PHYS 2 NOTES ALL (textbook and lecture chapters 7, 8, 11, 12 13)

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York University
Kinesiology & Health Science
KINE 3012
Tanya Da Sylva

Chapter 11 Respiratory System INTRODUCTION Primary function to obtain O2 for use of the bodys cells to eliminate CO2 that cells produce External Respiration It is the entire sequence of events in exchange between external environment and cells of body 4 Steps of External Respiration 1 Air is moved in and out of lungs Between external environment and alveoli done by breathingventilationVentilation is regulated according to the needs of the body for O2 and CO2 removal 2 O2 diffuses from air into alveoli into blood pulmonary capillaries CO2 goes into alveoli opposite direction 3 Blood transports O2 from lungs to tissues and CO2 from tissues to lungs 4 O2 and CO2 are exchanged between tissues and blocked by diffusion across capillariesAnatomy of Respiratory System 2 components1 Lungsaairways b alveoli 2 Chest wall LungsLungs occupy most of the thoracic cavity2 lungs separated by lobes supplied by each of the bronchi a Airways o Are between the atmosphere and where exchange of C02 and O2 occurs o Nasal pharynx nosepharynx throatesophagus Trachea o Since the pharynx is the passageway for food as well reflex mechanisms close the trachea during swallowing so food enters the esophagus not airways o The esophagus remains closed except when swallowing controlled in brainstem o The larynx is located on top of the trachea anteriorAdams apple o Vocal folds are on top of opening of larynx laryngeal muscles control length and shape of these muscles o Lips tongue soft palate modify vibrations into recognizable soundso During swallowing vocal cords are brought close together to prevent entry of food o After the larynx the trachea divides into left and right bronchibronchioles some gas exchange occursalveoli clustered ends of bronchioles gas exchange occurs between blood and alveoli o For flow in and out of alveoli the airway must remain open o The airways are kept open in many ways a The trachea and bronchi are encircled by cartilaginous rings that help airways resist compression during compression ex Coughing the trachea is an incomplete cartilaginous ring and connects both ends by smooth muscle b Bronchioles have no cartilage but have smooth muscle controlled by autonomic system thus can control the resistance between air flow between atmosphere and alveoli Poiselles Law o Airwaysconvection alveolidiffusionSmall arteries resistance to flowLarger arteries resistance to flowSA diffusion alveolithe beginning is convective air flowing through trachea then bronchi to diffusion bronchiolesalveoli b Alveoli o composed of 2 epithelial cells 1 type I in alveolar wall 2 type II secrete pulmonary surfactant helps lung expansion and stabilizes alveolar dimensions Chest WallFormed by 12 pairs of ribs which join the thoracic vertebraeRibs 17 join the sternum anteriorilyRib cage protects lungs and heartChest wall contains muscles that generate pressure required for airflowmain inspiratory muscles are 1 DiaphragmLarge sheet of skeletal muscle forms floor of thoracic cavity and separates it from thoracic cavityPenetrated by only esophagus and blood vessels in thoracic regionInnervated by phrenic nerves come from C3C5At rest diaphragm is dome shaped round part goes into thoracic cavityDuring inspiration it goes downward enlarging the volume of the thoracic cavity by increasing cavities vertical dimensionsThe abdominal wall pushes outward during inspiration as the descending diaphragm moves abdominal contents outward and forward5075 of enlargement of thoracic cavity during inspiration is due to contraction of diaphragmWhen the diaphragm contractsmoves down the volume of the lungs increases therefore pressure decreases since air moves from high pressure to low pressure air flows into the lungs 2 External intercostal muscles inspiratoryInternal intercostals lie between ribs and the external intercostals are lie right on top of the internal intercostalsExternal intercostals help enlarge the thoracic cavity laterally sidetoside and anteriorposteriorilyWhen the external intercostals contract they elevate the ribs moving sternum upward and outwardsIntercostal nerves activate these intercostal muscles T1T12Many physiologists think that main reason for activating external intercostals is to stabilize the chest wall from being sucked in during inspiration this increases the efficiency of the diaphragm because contraction is used to inflate the lungs rather than being wasted on moving the chest wall Internal intercostals expiratory Expiratory muscles consist of internal intercostals and abdominal muscles rectus abdominis transverse abdominis and externalinternal obliquesThese muscles are inactive in healthy humans but activated during exercise coughing sneezing when ventilatory demands increaseExpiratory can generate more pressure than inspiratory muscles since reflexes like coughing and sneezing are so importantInternal intercostals innervated by same thoracic nerves as external intercostals Abdominal innervated by nerves coming off T7L1 The Pleural Space
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