Muscle, Connective, and Nervous Tissue

Loose or Areolar CT

Loosely organized fibers

abundant blood vessels

empty space

Underlies all epithelia, connects skin to deep tissues, in serous membranes, between muscles, passageways for nerves and blood vessels

Adipose CT

Empty-looking cells with thin margins

nucleus pressed against cell membrane

Energy storage, insulation, cushioning

Subcutaneous fat and organ packing

Brown fat (hibernating animals) produces heat

Reticular CT

Mesh of reticular fibers and fibroblasts

Forms supportive stroma (framework) for lymphatic organs

Found in lymph nodes, spleen, thymus, and bone marrow

Dense Regular CT

Dense regular connective tissue

Densely packed, parallel collagen fibers

Compressed fibroblast nuclei

Elastic tissue/fibers, wavy sheets

Tendons attach muscles to bones and ligaments hold bones together

Dense Irregular CT

Densely packed, randomly arranged, collagen fibers and few visible cells

Withstands unpredictable stresses

Deeper layer of skin; capsules around organs

Hyaline Cartilage CT

Clear, glassy microscopic appearance because of unusual fineness of the collagen fibers

Usually covered by perichondrium

Articular cartilage, costal cartilage, trachea, larynx, fetal skeleton

Eases joint movement, holds airway open, moves vocal cords during speech

Elastic Cartilage CT

Cartilage containing elastic fibers

Covered with perichondrium

Provides flexible, elastic support

External ear and epiglottis

Fibrocartilage CT

Cartilage containing large, coarse bundles of collagen fibers

Never has perichondrium

Resists compression and absorbs shock

Pubic symphysis, menisci, and intervertebral discs

Bone CT

Compact bone is arranged in cylinders that surround central (haversian or osteonic) canals that run longitudinally through shafts of long bones Blood vessels and nerves travel through central canal

Bone matrix deposited in concentric lamella - onion like layers around each central canal

Fluid blood connective tissue

Transports cells and dissolved matter from place to place

Plasma—blood’s liquid ground substance

Formed elements—cells and cell fragments

Erythrocytes —red blood cells: transport O2 and CO2

Leukocytes —white bloodcells: defense against infection and other diseases

Thrombocytes (=platelets)— cell fragments involved in clotting and other mechanisms

Skeletal Muscle

Long, threadlike cells called muscle fibers

Most attach to bone

Contains multiple nuclei adjacent to plasma membrane

Striations—alternating dark and light bands

Voluntary—conscious control over skeletal muscles

Smooth muscle tissue

Lacks striations and is involuntary

Relatively short, fusiform cells (thick in middle, tapered at ends)

One centrally located nucleus

Visceral muscle—forms layers of digestive, respiratory, andurinary tract: propels contents through an organ, regulates diameter of blood vessels

Cardiac Muscle

Limited to the heart

Cardiac muscle fibers are shorter, branched, and blunted at ends

Contain one centrally located nucleus surrounded by light-staining glycogen

Intercalated discs join cardiocytes end to end

Provide electrical and mechanical connection

Striated and involuntary (not under conscious control)

Nervous tissue

specialized for communication by electrical and chemical signals

Consists of neurons (nerve cells)

• Detect stimuli

• Respond quickly

• Transmit coded information rapidly to other cells

Neuroglia (glial)

Protect and assist neurons– “Housekeepers” of nervous system

Soma (cell body)

Houses nucleus and other organelles

Cell’s center of genetic controland protein synthesis

Dendrites

Multiple short, branched processes

Receive signals from other cells

Transmit messages to neurosoma

Axon (nerve fiber)

Sends outgoing signals to other cells

Can be more than a meter long

Nervous Tissue