STRUCTURE AND FUNCTION
Chapter 20
HIERARCHY OF STRUCTURE (A REVIEW)
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From most exclusive to most inclusive
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Cells: structural and functional unit of a living organism
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Tissues: integrated group of cells with a common
function
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Circulatory, nervous, reproductive, and respiratory
Organism: a number of organ systems with different
functions to form 1 coordinated unit
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Heart, lungs, kidneys, brain, and liver
Organ systems: multiple organs that perform a vital
function
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4 main types: Epithelial, connective, muscle, and nervous
Organs: 2+ tissue types that work to perform a task
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Muscle fibers, neurons and erythrocyte
Interaction between systems to facilitate life
Example of emergent properties
SIMILARITY IN BODY PLANS

Results from
convergent evolution

Similar environmental
challenges face diverse
organisms
E.g water resistance
 Can decerase by
streamlining shape
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Can revise earlier
theories

Speed of Tyrannosaurus
rex
EPITHELIAL TISSUE (EPITHELIUM)
Covers body surfaces and lines internal organs
and cavities
 Basal (connecting base) and apical (free) ends
 Classified by cell layer and shape

Simple or stratified
 Squamous, cuboidal, and columnar
 Pseudostratified
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Shape and layer reflect function
Simple layers facilitate diffusion
 Stratified for abbrasive surfaces
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Cells move basal to apical while sloughing off old
EPITHELIAL TYPES
CONNECTIVE TISSUE

Sparse cells spread throughout a matrix they created

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Liquid, jelly, or solid
6 major types
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Loose connective: most common, matrix of collagen
(strength) and elastic (resilient) fibers
Fibrous connective: dense packing of collagen fibers;
tendons and ligaments
Adipose: stores fat in cells; fat droplet swell or shrink
with storage
Cartilage: dense collagen fibers (strong and flexible)
Bone: collagen in mineralized Ca2+, Mg2+, and P
Blood: matrix is plasma containing water, salts, and
dissolved proteins
OMENTUM
CONNECTIVE TYPES
MUSCLE TISSUE
Cells called
muscle fibers
Most abundant
tissue in most
animals
Contractile
proteins, actin
and myosin,
within cytoplasm
3 Types
Nucleus
NERVOUS TISSUE
CellBody
Senses stimuli
and transmits
information
throughout the
body
Structural,
functional unit
is a neuron
Tissue contains
neurons and
other
supporting cells
ORGANS
Each of the 4
tissue types
perform
different
functions
Together
contribute to
the functioning
of an organ
Bioengineers
have created
artificially in
the lab for
replacements
from a
recipients cells
ANATOMICAL TERMINOLOGY
Posterior
Sagittal plane
Anterior
ORGAN SYSTEMS
All interdependent and work together
 12 found in vertebrate animals
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Endocrine: controls hormones
Skeletal: bones for structure, support, and shape
Circulatory: nutrients and oxygen to body
Respiratory: exchange gases in body with environment
Muscular: produces movement and heat; produces heat
Integument: skin for protection and fluid retention
Lymphatic: lymph nodes to return excess fluid; immunity role
Immune: defense against infections
Urinary: bladder to excrete nitrogenous wastes and regulation
Digestive: ingest and breaks down food to obtain nutrients
Reproductive: gametes and gonads to preserve the species
Nervous: coordinates body activities and cell signaling
INTEGUMENT SYSTEM


Skin, hair, and nails
Structure
Epidermis (5 layers) of stratified squamous
 Dermis contains accessory structures
 Hypodermis contains adipose tissue; injection sites

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Functions
Tightly joined cells for protection
 Sensory receptors for environmental information
 Produce vitamin D, necessary for absorbing calcium

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Adequate sunlight necessary
Hair and nails
Oil secretion lubricate hair and inhibit bacterial growth
 Insulation, goose-bumps are remnants
 Nails for manipulation and scratching

SKIN SECTION
MOLECULAR EXCHANGE
O2 and nutrients must
enter cells
 CO2 and wastes must
exit
 Larger organisms
have smaller outer
surfaces than inner

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All cells must be in an
aqueous environment
Folds and alternate
structures within to
facilitate
HOMEOSTASIS AND FEEDBACK
Responses
minimize internal
changes due to
large external
ones
 Most homeostatic
controls due to
negative feedback
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One variable
change causes a
reverse change
Interaction of
stimulus, receptor,
control center, and
effector, and
response