Transcript Chapter 40 Presentation

Chapter 40
Basic Principles of Animal Form and
Function
Constraints on Size
An animal’s size and shape are referred
to as a body plan or design.
 It is limited mainly due to its surface
area to volume ratio.
 Organisms must be able to exchange
gases, nutrients, and water with the
external environment.
 Additionally, they must also be able to
get rid of wastes.

Tissues
Tissues are groups of cells with a
common structure and function.
 There are 4 main classes of tissue:

 1.
Epithelial
 2. Connective
 3. Muscle
 4. Nervous
1. Epithelial Tissue
Occurs in sheets
 Lines the inside and
outside of the body
and its cavities.
 Often are tightly
packed, joined with
tight junctions and
protects against
mechanical injury and
fluid loss.

1. Epithelial Tissue
The criteria for classifying epithelia are
the number of layers and the shapes of
the cells.
 1. Simple epithelium--single layer
 2. Stratified epithelium-- multiple layers
 3. Cuboidal cells--dice like
 4. Columnar--like columns
 5. Squamous--like floor tiles

2. Connective Tissue

Functions to bind and protect other tissues.
They are sparse and are linked together by a
web of fibers secreted by the cells of the
tissue itself.
 There are 3 kinds:



1. Collagenous fibers--make of collagen, nonelastic.
2. Elastic fibers--are long threads made of elastin.
Provides elasticity and complements collagen.
3. Reticular fibers--are thin and branched. Forms
fabric that joins connective tissue to adjacent
tissues.
3. Muscle Tissue
Composed of long muscle fibers.
 Large numbers of contractile units
called myofibrils are arranged in parallel
within the cytoplasm of these cells.
 Myofibrils are made of actin and
mysosin.
 Vertebrates have 3 types of muscle:
skeletal, cardiac, and smooth.

4. Nervous Tissue
Senses stimuli and transmits nerve
impulses from one part of the body to
the next.
 The neuron is the functional unit.
 Axon
 Dendrite

Tissues

Most animals
consist of different
tissues organized
into organs. These
organs are
organized into
organ systems that
carry out the major
body functions of
most animals.
Bioenergetic Strategies
There are two main bioenergetic
strategies:
 Endothermy
 Ectothermy
 Homeostasis is the steady state, and it
is the physiological process by which
animals maintain their internal
environment.

Regulating and Conforming

Regulating and conforming are two
extremes by which animals cope with
their environmental fluctuations.
Regulation
An animal is a regulator for an
environmental variable if it uses internal
control mechanisms to moderate
internal change in the face of external
fluctuations.
 Example:

 Freshwater
fish. They can maintain a
stable internal concentration of solutes in
the blood and interstitial fluid.
Conforming
An animal is a conformer for an
environmental variable if it allows an
internal condition to conform to the
external environment.
 Example:

 Some
spider crabs live in salt water and
don’t regulate their internal environment.
They conform to their surroundings.
Regulating and Conforming
No animal is a perfect regulator or
conformer.
 They regulate their internal process
while conforming to others with regard
to the external environment.

Homeostasis
Homeostatic mechanisms moderate
changes in internal environments and
have 3 functional components:
 1. A receptor
 2. A control center
 3. An effector

The Receptor
Detects a change in the internal
environment of an animal.
 Example: Body temperature.

The Control Center
Processes the information it receives
and directs an appropriate response.
 Example: Brain.

The Effector
The effector displays the appropriate
response.
 Example: Shivering, dilation or
constriction of blood vessels.

For Example:
The regulation of room temperature.
 The control center is the thermostat and
it contains a receptor called the
thermometer.
 When the temp falls below a set point, it
switches the heater (the effector) on.
 When the thermometer senses the temp
is above the set point, it switches the
heat off--negative feedback.

Negative Feedback
Occurs when the variable being
monitored counteracts any further
change in the same direction.
 There are only slight variations above
and below the set point in a negative
feedback system.
 Most homeostatic mechanisms in an
animal operate under this principle.

Positive Feedback
On the other hand occurs where a
change in an environmental variable
triggers mechanisms that amplify the
change.
 Example:

 During
childbirth, the head against the
uterine wall stimulates more contractions in
the uterus.
 Positive feedback completes childbirth.
Thermoregulation
This is the process by which animals
maintain an internal temperature within
a tolerable range.
 This ability is critical to survival because
enzyme function and membrane
permeability is dramatically affected by
large changes in temperature.

Thermoregulation
In general, ectotherms tolerate a greater
variation in internal temperature than do
endotherms.
 Endotherms regulate their high internal
temperature as their surroundings
fluctuate.
 Ectotherms regulate their temperature
more so by behavioral means.

Heat Exchange
Endotherms and ectotherms use 4
modes of heat exchange:
 1. Conduction
 2. Convection
 3. Radiation
 4. Evaporation

Thermoregulatory Functions
Thermoregulators function by balancing
heat loss with heat gain.
 There are 5 general categories to assist
with this:
 1. Insulation
 2. Circulatory Adaptation
 3. Evaporative Cooling
 4. Behavioral Responses
 5. Adjusting Metabolism

1. Insulation
Fat, hair, and/or feathers help to reduce
heat flow between the organism and the
surroundings.
 The integumentary system in mammals
acts as this insulating layer.

2. Circulatory Adaptations
Vasodilation, vasoconstriction work
together to transfer body heat form the
core to the surroundings.
 Vasodilation--vessels get larger.
 Vasoconstriciton--vessels get smaller.

3. Evaporative Cooling
Many animals have structural
adaptations that enable them to take
advantage of evaporation as a way of
controlling body temperature.
 For Example:
 Sweat glands, panting, and mucous
secretions.

4. Behavioral Adaptations

Behavioral responses are used by
endotherms and ectotherms as a
means to control body temperature.
 Basking
in the sun
 Migration
 Hibernation
5. Adjusting Metabolism
There are a variety of ways by which
animals can control their body
temperature by changing their metabolic
activity.
 In some mammals, hormones can
stimulate mitochondria to generate heat
instead of ATP--non-shivering
thermogenesis.

5. Adjusting Metabolism
In other mammals, a layer of brown fat
is found in the neck region and is
specialized in rapid heat production.
 Some female pythons can increase their
body temperature when incubating
eggs.

5. Adjusting Metabolism
Humans have nerve cells concentrated
in the hypothalamus to control
thermoregulation.
 These nerve cells are grouped together
and function as a thermostat regulating
mechanisms that increase or decrease
heat loss.
