Exocrine Glands Exocrine glands – “externally secreting” - secrete their products onto body surfaces (skin) or into body cavities Examples include mucous, sweat, oil, & salivary glands Almost all exocrine glands are multicellular. Are more numerous than endocrine glands Are classified according to duct type & structure of their secretory units

Functions of Connective Tissue 1- Binding & support 2 - Protection 3 - Insulation 4 - Transportation

Characteristics of Connective Tissue Characteristics of connective tissues 1 – All connective tissues arise from mesenchyme –(an embryonic tissue) so they all have a common tissue of origin 2 – Connective tissue has varying degrees of vascularity (amounts of blood vessels running through them) ex: cartilage has few blood vessels, bone has more 3 - Nonliving extracellular matrix, consisting of ground substance and fibers

Characteristics of Connective Tissue 3 – Connective tissue is composed mostly of nonliving extracellular matrix, consisting of ground substance & fibers which separates, often widely, the living cells of the tissue. (Other primary tissues are mostly composed of cells)

Types of Connective Tissue Proper 1 – Loose Connective Tissue 1) Areolar connective tissue - gel-like matrix with all three connective tissue fibers (collagen, elastic, & reticular) serves to bind body parts together while allowing them to move freely over one another wraps small blood vessels & nerves, surrounds glands, & cushions organs is widely distributed throughout body

Connective Tissue Proper: Loose Figure 4.9a

Connective Tissue Proper: Loose 2) Adipose connective tissue – (fat) richly vasculatized tissue that is similar to areolar connective tissue with closely packed adipocytes Functions: 1- reserves food stores 2- insulates against heat loss 3- supports 4 - protects

Connective Tissue Proper: Loose Found under skin, around kidneys, within abdomen, & in breasts Local fat deposits serve nutrient needs of highly active organs

Connective Tissue Proper: Loose Figure 4.9b

Connective Tissue Proper: Loose 3) Reticular connective tissue – loose ground substance with reticular fibers Reticular cells lie in a fiber network Forms a soft internal skeleton, or stroma, that supports other cell types Found in lymph nodes, bone marrow, & spleen

Connective Tissue Proper: Loose Figure 4.9c

Types of Dense Connective Tissue 2 - Dense Connective Tissue - all have fibers Also called fibrous connective tissues 1) Dense Regular connective tissue - contain closely packed bundles of parallel collagen fibers (running in same direction) with a few elastic fibers Makes up tendons & ligaments

Connective Tissue Proper: Dense Regular Figure 4.9d

Types of Dense Connective Tissue 2) Dense Irregular Connective Tissue – contains thick bundles of collagen fibers arranged in an irregular way with some elastic fibers can withstand tension in many directions providing structural strength is found in dermis & submucosa of digestive tract

Connective Tissue Proper: Dense Irregular Figure 4.9e

Types of Cartilage Types of Cartilage 1- Hyaline Cartilage – (gristle) most abundant cartilage in body Matrix has network of collagen fibers Functions: 1) supports 2) reinforces 3) cushions & 4) resists compression **provides firm support with some pliability Found in embryonic skeleton, end of long bones, nose, trachea, & larynx

Types of Dense Connective Tissue 2 - Dense Connective Tissue - all have fibers Also called fibrous connective tissues 1) Dense Regular connective tissue - contain closely packed bundles of parallel collagen fibers (running in same direction) with a few elastic fibers Makes up tendons & ligaments

Connective Tissue Proper: Dense Regular Figure 4.9d

Types of Dense Connective Tissue 2) Dense Irregular Connective Tissue – contains thick bundles of collagen fibers arranged in an irregular way with some elastic fibers can withstand tension in many directions providing structural strength is found in dermis & submucosa of digestive tract

Connective Tissue Proper: Dense Irregular Figure 4.9e

Types of Cartilage Types of Cartilage 1- Hyaline Cartilage – (gristle) most abundant cartilage in body Matrix has network of collagen fibers Functions: 1) supports 2) reinforces 3) cushions & 4) resists compression **provides firm support with some pliability Found in embryonic skeleton, end of long bones, nose, trachea, & larynx

Connective Tissue: Hyaline Cartilage Figure 4.9f

Types of Cartilage 2- Elastic Cartilage – nearly identical to hyaline cartilage but with more elastic fibers Maintains shape & structure while allowing flexibility Supports external ear (pinna) & epiglottis

Connective Tissue: Elastic Cartilage Figure 4.9g

Types of Cartilage 2- Fibrocartilage – structuaral intermediate between hyaline cartilage & regular connective tissues & has matrix similar to hyaline cartilage but less firm with thick collagen fibers found where strong support & the ability to withstand heavy pressure are required such as the intervertebral discs & in discs of knee joint provides tensile strength & absorbs compression shock

Connective Tissue: Fibrocartilage Cartilage Figure 4.9h

Connective Tissue: Bone (Osseous Tissue) Bone - hard, calcified matrix with collagen fibers also called osseous tissue Osteocytes (mature bone cells)are found in small spaces called lacunae & are well vascularized with blood vessels has exceptional ability to support & protect body structures due to its hardness, which is determined by collagen fibers & calcium salts found in extracellular matrix

Connective Tissue: Bone (Osseous Tissue) Figure 4.9i

Connective Tissue: Blood Blood – consists of red & white blood cells & plasma proteins in a fluid matrix (plasma) contained within blood vessels f unctions in the transport of respiratory gases, nutrients, & wastes is classified as a connective tissue because it developed from mesenchyme

Connective Tissue: Blood Figure 4.9j

Nervous Tissue Nervous Tissue – main componenet of nervous system Neurons – highly specialized branched nerve cells with long cellular processes that generate & conduct nerve impulses dendrites – respond to stimuli axons – carry impulses away from nerve cell body support cells transmits electrical signals from sensory receptors to effectors Found in the brain, spinal cord, and peripheral nerves

Nervous Tissue Support cells – nonconducting cells that support, insulate, & protect delicate neurons Neurons are found in brain, spinal cord, & peripheral nerves

Nervous Tissue Figure 4.10

Types of Muscle Tissue Muscle Tissue – highly cellular, well-vascularized responsible for most types of body movement 1- Skeletal Muscle - attaches to bones of skeleton Forms flesh of body & cause voluntary movement Skeletal muscle cells (called muscle fibers) are long, cylindrical, multinucleate cells with striations

Muscle Tissue: Skeletal Figure 4.11a

Types of Muscle Tissue 2- Cardiac Muscle - branching, striated, uninucleate cells interlocking at intercalated discs responsible for involuntary movement of heart 3- Smooth Muscle – has no striations propels substances along internal passageways (i.e., peristalsis) found in walls of hollow organs is involuntary muscle

Nervous Tissue Support cells – nonconducting cells that support, insulate, & protect delicate neurons Neurons are found in brain, spinal cord, & peripheral nerves

Nervous Tissue Figure 4.10

Types of Muscle Tissue Muscle Tissue – highly cellular, well-vascularized responsible for most types of body movement 1- Skeletal Muscle - attaches to bones of skeleton Forms flesh of body & cause voluntary movement Skeletal muscle cells (called muscle fibers) are long, cylindrical, multinucleate cells with striations

Muscle Tissue: Skeletal Figure 4.11a

Types of Muscle Tissue 2- Cardiac Muscle - branching, striated, uninucleate cells interlocking at intercalated discs responsible for involuntary movement of heart 3- Smooth Muscle – has no striations propels substances along internal passageways (i.e., peristalsis) found in walls of hollow organs is involuntary muscle

Muscle Tissue: Cardiac Figure 4.11b

Muscle Tissue: Smooth Figure 4.11c

Coverings & Lining Membranes Some of the body’s membranes incorporate more than 1 type of tissue. 1 – Cutaneous Membrane - cutis = skin Consists of stratified squamous epithelium firmly attached to a thick layer of dense irregular connective tissue (dermis)

Coverings & Lining Membranes 2- Mucous Membrane– also called mucosae line body cavities such as those of hollow organs of digestive, respiratory, & urogenital tracts that open to exterior & contain either stratified squamous or simple columnar epithelia

Coverings & Lining Membranes 3 – Serous Membrane – moist membranes found in closed ventral body cavities consists of stratified squamous epithelium resting on a thin layer of loose connective (areolar) tissue Are named by where they are located Pleura = lungs Pericardium = covering of heart Peritoneums = coverings in abdominopelvic cavity

Tissue Repair Steps of Tissue Repair – 1- Inflammation – caused by tissue trauma & is characterized by dilation of blood vessels, increase in vessel permeability, redness, heat, swelling, & pain Blood clot forms

Tissue Repair 2 – Organization restored the blood supply. Blood clot is replaced with granulation tissue 3 – Regeneration & Fibrosis If wound is small & damaged tissue can divide, the tissue will regenerate & cover the fibrous tissue When wound is extensive or damaged tissue cannot divide, it is repaired only by fibrous connective (scar) tissue.

Developmental Aspects 3 primary germ layers for early during embryonic development & becomes specialized into the 4 types of tissues. Ectoderm – top layer - nervous tissue comes from ectoderm Mesoderm – middle layer – muscle & connective tissue come from mesoderm Endoderm – inside layer – organs Epithelium arises from all 3 primary germ layers