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

• http://www.youtube.com/watch?v=hp-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 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