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 contracts2. Increase in Thoracic Volume3. Decrease in Lung Pressure4. Air Moves from High Low Pressure into the

Lungs5. Lung Pressure Increases & Equilibrates

• http://www.youtube.com/watch?v=hp-gCvW8PRY&feature=related

(3) Expiration• Expiration = Exhalation

(Expel Carbon Dioxide Gas)

1. Diaphragm relaxes2. Decrease in Thoracic Volume3. Increase in Lung Pressure4. Air moves from High Low Pressure out of

the lungs5. 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 O2 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 CO2 in blood than in alveoli Diffusion out of blood stream into lungs

– Release through respiratory system

• http://www.youtube.com/watch?v=DoSTehS7iq8

(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