ANHB2212 Lecture Notes - Lecture 9: External Intercostal Muscles, Pulmonary Pleurae, Intercostal Muscle

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rosetoad239

25 May 2018

School

UWA

Department

Anatomy and Human Biology/Anatomy, Physiology and Human Biology

Course

ANHB2212

Professor

Daniel Franklin

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Mechanisms of Breathing:

Breathing:

Quiet breathing: relaxed, unconscious, automatic

- uses diaphragm and intercostals

Forced breathing: unusually deep or rapid breathing

- diaphragm, intercostals and accessory muscles

lungs don’t ventilate themselves, only muscle contained within is smooth in the walls of the

bronchi and bronchioles

Inspiration – active part of breathing when air is sucked into the lungs by the reduction in intra-

thoracic pressure associated with increased thoracic volume.

Mechanism:

External inter-costal muscles contracted after stimulus of nervous impulses and the

diaphragm moves down (-1-10cm) toward the abdomen – induces expansion of the thoracic

cavity.

Lung is in connection with the chest wall via the pleura (parietal lining the rib cage, visceral

constituting lung surface) – via the pleura the lungs and chest wall are pulled in opposite

directions.

Results in negative pressure in the pleural cavity

keeping the lungs expanded and decrease pressure in

the alveoli – there is a pressure gradient between the

atmosphere at the nose/mouth to the negative pressure

in the alveoli.

Air thus flows down gradient and ventilates the alveoli.

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Expiration: passive part of breathing where the elastic recoil of the alveoli forces the air out of

the lungs

Mechanism:

Intercostal muscles contract (via ribs) and move back into their original position

Diaphragm moves back, reducing space in thoracic cavity, and increasing pressure in lung

Recoil of thoracic cage compresses lungs and raises intra-pulmonary pressure (+1cm H20)

In forced breathing the accessory muscles raise the pressure substantially (+40cm H20).

Anatomy of chest wall:

Thoracic cage: skeleton of the chest that comprises the thoracic vertebrae, ribs and sternum.

- Ribs and sternum form rib cage that supports the walls of the thoracic cavity

- Is broad inferiorly, narrow superiorly and relatively flattened in the anterior-posterior

plane.

2 primary functions:

1) Protection for structures in thoracic cavity

2) Attachment for muscles involved with – respiration

- movement of vertebral column

- movement of pectoral girdle and upper limbs

Regional anatomy:

12 thoracic vertebrae

Sternum

12 ribs on each side and respective costal cartilage.

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Thoracic inlet: superior opening (aperture) of thoracic cage.

- Approx. 5cm anteroposteriorly and 10cm transversely

- Bounded by superior border of the manubrium, posteriorly by the body of T1 and

laterally by the inner border of the 1st ribs.

Thoracic outlet: inferior opening (aperture)

- bounded posteriorly by T12, posterolaterally by 12th ribs, anteriorly by xiphoid process

and anterolaterally by costal margin.

Costal margin: portion of the inferior edge of the thorax defined by the articular cartilages of

ribs 7-10 (false ribs).

- Forms large inverted V-shape on the inferior border.

True ribs – 1-7, articulate directly via separate costochondral cartilages to the sternum.

- Gradually increase in length and radius of curvature

False ribs – 8-10, fuse together before reaching the sternum (shared costochondral cartilage)

Floating ribs – 11 and 12, don’t articulate with sternum,

Joints of ribs with sternum:

Via costal cartilage.

- Extends medially from anterior rib ends and articulate with the sternum (ribs 1-5) or

costal arch (ribs 6-10).

- Show the typical structure of hyaline cartilage – precursor of bone, widely dispersed type

II collagen fibres.

- Bound to sternal end of the rib by continuity of the periosteum of the bone and

perichondrium of the cartilage.

- Semi-moveable joint that permits flexibility in the rib cage whilst keeping the ribs

connected to the sternum

- Allows rib cage to expand with the lungs during deep inhalation

- Also serves to some degree as a shock absorber to anterior blows to the thoracic cage

- Remember about age related ossification of the cartilage.

First rib – synchondrosis – little flexibility, when rib elevated manubrium tilted upward

2-7 ribs – synovial sternocostal joints – allow slight gliding motion.

Manubrium and sternum – synchondrosis – as manubrium tilts the body of sternum doesn’t.

- Sternal angle increases with respiration

Body and xiphoid process – synchondrosis

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Document Summary

Diaphragm, intercostals and accessory muscles lungs don"t ventilate themselves, only muscle contained within is smooth in the walls of the bronchi and bronchioles. Inspiration active part of breathing when air is sucked into the lungs by the reduction in intra- thoracic pressure associated with increased thoracic volume. External inter-costal muscles contracted after stimulus of nervous impulses and the diaphragm moves down (-1-10cm) toward the abdomen induces expansion of the thoracic cavity. Lung is in connection with the chest wall via the pleura (parietal lining the rib cage, visceral constituting lung surface) via the pleura the lungs and chest wall are pulled in opposite directions. Results in negative pressure in the pleural cavity keeping the lungs expanded and decrease pressure in the alveoli there is a pressure gradient between the atmosphere at the nose/mouth to the negative pressure in the alveoli. Air thus flows down gradient and ventilates the alveoli.

Related Questions

QUESTION 1

Cellular respiration uses________to produce energy and releases ________as a waste product.

		O₂; CO₂
		CO₂; O₂
		ATP; G3P
		G3P; ATP

5 points

QUESTION 2

Select all of the following that compose the conducting pathways in the respiratory system.

		nasal cavity
		Pharynx
		Larynx
		Trachea
		Bronchi
		Alveoli

5 points

QUESTION 3

Match each structure with its' function.

- A. B. C. D. E. F. G.	Nasal Cavity
- A. B. C. D. E. F. G.	Alveoli
- A. B. C. D. E. F. G.	Larynx
- A. B. C. D. E. F. G.	Trachea
- A. B. C. D. E. F. G.	Bronchi
- A. B. C. D. E. F. G.	Bronchioles
- A. B. C. D. E. F. G.	Pharynx

A.	Throat
B.	Very small branches of bronchi within the lungs.
C.	Larger branching passages for air within the lungs.
D.	Location of gas exchange with the blood.
E.	Carries air from larynx and branches into bronchi.
F.	Location of the voice box, earliest location where only air passes.
G.	Carry air into the pharynx, earliest location of cleaning, warming, and humidifying the air.

8 points

QUESTION 4

Mammals are able to inhale because increasing the volume of the thoracic cavity will decrease the pressure within the lungs. This is called_____

		pump-controlled breathing
		forced inflation breathing
		negative-pressure breathing
		stretch breathing

6 points

QUESTION 5

Indentify which muscles are primarily responsible for quiet (normal, relaxed) inspiration?

		diaphragm
		internal intercostals
		sclaenes
		abdominal muscles

coffeepig115

Background

Almost all animal and plant cells require oxygen and give off carbon dioxide. This is called gas exchange and it occurs by passive diffusion. Some animals do all or most of their gas exchange across their skin (for example amphibians) but they have very low metabolisms and use very little oxygen and get rid of very little carbon dioxide.

On the other hand humans (and other mammals) have very high metabolic requirements and we canât rely on gas exchange over the limited 1.5 to 2.0 square meters of our skin to get enough oxygen in and carbon dioxide out fast enough. Our gas exchange takes place across a very thin membrane in the Alveoli of the lung and the gas exchange surface in humans is estimated to be between 50 and 100 square meters, or between 25 and 67 times our skin surface area.

Our lungs provide a huge surface for gas exchange but they are a dead-end system. Once the oxygen in the lungs is used up it needs to be replenished and carbon dioxide builds up in the air spaces in the lungs and needs to get out. This is where the diaphragm and a few of the skeletal muscles become important. In its relaxed state the diaphragm is at its longest and the space in the thoracic cavity (and the lungs) is small. When the diaphragm contracts it shortens, which increases the volume of the thoracic cavity (and the lungs). The increase in size means the pressure is lower in the lungs than outside so air comes into the lungs (inhalation). As the diaphragm relaxes, the lungs decrease in size enough that the pressure inside the lungs is higher than the external air pressure so air comes out (exhalation).

Introduction

In this lab you will be building a model of a lung and experimenting with different ways to breath.

Supplies:

In the Lab Kit

One round 9" balloon (one lung, we donât need two for this)
medium-sized plastic bag large enough to fit over bottom end of bottle (diaphragm)
medium-size, thin rubber band

You supply

plastic 2-liter soda bottle with bottom cut off (thoracic cavity)

Tape (optional)

Directions:

1. Insert the balloon through the open bottom of a modified 2-liter soda bottle and up over the neck of the bottle. Pull the end of the balloon over the edges of the neck of the bottle. The balloon is held open by the neck of the bottle.

2. Place the plastic bag over the bottom (open) end of the 2-liter bottle and use the rubber band to hold it in place. This will serve as the diaphragm. To inflate the lung, blow into the balloon just before you fasten the rubber band. You can also wrap tape over the edges of the plastic bag to minimize air leaks

3. Grasp the bottom of the plastic bag and pull it down and push it up. Watch as the "lungs" (the balloon) expand and contract as you do this. The balloon has to change size because the air space between the balloon and bottle must remain constant. (Well, it would if the seal around the plastic bag and bottle were perfect).

You may block the "trachea" (the neck of the bottle) so that the air supply is cut off and watch as nothing happens when the "diaphragm" is pushed in and out.

This model isnât perfect. None of the joints are air tight as they would be in a real thoracic cavity. Pull the âdiaphragm down and watch the lungs expand . If you hold it in place, the lungs will collapse again over time. This is because of leaks and is not how real lungs work. Pushing the diaphragm in and pulling it out over and over does give you an idea of how lungs work. As the diaphragm tightens, contracts (pull down on the plastic bag) the lungs fill with air. As the diaphragm relaxes (push up on the plastic bag) air is expelled from the lungs .

There are several different ways we breath, i.e. expand our thoracic cavity so that our lungs can expand. You have just made a demonstration model of the diaphragm at work. You can also use your rib cage to expand and contract so that you can inhale and exhale. There are muscles between and around your ribcage which you can use to change the size of your thoracic cavity.

This is approximately what your model of a lung will look like.

Answer the questions on the Report Page

Report Page Name

1. Put a hand on your lower ribcage and try moving your ribs out and in. Does air also move in and out?

2. Someone with an upper back or neck injury may not have the options of using diaphragm or ribs to breath. They can learn to use the clavicle and the muscles attached to expand their thoracic cavity a small amount and breathe independently for short periods of time. Put your hand on you clavicle and try to raise and lower just that bone without using your diaphragm or your ribs. It isnât easy but you should be able to get a little air into and out of your lungs this way. How effective do you think this way of breathing is?

3. When you take a really deep breath you use all these muscle groups to help. Take a really deep breath and notice that your ribs expand, your lower abdomen comes out (a sign that the diaphragm has contracted) and your shoulders lift a little (the upper chest and clavicle are working). Now take a relaxed breath. Only your abdomen should go in and out. The movement of your abdomen is a result of the contracting diaphragm pushing on the contents of your âgutâ which forces your abdomen to push out.

Do you breath in or out when your diaphragm contracts?\

4. If a hole were poked in your thoracic wall (the wall of the pop bottle â the hole should be at least the diameter of a pencil)

a. what would happen when you tried to breath? (This is a pneumothorax).

b. Is the space between the balloon and plastic bottle still required to remain constant?

5. Would it be possible to live with a paralyzed diaphragm? Explain your answer.

fuchsiamuskrat152

1. Match the word 1-39 above, with the descriptions labled a-t. Word 1-39 can be uses only one please!!

1. alveolar macrophages 2. alveoli 3. Bohr effect 4. bronchi 5. bronchiole 6. cerebral cortex 7. chloride shift 8. compliance 9. costal breathing 10. Daltonâs law 11. diaphragmatic breathing 12. epiglottis 13. eupnea 14. expiratory reserve volume 15. fauces 16. functional residual capacity 17. Haldane effect 18. Henryâs law 19. hilum 20. hypothalamus 21. inferior, middle, and superior nasal meatuses 22. inspiratory capacity 23. larynx 24. limbic system 25. medulla oblongata 26. nose 27. paranasal sinuses 28. pharynx 29. pleural membranes 30. pons 31. primary bronchus 32. secondary bronchus 33. surface tension 34. surfactant 35. terminal bronchiole 36. tertiary bronchus 37. total lung capacity 38. trachea 39. vital capacity

a) -------------------- serves as a sound resonating chamber; contains tonsils; directs air inferiorly

b) ------------------- passes air from pharynx into windpipe; site of sound production

c) ------------------ resonate(s) sound; not part of pharynx

D) ------------------ opening from oral cavity into pharynx

E) ----------------- carries air to a segment of a lung

F) -------------------- carries air directly into a respiratory bronchiole

G) ----------------- surround the lungs

H) ------------------ reduces surface tension at sites of gas exchange

i) -------------------- actual sites of gas exchange

j) --------------------- normal, quiet breathing

k) ----------------------- shallow breathing using just the external intercostal muscles

l) ------------------ amount of effort required to expand the lungs and chest wall

m) ------------------- tidal volume + inspiratory reserve volume, usually about 3600 mL in males

n) ----------------- tidal volume + inspiratory reserve volume + expiratory reserve volume; usually about 4800 mL in males

o) ------------------- residual volume + expiratory reserve volume; usually about 2400 mL in males

p) -------------------- states that the amount of gas that will dissolve in a liquid is proportional to the partial pressure of that gas and its solubility

q) ---------------- when pH decreases, O₂ saturation of hemoglobin decreases

r) ------------------ each gas in a mixture of gases exerts its own partial pressure

s) ------------------- sets basic rhythm of breathing

t) ------------------------ includes the pontine respiratory group

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ANHB2212 Lecture Notes - Lecture 9: External Intercostal Muscles, Pulmonary Pleurae, Intercostal Muscle

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