Lecture 6 - Locomotion PDF

Lecture 6 BIO202 Locomotion Chapter 6  Readings: Monday Nov 4 – Lecture 6 Locomotion Chapter 6 Learning...

Lecture 6 BIO202 Locomotion Chapter 6  Readings: Monday Nov 4 – Lecture 6 Locomotion Chapter 6 Learning Activities Labs/Tutorials Cycle A – Lab 4 Lab 4 Week 10 Cycle B – Tutorial 4 (Nov 4-10) Due Dates: Learning Worksheet 6 Sun. Nov 10, 10pm Cycle A – Pre-Lab 4 Quiz Due before Lab 4 Assessments Cycle A – Lab 3 Data Due before Lab 4 Analysis Cycle B – Tutorial 4 Due at the end of Worksheet Tutorial 4  Objectives Explore different types of muscles Outline the skeletal system Understand the physiology of muscle contraction  Types of Muscle - Anatomical Two main types based on the arrangement of actin (thin) and myosin (thick): 1. Striated: (striated appearance) Skeletal & cardiac Actin and myosin arranged in parallel (sarcomeres) Banding effect Voluntary control  Types of Muscle - Anatomical Two main types based on the arrangement of actin (thin) and myosin (thick): 2. Smooth: (not striated) Actin and myosin are not organized and do not have sarcomeres Makes up internal organs Not under voluntary control Types of Muscle - Functional Skeletal: control locomotion and any movement that can be consciously controlled (voluntary muscle); multinucleated Smooth: control of the walls of hollow organs and passages/vessels (involuntary); no striations like in skeletal muscle; 1 nucleus/cell Cardiac: in the heart for pumping blood throughout the body and maintaining blood pressure (involuntary); 1 nucleus/cell (Cardiomyocytes)  The Skeletal System Axial Skeleton – skull, vertebral column, sacrum, coccyx and rib cage Appendicular Skeleton – pectoral girdle, upper limbs, pelvic girdle and lower limbs  Joints / Articulation Fibrous Cartilaginous Synovial Fibrous joints held Connected by The synovial cavity has together by fibrous many structures that help cartilage to protect the joint and connective tissue Minimal movement also allow for a wide No cavity or space range of movements between the Angular movements: bones flexion (angle decreases) Minimal and extension (angle movement increases) Rotational movement: movement of shaking head ‘no’ Skeletal Musculature  Composition of Skeletal Muscle Muscles consist of long, cylindrical, multinucleated muscle fibers arranged in parallel Skeletal muscle cell = muscle fiber = Myofiber Each muscle fiber is made up of many parallel myofibrils made up of sarcomeres  The Sarcomere Sarcomere is the functional unit of the muscle cell Thin (actin) filament Thick (myosin) filament https://www.austincc.edu/apreview/PhysText/Muscle.html  Terminology in Contraction When (a) a sarcomere (b) contracts, the Z lines move closer together and the I band gets smaller. The A band stays the same width and, at full contraction, the thin filaments overlap. Muscle Contraction  Sliding Filament Model Proteins involved in muscle contraction: – Myosin molecules – Actin – Tropomyosin Muscles contract through cross-bridge interactions – Troponin between myosin heads and actin filaments (ATP and Ca2+ dependent) Controlling Muscle Contraction Most vertebrate skeletal muscles are neurogenic muscles and receive signals from a motor neuron The sarcolemma is rich in acetylcholine receptors (nicotinic) Excitation-contraction coupling: where electrical excitation of the plasma membrane leads to activation of a muscle contraction Postsynaptic  Excitation-Contraction Coupling The AP is conducted deep into the muscle fiber and causes the release of intracellular Ca2+ Transverse tubules are extensions of the plasma membrane that reaches deep into the muscle fiber T-tubules are associated with sarcoplasmic reticulum, which stores and releases Ca2+ during excitation-contraction coupling Binds to troponin complex allowing myosin cross-bridges to bind to actin thin filaments  Helpful Videos Skeletal Muscle Structure – https://www.youtube.com/embed/XoP1diaXVCI Cross-Bridges – https://www.youtube.com/watch?v=CepeYFvqmk 4&feature=youtu.be – https://youtu.be/7O_ZHyPeIIA?feature=shared Excitation-Contraction Coupling – https://youtu.be/UZNPv86y7Fg?feature=shared Questions?