“THE RESPIRATORY SYSTEM” HAP Chapter 16

Why breathe???

I. Introduction A. Why Breathe? 1. break down nutrients 2. produce ATP 3. excrete carbon B. What is the respiratory system? 1. Obtaining O 2 and removing CO 2

II. Organs of the Respiratory System A. Upper Tract 1. nose 2. nasal cavity 3. paranasal cavity 4. pharynx B. Lower Tract 1. larynx 2. trachea 3. bronchial tree 4. lungs

C. The Nose 1. comprised of bone and cartilage 2. nostrils (2) D. The Nasal Cavity 1. space behind nose a. Nasal septum – divides into right and left halves b. Nasal conchea – bones that give structure c. Goblet cells – produce mucous -swallow particles (why?)

E. Paranasal Sinuses 1. air filled spaces a. Lighten skull b. Resonant chambers used for voice F. Pharynx (Throat) 1. passageway for air and food 2. used for speech 3. parts… a. Nasopharynx b. Oropharynx c. Laryngopharynx

G. Larynx 1. enlargement above trachea 2. allows air in and out a. Home of the vocal cords 3. 3 cartilages a. Thyroid – “Adam’s apple” b. Cricoid c. Epiglottic

H. Trachea 1. aka  windpipe 2. flexible tube (2.5 cm diameter / 12.5 cm length) 3. splits into r/l bronchi 4. goblet cells 5. cartilage rings – C-shaped  prevent collapsing

I. Bronchial Tree 1. Primary Bronchi a. Initial split from trachea/5 th thoracic vertebra 2. Secondary Bronchi 3. Tertiary Bronchi 4. Bronchioles 5. Alveolar ducts 6. Alveolar sacs 7. Alveoli – tiny air sacs which are surrounded by capillary networks a. Increase surface area b. 300 million c feet 2

J. Lungs 1. pink, soft, spongy organs… 2. found in thoracic cage 3. Pleura – sac that lines the lungs… a. Visceral pleura – inner sac that connects to lungs b. Parietal pleura – outer sac that holds lungs to the thoracic cavity 4. right lobe (3) > left lobe (2)

III. Breathing Mechanism (Boyle’s Law) A. Def – air into and out of the body. 1. Inspiration – inhaling 2. Expiration – exhaling B. Inspiration 1. Atmospheric pressure = 760 mm Hg 2. How does air get into the lungs?  Diaphragm moves downward / ribs move out  lung volume increases  pressure decreases *Result…Outside air moves into the lungs

C. Expiration 1. How do we get air out of the lungs?  Elastic recoil of muscular and connective tissue  Diaphragm pushes upward  Pressure inside thoracic cavity increases  Air is forced outside of the body

Diaphragm is moving up thus the internal pressure increases causing the air to move out of the body

D. Respiratory Air Volumes and Capacities  tidal volume = amount that enters or leaves lungs -500 mL  inspiratory reserve volume = extra air that can be breathed in - 3,000 mL (past tidal volume)  expiratory reserve volume = extra air that can be breathed out - 1,100 mL (past tidal volume)  residual volume = amount that stays in the lungs permanently - 1,200 mL  total lung capacity = total amount of air that could be found in lungs.-5,800 mL  vital capacity = maximum amount a person can exhale after taking in a full breath. -4,600 mL

Respiratory Volumes and Capacities

IV. Control of Breathing A. The Respiratory Center (involuntary and voluntary) 1. Location – Brainstem a. Pons b. Medulla Oblongata 2. Special Areas a. Medullary Rhythmicity Area  dorsal respiratory group -basic inspiration rhythm (at rest) -send signals to diaphragm and other small muscles  ventral respiratory group -dormant at resting levels -activated during forceful breathing -send impulse to larger muscles used in breathing

b. Pneumotaxic Area  transmit impulses that inhibit inspiratory bursts from the dorsal respiratory group  controls the overall breathing rate -when transmitting = slow breathing -when not transmitting = fast breathing

B. Factors that Affect Breathing 1. High CO 2 levels (primary) 2. High H + ion levels 3. Low blood O 2 levels (minor) 4. Emotions (fear, pain, stress)

V. Alveolar Gas Exhange A. Respiratory Membrane 1. Simple Squamous Epithelial Cells 2. Covered in a capillary network 3. O 2 and CO 2 easily exchanged B. Diffusion (H  L) 1. Partial pressure – amount of pressure for each gas according to concentration.

GasLung (alveoli)Capillary O2O2 104 mmHg40 mmHg CO 2 40 mmHg45 mmHg

VI. Gas Transport A. Oxygen Transport 1. hemoglobin a. 98% of all O 2 b. Forms oxyhemoglobin -bond is unstable -O 2 is released -O 2 diffuses into nearby cells c. Factors which cause oxyhemoglobin to release O 2 -CO 2 levels, acids, increase in blood temp *Explains why working muscles get more O 2 Hypoxia – O 2 deficiency

B. CO 2 Transport (3 methods) 1. CO 2 dissolved in plasma a. Based on partial pressure b. Approx. 7% 2. Part of a compound formed with hemoglobin a. Binds with globulin (-NH 2 ) -carbaminohemoglobin b. Approx. 23% 3. Converted to Bicarbonate ion (HCO 3 - ) a. CO 2 + H 2 O  H 2 CO 3 (carbonic acid) -carbonic anhydrase (enzyme) b. Approx. 70%