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 Respiratory organs

Fish

Amphibians Lungs Cutaneous respiration

Amphibians

Birds Parabronchi Air sacs (lungs)

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 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 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 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