbon dioxide combines with heamoglobin to form carbaminohaemoglobin. The carbon dioxide is then transported in this form by the erythrocytes to the lungs. The smallest portion of carbon dioxide dissolves in the blood plasma and is transported in solution.  EFFECTS OF EXERCISE ON THE RATE AND DEPTH OF BREATHING EFFECTS OF EXERCISE ON THE RATE AND DEPTH OF BREATHING After exercise, several mechanisms ensure that the person’s body has enough oxygen available · Increased respiratory rate and depth to bring more oxygen into the lungs · Vasodilation in skeletal muscles to enhance blood flow / oxygen delivery · Increased cardiac output to pump oxygenated blood more rapidly to tissues HOMEOSTATIC CONTROL OF BREATHING  HOMEOSTATIC CONTROL OF BREATHING Carbon dioxide (CO2) levels in the blood increase above normal levels Receptor cells in the carotid artery in the neck are stimulated Cells send impulses to the medulla oblongata in the brain Medulla oblongata stimulates breathing muscles (intercostal muscles and diaphragm) and heart Breathing muscles contract more actively – increases the rate and depth of breathing; the heart beats faster More CO2 is taken to and exhaled from the lungs The CO2 levels in the blood return to normal  QUESTIONS JE 2023 & 2022 UNIT 4 Q 3,4,5 &8