The Muscular System

Question 1

Muscular System

Answer 1

● The Muscular System consists of the muscles of the body and their attachments: Tendons and Fascia
● When the muscle fibres contract the muscles change shape and move whichever part of the body they are attached to
● Can be voluntary or involuntary

Question 2

Functions of Muscle

Answer 2

● To produce a movement by contracting (or shortening) in reaction to nerves stimulus sent by brain through a motor nerve
● Give shape to the body
● Aid flow/movement of blood and lymph
● Store glycogen
● Produce heat and maintenance of body temperature – Homeostasis!

Question 3

Muscle Structure

Answer 3

● Muscle tissue is bound together in bundles and contained in sheath (Fascia), the end of which extends to form a tendon that attaches the muscle to other parts of the body

● Muscle is 75% water and 20% protein, 5% fats, mineral salts and glycogen

Question 4

Skeletal Muscle
(Voluntary and Striated)

Answer 4

● Under control of Central Nervous System
● Attached to the bone or skin by tendons causing movement of part of skeleton
● Under control of will
● Has cylindrical cells known as muscle fibres
● The stripes or striations are formed by thin protein Actin and thick protein Myosin filaments
● When the muscle contracts, the actin filaments slide between the myosin filaments, which causes a shortening and thickening of the fibres

Question 5

Involuntary
(Non-striated, Smooth)

Answer 5

● Controlled by Autonomic Nervous System
● Found within body organs, walls of blood and lymph vessels, digestive system, respiratory system, bladder and the uterus
● Bundles of fibres are surrounded by areolar tissue to form sheets of muscle, which form the wall of the organs

Question 6

Cardiac
(Looks like voluntary muscle but behaves like smooth muscle)

Answer 6

● Found only in heart
● Power mechanism responsible for hearts pumping action
● Automatic rhythmical contrition independent of nerve stimulus

Question 7

Chemistry of Muscle Contraction

Answer 7

● Stimulus is supplied by motor nerves
● Either at a point in the belly of the muscle at which a motor nerve enters a muscle
● At any point on the skin over a muscle at which electrical stimulation (via electrode) causes contraction of the muscle
● Energy for muscle contraction comes from glucose
● Obtained by using oxygen to breakdown carbohydrates
● After contraction, lactic acid is formed
● Oxygen converts lactic acid into carbon dioxide and water, which is then excreted
● Sudden and excessive exercise causes build up of lactic acid due to lack of oxygen
● This causes pain and discomfort and is known as muscle fatigue
● Rest and fresh blood supply are required to recover

Question 8

Muscle Origin and Insertion

Answer 8

● The origin is the attachment site that doesn’t move during contraction, while the insertion is the attachment site that does move when the muscle contracts

● The insertion is usually distal, or further away, while the origin is proximal, or closer to the body, relative to the insertion

Question 9

Body Types

Answer 9

Ectomorph
● Lean and long, with difficulty building muscle

Endomorph
● Big, high body fat, often pear-shaped, with a high tendency to store body fat

Mesomorph
● Muscular and well-built, with a high metabolism and responsive muscle cells