1. Regulation of Breathing
A negative feedback system
Mechanism to restore conditions to their original state
Diaphragm and intercostal muscles contract
Thoracic cavity increases
Inspiration occurs
medulla oblongata
Regulation of Breathing
 CO2 in the blood
 CO2 in the blood
Pressure receptors in alveoli
Thoracic cavity decreases
Expiration occurs
Diaphragm and intercostal muscles relax
Brain releases acetylcholine

2. Gas Exchange External Respiration Internal Respiration:
Respiratory system and circulatory system
Internal Respiration:
Circulatory system and cells

3. External Gas Exchange Alveoli are surrounded by capillary beds
Low-oxygen blood is pumped from the heart through the pulmonary artery  arterioles  capillaries
Oxygen diffuses from the alveoli  capillaries
Carbon dioxide diffuses from the capillaries  alveoli
Oxygen-rich blood is carried from capillaries  venules  pulmonary vein  heart
Heart then circulates the blood around the body

6. Internal Gas Exchange Oxygen diffuses from the blood  cells
Carbon dioxide diffuses from the cells  blood

7. Hemoglobin
Red blood cells contain hemoglobin, a pigment protein with an iron centre
Hemoglobin has a high affinity for oxygen and readily binds with oxygen to form oxyhemoglobin
Hemoglobin increases the efficiency of gas exchange by removing oxygen from the blood plasma. Therefore oxygen will continue to diffuse into the blood

8. Fun Facts! Noses: Whales: “Nose” is a blow hole on top of the head
Pigs: Noses act as a rooting device
Elephant: Nose used for manipulation
Sneeze: Reflex action caused by the irritation of the nasal passages
Hiccup: a spasm of the diaphragm; The sound comes from the epiglottis
dropping down over the glottis
Snoring: uvula vibrates and causes noise; happens only when air passage
through the mouth is small as when we are sleeping.
Laughing: consists of deep inspiration (breathing in) followed by a series
of short, spasmodic, expirations (breathing out); crying is similar
Yawning: indication of boredom, fatigue, and/or lack of oxygen; it is a
deep inspiration with the mouth fully open
Sighing: prolonged expiration