Unit 8: Muscle Physiology EGHS Science 2024-2025 PDF

Unit 8: Muscle Physiology EGHS Science Department Spring Semester 2024-2025 Agenda (01/23/2025) Intro to Muscle Physiology Lecture  Review: What are the 3 types of muscle and where can you find them?  Muscle Tissue Review A primary tissue type, divided into...

Unit 8: Muscle Physiology EGHS Science Department Spring Semester 2024-2025 Agenda (01/23/2025) Intro to Muscle Physiology Lecture  Review: What are the 3 types of muscle and where can you find them?  Muscle Tissue Review A primary tissue type, divided into: Skeletal muscle - Function= contract muscles (conscious) Location=all major muscles in the body (biceps, deltoid, etc.) Cardiac muscle - Function= muscle contraction (unconscious) Location= heart only! Smooth muscle - Function= muscle contraction (unconscious) Location= Visceral (walls of hollow organs ex: stomach, bladder) Multi-unit (walls of large arteries, trachea, arrector pili, etc) Connective Tissues Organization 1. Epimysium - outer membrane of the muscle. -separates the muscle from the surrounding tissue. 2. Perimysium - surround the muscle fiber bundles (fascicles) -Contains blood vessel and nerve supply to fascicle. 3. Endomysium - surrounds individual muscle cells aka muscle fibers. - Contains capillaries and nerve fibers contracting muscle cells. Formation of Skeletal Muscle Fiber s Skeletal muscle cells are called muscle fibers. -they are very long - they develop through fusion of mesodermal cells (myoblasts) - Muscle Fibers become very large and contain hundreds of nuclei. Structure of Skeletal Muscle 1) Skeletal Muscle 2) Fascicle- bundle of muscle fibers 3) Sarcolemma - cell membrane around muscle fibers. 4) Muscle Fibers - individual muscle cells. 5) Myofibril- basic rod like organelle in muscle fibers that is responsible for muscle contraction.. Organization of Skeletal Muscle Fibers Sarcolemma This is the cell membrane that can be found around muscle fibers (cells). It surrounds the sarcoplasm which is the cytoplasm of muscle fibers. Transverse Tubules T tubules are responsible for transmitting the action potential through the cell. They allow the entire muscle fibers to contract simultaneously. Organization of Skeletal Muscle Fibers Conti. Myofibrils Lengthwise subdivisions within muscle fiber Made up of bundles of protein filaments (myofilaments) Myofilaments are responsible for muscle contraction Sarcomeres - Functional units of myofibrils. Form striped or striated pattern within myofibrils Parts of the Sarcomere: 1) A bands –alternating dark, thick filaments; composed of myosin 2) M line: the center of A band at midline of sarcomere 3) I bands - light, thin filaments; composed of actin 4) Z lines: the centers of I bands and at 2 ends of sarcomere 5) H zone: is the center of the A band where there is no overlap between the thick and thin filaments. Organization of Skeletal Muscle Fibers Conti. Sarcoplasmic Reticulum This membranous structure surrounds each myofibril. The SR also stores calcium which can be released into the muscle fibers to cause contraction of the muscle.  Practice: Put the vocabulary terms in order of largest to smallest. Sarcolemma 1) Facicles Sarcomere 2) Sarcolemma Myofibril 3) Muscle fiber Muscle Fiber 4) Myofibril Fascicle 5) Sarcomere 1) 4) 2) 5) 3) Edpuzzle Students will watch the crash course video on Muscles- Muscle Cells and answer the questions as the video plays. You will be graded on this activity so make sure to complete it by tomorrow. (01/27) Agenda (01/24/2025) Continue Intro to Muscle Physiology Lecture Krieger Pages #137-141 Coloring Page #42  a. Review: Put the diagrams in order from smallest to b. largest. c. e, c, a, b, d d. e. Myofibril: Thick and Thin Filaments A-bands (thick filaments) are made out of myosin. I-band (thin filaments) are made out of actin. Myosin This is a protein with 2 globular heads that point out towards the actin and the tails that are the structural support. The heads are where the muscle contraction takes place since this is where the myosin and actin filaments interact. Myofibril: Thick and Thin Filaments Actin G-actin = globular F-actin - filament Tropomyosin- blocks myosin binding when muscle is relaxed. Troponin- this is made up of 3 polypeptides. This is what binds to the Myosin. Muscle Contraction 1) Action potential is generated and the muscle is stimulated at the neuromuscular junction. 1a) Acetylcholine is released via the neuron synapse and is accepted in the receptors on sarcolemma. 1b) Movement of sodium (Na+) and potassium (K+) ions through the channels results in depolarization (a loss of the difference in charge between the outside and inside of a cell) 2) Action potential then travels down the T-tubules. 3) Calcium is released from the sarcoplasmic reticulum. Muscle Contraction Conti. 4) Calcium (Ca2+) binds to troponin, shifting the actin filaments towards the center. This allows for the myosin to attach. 5) Myosin cross heads attach and detach, pulling the actin filaments toward the center. This requires ATP. 6) This allows the muscle to contract and muscle tension increases. 7) Calcium is removed/used and this causes the actin filaments to shift back into the original position (blocking the binding sites). 8) Muscle contraction ceases. Review Video The Mechanism of Muscle Contraction: https://www.youtube.com/watch?v=NfEJUPnqxk0&t=6s  How Muscles Grow Muscle Hypertrophy is when muscles grow from heavy training. This can lead to an increase in number of myofibrils, an increase in muscle fiber diameter and increase the amount of mitochondria/glycogen reserves. Muscle size/strength can be improved by frequent/brief/ intense workout. Muscle Atrophy is a lack of muscle activity that reduces the size, tone and power of the muscle. https://www.youtube.com/watch?v=2tM1LFFxeKg  Muscle Fatigue This is when muscle can no longer perform a required activity due to overuse of the muscle. Results of Muscle Fatigue: - Depletion of metabolic reserve - Low pH (lactic acid) - Muscle exhaustion and pain Recovery Period- is the time it takes for muscles to return to normal ability. (oxygen becomes available and mitochondrial activity resumes. Normal recovery period depends on how hard you push yourself. It can be an hour (moderate workout) to 3-5 days. https://www.youtube.com/watch?v=rLsimrBoYXc Agenda (01/27/2025) Working Day! - Krieger Pages #137-141 - Coloring Page #42 - Muscle Contraction Practice Agenda (01/28/2025) Muscle Contraction Poster  Muscle Contraction Poster Students will create a poster of how the muscle contracts using our notes on the 8 steps of contraction. It can be literal or you can use analogies to represent the steps. Make sure to include the title, step #s, images, color and bolded outlines (pens/markers). Agenda (01/29/2025) Muscle Contraction Bingo! Agenda (01/30/2025) Working Day! - Krieger Pages #137-141 - Coloring Page #42 - Muscle Contraction Steps Poster - McGraw Hill #12 Agenda (01/31/2025) Electronic Practice Quiz Agenda (02/03/2025) Working Day! - Krieger - Coloring - Muscle Contraction Practice - Muscle Contraction Poster - McGraw Hill #12 Agenda (02/04/2025) Walk Around Practice Test Agenda (02/05/2025) Kahoot! Agenda (02/07/2024) Muscle Physiology Exam What’s due today? 1. Krieger 2. Coloring 3. Muscle Contraction Practice 4. Muscle Contraction Poster 5. McGraw Hill #12