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
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