BIO 265 – Human A&P

Chapter 22

Respiratory System

Functions

• What are the functions?– Pulmonary ventilation (breathing)– Gas Exchange

Anatomy Overview

• Figure 22.1

Respiratory System

• The respiratory system is completely lined with mucous membranes– We produce about 1 liter of mucus each day!!!

– This forms a barrier and trap system

– Respiratory filtering and cilia• Runny noses and sluggish cilia

– The folds and hairs in the nasal cavity cause turbulence in the air we breath

• They also heat and humidify inspired air

• They get some of the heat and water back from expired air

– Figure 22.1

Respiratory System

– Sneezing reflex– Rhinitis and sinusitis– Tonsils– Figure 22.3

Respiratory System

• The epiglottis and pop! (Figure 22.3)

Respiratory System

• The coughing reflex can help expel anything in the trachea– Air speed can reach 100 mph during a cough!

• What is the Heimlich maneuver?– Figure 22.1

Respiratory System

• The larynx and vocal cords are involved in voice production– The vocal cords vibrate as air passes over them – Saxophone reed analogy– Laryngitis

• Figures 22.3 and 22.5

Respiratory System

• The pleural membranes line the lungs and thoracic cavity– The pleural cavity is filled with lubricating

pleural fluid– Figure 22.12

Respiratory System

• Pleurisy is an inflammation of the pleural membranes and causes painful breathing

• Collapsed lungs and pneumothorax (air in the pleural cavity)– Figure 22.12

Respiratory System

• Gas exchange occurs in the alveoli– Figures 22.8 and 22.9

Respiratory System

• Cell types in the alveolus– Type I cells make up the wall of the alveoli– Type II cells secrete surfactant to reduce the

surface tension of the water lining the alveolus• Infant respiratory distress syndrome

– Alveolar macrophages– Figure 22.9

Respiratory System

• Oxygen and carbon dioxide must pass through the respiratory membrane to get in and out of the blood– Surface area of the respiratory membrane is

about 40 times larger than the surface of the skin

– Figure 22.9

Gas Exchange

• What drives gas exchange in the lungs and the tissues?– Concentration gradients of O2 and CO2

– Figure 22.17

O2 Transport

• How is O2 transported?

– 98.5% bound to hemoglobin (Hb)

– Each Hb can bind 4 O2 molecules in a reversible reaction• Percent saturation changes with PO2

– Hb-O2 Dissociation Curve – Figure 22.20

O2 Transport

• CD Demo

O2 Transport

• Other factors affecting Hb– pH decrease lowers O2 binding

– PCO2 increase lowers O2 binding

– Temperature increase lowers O2 binding

– Why?

• Carbon monoxide poisoning – CO binds to Hb 200 times better than O2

CO2 Transport

• How is CO2 transported?

– 7-10% dissolved in plasma– ~20% bound to hemoglobin– ~70% as bicarbonate ions

• Reaction on board with carbonic anhdrase

• Figure 22.22

Regulation of Respiration

• Respiration rate is determined by the respiratory center in the medulla oblongata– No one knows for sure how rhythmic

ventilation results

• Predict the effect of O2, pH, and CO2 on respiration rate– CO2 is the major regulator of respiration rate

– Figure 22.25

Regulation of Respiration

– Hyperventilation can cause a major reduction in blood CO2 levels

• This can cause vasoconstriction to the point that the brain does not receive enough oxygen

• Breathing into a paper bag

– Fun activity

Respiratory Problems

• Mountain sickness – at high elevations not enough oxygen enters the blood– This leads to headaches, shortness of breath, nausea, and dizziness

• Chronic obstructive pulmonary disease (COPD) – smoking, dyspnea (difficulty breathing), coughing

• Asthma – allergic response causing constriction of bronchial passages

• Tuberculosis – bacterial lung infection• Cystic fibrosis – leads to thick mucus in the respiratory

system– Cl- ions are not pumped outside the cell, so water stays in the cells