GAS EXCHANGE IN ORGANISMS

Overview (DO NOT COPY) Breathing: a mechanical process that moves air in & out of the lungs June 23, 2016A.Y. Jackson – SNC2D2 Air inhaledAir exhaled INHALATION Diaphragm contracts (moves down) EXHALATION Diaphragm relaxes (moves up) Diaphragm Lung Rib cage expands as rib muscles contract Rib cage gets smaller as rib muscles relax

(DO NOT COPY) Respiration: a process in all cells (organisms) in the body where food (glucose) & oxygen are taken in to release energy (ATP) for the cell June 23, 2016A.Y. Jackson – SNC2D3 C 6 H 12 O 6 +6 O 2  6 CO 2 +6 H 2 O glucose+oxygen  carbon dioxide+water

Source of Oxygen Air about 20.96% oxygen (less at higher altitudes) about 79% nitrogen about 0.04% carbon dioxide Water amount of oxygen varies (0.6% – 0.8%) much less than air even lower in warmer water June 23, 2016A.Y. Jackson – SNC2D4 Overview (do not copy)

Overview Gas Exchange: provides a means of supplying an organism with O 2 and removing the CO 2 (waste) June 23, 2016A.Y. Jackson – SNC2D5

June 23, 2016A.Y. Jackson – SNC2D6 Gas Exchange Surfaces Gas Exchange: gases move by diffusion Requires: - moist surface - large area

Types of Gas Exchange and Surfaces Types of gas exchange: in simple organisms, gas exchange, does not require specialized surface 1. direct diffusion (ex: single cell organisms like bacteria and amoeba) in complex organisms, gas exchange requires specialized respiratory surfaces 2. gill (external or internal) system 3. tracheal system 4. lung system June 23, 2016A.Y. Jackson – SNC2D7

Gills are outfoldings of the body surface specialized for gas exchange have a simple shape in some animals, found outside of the body June 23, 2016 A.Y. Jackson– SNC2D8 Gas Exchange – 2. Gill Systems (external) Gills Tube foot Coelom

Gill arch Water flow Operculum Gill arch Blood vessel Gill filaments Oxygen-poor blood Oxygen-rich blood Water flow over lamellae showing % O 2 Blood flow through capillaries in lamellae showing % O 2 Lamella 100% 40% 70% 15% 90% 60% 30% 5% O2O2 The gills of many other animals are restricted to a local body region example: clams crayfish fish June 23, 2016A.Y. Jackson – SNC2D9 Gas Exchange – 2. Gill Systems (internal)

Effectiveness of gas exchange in some gills is increased by the flow of blood and water June 23, 2016A.Y. Jackson – SNC2D10 Gas Exchange – 2. Gill Systems (internal)

Gas Exchange – 3. Tracheal System Tracheal system: consists of tiny branching (tracheal) tubes that penetrate the body air enters the tracheae through openings called spiracles on the insect’s body surface air passes into smaller tubes called tracheoles (contain fluid) supply O 2 directly to body cells June 23, 2016A.Y. Jackson – SNC2D11 Tracheae Air sacs Spiracle Air sac Cell Body Trachea Tracheole Tracheoles Body wall Air Spiracle

Gas Exchange – 4. Lungs A system of branching ducts transports air to the lungs linked to blood transport system examples: most terrestrial vertebrates spiders land snails June 23, 2016A.Y. Jackson – SNC2D12

Amphibians: gas exchange through skin and lungs frogs draw air into their mouth by contracting muscles in their throat and mouth during hibernation, gas exchange occurs exclusively through skin June 23, 2016A.Y. Jackson – SNC2D13 Gas Exchange – 4. Lungs

Birds: birds have lungs and air sacs: air sacs are not sites of gas exchange air sacs enable a one-way flow of air through lungs June 23, 2016A.Y. Jackson – SNC2D14 INHALATION Air sacs fill EXHALATION Air sacs empty; lungs fill Anterior air sacs Trachea Lungs Posterior air sacs Air 1 mm Air tubes (parabronchi) in lung

Gas Exchange – 4. Lungs Mammals: passageway connects internal lungs to external environment system of tubes (held open by rings of cartilage) allow air to flow in and out of lungs tubes lead to tiny air sacs (alveoli) June 23, 2016A.Y. Jackson – SNC2D15 air enters via trachea (windpipe) trachea branches into two bronchi (one bronchus to each lung) bronchi branch into bronchioles many alveoli (one alveolus) at the end of the bronchioles

Gas Exchange – 4. Lungs (fill in blanks on handout) Mammals: Many alveoli at the end of the bronchioles walls made of flat cells; only one cell thick each alveolus lined with moisture surrounded by capillary network carrying blood June 23, 2016A.Y. Jackson – SNC2D16

Gas Exchange – 4. Lungs June 23, A.Y. Jackson – SNC2D

Homework June 23, 2016A.Y. Jackson – SNC2D18 Gas Exchange Homework Sheet