Download Plants and Animals – Common Challenges

Plants and Animals –
Common Challenges
Chapter 27
Impacts, Issues
A Cautionary Tale
 A multicelled organism must keep conditions
inside its body within a range cells can tolerate;
Korey Stringer died from heat stroke after
football practice on a hot, humid day
Introduction to Anatomy and Physiology
 Anatomy
• The study of body form (structures)
 Physiology
• The study of how body parts are put to use
(function)
27.1 Levels of Structural Organization
 Tissue
• One or more cell types (and often extracellular
matrix) that collectively perform a specific task
 Organ
• Two or more tissues in specific proportions that
interact to carry out a specific task
 Organ system
• Organs that interact in one or more tasks
Growth Versus Development
 Growth
• An increase in number, size, and volume of cells
(quantitative)
 Development
• A series of stages in which specialized tissues,
organs and organ systems form in heritable
patterns (qualitative)
Evolution of Form and Function
 All anatomical and physiological traits have a
genetic basis and have been affected by natural
selection
 Plants and animals adapted to life on dry land
with structures to move gases and retain
moisture
Anatomy of a Tomato Plant
Flower, a
reproductive organ
shoot
system
(aboveground
parts)
root
system
(belowground
parts,
mostly)
Cross-section of a leaf, an
organ of photosynthesis
and gas exchange
Cross-section of a stem, an
organ of structural support,
storage, and distribution
of water and food
Fig. 27-2, p. 462
The Human Respiratory System
Ciliated cells and mucussecreting cells of a tissue
that lines respiratory airways
Organs (lungs),
part of an organ
system (the
respiratory
tract) of a
whole organism
Lung tissue (tiny air sacs)
laced with blood capillaries—
one-cell-thick tubular
structures that hold blood,
which is a fluid connective
tissue
Fig. 27-3, p. 463
The Internal Environment
 Plant and animal cells are surrounded by their
internal environment: extracellular fluid (ECF)
 To keep cells alive, body parts work together to
keep the internal environment within tolerable
limits (homeostasis)
A Body’s Tasks
 Essential functions of plants and animals:
• Maintain favorable conditions for cells
• Acquire and distribute water, nutrients and other
raw materials, and dispose of wastes
• Defend against pathogens
• Reproduce
• Nourish and protect gametes and embryos
27.1 Key Concepts
Many Levels of Structure and Function
 Cells of plants and animals are organized in
tissues
 Tissues make up organs, which work together in
organ systems
 This organization arises as the plant or animal
grows and develops
 Interactions among cells and among body parts
keep the body alive
27.2 Common Challenges
 Although plants and animals differ in many
ways, they share some common challenges
Animation: Morphology of a tomato plant
Gas Exchange
 Diffusion
• Ions or molecules of a substance move from a
place where they are concentrated to one where
they are scarce
 Aerobic respiration
• The pathway that releases energy from food or
photosynthetic products using oxygen and
releasing carbon dioxide
Internal Transport
 Very small organisms can exchange materials
with the environment by diffusion; larger
organisms have vascular tissues
 Plants have xylem and phloem
 Animals have a circulatory system with blood
vessels
Internal Transport
Maintaining the Water-Solute Balance
 Passive transport
• A material moves in or out of ECF down its
concentration gradient through a transport protein
 Active transport
• A protein pumps one specific solute from a region
of lower concentration to a region of higher
concentration (requires energy)
Cell-to-Cell Communication
 Specialized cells release signal molecules that
help control and coordinate events in the body
•
•
•
•
Growth
Development
Maintenance
Reproduction
Variations in Resources and Threats
 Each habitat has a specific set of resources
(water, nutrients, light, temperature) and
challenges (predators, pathogens, parasites)
 Competition and variation in these factors
promotes diversity of form and function
Forms of Protection
27.2 Key Concepts
Similarities Between Animals and Plants
 Animals and plants exchange gases with their
environment, transport materials through their
body, maintain volume and composition of their
internal environment, and coordinate cell
activities
 They also respond to threats and to variations in
available resources
27.3 Homeostasis in Animals
 Detecting and responding to changes is a
characteristic trait of all living things and the key
to homeostasis
Three Components
Maintain Homeostasis in Animals
STIMULUS Sensory input into the system
Receptor
Integrator
Effector
such as a free
nerve ending in
the skin
such as the
brain or the
spinal cord
a muscle
or a gland
Fig. 27-7, p. 466
Negative Feedback
 Negative feedback mechanisms
• A change leads to a response that reverses that
change
• Example: A furnace turns off and on to maintain a
set temperature; similar mechanisms maintain
human body temperature
Homeostatic Controls
of Human Body Temperature
STIMULUS
Body’s surface
temperature
skyrockets
after exertion
on a hot, dry
day.
RESPONSE
Body’s surface
temperature
falls, which
causes sensory
receptors to
initiate shift in
effector output.
Receptors
Sensory receptors
in skin and
elsewhere detect
the change in
temperature.
Integrator
Hypothalamus
(a brain region)
compares input from
receptors against a
set point for the body.
Effectors
Pituitary gland and
thyroid gland
trigger adjustments
in activity of many
organs.
Effectors
Different types of effectors carry out specific (not general) responses:
Skeletal muscles Blood vessels in skin
Sweat gland
Adrenal
in chest wall
expand as muscle in
secretions
gland
contract more
their wall relaxes; more increase; the secretions
frequently; faster metabolic heat gets
evaporation
drop off;
breathing speeds
heat transfer from shunted to skin, where of sweat cools excitement
it dissipates into the air. body surfaces. declines.
lungs to air.
Effectors collectively call for an overall
slowdown in activities, so the body
generates less metabolic heat.
Fig. 27-8a, p. 466
STIMULUS
Body’s surface
temperature
skyrockets
after exertion
on a hot, dry
day.
RESPONSE
Body’s surface
temperature
falls, which
causes sensory
receptors to
initiate shift in
effector output.
Receptors
Sensory receptors
in skin and
elsewhere detect
the change in
temperature.
Integrator
Hypothalamus
(a brain region)
compares input from
receptors against a
set point for the body.
Effectors
Pituitary gland and
thyroid gland
trigger adjustments
in activity of many
organs.
Effectors
Different types of effectors carry out specific (not general) responses:
Skeletal muscles Blood vessels in skin
Sweat gland
Adrenal
in chest wall
expand as muscle in
secretions
gland
contract more
their wall relaxes; more increase; the secretions
frequently; faster metabolic heat gets
evaporation
drop off;
breathing speeds
heat transfer from shunted to skin, where of sweat cools excitement
it dissipates into the air. body surfaces. declines.
lungs to air.
Effectors collectively call for an overall
slowdown in activities, so the body
generates less metabolic heat.
Stepped Art
Fig. 27-8a, p. 466
dead, flattened
skin cell
sweat gland
pore
Fig. 27-8b, p. 466
Animation: Control of human body
temperature
Positive Feedback
 Positive feedback mechanisms
• A chain of events intensifies the change from the
original condition, leading to a change that ends
feedback
• Example: Childbirth contractions
27.4 Heat-Related Illness
 Heat stroke is a failure of homeostasis that can
cause irreversible brain damage or death
 Symptoms: dizziness, blurred vision, muscle
cramping, weakness, nausea and vomiting
 Risk factors: Sweating, heat and humidity, age,
medical condition, pregnancy
 First aid: Water, ice packs, call for medical aid
27.5 Does Homeostasis Occur in Plants?
 Mechanisms that control homeostasis in plants
are not centrally controlled
 Systemic acquired resistance: Affected cells
release signaling molecules that cause release
of protective organic compounds
 Compartmentalization walls injured and
infected tissues with resins and toxic compounds
Compartmentalization Response
A Strong
B Moderate
C Weak
Fig. 27-9, p. 468
Animation: Compartmentalization
responses
Sand, Wind, and Yellow Beach Lupine
 Lupine adaptations to beach environment:
• Nitrogen-fixing bacteria provide nutrients
• Hairs trap moisture that evaporates from stomata
• Leaves fold in hot, windy conditions
Rhythmic Leaf Folding
 Circadian rhythm
• A biological activity pattern in plants or animals
that recurs with a 24-hour cycle
• Example: Rhythmic leaf folding might help reduce
heat loss at night
Rhythmic Leaf Folding
1 A.M.
6 A.M.
Noon
3 P.M.
10 P.M.
Midnight
Fig. 27-11, p. 469
Animation: Rhythmic leaf movements
27.3-27.5 Key Concepts
Homeostasis
 Homeostasis is the process of keeping
conditions in the body’s internal environment
stable
 The feedback mechanisms that often play a role
in homeostasis involve receptors that detect
stimuli, an integrating center, and effectors that
carry out responses
27.6 How Cells Receive
and Respond to Signals
 Communication among distant body cells
requires special molecules that travel through
ECF, blood, or plant vascular systems
• Signal reception
• Signal transduction
• Cellular response
 Example: Apoptosis (programmed cell death)
Three Steps in Signaling
Signal
Reception
Signal binds to a
receptor, usually
at the cell surface.
Signal
Transduction
Binding brings
about changes in
cell properties,
activities, or both.
Cellular
Response
Changes alter cell
metabolism, gene
expression, or rate
of division.
Fig. 27-12a, p. 470
Signal Transduction Pathway
Signal to
die docks at
receptor.
Signal
leads to
activation
of proteindestroying
enzymes.
Fig. 27-12b, p. 470
Apoptosis
Apoptosis: When Cell Signaling Fails
27.6 Key Concepts
Cell Communication in Multicelled Bodies
 Cells of tissues and organs communicate by
secreting chemical molecules into extracellular
fluid, and by responding to signals secreted by
other cells
Animation: Formation of human fingers
Animation: Negative feedback system
Animation: Structures that function in
human respiration
Video: Too hot to handle