Tissues Pt. 1

BIOL 2120K, Human Anatomy & Physiology I

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Introduction

Tissues, Part 1: Crash Course A&P #2

Tissue Overview

  • The body contains at least 200 distinct & specialized cell types.

  • These cells contain essentially the same internal structures, yet they vary enormously in shape and function.

  • The different types are organized into layers of cells that perform common or related function, a level of organization referred to as tissue

  • There are 4 main types: Epithelial, Connective, Nervous, & Muscle

Be Able to Identify:

  • Whether a tissue is a Nervous, Muscular, Epithelial, or Connective Tissue

  • The specific types of tissue within each category

  • The function of that tissue

  • Where that tissue occurs

Nervous Tissue

Concentrated in the Central Nervous System

  • Brain

  • Spinal cord

Nervous Tissue Functions

  • Synonyms for nervous tissue: neural tissue, nerve tissue

  • Regulates and controls body functions

  • Rapidly senses internal or external environment

  • Processes information and controls responses

  • Two specialized types of cells
    1. Neurons: specialized nerve cells that generate and conduct electrical nerve impulses
    2. Neuroglia: supporting cells that support, insulate, and protect neurons
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Basic Neuron Structure

  • Cell body: includes most of the cytoplasm, the organelles, and the nucleus


  • Dendrites: branch off the cell body and appear as thin extensions, these receive incoming signals


  • Axon (nerve fiber): extends from the cell body and can be wrapped in an insulating layer known as myelin, carries outgoing electrical signals to their destination

  • Synapse: the gap between nerve cells, or between a nerve cell and its target, for example, a muscle or a gland, across which the impulse is transmitted by chemical compounds known as neurotransmitters.
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Muscle Tissue

Overview

  • Contracts and produces all body movement

  • Highly vascularized

  • Muscle cells possess myofilaments made up of actin and myosin proteins that bring about contraction

3 Types of Muscle Tissue

  1. Skeletal muscle tissue - Large body muscles responsible for movement; attached to and causes movement of bones

  2. Cardiac muscle tissue - Found only in the heart

  3. Smooth muscle tissue - Found in walls of hollow, contracting organs (blood vessels; urinary bladder; respiratory, digestive, and reproductive tracts)

Muscle Cells

Characteristics of different muscle tissues:


  • Striated (muscle cells with a banded appearance) vs. Nonstriated (not banded; smooth)

  • Muscle cells that have a single nucleus vs. Muscle cells that are multinucleate

  • Voluntarily (consciously) vs. Involuntarily (automatically)

References