Anatomy & Physiology II Misericordia University Respiratory System Anatomy & Physiology II Tony Serino, Ph.D. Biology Department Misericordia University

Respiration External Respiration Internal Respiration The exchange of gas between the blood and external environment (usually includes ventilation) Internal Respiration The exchange of gas between the blood and the tissues Cellular Respiration Burning of fuel to produce energy within cells Ventilation (Breathing) Movement of air in and out of the lungs

Respiratory Organs Divided into: Upper Respiratory Tract Includes: nostrils (nares), nasal cavity, and nasopharynx Lower Respiratory Tract Includes: larynx, trachea, bronchi, and lungs Conducting Air passages include: nares to terminal bronchioles Move air to respiratory membrane Condition the air Moisten, Warm, Clean

Upper Respiratory Tract

Beginning of Lower Respiratory Tract

Larynx

Trachea

Mucous Membrane (pseudostratified columnar epithelium)

Bronchi Primary bronchi lead to to each lung (left and right) Secondary (lobar) bronchi lead to each lung lobe (3 on right and 2 on left)

Bronchi Branches Tertiary Bronchi Primary Bronchi Secondary Bronchi Tertiary (segmental) bronchi lead to each lung broncho-pulmonary segment Bronchi continue to divide at least 20 more times.

Broncho-pulmonary Segments

Right Lung Left Lung

Bronchioles Air passages less than 1 mm in diameter are bronchioles. The terminal bronchioles are the last of the purely conducting air passages.

Alveoli highly specialized for Gas Exchange Lots of Surface Area Highly vascular Thin walls

Alveolus

P = pressure to collapse T = surface tension r = radius Role of surfactant is to decrease surface tension in alveoli.

Pressures affecting Breathing

Inspiration

Expiration

Pressure changes around lung

Only used during rapid breathing.

Lung Volumes

Normal Lung Volumes

Partial Pressure Favors Resp. Gas Movement

Time to Complete O2 Saturation in Pulmonary Capillaries

Oxygen Content of Blood PO2 = 100 mmHg Whole Blood Plasma Oxygen Oxyhemoglobin Total Volume of Oxygen = 0.3ml Plasma + 20 ml whole blood

Hemoglobin

Oxyhemoglobin Dissociation Curve

Hemoglobin Affinity for Oxygen: Effect of Temperature Affinity decreases with increasing Temperature

Hemoglobin Affinity for Oxygen: Effect of pH Affinity decreases with increasing acidity (i pH)

Gas Exchange in Lungs

Gas Exchange in Tissues

Neural Control of Breathing Voluntary control located in cerebral cortex and acts through the corticospinal tract. Involuntary located in pons and medulla acting through the spinal cord in the roots of the phrenic nerve (C3-C5) and thoracic cord roots of the external (inspriation(I)) and internal (expiration(E)) intercostal nerves PRG –pontine resp. group (formerly the apneustic and pneumotaxic centers) –play role in smoothing between insp. and exp., especially during sleep, vocalization and exercise. VRG and DRG – ventral and dorsal resp. group of the medulla. DRG primarily responsible for inspiration; VRG mixture of I and E neurons contains Pre-Botzinger complex which may be pacemaker cells for respiration

Neural control of Breathing PRG Red is inhibitory Black is excitatory DRG VRG Hering-Breuer Reflex I neurons E neurons Ext. Intercostals & diaphragm Int. Intercostals Lung Stretch Chemoreceptors

Medulla sensitive to H+ directly

Factors Effecting Respiratory Centers

CO2 Drive

COPD