The Muscular System FQ What is the hierarchal

The Muscular System • FQ: What is the hierarchal structure of a muscle cell from the tiniest fiber to the largest muscle mass? • ET: Grab a copy of the article from the front of the room? Read and highlight important information from the article

The Muscular System • ET: Wh at are the four majo r roles of muscle the body tissue in ? Use book • Focus Questions 1. FQ: What are the following: endomysium, perimysium, epimysium, tendon, and aponeurosis? • Coloring Sheet • POGIL

The Function of Muscles • Four important roles for the body: 1. 2. 3. 4. Produce movement Maintain posture Stabilize joints Generate Heat

Review of Muscle Tissue Types • All muscle cells are elongated, thus we call them fibers • All muscle cells can contract • Myo/Mys (muscle) • Sarco (flesh)

e l c s u M Skeletal • Connects muscle to bone • Appears striped (striated) • Voluntary • May contract rapidly, and forcefully but tires easily • Structure 1. Endomysium 2. Perimysium 3. epimysium

Smooth Muscle • No striations • Involuntary, slow and constant contractions • Lines hollow visceral organs – stomach, bladder, intestines • Propels substances along a definite track within the body – food • Double layered Sheet of thin cells running circularly and longitudinally

e l c s u M Cardiac • Heart only • Striated • Slow, constant contractions • Figure-8 shaped bundles that pump blood

Microscopic Anatomy of Skeletal Muscle • Sarcolemma – the plasma membrane • Myofibrils – bundles of myosin (thick) and actin (thin) proteins • Sarcoplasmic reticulum – Store and release calcium for muscle contraction

Muscular System Lesson 2 Skeletal Muscle Activity

Stimulation and Contraction of Muscles c s u m o d • FQ: How ove? m / t c a r t n o c • ET: Review anatomy of a skeletal muscle cell using your coloring sheet.

Nerve Stimulus and Action Potential • The neurotransmitter • Acetylcholine (Ach) is released by Axon terminal. • This makes the membrane of the muscle fiber (sarcolemma) permeable to sodium ions. This rush of positively charged ions creates a concentrations gradient/electrical current called an Action Potential.

Mechanism of Muscle Contraction 1. Ca+ ions cause troponin and tropomyosin (regulatory proteins) on the actin filament to change shape and move out of the way so that myosin can bind to it forming a cross bridge 2. using ATP, the myosin head bends toward the center of the sarcomere pulling actin filament (power stroke) 3. Detachment – ATP binds to the myosin head and weakens the cross bridge bond 4. The energy released by ATP reactivates the myosin for another contraction to occur

Muscular System Lesson 3 Providing Energy for Contraction

How does muscle keep up with all the ATP that they need? • 3 Pathways 1. Direct phosphorylation of ADP by creatine phosphate 2. Aerobic respiration 3. Lactic acid fermentation

Direct phosphorylation of ADP by Creatine Phosphate • Creatine phosphate gives its phosphate to ADP to make ATP • CP stores only last about 20 seconds

Aerobic Respiration • Requires Oxygen • 36 ATP / Glucose • Slow compared to CP

Lactic Acid Fermentation • Does not require oxygen • Quicker than CR (2. 5 x faster) • Uses huge amounts of glucose for not a lot of ATP • Good for 30 to 40 seconds of strenuous exercise • Build up of lactic acid causes muscle fatigue and soreness

2 Types of Muscle Contraction • Isotonic – Normal muscle contraction where the fibers are successful in their sliding motion • Isometric – when the fibers attach but cannot slide, like when you try and lift something too heavy. The muscle cannot contract, even though you are engaging it to lift something

• Continuous partial contraction that cannot be consciously controlled • The nervous system stimulates these fibers in a systematic way all the time so that you can move when you decide to move What is Muscle “TONE”? ?

How Does Exercise Effect Muscles? • Aerobic exercise causes muscles to become flexible with a greater resistance to fatigue – Blood supply to the cell increases – Mitochondria increase in number – Increases overall body cell metabolism – Strengthens bone – Strengthens and enlarges the heart – Improves gas exchange in the lungs

How Does Exercise Effect Muscles? • Resistance training (isometric) causes individual muscle cells to develop more fibers and connective tissue – Increases strength and ability to lift – If you exercise your core you’re a providing stability to your entire body