Download Unit 8 Muscles - Structure and Contraction 1. Warm-up

Unit 8
Unit 8
Muscles - Structure and Contraction
1. Warm-up
Try a few TONGUE TWISTERS.
Good, better, best,
Never let it rest,
Till your good is better
And your better best.
Tonight is a light night, so you
mustn't light a night light on a
light night like this.
2. Reading
Task 1
Can you match up these sentences to complete some idioms which use parts of the body?
What's their Slovak meaning?
1. I'm
so busy. I hardly know if
2. His fingers are
3. He always lies
a) all thumbs.
b) I'm on my head or my
heels.
c) to my face.
A) Neviem, kde mi hlava
stojí.
B) Má obe ruky ľavé.
C) Klame mi do očí.
Structure of muscles
Muscle is an excitable tissue, meaning that it can be stimulated mechanically,
chemically or electrically to produce an action potential. There are about 650 muscles in the
human body, about 40% of the body is skeletal muscle, 5-10 % cardiac and smooth muscle.
Muscles may connect directly to the tough connective-tissue layer on a bone's surface or may
grade into tendons – extremely tough bundles of collagen fibers which connect to bones.
Each of the muscles is made up of thousands of thin long, cylindrical cells called
muscle fibers.The muscle cell is packed full of thinner fibres called myofibrils. These fibres
contain protein filaments, called thick and thin myofilaments, which slide against each other
when a muscle contracts. Muscle cells contain filaments of two kinds of proteins, actin and
myosin, which slide past each other as the muscle contracts.
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Unit 8
Figure 8.1 Two kinds of proteins-actin and myosin in musle fiber (available on <http://
www.abcbodybuilding.com/ actin_myosin.jpg>)
Figure 8.2 Structure of skeletal muscle (available on<http://
www.sirinet.net/~jgjohnson/musculestructureoh.jpg>)
Characteristics of muscles:




excitability - responds to stimuli, e.g. nervous impulses
contractility - able to shorten in length
extensibility - stretches when pulled
elasticity - tends to return to original shape and length after cotraction or extension
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Unit 8
Contraction
In a relaxed muscle, thick and thin myofilaments overlap each other a tiny bit. When a
muscle cell is stimulated by a nerve impulse, these myofilaments slide past each other until
they completely overlap. This makes the muscle cell shorter and fatter. The more shortened
muscle cells there are in a muscle, the greater contraction of the muscle as a whole. Muscles
can only pull or contract, not push. Muscles are grouped together in pairs on the skeleton.
When one muscle of a pair contracts, the other relaxes. Simple movements involve the
relative activities of sets of muscles that act in opposition to each other: the agonist, or prime
mover muscle and its antagonist muscle.
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Unit 8
Task 2
Read the text above carefully and find all adjectives in the text.
Task 3
Answer the questions.
1.What is muscle?
2. How many muscles are there in the human body?
3. What is the structure of muscle?
4. Can you characterize function of muscles?
5. Explain the contraction of muscles.
3. Grammar Presentation
Adjectives: comparatives and superlatives
There is more than one way to form the comparative of adjectives:
- for one-syllable and two syllable adjectives ending in -y, use adjective + -er, e.g. bigger,
easier
- for other adjectives of two or more syllabes, use more/less + adjective, e.g. more pleasant.
There is more than one way to form the superlative of adjectives:
- for one or two-syllable adjectives ending in -y, use the + adjective + -est, e.g. the nicest
- for most other adjectives of two or more syllables, use the most/the least + adjective, e.g.
the most comfortable.
There are irregular forms of adjectives, e.g. good – better – best
bad – worse – worst
Task 1
Write the comparative and superlative forms of these adjectives:
thin, long, short, thick, fat, great, excitable, tiny
Task 2
Read the text about the structure of muscles. Write down the comparative form of
adjectives from the text.
4. Writing
Write a short paragraph about the muscle structure and contraction. You may make
longer sentenses by combining them with coordinate conjunctions (and, but, or, so),
subordinate conjunctions (after, because, before, if, when while, until, although) or
conjunctive adverbs (as a result, besides, however, in addition, moreover, on the other
hand, therefore).
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Unit 8
Vocabulary
actin [æktin] – aktín
action potential [ækšn potenšl] – akčný potenciál
bit [bit] – kúsok, hrot
cell [sel] – bunka
contraction [kəntrækšn] – sťah, skrátenie
contractility [kontræktility] – skracovanie
contract [kontrækt] – skrátiť
elasticity [elæstisiti] – pružnosť
excitable [exciteibl] – vzrušený
excitability [iksitebility] – vzrušenie, rozrušenie
extensibility [ikstenzibility] – rozsiahlosť
fiber [fibə] – vlákno
filament [f iləmənt] – filament, vlákno
impulse ['impals] – podnet, impulz
myosin [maiəsin] – myozín, svalová bielkovina
muscle [masl] – sval
cardiac m. [kardiæk] – srdcový
sceletal m. [skeletl] – kostrový
smooth m. [smu: t] – hladký
myofibril [maiəfaibrəl] – myofibrila, svalové vlákenko
myofilament [maiəfiləment] – myofilament, bielkovinové vlákno myofibrily
nerve impulse [nə: v impals] – nervový impulz
overlap [əuvəlæp] – prekrývať
prime mover [ praimə mu:və] – hnací stroj, východisko pohybu
pull [pul] – ťahať
push [puš] – tlačiť
slide [slaid] – kĺzať sa, šmýkať
tiny [taini] – nepatrný , drobný
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