Respiration Chapter 42

Respiration  Gas exchange  Movement of gas across membrane  Diffusion (passive)  To improve gas absorption  Increase surface area for diffusion  Decrease distance diffused gas travels  Respiratory organs

Fish

Amphibians  Lungs  Cutaneous respiration

Amphibians

Birds  Parabronchi (lungs)  Air sacs

Fig Anterior air sacs Posterior air sacs Lungs Air Lungs Air 1 mm Trachea Air tubes (parabronchi) in lung EXHALATION Air sacs empty; lungs fill INHALATION Air sacs fill

Anatomy  Mouth (nose)  Pharynx (back of throat)  Larynx (voice box)  Trachea

Anatomy

 Bronchi (Bronchus)  Bronchioles  Alveoli  Air sacs  Gas exchange  One cell layer thick  Lung tissue consists of millions

Anatomy

 Lungs  3 right lobes  RUL, RML, RLL  2 left lobes  LUL, LLL

Anatomy

 Lung covered by a double folded membrane  Visceral pleural membrane:  Covers the lung  Parietal pleural membrane:  Lines inner wall of thoracic cavity

Anatomy  Pleural cavity:  Space between two membranes  Filled with fluid  Helps with movement of lungs

Breathing  Diaphragm  Muscle  Separates thoracic cavity from abdominal cavity  Intercostal muscles  Muscles between the ribs

Inhalation (inspiration)  Diaphragm contracts & flattens  Intercostal muscles contract  Raises the ribs  Increases volume (decreases pressure)  Air flows into the lungs

Exhalation (expiration)  Diaphragm relaxes & elevates  Intercostal muscles relax  Ribs lower  Decreased volume  Forces air out

Breathing

Breathing measurements  Tidal volume  Amount of air moved into & out of lungs at rest  Vital capacity  Maximum amount of air that can be expired after forceful exhalation

Breathing measurements

Control of breathing  Normal breathing  Medulla oblongata  Respiratory control center  Neurons send impulse for muscles (diaphragm/intercostal) to contract  Inspiration (inhalation)  Stop sending impulse  Expiration (exhalation)

Control of breathing  Blood O 2 & CO 2 in normal range  Neurons respond to a change in O 2 & CO 2  More response to CO 2  Increase CO 2  Increases carbonic acid (H 2 CO 3 )  CO 2 + H 2 O ⇆ H 2 CO 3 ⇆ H + HCO 3  Lowers pH

Control of breathing  Stimulates peripheral chemoreceptors  Aorta & carotids  Send impulses to respiratory control center (medulla oblongata)  Stimulates increased breathing

Control of breathing  Central chemoreceptors  Located in brain  Respond to increased amount of CO 2  Peripheral receptors immediate response  Central receptors maintained response until pH is back to normal

Transport of gas  Hemoglobin  Contains four heme groups  Center of each heme group is an iron  Oxygen binds the iron (4 O 2 molecules)  Oxygen in blood is mostly bound to Hgb  Little is dissolved plasma

Transport of gas

 Oxyhemoglobin  Hemoglobin full of oxygen  Lungs  Deoxyhemoglobin  Hemoglobin releases some oxygen  Capillaries

Transport of gas  Blood that leaves lungs 97% saturated  Circulates oxygen diffuses into tissues  75% saturated  Allows for reserves of oxygen  Exercise  Cardiac arrest

Transport of gas  Decreased pH  Lower affinity of oxygen for hemoglobin  Releases oxygen  Increased temperature  Lower affinity  Exercise  Increased CO 2, decreased pH, increased temperature  Increased release of O 2 to muscles

Transport of gas  CO 2  In tissues  Small amount bound to protein part of Hgb  Remaining CO 2 in RBC  Forms carbonic acid H 2 CO 3  Carbonic anhydrase

Transport of gas  Carbonic acid separates  Bicarbonate (HCO 3 -1 ) & H +1  Buffer  Blood at alveoli  Carbonic anhydrase reverses  Forms water & CO 2  CO 2 diffuses into lungs

Abnormalities  Emphysema  Lung disease that destroys alveoli sacs  Decreases vital capacity  Traps air  Hypoventilation  Decreased air movement increased CO 2  Hyperventilation  Increased air movement decreased CO 2

Emphysema