1. RESPIRATORY SYSTEM
Ch. 42
The second half

2. Aquatic Gas Exchange Advantage: Keeping surface moist is no problem
Disadvantage:
O2 concentrations in water are low, especially in warmer and saltier environments

3. Terrestrial Gas Exchange
Advantages:
O2 diffuses faster in air
Air contains much more O2 than water
Disadvantage:
Surfaces must be internal to avoid loss of water due to evaporation

4. Ventilation
Ventilation increases the amount of O2 taken in – stagnant water is no good
Crayfish wave their appendages to create currents – brings fresh water to gills
Fish force water across their gills
Blood also runs countercurrent to the water
Taking in and forcing out O2 from lungs

5. Protists and Less Complex Animals
Once again, less complex organisms do not need complex organ systems
Gas exchange takes place due to diffusion

6. Insects Have a series of openings along their sides called SPIRACLES
Tubes called TRACHEA lead from spiracles to all of the body tissues
Open circulatory system does not transport O2 and CO2

8. Fish
Most fish breathe with gills – feathery filaments that contain capillaries and a large surface area for gas exchange
They breathe by pumping water through the mouth, over gill filaments and out through slits in the sides of the pharynx
Double Pump System: by decreasing pressure in mouth, water is forced in; by increasing pressure in mouth, water is forced out through the opercula

10. Fish
Because the gills are so VASCULAR and have a large surface area, gas exchange can happen adequately

11. Fish
Countercurrent blood flow increases the efficiency of obtaining O2 from water

12. Human Respiration Works together with the circulatory system
Exchange of gases between atmosphere, blood, and cells
If respiratory system and/or circulatory system fails, death will occur
Cells need O2 for work; release CO2 as a waste product
Accumulation of excess CO2 is toxic to cells and MUST be removed

13. Respiratory System
Intakes oxygen
Releases carbon dioxide waste
Circulatory system
Transports gases in blood between lungs and cells

14. Respiratory Structures and Organs

15. Respiratory Structures and Organs
Nose – made of cartilage and bone and is designed to warm, moisten, and filter air as it comes into the system
Pharynx – (throat) conducts food and air; exchanges air with Eustachian tube to equalize pressure

16. Respiratory Structures and Organs
Larynx – (voice box) connects the pharynx and the trachea; made of cartilage; contains vocal cords
Epiglottis – flap of tissue that covers trachea; ensures food travels down the esophagus
nasal cavity
pharynx
larynx

17. Respiratory Structures and Organs
Trachea – (windpipe) tubular passage way for air; carries air to the lungs, C-shaped cartilage rings, divides at end
Bronchi – pair of tubes that branch from trachea and enter lungs; have cartilage plates; lining is ciliated & secretes mucus
larynx
trachea
bronchi
bronchioles

18. Respiratory Structures and Organs
Bronchioles – tiny tubes lacking cartilage and cilia; possess smooth muscle
bronchiole
smooth muscle
Autonomic nervous system regulates diameter of bronchioles
Sympathetic division dilates bronchioles
Parasympathetic division constricts bronchioles

19. Respiratory Structures and Organs
Alveoli – cup shaped structures at the end of the bronchioles that resemble bunches of grapes; are in direct contact with capillaries (gas exchange); covered with SURFACTANT that keep them from collapsing

20. Alveoli

21. Lungs – paired, cone-shaped organs that are surrounded by a pleural membrane, made of elastic tissue, and divided into lobes

22. Mechanics of Breathing
Inhaling (active process) – Air moves in. Why??
Gases move from an area of high pressure to low pressure
During inspiration – diaphragm pulls down and lungs expand
When lungs expand, it INCREASES the VOLUME, which DECREASES the PRESSURE inside lungs
Lung pressure is lower than outside pressure, so air moves in

24. Mechanics of Breathing
Exhaling (passive process) – breathing out
Diaphragm and muscles relax
Volume in lungs and chest cavity decreases, so now pressure inside increases
Air moves out because pressure inside is HIGHER than OUTSIDE atmosphere

25. Respiration What is respiration?
External respiration – exchange of O2 and CO2 between respiratory surfaces and the blood (breathing)
Internal respiration – exchange of O2 and CO2 between the blood and cells
Cellular respiration – process by which cells use O2 to produce ATP

26. External Respiration Exchange of O2 and CO2 between alveoli and blood
Partial pressure of O2 higher in alveoli than blood so O2 diffuses into blood
Partial pressure of CO2 higher in blood than alveoli, so CO2 moves into alveoli in opposite direction and gets exhaled out

28. Internal Respiration Exchange of O2 and CO2 between blood and tissues
Pressure of O2 higher in blood than tissues so O2 gets release into tissues.
Pressure of CO2 higher in tissue than in blood so CO2 diffused in opposite direction into blood.
CO2 Is a waste product
O2 Is used in cellular respiration

30. Gas Exchange Earth’s atmosphere is about 78% Nitrogen and about 21% O2
What happens to the air when we inhale?
300 million alveoli in a healthy lung
Hemoglobin can hold four O2 molecules
GAS
INHALED
EXHALED O2
20.71%
14.6%
CO2
.004%
4.0%
H2O
1.25%
5.9%

31. Gas Transport in Blood Carbon dioxide
70% as bicarbonate ion (HCO3-) dissolved in plasma
23% bound to hemoglobin
7% as CO2 dissolved in plasma
Oxygen
99% bound to hemoglobin
1% as O2 dissolved in plasma
Carbon monoxide poisoning occurs because CO binds to hemoglobin more readily than O2

32. Control of Breathing
Breathing is regulated by the rhythmicity center in the medulla of brain
Medulla stimulates inspiratory muscles (diaphragm & external intercostal muscles)
rhytmicity center

33. Control of Breathing
The most important factor affecting the rhythmicity center is CO2
 in arterial CO causes  in acidity of cerebrospinal fluid (CSF)
 in CSF acidity is detected by pH sensors in medulla
medulla  rate and depth of breathing

34. Respiratory System Disorders
Asthma – muscles of bronchioles constrict, drastically reducing ventilation
Emphysema – destruction of alveoli
Tuberculosis – highly contagious bacterial infection
Lung cancer – 90% of lung cancer victims have a history of smoking