Do Now 10/14/14 1.What are the different types of muscle tissue in the body? 2.Which types of muscle tissue are voluntary? Involuntary? 3.Describe what it feels like when you feel a muscle “twitch.”

Muscular System

Types of Muscle Skeletal – striated & voluntary Smooth – involuntary Cardiac - heart

By the end of class, we will be able to… Describe the functions of skeletal muscle tissue Describe the anatomy of skeletal muscle tissue

Skeletal Muscles’ Functions 1. Body movement – contractions of muscles move the body 2. Maintenance of posture – postural muscles continuously contract when you are awake to keep you from collapsing 3. Protection and support – protect internal organs 4. Storage and movement of materials – sphincters contract and relax to permit passage of materials 5. Heat production – energy is used for muscle contraction and heat is produced as a result

What allow skeletal muscles to serve these functions? Conductivity – electrical change travels along the membrane of muscle cell Contractility – proteins in muscle cells slide past one another, causing the muscle itself to shorten Excitability – muscle cells respond to nervous system stimulation Elasticity – special fibers act like compressed coils when a muscle contracts; when the tension is released in the fibers, the muscle returns to normal length Extensibility – muscle cells can lengthen

Muscles and Muscle Fibers Muscles are composed of many fibers that are arranged in bundles called FASCICLES Individual muscles are separated by FASCIA, which also forms tendons and aponeuroses

Fascicle

Muscle Fascicle Muscle Fiber Myofibril Myofilament

Connective Tissue within Skeletal Muscle Cells In order of most superficial to most deep within the skeletal muscle: 1. Epimysium – surrounds whole skeletal muscle 2. Perimysium – surrounds the fascicle 3. Endomysium – surrounds the muscle fiber

Fascicle Myofilament

Within the Muscle Fiber… Sarcolemma = muscle fiber membrane Sarcoplasm = inner material surrounding fibers (like cytoplasm) Myofibrils = individual muscle fibers  made of myofilaments

Within the Myofibril… Contains protein filaments (myofilament) – ACTIN (thin) and MYOSIN (thick) These filaments overlap to form dark and light bands on the muscle fiber  A band = dArk thick (myosin) *H zone = only thick, no thin overlap  I band = lIght thIn (actin) – only thin In the middle of each I band are Z disc. One sarcomere is one Z disc to the other

It is important to remember the heirarchy fasicles myofibrils myofilaments actin myosin

It is important to remember the heirarchy fasicles myofibrils myofilaments actinmyosin

muscleepimysium myofibrilsmyofilament sarcomere muscle fiber

muscle epimysium myofibrils sarcomere muscle fiber myofilament

Homework Read and take notes on 10.3 due Th, 10/16 Muscle Contraction Quiz on Mon, 10/20 Sliding Filament Project due Fri, 10/24 Muscular System Test on Tues, 10/28

Exit Ticket 1. What is the name of the layers of connective tissue that separate muscles? a) Fascicle b) Myofibril c) Fascia d) Sarcomere 2. What is the name of the bundles of muscle fibers that make up a muscle? a) Fascicle b) Myofibril c) Fascia d) Sarcomere 3. What are the names of the bundles of protein fibers that make up a muscle fiber? a) Fascicle b) Myofibril c) Fascia d) Sarcomere 4. What do I call the repeating section of a myofibril that goes from Z line to Z line? a) Fascicle b) Myofibril c) Fascia d) Sarcomere 5. What is the name of the thick filament that makes up muscle fibers? a) Myofibril b) Actin c) Myosin d) Sarcomere 6. What is the name of the thin filament that makes up muscle fibers? a) Myofibril b) Actin c) Myosin d) Sarcomere