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Tissues & Organs of Humans
Chapter 4
Themes of organism function

1. Structure and function are correlated
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2. Life has the ability to adjust to its
environment physiologically & ultimately
as adaptation
4 basic Human Tissue Types
1.
2.
3.
4.
Epithelia
Connective
Muscle
nervous
1. Epithelia

sheets of tightly packed epithelial cells

covers outside of the body (skin or epidermis) &
lines organs & cavities inside body (endothelium)

classified by numbers of layers & shape of cells

function to


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a) absorb nutrients
b) lubricate a surface
c) secrete chemicals - glands.
Glands

Exocrine glands: secretion into ducts to
exterior of body

Endocrine glands: secretion into the blood to
carry chemical messages throughout the body
2. Connective Tissue

Not tightly packed, cells are scattered throughout
an extracellular matrix
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Functions: bind & support other tissues
Main component matrix fibrous protein collagen.
Two possible cell types of matrix
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matrix may be liquid, solid, or jelly-like
a) fibroblasts - secretes collagen
b) macrophages - amoeboid cells that roam matrix
eating bacteria and dead cells
Tissue examples: cartilage, bone, & blood
Loose Connective Tissue

function - bind epithelia to underlying tissues,
hold organs in place, or transport of materials


1.
2.
3.
4.
fibers are loosely woven
Examples:
Collagenous fibers - do not tear easily; keeps
flesh on bone
Elastic fibers (elastin) - resist stretching,
rubbery
Adipose tissue - contains cells which store fat,
bound in a fibrous matrix; cells shrink or swell
Blood - matrix is liquid (plasma), transport
Fibrous Connective Tissue
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dense, tightly woven, in parallel bundles
Types Fibrous Connective Tissue:
a. Tendons - connect muscle to bone
b. Ligaments - connect bone to bone at joints
c. Cartilage - flexible; nose, ears, between
vertebrae
d. Bone - hardest connective
Functions of Bone
1.
2.
3.
4.
5.
supports the body (against gravity)
attachment point for muscles
protects organs e.g. ribcage, skull
some bones produce red blood cells
acts as a reservoir for calcium
3. Muscle Tissue
1.
2.
3.
Skeletal
Cardiac
smooth
Skeletal (striated) muscle

attaches to bones

moves the skeleton

voluntary - under conscious nervous control

striated (striped) appearance
Cardiac muscle or heart muscle

Striated w/ intercalated disks

cells only contain a single nucleus

under control of autonomic nervous system
(unconscious control)
Smooth muscle

lacks the striations of skeletal muscle

involuntary muscle, under autonomic
control

visceral muscle - operates the gut; found in
iris of eye, base of hairs, uterus
4. Nerve Tissue

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composed of neuron cells
receives information from environment (stimulus)
through sensory receptors
information sent as electrical & chemical signals
to brain
Brain interprets signals and produces proper
response
signals are then sent from brain to effectors where
response is initiated
Homeostasis ("same state")

maintenance of physiological conditions
required to support the life of the organism
Homeostatic response

serves to keep physiological conditions
within a certain acceptable range to support
life.

generally automatic, brought on by
feedback loops
Feedback Loops

negative or positive (more on this later).

continuous, automatic adjustments, collectively
called regulation.

regulation maintained by the nervous system &
endocrine system.
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Nervous System Control

simple rapid & automatic reflex reaction
causing a regulatory response to a potential
threat. (e.g. knee jerk)

interaction between nervous system &
musculoskeletal system
Endocrine System Control

acts more slowly than nervous system

changes in levels of nutrients in the bloodstream
trigger the release of hormones

hormones effect target tissues or organs