1. Respiratory System

2. Respiratory System
Major function is to supply the body with oxygen and dispose of carbon dioxide
Most of the carbon dioxide waste is used as blood’s buffer system

3. 4 Processes of Respiration
Pulmonary ventilation: movement of air into and out of the lungs so that gases are continuously refreshed.
External respiration: movement of oxygen from the lungs to the blood and of carbon dioxide from the blood to the lungs

4. 4 Processes cont.
Transportation: movement of oxygen to the tissues and carbon dioxide from the tissues to the lungs.
Internal respiration: movement of oxygen from blood to the tissue cells and of carbon dioxide from the cells to blood.

5. Atmospheric Gas: mixture
Nitrogen: 78%
Must be eaten to obtain for body
Nitrogen is fixed by bacteria for plants to absorb
Nitrogen is introduced to the soil also through lightning
Oxygen: 20.9%
Combustible at 22%
Released by organisms that perform photosynthesis
Used by organisms for cellular respiration

6. Atmospheric Gases, cont.
Carbon dioxide: 0.04%
Waste product of cellular respiration
Carbon dioxide comes from pollution
Green organisms use CO2 for photosynthesis
Water Vapor: 0.46%
Percentage of water vapor in air is called dewpoint
Higher the dewpoint = higher the humidity

7. Respiratory System Parts
1. nose: external portion supported by bone and cartilage
Internal nasal cavity is divided by the septum and lined with mucosa.
Roof is lined with olfactory epithelium
Terbinate bone line the nasal cavity
Produce mucus, filter, warm, and humidify the incoming air, resonance chamber for speech.

10. Parts, cont. 2. paranasal sinuses: mucosa lined air-filled cavities
Decreases the weight of the skull, and performs the same functions as the nose

11. Parts, cont. 3. Pharnyx: back of the throat.
3 divisions: nasopharynx. Oropharnyx, and laryngopharynx
Houses the tonsils- lymphoid tissue
Passageway for both food and air

12. Parts, cont. 4. Larynx: connects the throat to the trachea
Contains a cartilage framework that includes the epiglottis
Epiglottis closes over the trachea when swallowing
Houses vocal cords
Air passageway into the lower respiratory tract

15. Parts, cont.
Trachea: flexible tube connecting the larynx and the bronchi
Walls contain C-shaped cartilage rings that are incomplete posteriorly
(keep the airway open)
**air passageway, cleans,
warms, and moistens
the incoming air

16. Parts, cont.
Bronchial tree: right and left bronchi that subdivides into the bronchioles
Has the same function as the trachea, can become inflamed and can restrict air flow- asthma

17. Parts, cont. Alveoli: microscopic chambers at terminal bronchioles
Walls are simple squamous epithelium
Site of gas exchange

18. Parts, cont. Pleurae membranes
Produces surfactant; lubricating solution that decreases friction

20. Mechanics of Breathing
Remember Boyle’s Law???
If the volume increases, then the pressure must decrease (or vice versa)
P1V1 = P2V2

21. Breathing occurs when the contraction or relaxation of muscles around the lungs changes the total volume of air within the air passages (bronchi, bronchioles) inside the lungs.
When the volume of the lungs changes, the pressure of the air in the lungs changes in accordance with Boyle’s Law.

22. If the pressure is greater in the lungs than outside the lungs, then air rushes out. If the opposite occurs, then air rushes in.

23. Mechanics of Breathing: Inspiration
Diaphragm contracts and lowers, thus increasing the size of the thoracic cavity.
External intercostal muscles contract elevating the ribs and sternum.
Total volume of internal air passages increases, air pressure inside the lungs decreases below that of air outside the body.
Because gases move from regions of high pressure to low pressure, air rushes into the lungs.

24. Mechanics of Breathing: Expiration
Diaphragm relaxes and raises, thus decreasing the size of the thoracic cavity.
External intercostal muscles relax lowering the ribs and sternum.
Elastic fibers cause the lungs to recoil to original volume
Total volume of internal air passages decrease, air pressure inside the lungs increases below that of air outside the body, air rushes out.

26. https://www.youtube.com/watch?v=F0OB kR00OZE

27. Control of Breathing The autonomic nervous system controls breathing.
The respiratory center that controls the rate of breathing is in the medulla.

28. Factors that influence the Medulla
Oxygen:
Peripheral chemoreceptors located in the carotid and aorta detect the amount of oxygen in the blood. If the oxygen concentration is low, they tell the medulla to increase breathing.
Carbon dioxide:
These receptors also monitor carbon dioxide levels in the CSF. If too high, then signals are sent to respiratory centers to increase the rate and depth of breathing.

29. Other Factors that influence the Medulla
pH:
If the blood becomes too acidic, then signals are sent to the centers to speed up
Stretch:
If the lungs are overinflated, respiratory centers are signaled to exhale
Signals from brain centers:
Nerve cells in the hypothalamus and cortex
During pain or strong emotions, hypothalamus tells the centers to speed up, slow down, or stop