Plants and Animals –

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					                     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
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
27.2 Common Challenges
 Although plants and animals differ in many ways, they share some
  common challenges
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
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
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

 They also respond to threats and to variations in available
27.3 Homeostasis in Animals

 Detecting and responding to changes is a characteristic trait of all
  living things and the key to homeostasis
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
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,

 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

 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
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

27.3-27.5 Key Concepts

 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
  • Signal reception
  • Signal transduction
  • Cellular response

 Example: Apoptosis (programmed cell death)
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