Connective Tissue Found throughout the body most abundant

Connective Tissue • Found throughout the body; most abundant and widely distributed of all the tissues • Four main types: – Connective tissue proper – Cartilage – Bone – Blood • Characteristics: Tissue with large matrix inside of it, rich supply of blood vessels, composed of many types of cells

Connective Tissue Proper: Areolar • Fibers: collagen, elastic • Wraps and cushions all internal organs • Attached to all epithelial tissue • Dermis: small layer of areolar tissue

Connective Tissue Proper: Dense Regular Tissue • Dense because the collagen fibers are packed together • Distinct wave: made to withstand force in one direction • Found in tendons and some ligaments and aponeuroses

Connective Tissue Proper: Adipose • The “spaces” are the cells, with nuclei squished against the sides – The clear parts are oil droplets • Function: insulation, cushions and protects organs, and reserve fuel • Found: under skin in the abdomen, around kidneys & eyeballs, in breasts

Connective Tissue Proper: Reticular • Provides a framework for white blood cells, mast cells and macrophages = all part of the immune system – Lymphoid organs: spleen lymph nodes and bone marrow

Connective Tissue: Bone Haversian Canal a series of tubes around narrow channels formed by lamellae Osteoblast Bone forming Cells Osteocyte an osteoblast that has become embedded within the bone matrix, occupying a bone lacuna Lamella Osteoblasts deposit the matrix in the form of thin sheets which are called lamellae. Canaliculi provide the means for the osteocytes to communicate with each other and to exchange substances by diffusion. Lacuna In the matrix, osteoblasts become encased in small hollows within the matrix Volkmann’s Canal These canals establish connections of the Haversian canals with the inner and outer surfaces of the bone

Bone (osseous tissue) • Compact bone: looks like rings of tree • Function: structural support, give body its shape, act as attachment points for muscles • Location: bones

Connective Tissue: Spongy Bone or Cancellous Bone • Doesn’t occur in ring shape like compact bone • Still has lacuna – *single lacuna spread out • Rest of tissue (pink) is called trabeculae

Connective Tissue: Spongy Bone Red marrow (consisting mainly of hematopoietic) tissue and Red blood cells, platelets and most white blood cells arise in red marrow, found mainly in the flat bones. Yellow marrow (consisting mainly of fat cells). Yellow marrow is found in the hollow interior of the middle portion of long bones.

Connective Tissue: Hyaline Cartilage • Distinguishing characteristic: – Pairs of lacunae • Supports and reinforces structures (like bone), but can bend • Found: ends of long bones, connects ribs to sternum, found at end of nose, in trachea and larynx

Connective Tissue: Blood • Mature red blood cells do not have a nucleus • WBC: have a nucleus – Neutrophils and Lymphocyte, monocyte (pictured) • Function: transport respiratory gases • Location: in blood vessels

Muscle Tissue • Highly specialized to contract and produces most types of body movement • Three types of Muscle Tissues: – Smooth Muscle – Cardiac Muscle – Skeletal Muscle

Smooth Muscle Tissue • Smooth: no striations • Lines hollow structures: – airways to lungs, stomach, intestines, gallbladder, and urinary bladder • Involuntary control: propels substances along predetermined pathways

Skeletal Muscle • Cells are long, multinucleated, and striated • Voluntary control • Location: in skeletal muscles attached to bones or occasionally to skin

Cardiac Muscle • Uni-nucleated • Intercalated discs allow the cardiac muscle to act as a unit • Involuntary control • Function: propels blood into circulation as it contracts • Forms the bulk of the wall of the heart • Found: only in the heart

Nervous Tissue • 2 main cell types found in nervous tissue – Neuroglia: functionally support, protect and insulate neurons and bind them together – Neurons: respond to stimuli and conduct impulses to and from all body organs • Found: Brain, spinal cord, and nerves

Parts of the neuron • Dendrites: branched processes that receive stimuli and conduct nerve impulses toward the cell body. (input portion of neuron) • Cell body: contains nucleus and specialized organelles • Axon: cytoplasmic extension that conducts nerve pulses away from the cell body. (output)

Integumentary System • Skin (integument) – largest organ of the body • Accessory organs: hair, glands, and nails • Roles: – Mechanical and chemical protection – Thermal protection – Microorganisms – Prevents water loss – Secretory system (waste products) – Vitamin D synthesis – Cutaneous sense organs

Layers of the skin • 2 main layers: – Epidermis: stratified into 4 structural layers (or 5 layers in palms and soles) – Dermis: consists of 2 layers • Hypodermis or superficial fascia (subcutaneous layer)- not part of the skin, but binds dermis to underlying organs

Epidermis

Dermis • Second, deeper part of the skin • Composed mainly of connective tissue • Blood vessels, nerves, glands, and hair follicles are embedded in the dermal tissue. • Dermis is divided into a superficial papillary region and a deeper reticular region

Dermis • Papillary region – more superficial dermal layer; in contact with epidermis; – Composed of areolar connective tissue – Dermal papillae –nipple shaped structures indent into the epidermis and contain loops of capillaries. Some dermal papillae contain tactile receptors called corpuscles of touch or Meissener corpuscles [4] which are touch receptors. – Responsible for fingerprints

Dermis • Reticular layer of the dermis – Deepest skin layer – dense irregular connective tissue Hypodermis Layer • Subcutaneous layer is deep to the dermis and is not part of the skin • Consists of areolar and adipose tissues

Glands of the Skin Several kinds of exocrine glands are associated with the skin • Sudoriferous glands or sweat glands empty their secretions onto the skin surface through pores or into hair follicles. • Sweat glands: two main types based on their structure, location and type of secretion. – Eccrine and Apocrine

Eccrine Sweat Glands • Simple, coiled tubular glands are much more common than Apocrine • Regulate body temperature through perspiration/evaporation • Also plays a role in elimination – perspiration is diluted urine

Apocrine Sweat Glands • Found: skin of axilla, groin, anal regions, areolae areas of the breasts, and bearded areas of the face in men. • Begin functioning at puberty. In women cells of apocrine sweat glands enlarge around ovulation and shrink during menstruation • Secretions are more viscous (thicker) than eccrine secretions and contain the same compounds as eccrine sweat plus lipids and proteins, pheromones. – Pheromones are chemical signals exuded by many animals -including humans -- that evoke sexual behavior • Mammary glands are specialized apocrine glands that secrete milk

Sebaceous glands (oil gland) • Usually connected to hair follicles • Secrete sebum which is a mixture of fats, cholesterol, proteins, inorganic salts and pheromones • Sebum coats the surface of hairs and prevents excessive evaporation of water from the skin, keeps the skin soft and inhibits growth of certain bacteria • Sebaceous glands are found in the skin all over the body except for the palms of the hands and the soles of the feet. – grasping grip and the traction needed for the soles of the feet would be compromised

Hair follicle • Hair follicle surrounds the root and consists of columns of dead, keratinized cells bonded together by extracellular proteins – Hair shaft is the superficial portion of the hair, most of which projects from the surface of the skin. – Hair root is the portion of the hair deep to the shaft that penetrates into the dermis and sometimes into the subcutaneous layer. – Arrector pili muscle is the smooth muscle that extends from the superficial dermis of the skin to the side of the hair follicle

• Arrector pili muscle is the smooth muscle that extends from the superficial dermis of the skin to the side of the hair follicle. [14]

Microscope Slide #21