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Muscles are the active part of the motor apparatus: their contractions are producing various movements, when they are active. Functionally we divide all muscles into two groups: voluntary and involuntary muscles.

Muscle is a contractile tissue (сокращающаяся ткань) and is derived from the mesodermal layer (мезодермальный слой) of embryonic cells. Muscle cells contain contractile filaments (нити) that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth (гладкие) muscles. Their function is to produce force and cause motion.

There are three types of muscle tissue recognized in vertebrates (позвоночные):

Skeletal muscle or "voluntary muscle" (произвольно сокращающаяся мышца) is anchored (закреплена) by tendons (сухожилия) to bone and is used to effect skeletal movement such as locomotion (передвижение) and in maintaining posture (осанка). Though this postural control is generally maintained as an unconscious (бессознательный) reflex, the muscles responsible react to conscious control like non-postural (непостуральный) muscles. An average adult male is made up of 42% of skeletal muscle and an average adult female is made up of 36%.

Smooth muscle or "involuntary muscle" is found within the walls of organs and structures such as the esophagus (пищевод), stomach, intestines, bronchi, uterus, urethra, bladder, blood vessels. Unlike skeletal muscle, smooth muscle is not under conscious control.

Cardiac muscle is also an "involuntary muscle" but is more akin (схожа) in structure to skeletal muscle, and is found only in the heart.

 

Answer the questions.

1. Give the definition of the word ‘muscle’.

2. What do muscle cells contain?

3. How are they classified?

4. What is a skeletal muscle?

5. What is a smooth muscle?

6. What is a cardiac muscle?

The Muscular System

There are more than 600 muscles in the Human Body!!!

Muscles are…

· Needed for all types of movement

· Needed to pump blood

· Needed to breathe (diaphragm muscle)

· Needed to produce body heat and regulate body temperature

· Needed to protect internal organs.

There are 3 Types of Muscle

Skeletal Muscle

Move your bones (also your face, eyes etc) Voluntary (you can control them) Over 400 skeletal muscles in your body Long cells with several nuclei (along edges of cell) Stripes called striations in cell (visible in high power)  

Cardiac Muscle

The muscle of the Heart Involuntary (you cannot control them) Works 24 hours a day every day of your life!!! Strongest type of muscle Only one nucleus per cell (usually in center of cell) Some striping (striations) but not as much as skeletal muscle
Smooth Muscle The muscles of the esophagus, stomach, intestines and other internal organs Involuntary (you cannot control them) Contract slowly and smoothly Can remain contracted for long periods of time Usually one nucleus per cell (usually in center of cell) No striping (striations)
     

How a Muscle Works

A skeletal muscle works by CONTRACTING (getting shorter).

The muscle can shorten as much as 1/3 its resting length.

Each muscle cell is made up of many smaller MYOFIBRILS

The MYOFIBRILS are in contact with a nerve ending.

The nerve releases a chemical called a NEUROTRANSMITTER.

The Neurotransmitter stimulates the entire muscle cell to contract.

Muscles work in pairs. The biceps muscle will bend the arm at the elbow and the triceps muscle will straighten the arm. While one muscle in the pair contracts the other must relax.

Video tasks:

1. Give the four properties possessed by muscle tissue.
2. Differentiate between skeletal, smooth and cardiac muscle.
3. Describe how muscles work together to create movement.
4. Discuss the ways in which skeletal muscle fiber cells differ from other cells in the body.
5. Describe the effects of strenuous exercise on the muscular system.
6. Tell how the terms "voluntary and "involuntary relate to muscular tissue.

УРОК №6. НЕРВНАЯ СИСТЕМА. NERVOUS SYSTEM

Vocabulary:

a network - сеть to transmit - передавать brain - мозг spinal cord – спиной мозг ganglia – нервные узлы the brain stem – кора мозга the cerebrum – головной мозг the cerebellum - мозжечок the diencephalon – промежуточный мозг approximately - приблизительно glia - глия nerve fibers – нервное волокно axon – аксон, осевой цилиндр Medulla oblongata – костный мозг the pons – варолиев мост (часть заднего мозга) the bulk- объём hemisphere - полушарие frontal lobe – лобная доля temporal lobe – височная доля parietal lobe – теменная доля occipital lobe – затылочная доля fore - передний thalamus - таламус, зрительный бугор coalesce - срастаться


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