Chapter 13. The Respiratory System.

Transcription

1 Chapter 13 The Respiratory System

2 Primary Function of Breathing Gas Exchange (simple diffusion) Oxygen from the air enters the blood to be carried to all body cells Carbon dioxide from the blood enters the lungs to be removed

3 Overview of Breathing Inspiration Breathing in Also called inhalation Air is conducted into the lungs Expiration Breathing out Also called exhalation Air is conducted out of the lungs

4 Four Respiratory Events Pulmonary Ventilation (breathing) the entry and exit of air into and out of lungs External Respiration Gas exchange between air and blood site = lungs Internal Respiration Gas exchange between blood and tissue fluid site = tissues Transport of gases To and from the lungs and the tissues

5 Why O 2? Cellular Respiration Production of ATP in the cells ATP = energy supply for the cells Requires oxygen Releases carbon dioxide Cellular respiration requires the four respiratory events

6 Overview Upper Nose Nasal Cavity Pharynx Larynx Lower Trachea Bronchi Lungs

7 The Nasal Cavity Nasal Conchae bony ridges Increase surface area Olfactory Epithelium high in the nasal cavity Odor receptors on the cilia of cells The Nasal Septum Bony separation between the nasal cavities

8 The Nasal Cavity cleansing of air by coarse nostril hair, cilia, and mucus Cilia inside nasal cavity beat mucus into the throat for swallowing Cilia in trachea and bronchi beat mucus upward into the pharynx Lysozymes in mucus-kills bacteria

9 The Nasal Cavity mucous membrane warms and moistens inhaled the air Cools air during expiration Moisture deposited on trachea Nose may drip condensation

10 Mucociliary Escalator What tissue type?

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12 The Pharynx Commonly referred to as the throat Passageway and connection between the nasal and oral cavities Three parts: Nasopharynx Oropharynx common path for food and air Laryngopharynx -Leads to the larynx

13 The Larynx The voicebox Cartilaginous structure Passageway of air between the pharynx and the trachea Adam s apple thyroid cartilage Vocal cords mucosal folds Glottis opening between the folds Vibrate to produce sound

14 Vocal cords

15 Swallowing of food The larynx moves up against the epiglottis Epiglottis a flap of elastic cartillage closes Food is prevented from entering the larynx through the glottis

16 The Trachea Commonly known as the windpipe Flexible tube connects larynx to the primary bronchi Ventral (anterior) to the esophagus Is held open via a C-shaped cartilage Is lined by pseudostratified ciliated columnar epithelium

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18 Tracheostomy Insertion of a breathing tube via an incision in the trachea

19 The Bronchial Tree The trachea divides into R and L primary bronchi The primary bronchi branch into secondary bronchi The secondary bronchi branch into tertiary bronchi Brochioles the smallest conducting airways Contraction of smooth muscle during Asthma attack

20 Alveoli Pockets (sacs) connected to each bronchiole Fill up with air during inhalation Simple squamous epithelium Site of gas exchange Surrounded by pulmonary capillaries

21 The Lungs Paired organs inside the ribcage Each lung is inside its own pleural cavity Each lung is surrounded by visceral and parietal pleura Apex superior narrow portion Base inferior broad portion Lies on top of the diaphragm Divided into lobules made of alveoli

22 Location of the Lungs Thoracic cavity (sealed) Ribs join Sternum anteriorly & Vertebrae posteriorly Intercostal muscles between ribs Diaphragm thin muscle, forms the floor Pleurae Visceral on the lung surface Parietal attached to the thoracic wall Pleural fluid in between Intrapleural pressure between the pleura Lower than the atmospheric pressure Keeps lungs inflated

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24 Ventilation Entry and exit of air into and out of the lungs

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26 Inspiration Active phase of ventilation Diaphragm and intercostals contract Diaphragm flattens Ribs move up and out Lungs volume increases Air pressure in alveoli decreases (intrapulmonary pressure) Partial vacuum Alveolar P < atmospheric P Inward passive airflow until pressures equalize

27 Expiration Usually a passive phase No muscle effort required Diaphragm and external intercostal muscles relax Dome shaped diaphragm Rib cage down and in Lungs recoil P intra-alveolar (intrapulm.) > P atmosphere Prevention of collapse due to surfactant on alveoli Surfactant lowers surface tension

28 Maximum Inspiratory Effort Exercise, Strenuous activities Accessory Muscles of respiration required: Erector spinae (back), abdominals Pectoralis minor (chest) Scalene and sternocleidomastoid (neck) Maximum lung expansion

29 Forced Expiration Blowing into a musical instrument Using Internal intercostals, abdominals

30 Spirometer Determines if a medical problems is preventing lungs from: Filling with air Releasing air Spirometer records the volume of air exchanged during: Normal and deep breathing Spirogram is created

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32 Respiratory Volumes Tidal Volume amount of air that moves in and out when we are relaxed 500ml Vital Capacity - amount of air that moves in and out during deep breathing Inspiratory Reserve V + Expiratory Reserve V. Inspiratory Reserve Volume 2900ml above the tidal volume forced inspiration Expiratory Reserve Volume 4900 ml

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34 Dead Air Space Inhaled air that never reaches the alveoli Remains in the nasal cavities, trachea, bronchi, and bronchioles About 30% of the tidal volume Can reduce this by breathing slowly and deeply

35 Residual Volume Air that is not exhaled and remains in the alveoli About 1000ml Has a large amount of CO2 Is not used for gas exchange Increase in residual volume in Emphysema Vital capacity is reduced

36 Respiratory Control Nervous Input Chemical Input

37 Normal Ventilation Normal adult breathing rate: ventilations/minute Controlled by the primary respiratory center Located in medulla oblongata

38 Primary Respiratory Center Automatic motor input to the diaphram The phrenic nerve

39 Normal Breathing Rhythm Pons in conjunction with medulla oblongata

40 Other Nervous Input Additional input from the higher Centers of the brain can cause changes in breathing cerebral cortex limbic system hypothalamus emotions Conscious control of respiration: Temporary holding of breath

41 Protective Mechanisms Hering-Breuer Reflex Limits extent of inspiration Prevents over-expansion of lungs Vagus control

42 Chemical Control of the Repiratory Center Chemoreceptors in the resp. center Input via levels of CO2 and H+ Increase in levels of CO2 and H+ Increase in the rate and depth of breathing

43 Influence of Oxygen levels No direct influence on the primary resp. center Low O2 levels sensed by chemoreceptors in: Carotid bodies Aortic bodies

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45 Control via Carotid and Aortic Bodies Low blood oxygen concentration increase in the rate of respiration

46 Pulmonary Circulation

47 Pulmonary Circulation RV Pulm. A. Lungs gas exchange Pulm V. Left A

48 Gas Exchange in the Lungs Capillaries surround alveoli O2 diffuses into the capillaries CO2 diffuses out of the capillaries

49 Gas Exchange in the tissues Internal respiration At the systemic capillaries and tissues O2 enters the tissues CO2 enters the capillaries

50 Gas transport O2 transport via: Fe in Hb plasma (2-3% only) CO2 transport: Plasma + cytoplasm of RBCs (10%) Globin of Hb (30%) CO2 + H2O Carbonic acid (H2CO3) (H+) + (HCO3-) majority

51 Hemoglobin Protein involved in gas exchange Inside RBCs

52 Homeostasis Regulation of blood ph via respiratory control!