Muscle Structure and Function
description
Transcript of Muscle Structure and Function
![Page 1: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/1.jpg)
![Page 2: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/2.jpg)
Types of Muscle• The human body is comprised of over 600 muscles• Muscle makes up 30-35% (in women) and 42-47% (in men) of body mass.
Three types of muscle:
Skeletal muscle
Smooth muscle
Cardiac muscle
![Page 3: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/3.jpg)
Key TermsTendons - tough bands of connective tissue that join muscle to
boneAponeurosis – a sheet-like membrane that serves as a fascia to
bind muscles together or to connect muscle to bone
ex. Palmar aponeurosis
Fascia – connective tissue that covers, supports, and separates muscles
ex. Fascia lata (thigh), brachial fascia (upper arm)
Tissue - masses of cells that have similar function and formMuscle tissue - collection of cells that shorten during
contraction, therefore creating tension that results in movement
![Page 4: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/4.jpg)
A. Skeletal (Striated) Muscle
Muscles that are attached to the bones via connective tissue tendons– During muscle contraction, skeletal muscle
shortens and moves various parts of the skeleton
– We have voluntary control of our muscles, meaning they are activated through signals carried to the them via nerves
– Referred to as striated, because their appearance is a series of alternating light and dark stripes (myofilaments)
– Repetitive contraction leads to fatigue
![Page 5: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/5.jpg)
B. Smooth Muscle
Muscles surrounding your body’s internal organs, as well as your blood vessels, respiratory tract, iris (eye) & gastro-intestinal tract– The contractions are slow and uniform and can
remain for long periods of time
– Activation is involuntary
– Fatigue resistant
– Fibres are arranged in dense sheets, therefore appearing smooth
![Page 6: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/6.jpg)
C. Cardiac Muscle
Muscles found only in the heart.– Functions to provide the contractile
activity of the heart (pumping blood to the rest of the body)
– Is very fatigue resistant
– Activation of cardiac muscle is involuntary
– Striated
![Page 7: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/7.jpg)
a) Muscle b) Fascicle c) Muscle fiber d) Myofibril
Components of skeletal muscle
![Page 8: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/8.jpg)
Muscle StructureBeginning at the muscle (superficial to deep):
• Epimysium: connective tissue surrounding the whole muscle (many fascicles)
• Perimysium: connective tissue surrounding each fascicle
• Fascicle: perimysium wrapped muscle fibres
• Endomysium: connective tissue surrounding each muscle fibre
• Muscle fiber: muscle cell
• Sarcolemma: a plasma membrane beneath the endomysium that contains the cells sarcoplasm
• Sarcoplasm: similar to cytoplasm of other cells, containing large amounts of glucose & myoglobin (protein that stores oxygen)
![Page 9: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/9.jpg)
• Myofibrils: rodlike contractile elements, that occupy most of the muscle cell and are composed of sarcomeres arranged end to end
• Sarcomeres: a contractile unit composed of myofilaments (actin & myosin)
• Myofilaments:o Myosin (thick): made up of a “head” (attachment site for actin) & “tail”o Actin (thin):
− tropomyosin: arranged along the actin filament, and when relaxed prevent myosin head from binding to actin
− troponin: binding site for calcium
Muscle Structure Cont’d
![Page 10: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/10.jpg)
Properties of a Muscle Fibre
Irritability - ability of muscle to respond to stimulus
Conductivity - ability to transmit nerve impulses
Contractibility - ability to shorten in length
Extensibility - ability to extend in length
Elasticity - ability to stretch and return to normal position
![Page 11: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/11.jpg)
Muscle Teamwork
Agonist (prime mover): • the muscle or group of
muscles producing a desired effect
Antagonist: • the muscle or group of
muscles opposing the action• lengthens when the agonist
muscle contracts
![Page 12: Muscle Structure and Function](https://reader035.fdocuments.net/reader035/viewer/2022062410/568162b6550346895dd33f2a/html5/thumbnails/12.jpg)
Contractile Machinery:
Origin & InsertionIn order for muscles to contract, they must be attached to the bones to create movement.
Origin: the end of the muscle attached to the bone that does not move (proximal attachment)
Insertion: the point of attachment of the muscle on the bone that moves (distal attachment)