Human Respiratory System

1. Human Respiratory System Hanes Magnet School 7th Grade Science Mr. Bombick

2. Human Respiratory Tract Outline • Anatomy of the Respiratory Tract (both Upper and Lower Tracts) • Control of Breathing • Physiology of Breathing • Measurements of Human Breathing • Homeostatic Mechanisms of the Respiratory System • Diseases of the Respiratory Tract

3. Respiratory Tract-Anatomy • The respiratory tract can be divided into two major parts, the upper and lower respiratory tract • The upper respiratory tract consists of the nose and the pharynx • The lower respiratory tract consists of the trachea and the lungs

4. Events in the Upper Respiratory Tract The nose and pharynx make up the upper respiratory tract. The upper respiratory tract has several important functions which include the filtering of air, the warming of the air, and humidifying the air before the air reaches the lower respiratory tract. The air finally flows into the region of the larynx.

5. Upper Respiratory Tract-Anatomy

6. Lower Respiratory Tract-Larynx The larynx contains two major parts; the vocal cords and the epiglottis. The epiglottis is a flap of cartilage that helps prevent food from going into the lower respiratory tract. Stimulation of the larynx by ingested food also initiates a type of coughing or gag reflex to help prevent food from getting into the lower respiratory tract. A person can choke on food if the epiglottis fails to close the opening of the trachea. The vocal cords consists of two folds of connective tissue that becomes stretched and vibrated when air passes through. The length of the vocal cords determines the pitch of the sound and the volume of sound is dependent on the intensity of expiration. Sound is only produced when air is passing through the cords. The production of sound can definitely be under voluntary control.

7. Lower Respiratory Tract-Continued • The trachea is the major airway from the larynx to the two bronchi • The trachea is surrounded by cartilaginous rings that help maintain the tubular shape • Two bronchi branch off of the trachea • The bronchi go into the lungs and start to branch into smaller tubes called bronchioles • The terminal parts of the smallest bronchioles create the alveolar sacs where gas exchange occurs

8. Lower Respiratory Tract-Anatomy

9. Control of Breathing Breathing is an automatic and rhythmic action produced by bundles of neurons in the pons and medulla of the hind brain.

10. Respiratory Physiology

11. Homeostasis of Respiration • Central chemoreceptors of the central nervous system are sensitive to pH in the blood (increased CO2 in the blood means more acidic conditions and therefore, lower pH) and adjust breathing rate accordingly • Peripheral chemoreceptors detect variations of the oxygen in the arterial blood, in addition to detecting arterial CO2 and pH (decrease in pH increases breathing rate)

12. Homeostasis of Respiration (cont.) • Mechanoreceptors are located in the airways and lung lining to control reflex reactions that prevent over inflation of the lungs. Other upper airway mechanoreceptors control responses as coughing, sneezing, closure of the glottis, and hiccups. A spinal cord reflex is responsible for activation of respiratory muscles for a gasping response, hypoventilation, and increases in breathing frequency and volume. • In addition, respiration can be affected by conditions such as emotional state (limbic system) or temperature (hypothalamus). • Voluntary control of respiration originates from the cerebral cortex although chemoreceptors are capable of overriding conscious control.

13. Emphysema Normal Lung Emphysema

14. Lung Cancer

15. Cystic Fibrosis

16. Respiratory Pathologies • Cancers of the Respiratory System (include all structures of the respiratory system) • COPD (Chronic Obstructive Pulmonary Disease) includes chronic bronchitis and emphysema • Cystic Fibrosis • Variety of infections (viral, bacterial, protists, helminthes, nematodes, fungi, etc.) • Asthma