Prevention of alveolar collapse

The lungs make a surfactant, a surface-active lipoprotein complex (phospholipoprotein) formed by type II alveolar cells. It floats on the surface of the thin watery layer which lines the insides of the alveoli, reducing the water's surface tension.

The surface tension of a watery surface (the water-air interface) tends to make that surface shrink.^[6] When that surface is curved as it is in the alveoli of the lungs, the shrinkage of the surface decreases the diameter of the alveoli. The more acute the curvature of the water-air interface the greater the tendency for the alveolus to collapse.^[6] This has three effects. Firstly the surface tension inside the alveoli resists expansion of the alveoli during inhalation (i.e. it makes the lung stiff, or non-compliant). Surfactant reduces the surface tension and therefore makes the lungs more compliant, or less stiff, than if it were not there. Secondly, the diameters of the alveoli increase and decrease during the breathing cycle. This means that the alveoli have a greater tendency to collapse (i.e. cause atelectasis) at the end of exhalation that at the end of inhalation. Since surfactant floats on the watery surface, its molecules are more tightly packed together when the alveoli shrink during exhalation.^[6] This causes them to have a greater surface tension-lowering effect when the alveoli are small than when they are large (as at the end of inhalation, when the surfactant molecules are more widely spaced). The tendency for the alveoli to collapse is therefore almost the same at the end of exhalation as at the end of inhalation. Thirdly, the surface tension of the curved watery layer lining the alveoli tends to draw water from the lung tissues into the alveoli. Surfactant reduces this danger to negligible levels, and keeps the alveoli dry.^[6][32]

Pre-term babies who are unable to manufacture surfactant have lungs that tend to collapse each time they breathe out. Unless treated, this condition, called respiratory distress syndrome, is fatal. Basic scientific experiments, carried out using cells from chicken lungs, support the potential for using steroids as a means of furthering development of type II alveolar cells.^[33] In fact, once a premature birth is threatened, every effort is made to delay the birth, and a series of steroid injections is frequently administered to the mother during this delay in an effort to promote lung maturation.^[34]

Clinical significance

Disorders of the respiratory system can be classified into several general groups:

· Airway obstructive conditions (e.g., emphysema, bronchitis, asthma)

· Pulmonary restrictive conditions (e.g., fibrosis, sarcoidosis, alveolar damage, pleural effusion)

· Vascular diseases (e.g., pulmonary edema, pulmonary embolism, pulmonary hypertension)

· Infectious, environmental and other "diseases" (e.g., pneumonia, tuberculosis, asbestosis, particulate pollutants)

· Primary cancers (e.g. bronchial carcinoma, mesothelioma)

· Secondary cancers (e.g. cancers that originated elsewhere in the body, but have seeded themselves in the lungs)

· Insufficient surfactant (e.g. respiratory distress syndrome in pre-term babies).

Disorders of the respiratory system are usually treated by a pulmonologist and respiratory therapist.

Where there is an inability to breathe or an insufficiency in breathing a medical ventilator may be used.

 

References

1. Ganong, W.F. Review of Medical Physiology (seventeenth edition). New Jersey, Prentice-Hall, 1995.

2. Jannsens, JP, Pache JC, Nicod LP. ‘Physiological changes in respiratory function associated with ageing,’ European Respiratory Journal. 1999, 13(1):197-205

3. Johnson, L.R. Essential Medical Physiology (second edition). Philadelphia, Lippincott Williams & Wilkins, 1998.

4. Last, L.J. Aids to Anatomy (twelfth edition). London, Balliere, Tindall & Cassell, 1962.

5. Moore, K.L., Dalley, A.F. Clinically Oriented Anatomy (fourth edition). Baltimore, Lippincott Williams & Wilkins, 1999.

6. Robinson, M.J., Roberton, D.M. Practical Paediatrics (fifth edition). Sydney: Churchill Livingstone, 2003.

 

Sources:

https://en.wikipedia.org/wiki/Respiratory_system

https://www.livescience.com/22616-respiratory-system.html

https://www.myvmc.com/anatomy/respiratory-system/

http://www.innerbody.com/anatomy/respiratory

https://www.britannica.com/science/human-respiratory-system/Introduction

https://www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022181/full information

https://www.visiblebody.com/learn/respiratory/5-functions-of-respiratory-system

 

 

Unit 9

Digestive system

T opic Digestive System

Grammar Paired Conjunctions Revision – ing forms

Vocabulary Digestive System, Noun suffix – y Adjective suffix – ful, - ive (-ative, -itive) Revision Noun suffixes – um, -tion, - ment Adjective suffix – al, - ic, - ary Verb suffix - ate

Reading ‘Gastrointestinal tract’, ‘Some facts about Stomach’

Listening ‘GI Organs and their Functions’ (video)

Speaking Pair work (Structure and Functions of GI), Group Work (Discussion), Summary

Getting started

1. Look at the pictures and answer the questions:

Ø What are children doing in the pictures?

Ø What food are they having?

Ø What food did you have being a child? For everyday meals? In cafes?

  2.Look at the food in pictures below:

Ø What food do you prefer now?

Ø Choose pictures with ‘good food’ and ‘bad food’. Explain your choice.

Ø Why do we need food?

Ø What system digests the food taken in?

Vocabulary forhelp ing you to cope with texts and tasks:

Word building:

Noun Suffix – y

Adjective suffix – ful, ive (-ative, -itive)

See Unite 2 for the noun suffix – tion, - ment

See Unite 5 for the adjective suffix – al, -ic

See Unite 7 for the noun suffix – um, the adjective suffix – ary, the verb suffix – ate

 

Suffix – y forms nouns:

1. (added to verbs) indicating the act of doing what is indicated by the verbal element: inquiry.

2. (esp with combining forms of Greek, Latin, or French origin) indicating state, condition, or quality: geography; jealousy, anatomy, histology

Suffix – ful is used to form adjectives from nouns meaning ‘full of’, ‘characterized by’: shameful, beautiful, careful; ‘tending to’, ‘able to’: wakeful, harmful; ‘as much as will fill’: spoonful.

Suffix – ive (-ative, -itive) is a suffix of adjectives (and nouns of adjectival origin) expressing tendency, disposition, function, connection, etc.: active, destructive, passive

 

3. Define the part of the speech of the words given below and translate them into Russian:

Digestive, digestional tract, energy, adjective, movement, digestion, collection, anatomic, accessory, salivary, function, anatomy, buccal, duodenum, pyloric, jejunum, ileum, cecum, colic, rectum, oral, cavity, mediastinum, thoracic, gastric, abdominal, functional, lateral, symbiotic, body through, anal, accessory, fundamental, hepatic, locate, pancreatic, vital, harmful

 

4. Read and translate the anatomical terms of Latin-Greek origin. Pay your attention to the pronunciation of the words:

Oral[`Lr(q)l], diaphragm[`daIqfrxm], mediastinum [,mJdIq`staInqm], inferior[In`fIqrIq], segment[`segmqnt], digest[daI`Gest], stomach[`stAmqk], esophagus[J`sOfqgqs], enzyme[`enzaIm], saliva[sq`laIvq], pancreas[`pxNkrIqs], buccal [`bAk(q)l], uvula [`jHvjqlq], duodenum [,djHeV`dJnqm], jejunum[GI`GHnqm], ileum[`IlIqm], pyloric[pAI`lOrIk], sphincter[`sfIN(k)tq], cecum[`sJkqm], appendix[q`pendIks], flexure[`flekSq], colon[`kqulOn], sigmoid[`sIgmOId], rectum[`rektqm], anus[`eInqs], mucosa[mjH`kqusq], gastric [`gxstrIk], acid [`xsId], lobule [`lObjHl], hepatic [hI`pxtIk]

 

Useful vocabulary:

gastrointestinal tract [,gxstrqVIn`testInl trxkt]– желудочно-кишечныйтракт

uppertract[`Apqtrxkt]– верхнийотделжелудочно-кишечноготракта

lowertract [`lquqtrxkt]– нижний отдел желудочно-кишечного тракта

todigest[daI`Gest]– переваривать, усваивать

digestion[daI`GesC(q)n]– пищеварение, усвоение

toextract[Ik`strxkt]– извлекать, выделять

toexpel[Ik`spel]– исключать, выгонять

topertainto[pW`teIn]– иметь отношение, принадлежать

stomach [`stAmqk] - желудок

small intestine[smLl In`testIn]  – тонкаякишка

large intestine [lRG In`testIn]– толстаякишка

intestines[In`testIns]– кишечник

mouth[mauT] –рот

uvula[`jHvjqlq]- язычок

esophagus[J`sOfqgqs] - пищевод

torelease[rI`lJs] – высвобождать, выбрасывать, выделять

tomoisten[`mOIs(q)n]– увлажнять, смачивать

toswallow[`swOlqu] – глотать

tochew[CH] - жевать

accessoryorgan[qk`ses(q)rI `Lgqn]– вспомогательныйорган, добавочныйорган

tongue[tAN]- язык

salivarygland[`sxlIv(q)rIglxnd]– слюннаяжелеза

pancreas[`pxNkrIqs]– поджелудочная железа

liver[`lIvq]- печень

gallbladder[`gLl,blxdq]– желчный пузырь

holloworgan`Lgqn]– полый орган

topropel[prq`pel]– двигать, толкать вперёд

contents[`kOntqnts]- содержимое

grossanatomy[grqusq`nxtqmI] – макроскопическая анатомия

microscopicanatomy[,maIkrq`skOpIkq`nxtqmI] - гистология

todescribe[dI`skraIb]– описывать, характеризовать

duodenum[,djHeV`dJnqm]– двенадцатиперстная кишка

jejunum[GI`GHnqm]– тощая кишка

ileum[`IlIqm]– подвздошная кишка

bowel[`bauql]– кишечник, внутренности

cecum[`sJkqm]– слепая кишка

toascend[q`send] - подниматься, восходить

colon[`kqulOn]- ободочная кишка

spleen[splJn]- селезёнка

todescend (downsmth) [dI`send] – нисходить, понижаться

rectum[`rektqm] - прямаякишка

anus[`eInqs] – анус, заднийпроход

toaid (insmth) [eId]– помогать (вчём-либо)

tomeasure[`meZq] (inlength, inwidth) - измерять, отсчитывать, составлять…….. вдлину, ширину

mucosa[mjH`kqusq] – слизистаяоболочка

atthelevelof[`lev(q)l] – науровне

todeliver[dI`lIvq] - доставлять

gastricjuice[`gxstrIkGHs] – желудочныйсок

average[`xv(q)rIG]– средний, средняя величина

toexpand[Ik`spxnd]– расширяться, растягиваться, увеличиваться

toconstitute[`kOnstItjHt]– составлять, основывать

abdominalcavity[`kxvqtI]– брюшная полость

ridge[rIG]– выступ, неровность, гребень

tobreakdown[breIk] (broke, broken) – разрушаться, распадаться

tosecrete[sI`krJt]- выделять

toweigh[weI] – весить, взвешивать

weight[weIt]- вес

hepaticduct[hI`pxtIk dAkt]– печёночныйпроток

bile[baIl]-желчь

endocrinegland [`endqukraIn glxnd] - эндокриннаяжелеза

exocrinegland[`Fksq(V)krAIn glxnd] – железавнешнейсекреции

vitalfunction[`vaIt(q)l `fANkS(q)n]– жизненнаяфункция (организма)

defensivemechanism[dI`fensIv `mekqnIzm]– защитныймеханизм

harmful[`hRmf(q)l] – вредный, вредоносный

immune system [I`mjHn `sIstqm] – иммуннаясистема