Unit 3: Circulatory System

(1) Respiration (“Breathing”) Includes: –Movement of air in and out of lungs. –Gas exchange between blood + alveoli. –Transportation of oxygen and carbon dioxide via the blood. –Gas exchange between blood + tissue cells.

(2) Inspiration Inspiration = Inhalation (Fill with Oxygen Gas) 1.Diaphragm contracts 2.Increase in Thoracic Volume 3.Decrease in Lung Pressure 4.Air Moves from High  Low Pressure into the Lungs 5.Lung Pressure Increases & Equilibrates

gCvW8PRY&feature=relatedhttp:// gCvW8PRY&feature=related

(3) Expiration Expiration = Exhalation (Expel Carbon Dioxide Gas) 1.Diaphragm relaxes 2.Decrease in Thoracic Volume 3.Increase in Lung Pressure 4.Air moves from High  Low Pressure out of the lungs 5.Lung Pressure Decreases & Equilibrates

(4) Gas Exchange Exchange between Oxygen & Carbon Dioxide Alveoli = Part of Respiratory System –Contain intake of oxygen –Get rid of carbon dioxide Capillaries & Blood = Part of Cardiovascular System –Take Carbon dioxide from respiring cells  Alveoli –Take oxygen from alveoli  cells Alveoli covered in Capillaries  Diffusion Across

(5) Oxygen Exchange –Taken in through respiratory system –Held in alveoli of lungs –Higher Concentration of O 2 in alveoli than blood stream  Diffusion into blood stream –Binds with hemoglobin in red blood cells –Transported to tissues in need of oxygen

(6) Carbon Dioxide Exchange –Released from cells during cellular respiration –Binds with hemoglobin AND stored in plasma as carbonic acid/bicarbonate –Higher Concentration of CO 2 in blood than in alveoli  Diffusion out of blood stream into lungs –Release through respiratory system

S7iq8http:// S7iq8

(7) Regulation of Respiration Controlled by the Medulla & Pons: –Medulla sets basic respiration rate –Pons maintains inspiratory + expiratory rhythm set by medulla –Pons also increases/decreases rates during various circumstances Alveoli & Bronchioles lined with stretch receptors: –Trigger expiration during over-inspiration –Common during heightened emotion or physical activity Lack of Oxygen  Large Gasps / Yawning –Impulse sent to brain to cause intake of oxygen –Result = Gasp for air

(8) Respiratory Rate Should be approx. 15 respirations/minute. Factors Impacting Rate: –Physical Activity & Changes in Cellular Respiration –Conscious Control –Changes in emotion + environmental stimuli –Levels of carbon dioxide + oxygen in blood: Carbon dioxide concentrations monitored by pH Oxygen concentrations monitored by chemoreceptors in aortic arch