Muscle Tissue Function is to contract or shorten

Muscle Tissue • Function is to contract, or shorten, to produce movement • Three types: 1. Skeletal muscle 2. Cardiac muscle 3. Smooth muscle © 2015 Pearson Education, Inc.

Muscle and Nervous Tissue Pages 97 -101

Three types of muscle tissue • Skeletal • Cardiac • Smooth

Skeletal Muscle Tissue • Voluntarily (consciously) controlled • Attached to the bones or skin • Produces gross body movements or facial expressions • Characteristics of skeletal muscle cells – Striations (stripes) – Multinucleate (more than one nucleus) – Long, cylindrical shape © 2015 Pearson Education, Inc.

Figure 3. 20 a Type of muscle tissue and their common locations in the body. Nuclei Part of muscle fiber (a) Diagram: Skeletal muscle Photomicrograph: Skeletal muscle (195×)

Cardiac Muscle Tissue • • Involuntarily controlled Found only in the heart Pumps blood through blood vessels Characteristics of cardiac muscle cells – Striations – One nucleus, short, branching cells • Look somewhat like bamboo – Intercalated discs: • Areas between cells which contain gap junctions to connect cells together so that the impulse spreads across the heart to create one contraction at a time © 2015 Pearson Education, Inc.

Figure 3. 20 b Type of muscle tissue and their common locations in the body. Intercalated discs Nucleus (b) Diagram: Cardiac muscle Photomicrograph: Cardiac muscle (475×)

Compare the two- note the differences Skeletal Cardiac

Smooth Muscle Tissue • Involuntarily controlled • Found in walls of hollow organs such as stomach, uterus, and blood vessels – where constricting and enlarging is required – Peristalsis: a wavelike activity that moves digested material through the small intestine • Characteristics: – No visible striations – Single nucleus – Spindle-shaped cells © 2015 Pearson Education, Inc.

Figure 3. 20 c Type of muscle tissue and their common locations in the body. Smooth muscle cell Nuclei (c) Diagram: Smooth muscle Photomicrograph: Sheet of smooth muscle (285×)

Nervous Tissue • Two types of cells: – Neurons – nerve support cells called neuroglia • these insulate, protect, and support neurons • Function: receive and conduct electrochemical impulses to and from body parts – Irritability – Conductivity © 2015 Pearson Education, Inc.

Figure 3. 21 Nervous tissue. Brain Nuclei of supporting cells Spinal cord Nuclei of supporting cells Cell body of neuron Neuron processes Diagram: Nervous tissue Photomicrograph: Neurons (320×)

Figure 3. 22 Summary of the major functions and body locations of the four tissue types: epithelial, connective, muscle, and nervous tissues. Nervous tissue: Internal communication • Brain, spinal cord, and nerves Muscle tissue: Contracts to cause movement • Muscles attached to bones (skeletal) • Muscles of heart (cardiac) • Muscles of walls of hollow organs (smooth) Epithelial tissue: Forms boundaries between different environments, protects, secretes, absorbs, filters • Lining of GI tract organs and other hollow organs • Skin surface (epidermis) Connective tissue: Supports, protects, binds other tissues together • Bones • Tendons • Fat and other soft padding tissue

Tissue Repair (Wound Healing) • Occurs in two ways: 1. Regeneration • Replacement of destroyed tissue by the same kind of cells; cells divide to make new ones 2. Fibrosis • Repair by dense (fibrous) connective tissue (scar tissue) © 2015 Pearson Education, Inc.

Tissue Repair (Wound Healing) • The type of healing is determined by: 1. Type of tissue damaged 2. Severity of the injury © 2015 Pearson Education, Inc.

Events in Tissue Repair • Inflammation – Capillaries become very permeable – Clotting proteins migrate into the area from the bloodstream – A clot (visible fibers from blood) walls off the injured area • Granulation tissue forms – Growth of new capillaries – Phagocytes dispose of blood clot and fibroblasts – Rebuild collagen fibers © 2015 Pearson Education, Inc.

Events in Tissue Repair • Regeneration of surface epithelium – Scab detaches – Whether scar is visible or invisible depends on severity of wound • Scar tissue is constructed of many collagen fibers © 2015 Pearson Education, Inc.

Regeneration of Tissues • regenerate easily – Epithelial tissue (skin and mucous membranes) – Fibrous connective tissues and bone • regenerate poorly – Skeletal muscle – Dense connective tissues like tendons, ligaments • replaced largely with scar tissue – Cardiac muscle – Nervous tissue within the brain and spinal cord © 2015 Pearson Education, Inc.

Development Aspects of Cells and Tissues • Growth via cell division continues through puberty • Cell exposed to friction replace lost cells throughout life (like epithelial cells) • Connective tissue forms repair (scar) tissue – Scar tissue is a form of connective tissue constructed of many collagen fibers • Cells that lose ability to divide: (become amitotic) – muscle tissue (by the end of puberty) – Nervous tissue (shortly after birth) © 2015 Pearson Education, Inc.