The skin is an example of a cutaneous membrane. Aggregations of cells in the human body be classified into four types of tissues: epithelial, connective, muscle, and nervous. Epithelial tissues act as coverings, controlling the movement of materials across their surface. Connective tissue binds the various parts of the body together, providing support and protection. Muscle tissue allows the body to move and nervous tissues functions in communication.
All cells and tissues in the body derive from three germ layers: the ectoderm, mesoderm, and endoderm. Membranes are layers of connective and epithelial tissues that line the external environment and internal body cavities of the body. Synovial membranes are connective tissue membranes that protect and line the freely-movable joints.
Epithelial membranes are composed of both epithelial tissue and connective tissue. These membranes are found lining the external body surface cutaneous membranes and mucous membranes or lining the internal body cavities serous membranes.
The four types of tissues in the body are epithelial, connective, muscle, and nervous. Epithelial tissue is made of layers of cells that cover the surfaces of the body that come into contact with the exterior world, line internal cavities, and form glands. Connective tissue binds the cells and organs of the body together and performs many functions, especially in the protection, support, and integration of the body.
Muscle tissue, which responds to stimulation and contracts to provide movement, is divided into three major types: skeletal voluntary muscles, smooth muscles, and the cardiac muscle in the heart. Nervous tissue allows the body to receive signals and transmit information as electric impulses from one region of the body to another. The zygote is described as omnipotent because it ultimately gives rise to all the cells in your body including the highly specialized cells of your nervous system.
Describe this transition, discussing the steps and processes that lead to these specialized cells. The zygote divides into many cells. As these cells become specialized, they lose their ability to differentiate into all tissues. Nervous tissue allows the body to receive signals and transmit information as electric impulses from one region of the body to another.
The zygote is described as totipotent because it ultimately gives rise to all the cells in your body including the highly specialized cells of your nervous system. Describe this transition, discussing the steps and processes that lead to these specialized cells. The zygote divides into many cells. As these cells become specialized, they lose their ability to differentiate into all tissues. At first they form the three primary germ layers. Following the cells of the ectodermal germ layer, they too become more restricted in what they can form.
Ultimately, some of these ectodermal cells become further restricted and differentiate in to nerve cells. Synovial membranes are a type of connective tissue membrane that supports mobility in joints.
The membrane lines the joint cavity and contains fibroblasts that produce hyaluronan, which leads to the production of synovial fluid, a natural lubricant that enables the bones of a joint to move freely against one another. Skip to content The Tissue Level of Organization. Learning Objectives By the end of this section, you will be able to: Identify the four main tissue types Discuss the functions of each tissue type Relate the structure of each tissue type to their function Discuss the embryonic origin of tissue Identify the three major germ layers Identify the main types of tissue membranes.
The Four Types of Tissues Epithelial tissue , also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, lines internal cavities and passageways, and forms certain glands. Four Types of Tissue: Body. The four types of tissues are exemplified in nervous tissue, stratified squamous epithelial tissue, cardiac muscle tissue, and connective tissue in small intestine.
Embryonic Origin of Tissues and Major Organs. Tissue Membranes A tissue membrane is a thin layer or sheet of cells that covers the outside of the body for example, skin , the organs for example, pericardium , internal passageways that lead to the exterior of the body for example, abdominal mesenteries , and the lining of the moveable joint cavities.
Tissue Membranes. The two broad categories of tissue membranes in the body are 1 connective tissue membranes, which include synovial membranes, and 2 epithelial membranes, which include mucous membranes, serous membranes, and the cutaneous membrane, in other words, the skin.
Epithelial Membranes The epithelial membrane is composed of epithelium attached to a layer of connective tissue, for example, your skin. Chapter Review The human body contains more than types of cells that can all be classified into four types of tissues: epithelial, connective, muscle, and nervous. Interactive Link Questions View this slideshow to learn more about stem cells. Epithelial tissue , also referred to as epithelium, refers to the sheets of cells that cover exterior surfaces of the body, lines internal cavities and passageways, and forms certain glands.
Connective tissue , as its name implies, binds the cells and organs of the body together and functions in the protection, support, and integration of all parts of the body. Muscle tissue is excitable, responding to stimulation and contracting to provide movement, and occurs as three major types: skeletal voluntary muscle, smooth muscle, and cardiac muscle in the heart. Nervous tissue is also excitable, allowing the propagation of electrochemical signals in the form of nerve impulses that communicate between different regions of the body Figure.
The next level of organization is the organ, where several types of tissues come together to form a working unit. Just as knowing the structure and function of cells helps you in your study of tissues, knowledge of tissues will help you understand how organs function.
The epithelial and connective tissues are discussed in detail in this chapter. Muscle and nervous tissues will be discussed only briefly in this chapter. Embryonic Origin of Tissues The zygote, or fertilized egg, is a single cell formed by the fusion of an egg and sperm. After fertilization the zygote gives rise to rapid mitotic cycles, generating many cells to form the embryo.
The first embryonic cells generated have the ability to differentiate into any type of cell in the body and, as such, are called totipotent , meaning each has the capacity to divide, differentiate, and develop into a new organism. As cell proliferation progresses, three major cell lineages are established within the embryo. As explained in a later chapter, each of these lineages of embryonic cells forms the distinct germ layers from which all the tissues and organs of the human body eventually form.
Figure shows the types of tissues and organs associated with the each of the three germ layers. Note that epithelial tissue originates in all three layers, whereas nervous tissue derives primarily from the ectoderm and muscle tissue from mesoderm.
View this slideshow to learn more about stem cells. How do somatic stem cells differ from embryonic stem cells? A tissue membrane is a thin layer or sheet of cells that covers the outside of the body for example, skin , the organs for example, pericardium , internal passageways that lead to the exterior of the body for example, abdominal mesenteries , and the lining of the moveable joint cavities.
There are two basic types of tissue membranes: connective tissue and epithelial membranes Figure. Connective Tissue Membranes The connective tissue membrane is formed solely from connective tissue. These membranes encapsulate organs, such as the kidneys, and line our movable joints. A synovial membrane is a type of connective tissue membrane that lines the cavity of a freely movable joint. For example, synovial membranes surround the joints of the shoulder, elbow, and knee.
The extracellular matrix is like gelatin in consistency and is often referred to as Wharton's jelly. Loose Connective Tissue "packing material". Areolar Connective Tissue Areolar connective tissue is the least specialized and has all the cells and fibers found in connective tissue proper. This tissue is loosely organized and easily distorted but is also resilient.
This permits movement between connected tissues. It is found immediately under the dermis of the skin and other epithelia, between muscles, around blood vessels and nerves. This tissue is highly vascular and provides the vascular support for epithelial tissue.
The loose, open nature of this tissue also provides the major pathway for cells of the immune system to reach sites of damage or invasion. Adipose Tissue The distinction between adipose tissue and areolar tissue is arbitrary as areolar tissue is considered adipose tissue when there is a high concentration of adipocytes. Adipose tissue pads, cushions, insulates, and packs and fills spaces between other tissues. Reticular Tissue This tissue is characterized by the predominance of reticular fibers.
It forms the stroma in various organs including liver, spleen, lymph nodes and bone marrow. Dense Connective Tissue Connective tissue with a high concentration of collagen fibers. Dense Regular Connective Tissue Connective tissue in which the collagen fibers are arrayed in parallel.
Tendons The parallel arrays of fibers form cords that attach muscle to bone. Aponeuroses Parallel arrays form flat sheets of connective tissue that connect flat muscles to their attachments. Elastic Tissue Elastic fibers predominate and give the tissue greater resilience. Found in the wall of large blood vessels, underlying transitional epithelium and surrounding respiratory passages. Ligaments Similar to tendons but attaching bone to bone.
Ligaments often contain a significant number of elastic fibers in order to better tolerate stretching. Elastic ligaments have a predominance of elastic fibers.
Dense Irregular Connective Tissue Bundles of collagen fibers are oriented in various directions to form a meshwork. The orientation of fibers enables tissue to resist stresses from many directions. This tissue is found in the dermis of the skin and forms fibrous coverings on the surface of cartilage and bone. Dense irregular connective tissue also forms tough capsules around organs and joints.
Fluid Connective Tissue Includes blood and lymph. Supporting Connective Tissue. Cartilage The matrix contains numerous fibers and the ground substance has complex polysaccharides, including chondroitin sulfate and keratan sulfate, that forms links with protein molecules. The matrix as a result is firm , but pliable.
Cartilage combines tensile strength with flexibility and resilience. The matrix is produced by both chondroblasts and chondrocytes and is maintained by chondrocytes. Chondrocytes exist in spaces of the matrix called lacunae sing.
Separate pieces of cartilage are encased in dense connective tissue sheaths called perichondria singular : perichondrium. The perichondrium has two layers, and outer fibrous layer for support, protection and attachment, and an inner cellular layer for growth and maintenance. Cartilage is avascular and all nutrient and waste product exchange occurs by diffusion through the matrix. Formation and Growth Cartilage grows by two mechanisms: Appositional growth - Fibroblasts of the cellular layer of the perichondrium differentiate into chondroblasts that produce matrix and become chondrocytes when embedded in matrix.
Interstitial growth - Chondrocytes within the matrix divide by mitosis and produce additional matrix that causes internal expansion of cartilage. Types of Cartilage. Hyaline Cartilage hyaline means glassy This is the most common type of cartilage. It is the weakest type of cartilage but is still tough and flexible.
The matrix contains collagen fibers that are thinner than the most common type of cartilage Type I and do not pick up stain. This gives this cartilage a glassy appearance. Hyaline cartilage connects ribs to the sternum as costal cartilage, supports the conducting passages of the respiratory tract larynx, trachea and bronchi , and forms the articular surfaces of moveable joints. Elastic Cartilage Elastic cartilage contains numerous elastic fibers that make it very resilient and flexible.
It is found in the pinnae of the outer ear, in the epiglottis and cuneiform cartilages of the larynx , and supporting the auditory canal. Fibrocartilage Fibrocartilage is a combination of dense regular connective tissue and hyaline cartilage. The denser concentration and more regular arrangement of collagen fibers makes this composite tissue tougher and more durable.
Fibrocartilage is found in intervertebral discs, pubic symphysis, and in the menisci sing. Bone Bone will be covered later. Epithelia and their underlying connective tissue form membranes that cover and protect other structures and tissues.
There are four types of membranes. Mucous Membranes Mucous membranes line passageways into the body that are continuous with the exterior. These passageways include the digestive, urinary, reproductive and respiratory tracts.
This lining is kept moist and lubricated at all times by secretions including the mucus secreted by mucous glands. The areolar connective tissue that attaches the epithelium to the underlying tissue is called lamina propria.
Serous Membranes Serous membranes are very thin and transparent and line compartments of the ventral body cavity:.
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