Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Chapter 42
Document related concepts
no text concepts found
Transcript
Chapter 24 …. a little anatomy and physiology Levels of organization in the vertebrate body 1. Cells Organ and organ systems 2. Tissues - groups of cells with similar structure and function Organ and organ systems 3. Organs - structures composed of several different tissues that form structural/functional unit. Organ 4. Organ systems - group of organs that carry out major activities of the body. Tissues Four Types *epithelial *connective *muscle *nerve Epithelial Tissue Epithelium covers every major surface of the vertebrate body (inside and out) Epithelial Tissue Types of epithelial tissues – simple - one layer thick • squamous • cuboidal • columnar – stratified - several cell layers thick Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Simple Epithelium Epithelial Tissue Cuboidal epithelium Simple columnar epithelium Pseudostratified ciliated columnar epithelium Stratified squamous epithelium Simple squamous epithelium Stratified Epithelium Connective Tissue Collagenous fiber Cartilage Chondroitin sulfate Nuclei 30 µm 100 µm Elastic fiber Chondrocytes Fat droplets Fibrous connective tissue Adipose tissue Osteon White blood cells Blood 55 µm 700 µm Bone 150 µm 120 µm Loose connective tissue Central canal Plasma Red blood cells Connective Tissue Mainly binds and supports other tissues Connective Tissue Cells scattered embedded in an extracellular matrix Connective Tissue Matrix consists of fibers in a liquid, jellylike, or solid foundation Connective Tissue 3 connective tissue fibers, all protein: – Collagenous fibers: strength and flexibility – Elastic fibers: stretch and snap back to their original length – Reticular fibers: join connective tissue to adjacent tissues Connective Tissue • Connective tissue contains cells, including – Fibroblasts that secrete the protein of extracellular fibers – Macrophages that are involved in the immune system Connective Tissue in Vertebrates Loose connective tissue: binds epithelia to underlying tissues and holds organs in place Cartilage: strong and flexible support material Fibrous connective tissue: in tendons, which attach muscles to bones, and ligaments, which connect bones at joints Connective Tissue in Vertebrates Adipose tissue: stores fat for insulation and fuel Blood: is composed of blood cells and cell fragments in blood plasma Bone: is mineralized and forms the skeleton Loose connective tissue Chondrocytes Cartilage Elastic fiber Chondroitin sulfate Nuclei Fat droplets Adipose tissue Osteon 150 µm Fibrous connective tissue 30 µm 100 µm 120 µm Collagenous fiber White blood cells Blood 55 µm 700 µm Bone Central canal Plasma Red blood cells Fibrous connective tissue Nuclei 120 µm Loose connective tissue 30 µm Collagenous fiber Fat droplets Elastic fiber 150 µm Adipose tissue Muscle Tissue long cells called muscle fibers, which contract in response to nerve signals 3 Types of Vertebrate Muscle Muscle Tissue Multiple nuclei Muscle fiber Sarcomere Skeletal muscle Nucleus 100 µm Intercalated disk 50 µm Cardiac muscle Nucleus Smooth muscle Muscle fibers 25 µm Skeletal muscle, or striated muscle, is responsible for voluntary movement Multiple nuclei Muscle fiber Sarcomere 100 µm Smooth muscle is responsible for involuntary body activities Nucleus Muscle fibers 25 µm Cardiac muscle is responsible for contraction of the heart Nucleus Intercalated disk 50 µm Nervous Tissue senses stimuli and transmits signals throughout the animal Nervous Tissue Neurons (nerve cells) transmit nerve impulses Glial cells (glia) nourish, insulate, and replenish neurons 40 µm Dendrites Cell body Glial cells Axon Neuron Axons Blood vessel 15 µm 40 µm Neuron Dendrites Cell body Axon Glial cells Glial cells Axons Blood vessel 15 µm Muscle contraction p. 1105 Muscle Vertebrate skeletal muscle structure Muscle Bundle of muscle fibers Nuclei Single muscle fiber (cell) Muscle fibers (cell) Plasma membrane Myofibril Myofibril Z lines Thin filaments Thick filaments Sarcomere Myofilaments *Thin filaments consist of two strands of actin and one strand of regulatory protein *Thick filaments are myosin molecules TEM M line 0.5 µm Thick filaments (myosin) Thin filaments (actin) Z line Z line Sarcomere Myosin (thick) Actin (thin) Muscle Sarcomere Bundle of muscle fibers Nuclei Single muscle fiber (cell) Plasma membrane Myofibril Z lines Sarcomere Sarcomere TEM M line 0.5 µm Thick filaments (myosin) Thin filaments (actin) Z line Z line Sarcomere The Sliding-Filament Model of Muscle Contraction Filaments slide past each other longitudinally, producing more overlap between thin and thick filaments • A muscle contracts and shortens because its myofibrils contract and shorten. Sliding filament mechanism of contraction Sarcomere Z M Relaxed muscle Contracting muscle Fully contracted muscle Contracted Sarcomere 0.5 µm Z Interaction of thick and thin filaments Thick filament Thin filaments Thin filament ATP Myosin head (lowenergy configuration Thick filament Thick filament Thin filaments Thin filament ATP Myosin head (lowenergy configuration Thick filament Actin ADP Pi Myosin binding sites Myosin head (highenergy configuration Thick filament Thin filaments Thin filament Myosin head (lowenergy configuration ATP Thick filament Actin ADP Pi ADP Pi Cross-bridge Myosin binding sites Myosin head (highenergy configuration Thick filament Cross bridge cycle Thin filaments Thin filament Myosin head (lowenergy configuration ATP ATP Thick filament Thin filament moves toward center of sarcomere. Actin ADP Myosin head (lowenergy configuration ADP + Pi Pi ADP Pi Cross-bridge Myosin binding sites Myosin head (highenergy configuration The Role of Calcium and Regulatory Proteins • A skeletal muscle fiber contracts only when stimulated by a motor neuron • When a muscle is at rest, myosin-binding sites on the thin filament are blocked by the regulatory protein tropomyosin • For a muscle fiber to contract, myosin-binding sites must be uncovered • This occurs when calcium ions (Ca2+) bind to a set of regulatory proteins, the troponin complex • Muscle fiber contracts when the concentration of Ca2+ is high; muscle fiber contraction stops when the concentration of Ca2+ is low Control of muscle contraction Ca2+-binding sites Tropomyosin Actin Troponin complex Tropomyosin: that blocks myosin from binding to thin filament (a) Myosin-binding sites blocked Ca2+ Myosinbinding site (b) Myosin-binding sites exposed Troponin complex: regulatory proteins which binds to Ca2+ Sarcoplasmic reticulum Synaptic terminal Motor neuron axon T tubule Mitochondrion Sarcoplasmic reticulum (SR) Myofibril Plasma membrane of muscle fiber Ca2+ released from SR Sarcomere Synaptic terminal of motor neuron T Tubule Synaptic cleft ACh Plasma membrane SR Ca2+ ATPase pump Ca2+ ATP CYTOSOL Ca2+ ADP Pi Control of Muscle Contraction • When Ca++ concentration of the muscle cell cytoplasm is low, tropomyosin inhibits cross-bridge formation and the muscle is relaxed. • Action potentials travel to the interior of the muscle fiber along transverse (T) tubules • The action potential along T tubules causes the sarcoplasmic reticulum (SR) to release Ca2+ • The Ca2+ binds to the troponin complex on the thin filaments • This binding exposes myosin-binding sites and allows the cross-bridge cycle to proceed Muscle Bundle of muscle fibers Nuclei Single muscle fiber (cell) Plasma membrane Myofibril Z lines Sarcomere TEM M line 0.5 µm Thick filaments (myosin) Thin filaments (actin) Z line Z line Sarcomere
