Chapt 40 Lecture

8/8/2019 Chapt 40 Lecture

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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

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Chapt 40 Lecture