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Copyright (c) The McGraw-Hill
Companies, Inc. Permission requiredfor reproduction or display. 1
CHAPTER 40
INTRODUCTIONTO ANIMAL FORM
AND FUNCTION
Prepared by
Brenda Leady, University of Toledo
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All animal cells share similarities in theways in which they
Exchange materials with their surroundings Obtain energy from organic nutrients
Synthesize complex molecules
Duplicate themselves Detect and respond to signals in their
immediate environment
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Tissues Specialized cells of a given types cluster
together
4 categories
Muscle
Nervous
Epithelial
Connective
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Muscle tissue Cells specialized to contract
3 types
Skeletal attached to bone or exoskeleton for
locomotion, voluntary control
Smooth surrounds hollow tubes and cavities
for propulsion of contents, involuntary control Cardiac only in the heart, involuntary control
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Nervous tissue Initiate and conduct electrical signals from
one part of the animals body to another
Electrical signals produced in one nervecell may stimulate or inhibit other nervecells to
Initiate new electrical signals
Stimulate muscle to contract
Stimulate glands to release chemicals
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Epithelial tissues Sheets of densely packed cells that
Cover the body or individual organs
Line the walls of body cavities
Specialized to protect and secrete or
absorb
Rest on basal lamina or basement
membrane
Can function as selective barriers
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Connective tissues Connect, anchor, and support
Includes blood, adipose, bone, cartilage,
loose and dense connective tissue
Form an extracellular matrix around cells
Provides scaffold for attachment
Protects and cushions
Mechanical strength
Transmit information
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Organs Composed of 2 or more kinds of tissues
Organ system different organs work
together to perform an overall function Organ systems frequently work together
nervous and endocrine system
Spatial arrangement of organs into organ
systems part of overall body plan Body plan controlled by highly conserved
family of genes with homologs in allanimals
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Organ Development and Function Are
Controlled by Homeotic Genes
Homeotic genes family of ancient highlyconserved genes found in all animals
Determine timing and spatial patterning ofthe anteroposterior body axis duringdevelopment
In vertebrates known as Hox genes
Important role in determining where organsform
Hox genes also important for growth,development and function of organs in adults
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Body fluids 2 main compartments
Intracellular fluid inside cells
Extracellular fluid outside cells Plasma fluid portion of blood
Interstitial fluid fluid between cells
Separate in closed systems
Hemolymph intermingles to fluids in many inverts
Intracellular and extracellular fluid can bevery different in solute composition
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Movement of water Plasma membranes tend to be highly
permeable to water and
Fluid moves readily between compartments Osmosis
Swollen or shrunken cells do not operate
well Can happen when cells exposed to more
dilute (hypoosmotic) or more concentrated(hyperosmotic) extracellular fluids
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Movement of solutes Passive diffusion
Movement of a solute down its concentration
gradient No carrier orATP required
Only lipid soluble molecules
Transport proteins used in
Facilitated diffusion passive
Active transport
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Structure and function Key theme is structure determines function
Compare respiratory systems of insect
and mammal
Structural similarities suggest similar function
Tubes connect with the outside environment
terminating in 1 cell thick structures Tubes serve as air conduits
Thin cells with high surface area for diffusion
of gases
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All organs that mediate diffusion or
absorption have an extensive surface area
Increased space requirements avoided by
shape changes
Folding for example
SA/V surface area to volume ratio
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Homeostasis Process of adjusting to the external environment
and maintaining a stable internal environment
Conformers maintain same fluid compositionas environment cheaper
Regulators internal composition of fluids
different from environment more expensive
Animal can be both with respect to different
variables
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No physiological function is constant for very
long, which is why we call them variables
Normally, blood sugar (glucose) remains at fairly
steady and predictable levels in any healthy
individual
After a meal the level of glucose in your blood
can increase quickly
If you skip a meal, your blood sugar level may
drop slightly Homeostatic mechanisms restore blood glucose
to normal levels in the blood
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Homeostatic control systems Sensor monitors particular variable
Integrator compares signals from the
sensor to a baseline set point
Effector compensates for deviations
between actual value and set point
Example body temperature in mammals
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Feedback
Fundamental feature of homeostasis
Major way disturbances are minimized
Negative feedback
Positive feedback
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Negative feedback
Variable being regulated brings about
responses that move the variable in the
opposite direction
Decrease in body temperature leads to
responses that increase body temperature
May occur at organ, cellular or molecularlevel
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Positive feedback
Far less common
Accelerates a process
Reinforces the direction of the change
Birth in mammals
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Feedforward regulation
Animals body begins preparing for a
change in some variable before it occurs
Anticipatory
Speeds up homeostatic responses and
minimizes deviations from the set point
Many result from or are modified by
learning
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Pavlov Demonstrated the Relationship
Between Learning and Feedforward
Processes
Demonstrated that feedforward processesassociated with digestion could be
conditioned to an irrelevant stimulus Used ticking metronome (not ringing bell)
Conditioned stimulus by itself can elicit
increased salivation Other sounds and stimuli also worked
Conditioned response not permanent
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Local homeostatic responses
Some homeostatic responses may be highlylocalized
Paracrine signaling molecules released intointerstitial fluid to act on nearby cells
Neurotransmitters released from one nerve celltravel to an adjacent nerve cell
In contrast, hormones are chemical messengersproduced in a gland, secreted into the blood,and act on distant cells