Respiration Chapter 42 Respiration Gas exchange Movement of

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

Respiration ® Advanced organisms ® Respiratory organs ® Increases surface area ® Allow greater diffusion rates ® External environment is closer to internal fluids

Fish ® Gills located behind the buccal (mouth) cavity ® Fish swims with mouth open ® Water flows over gills ® Gills contain blood vessels ® Absorb O 2

Fish

Land animals ® 1. Gills flatten out in air ® 2. Water loss to air is too great with gills

Amphibians ® Lungs ® Out pouching of gut ® Connected to pharynx ® Positive pressure ® Open mouth fill buccal cavity with air ® Close mouth elevate floor of mouth ® Forces air into lungs ® Cutaneous respiration

Amphibians

Birds ® Parabronchi (lungs) ® Gas exchange happens ® 2 groups of air sacs ® Anterior, posterior ® Inhales ® Air enters ® Posterior sacs fills with outside air ® Anterior sacs fills with air from lungs

Birds ® Exhales ® Air is forced out ® Posterior sacs empties in the lung ® Anterior sacs is exhaled

Fig. 42 -26 Anterior air sacs Posterior air sacs Air Trachea Lungs Air tubes (parabronchi) in lung INHALATION Air sacs fill EXHALATION Air sacs empty; lungs fill 1 mm

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

Anatomy

Anatomy

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

Anatomy

Anatomy

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

Anatomy

Anatomy

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 ® Increases carbonic acid (H 2 CO 3) ® CO 2 + H 2 O ⇆H 2 CO 3 ⇆ H + HCO 3 ® Lowers p. H

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 p. H 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

Transport of gas ® Oxyhemoglobin ® Hemoglobin full of oxygen ® Lungs ® Deoxyhemoglobin ® Hemoglobin ® Capillaries releases some oxygen

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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 p. H ® Lower affinity of oxygen for hemoglobin ® Releases oxygen ® Increased temperature ® Lower affinity ® Exercise ® Increased CO 2, decreased p. H, 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