Muscle Anatomy Chapter 7 PDF

CHAPTER 10 Muscle Tissue  Muscle Tissue Introduction Structure of Skeletal Muscle Introduction Three types of muscle: 1. Skeletal: function: to move the skeletal of the body (voluntary) 2. Cardiac: forms most of the heart wall (involuntary) 3. Smooth: located in the...

CHAPTER 10 Muscle Tissue  Muscle Tissue Introduction Structure of Skeletal Muscle Introduction Three types of muscle: 1. Skeletal: function: to move the skeletal of the body (voluntary) 2. Cardiac: forms most of the heart wall (involuntary) 3. Smooth: located in the walls of hollow structures: blood vessels, airways, and organs (involuntary) Muscles comprise largest group of tissues in body Muscle (all three types) makes up about 40-50% of total body mass. Presentation focused primarily on skeletal muscle  Muscle Tissue Introduction Structure of Skeletal Muscle Connective Tissue Coverings Typical Skeletal Muscle consists of 1 whole muscle connected by tendons (1) to the skeleton Muscles have a reddish appearance duo to high vascularization Tendons are whitish due to being minimally vascular and presence of collagen fibers. Muscle Structure Whole muscle is covered in a dense connective tissue called Epimysium (2). 2 Whole muscle is divided into smaller “bundles” called 3 Fascicles (3) which are covered in connective tissue 4 called Perimysium (4). Fascicles are divided into smaller bundles called Muscle 3 Fibers (5) which are covered by connective tissue called 6 Endomysium (6). 5 Muscle Fibers are the “cells” of muscle. Tendons 1 Tendons are a continuous mass of connective tissues (endomysium, perimysium and epimysium) that emerge from muscle at both ends. At bone, the tendon is continuous with the bone periosteum (1). This is what makes the muscles so strong Nerves and Blood Supply Skeletal Muscles are supplied with nerves and blood. These nerves are called Somatic Motor Neurons. Arteries and veins generally accompany the nerve into the Skeletal muscle Somatic Motor Neuron Muscle Fiber (muscle cell) Muscle Fibers are the “cells” of muscle. Most important component of muscle. During embryonic development, muscle fibers arise from the fusion of hundreds of myoblast cells (1) Each mature Muscle Fiber (muscle cell) has a hundred or more nuclei. 1 Sarcolemma, Nuclei, T tubules The Sarcolemma (1) (blue covering) is the plasma membrane of Muscle Fiber. Multiple nuclei (2) are located just beneath the sarcolemma T tubules (thin blue vessels) (3) tunnel from surface to inner aspects of muscle fiber. Action Potentials propagate along the sarcolemma (1) and down the T tubules (3) into the depths of muscle fiber. 1 2 3 Myofibrils and Sarcoplasmic Reticulum Muscle fibers are composed of multiple Myofibrils (1) which are contractile elements of skeletal muscle and extend entire length of muscle fiber. Encircling each myofibril are calcium-filled (Ca2+) sacs called the Sarcoplasmic Reticulum (2). When an Action Potential is carried by the T tubule into the muscle fiber, it causes release of calcium ions from the sarcoplasmic reticulum. Sacrolemma - blue sac, plasma membrane covering the muscle fibres Sarcoplasmic reticulum - sac with calcium 2+ in it. initiates muscle 2 contraction Sarcomeres - basic area for muscle 1 contraction. 3 Filaments and Sarcomere Within myofibrils are smaller structures called “filaments” There are Thick and Thin filaments. Thin filaments (1) are composed of actin, troponin, and tropomyosin Thick filaments (2) are composed of myosin 2 They are arranged in compartments called Sarcomeres (3) 1 Sarcomeres are the basic functional units of muscle contraction Z-discs (4) separates one sarcomere from 3 another. 4 Therefore, a sarcomere extends from one Z disc to the next Z disc. A single bicep muscle fiber contains 100,000 sarcomeres Sarcomere: Bands and Lines We will look at three bands and one line. A Band (1): extends the entire length of thick filaments. I Band (2): contains Thin filaments but no Thick filaments. H Band (3): contains Thick filaments but no Thin filaments Mnemonic: “The letter “I” is thin 3 (contains thin filaments), The letter “H” is thick (contains thick 2 1 filaments). M Line (yellow dot): a supporting protein that holds Thick filaments together at center of sarcomere Muscle Proteins Myofibrils are composed of three kinds of proteins: 1. Contractile proteins (generate force during contraction) 2. Regulatory proteins (help switch contractile proteins on and off) 3. Structural Proteins Keep the Thick and Think filaments in proper alignment) Give the myofibrils elasticity Link myofibrils to the sarcolemma and extracellular matrix. Contractile Proteins The two Contractile Proteins are Myosin (component of Thick filament) and Actin (component of Thin filament) Myosin: Functions as a “motor” protein. Motor proteins convert ATP’s energy into mechanical energy = production of force About 300 myosin molecules form a single myosin filament (pictured below) Contractile Proteins Thick filament: Myosin Myosin shaped like a twisted golf club Twisted tail (1) points to M-line and forms shaft of thick filament. Myosin has two heads (2) and each head has two binding sites: 1. An Actin-Binding site (A) 2. An ATP Binding site (B) 2 A B 1 Contractile and Regulatory Proteins Thin Filament: Actin, Troponin, Tropomyosin Main component is Actin (1), round spheres which are twisted into a helix. Part of Thin filaments are two “Regulatory proteins” 1. Tropomyosin Tropomyosin (2): rope-like structure. During relaxation it covers Actin Binding site This prevents Myosin from binding to Actin. 1 2 Contractile and Regulatory Proteins 2. Troponin Troponin (3): three binding sites. During contraction calcium binds to troponin activating it Activated troponin rises away from actin pulling tropomyosin (rope- like) with it. Result: Actin binding sites exposed to myosin. Result: myosin can now bind to actin = muscle contraction 3 Two Structural Proteins 1) Titin 50 times larger than an average protein / largest protein in the body Spans half a sarcomere from Z disc to M line. Very elastic: can stretch four times in length Functions: Anchors Thick filament to both Z disc and M Line Helps sarcomeres return to their resting length after contraction Prevents sarcomere overstretching 2) Myomesin: Molecules of myomesin form M line which holds Thick filaments in alignment. 1 Introduction to Sliding Filament Mechanism Skeletal muscle shortens during contraction because Thick and Thin filaments slide over one another. This is known as “Sliding Filament Mechanism”. Muscle contraction occurs because Myosin heads attach to and “walk” along the Thin filaments at both ends of sarcomere. This “pulls” Thin filaments towards the M line / and pulls both Z discs towards the M line Sarcomere shortens / however the lengths of Thin and Thick filaments do not change. Relaxed Sarcomere Contracted Sarcomere Types of Skeletal Muscle Fibers (know the information on this slide) Functional Slow Oxidative (SO) Fast Oxidative Fast Glycolytic (FG) characteristic (Type I Fibers) Glycolytic (FOG) (Type IIb Fibers) (Type II Fibers) Capacity for High Intermediate Low generating ATP Rate of ATP use Slow Fast Fast Contractile velocity Slow Fast Fast Resistance to Fatigue High Intermediate Low Primary Function -Maintaining posture Walking / sprinting Rapid, intense -Aerobic endurance movement of short activities duration SO: lots of blood capillaries and mitochondria / generate ATP via aerobic metabolism (with oxygen) FOG: largest fibers / many blood capillaries / generate ATP via anaerobic metabolism (without oxygen) FG: few blood capillaries / few mitochondria / white in color / anaerobic metabolism Just for Review. Information on this screen will not be on the Test.  Time: 2:11 Video from youtube video:Smooth Structure of skeletal muscle explained in simple terms //https://youtu.be/SCznFaTwTPE  Muscle Phonological chunks Visuospatial chunks Structure Whole muscle (EPI), Fascicle (PERI), Muscle Fiber (cell) (ENDO) Tendons: epi, peri, endo Somatic motor neurons Sarcolemma = plasma membrane Myofibrils Thick (myosin) / Thin (actin, tropomyosin, troponin) Arranged in sarcomere (functional unit of contraction) Proteins Contractile: Actin Myosin Regulatory: Troponin Tropomyosin Structural: Titin, myomesin  Bone and Muscle Questions 1. What are the two main minerals bone stores? _____________________________ Minerals & Phospherus 2. RBM produces RBC, WBC, and platelets by what process? _____________________ 3. The bone region between the diaphysis and the epiphysis is called the _____________ Metaphysis 4. The tough outer covering of bone is called the ______________ Periosteum 5. _____________ are bone building cells and are immature/mature cells 6. _______________ are concentric rings-like structures around the osteonic canal. 7. Spongy bone is referred to as _____________ bone tissue. 8. What stem cells crowed together into general 3-D shape of bones? ________________ Mesenchymal 9. With bone growth in length, which zone has chondrocytes arranged in stacks of coins? ________________________ 10. What are the three types of muscle? ______________________________________ Smooth, Cardiac and Skeletal 11. Fascicles are covered by what connective tissue? ____________________________ Perimysium 12. In muscle, what are the Calcium-filled sacs called? ____________________________ Sacroplasmic reticulum 13. Thin filaments are composed of what three components? _________________________ Actin, Tropomyosin, Troponin 14. What is the largest protein in the body? ____________ Titin 15. What type of Skeletal Muscle Fiber has the greatest capacity for generating ATP? ____________________________ Slow Oxidative (Type I Fiber)