Exocrine Glands Exocrine glands – “externally secreting” - secrete their products onto body...

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

• 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


• 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


– Found under skin, around kidneys, within abdomen, & in breasts

– Local fat deposits serve nutrient needs of highly active organs


Figure 4.9b


• 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


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


• 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


• 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


• 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 TissueSupport 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 TissueSupport 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)


• 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


• 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

Exocrine Glands Exocrine glands – “externally secreting” - secrete their products onto body...

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