22 1 The Body s Organization 22 1 The Body s Organization cont The body of multicellular organisms has a hierarchical structure The body is composed of several organ systems An organ system is composed of one or more organs An organ is composed of tissues Tissues are composed of cells 22 1 The Body s Organization cont 22 1 The Body s Organization cont The bodies of animals are composed of four main tissue types Epithelial tissues covers the body surface and lines the body cavities Connective tissue binds and supports parts of the body Muscular tissue provides movement Nervous tissue conducts nerve impulses and interprets stimuli All tissues except the nervous tissue are subdivided into even more types Epithelial Tissue Protects Substances that must enter or exit the body typically pass across the epithelial cell layer This means that epithelial cells are widely distributed in animal bodies Cells of the epithelial layers differ in their shape and their function Epithelial Tissue Protects cont Squamous epithelium consists of flattened cells that line the lungs and blood vessels Cuboidal epithelium consist of cuboidal cells that line the kidney tubules 1 Epithelial Tissue Protects cont Epithelial Tissue Protects cont Columnar epithelium consists of pillar shaped cells that line the digestive tract Pseudostratified epithelium are mucus secreting cells that line the trachea Epithelial Tissue Protects cont The skin of animals is comprised of stratified epithelium reinforced with keratin Epithelial Tissue Protects cont The lining of the ureters urethra and urinary bladder is composed of transitional epithelium Transitional epithelial cells are capable of stretching and sliding past each other while still maintaining a barrier This barrier prevents urine from diffusing back into the body Epithelial Tissue Protects cont Epithelial cells are constantly replaced by cell division However this extensive rate of cell division means that epithelial cells are more likely to become cancerous than other cell types Connective Tissue Connects and Supports All types of connective tissue serve the same general function Connective tissue binds organs together Connective tissue provides support and protection Cells of the connective tissue are generally separated by a noncellular matrix material such as collagen fibers 2 Loose Fibrous and Related Connective Tissues Loose Fibrous and Related Connective Tissues cont Loose fibrous connective tissue occurs below the epithelium Adipose tissue is composed of fibroblasts that store fat This tissue forms a protective covering over the organs Adipose tissue lacks a matrix and is located beneath the skin and around the heart and kidneys The loose fibrous connective tissue is composed of cells called fibroblasts Loose Fibrous and Related Connective Tissues cont Loose Fibrous and Related Connective Tissues cont Dense fibrous connective tissue contains many collagen fibers tightly packed together The cells of the cartilage lie in chambers called lacunae Tendons which connect muscles to bones are one example The matrix of the cartilage is flexible yet solid Ligaments are another example and connect bones together at the joints Loose Fibrous and Related Connective Tissues cont Hyaline cartilage is the most common type of cartilage in the body Loose Fibrous and Related Connective Tissues cont Bone is the most rigid connective tissue The matrix is composed of inorganic salts deposited on collagen fibers Compact bone is the most common type of bone in the body 3 Blood Blood cont The blood considered by some to be a liquid connective tissue consists of several cell types suspended in a liquid called plasma Red blood cells are disk shaped cells that carry oxygen in the bloodstream The plasma can be considered to be the matrix for the blood The five types of white blood cells protect the body from infection There are three cell types in the blood Red blood cells White blood cells Platelets Blood cont Platelets are cellular fragments from the bone marrow that seal cuts and damaged blood vessels Muscular Tissues Move the Body Muscle tissues are frequently called contractile tissues because they contain contractile protein filaments such as actin and myosin There are three types of muscle tissues Skeletal Cardiac Smooth Muscular Tissues Move the Body cont Muscular Tissues Move the Body cont Skeletal muscle is voluntary muscle Cardiac muscle is found in the walls of the heart Skeletal muscle is attached to bones to facilitate movement Cardiac muscle is involuntary muscle Skeletal muscle cells are called fibers and are striated because of the actin and myosin bands Cardiac muscle cells are highly branched interconnected and bounded on each end by intercolated disks 4 Muscular Tissues Move the Body cont Nerve Tissue Communicates Smooth muscle is involuntary muscle without striations Nervous tissues control body functions and responds to environmental stimuli Smooth muscle is also called visceral muscle because it lines the walls of the organs and blood vessels The function of the nervous tissues depends upon three factors Sensory input delivered by nerves to the brain and spinal cord Integration of data by the brain and spinal cord Motor output triggered by nerves carrying impulses from the brain and spinal cord Nerve Tissue Communicates cont Nerve Tissue Communicates cont The cells of the nervous tissue are called neurons Neurons have three structural aspects Dendrites conduct signals to the cell body The cell body is the main part of the cell Axons conduct signals away from the cell body Nervous tissue also has neuroglia that support and nourish the neurons Organs and Organ Systems Organs are composed of one or more tissues Organs integrate the function of different tissues providing functions that the individual tissues lack The function of organ systems is similarly dictated by the organs present Organs and Organ Systems cont The organ systems of the body can be divided into five categories based upon their function Transport of fluids Body maintenance Control of the body systems Sensory input and motor output Reproduction 5 Transport Transport cont The cardiovascular system consists of the heart and blood vessels The lymphatic system consists of the lymph nodes lymph fluid and lymphatic vessels This system carries blood through the body to deliver nutrients and remove wastes This system collects excess fluid and fat from the body and returns it to the heart Maintenance of