1. Physiology of breathing
Respiratory System
Physiology of breathing

2. Regulates blood oxygen and carbon dioxide levels.
Human Respiratory System
Functions:
Works closely with circulatory system, exchanging gases between air and blood:
Takes up oxygen from air and supplies it to blood (for cellular respiration).
Removal and disposal of carbon dioxide from blood (waste product from cellular respiration).
Homeostatic Role:
Regulates blood pH.
Regulates blood oxygen and carbon dioxide levels.

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What Is Respiration?
What Is Respiration?
In biology, respiration means different things.
Cellular respiration is the release of energy from the breakdown of food in the presence of oxygen (occurs in the?????)
At the organism level, respiration is the process of gas exchange—the release of carbon dioxide and the uptake of oxygen that occurs between RBCs and alveoli
Breathing is the actual mechanical intake of air
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5. External Respiration Gas exchange between pulmonary blood and alveoli
Movement occurs toward the area of lower concentration of the diffusing substance
Un-oxygenated blood is transformed into oxygenated blood and returned to heart

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Gas Exchange
Gas exchange takes place in the alveoli.
Oxygen diffuses into the blood.
Carbon dioxide in the blood diffuses into the alveolus.
Let’s examine this up close O2
CO2
Gas exchange occurs by diffusion across the membrane of an alveolus and a capillary.
Capillary
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7. Diffusion Gradients Oxygen Carbon dioxide
Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary
P02 in blood decreases because of mixing with deoxygenated blood
Oxygen moves from tissue capillaries into the tissues
Carbon dioxide
Moves from tissues into tissue capillaries
Moves from pulmonary capillaries into the alveoli

8. Internal Respiration
At capillaries, gas exchanges must be made between blood and tissue cells
Oxygen is dropped off and carbon dioxide is loaded into the blood from tissues

9. Respiratory Sounds
Bronchial Sounds: Produced by air rushing through the large respiratory passageways like the trachea and bronchi
Vesicular Sounds: Produced as air fills the alveoli

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Ventilation
Also known as BREATHING
Lungs are sealed in pleural membranes inside the chest cavity.
At the bottom of the cavity is a large, flat muscle known as the diaphragm.
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
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12. Ventilation - Breathing
During inhalation, the diaphragm contracts and the rib cage rises up.
This expands the volume of the chest cavity.
The chest cavity is sealed, so this creates a partial vacuum inside the cavity.
Atmospheric pressure fills the lungs as air rushes into the breathing passages.
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
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13. Inspiration Inspiration or inhalation
Diaphragm and external intercostals contract, thoracic cavity increases
Diaphragm moves inferorily
External intercostals lift the rib cage and thrust out the sternum

14. Muscles of Inhalation Intercostal muscles: Accessory muscles
Diaphragm:
contraction draws air into lungs
75% of normal air movement
Intercostal muscles:
assist inhalation
25% of normal air movement
Accessory muscles
sternocleidomastoid
serratus anterior
pectoralis minor
scalene muscles

15. Ventilation - Breathing
Often exhaling is a passive event.
When the rib cage lowers and the diaphragm relaxes, pressure in the chest cavity is greater than atmospheric pressure.
Air is pushed out of the lungs.
During inhalation the rib cage rises and the diaphragm contracts, increasing the size of the chest cavity.
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16. Expiration Expiration or exhalation
Passive process that relies on natural elasticity
Expiration is effortless, but if the respiratory is narrowed by spasms, mucus or fluid this process becomes active

17. Muscles of Respiration

18. Ventilation - Breathing
Movement of air into and out of lungs via negative pressure pump mechanism
Air moves from area of higher pressure outside the lung to area of lower pressure created in the thorax and lungs by diaphragm
Pressure is inversely related to volume in that as pressure goes down lung volume goes up

19. Normal Breathing Cycle

21. Tidal Volume (TV)
Amount of air moved into and out of lungs with a normal breath
about 500ml

22. Vital Capacity The total amount of air that a person can exhale.
About 4600 ml

23. Residual Volume
After the most forceful expiration this is the amount of air that remains in the lungs
About 1200 ml

24. Total Lung Capacity
Vital capacity plus residual volume
About 5800 ml

26. Non-respiratory Movevents
All of these move air out of the respiratory system for function other than breathing
Examples: cough, sneezing, crying, laughing, hiccups, and yawn.

27. Cough
The cough is a reflex action--when there is an irritant present in the lungs the body responds by coughing.

28. Sneezing
Sneezing is caused by irritation to the mucous membranes of the nose or throat.
Clears the Upper respiratory tract

29. Hiccups Irritation of the diaphragm that causes spasms
Could be from eating too fast, excitement, or irritation in the stomach or throat.

30. Yawn
Yawning is an involuntary action that causes us to open our mouths wide and breathe in deeply.

31. Interesting Yawning Facts The average yawn lasts about six seconds.
Your heart rate can rise as much as 30 percent during a yawn.
55 percent of people will yawn within five minutes of seeing someone else yawn.
Blind people yawn more after hearing an audio tape of people yawning.
Reading about yawning will make you yawn.
Olympic athletes often yawn before competition.

32. How Breathing Is Controlled
Breathing is controlled by the medulla oblongata.
The medulla oblongata monitors carbon dioxide in the blood.
As carbon dioxide increases, nerve impulses make the diaphragm contract, bringing air into the lungs.
The higher the carbon dioxide level, the stronger the impulses.
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33. What can affect the medulla oblongata?
Suppression as with an overdose of sleeping pills, morphine, or alcohol can cause respiration to stop. Death will occur!!

34. Factors Influencing Respiratory Rate and Depth
Physical Factors
Increased body temperature
Exercise
Speech
Singing
Non-respiratory air movements
Chemical Factors
Changes in levels of carbon dioxide more so than the need to intake oxygen
Conscious Control
Emotional Factors
Fear, Anger, Excitement

35. Changes in Respiratory System at Birth
Before birth:
pulmonary vessels are collapsed
lungs contain no air, filled with fluid
During delivery:
placental connection is lost
At birth:
Fluid is drained and the respiratory passage is filled with air
Baby’s first breath!!

36. 3 Effects of Aging on the Respiratory System
Elastic tissues deteriorate:
reducing lung compliance
lowering vital capacity
Arthritic changes:
restrict chest movements
limit respiratory minute volume
Emphysema:
affects individuals over age 50
depending on exposure to respiratory irritants (e.g., cigarette smoke)

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Lung Capacity Lab
Objective: Measure the amount of air your lungs can hold
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