Chapter 40

Problem Solving Animals must solve basic challenges of life:

Obtain oxygen Nourish themselves Excrete waste products Move

These questions will be addressed throughout our next unit.

Unifying themes that will be introduced here: Form & function are closely related

Vocabulary

Anatomy – is the study of the structure of an organism

Physiology – is the study of the functions an organism performs

Bioenergetics – how organisms obtain, process, and use their energy resources.

Homeostasis – regulating internal temperature

40.1

Physical laws and the environment constrain animal size and shape.

An animal’s size and shape (body plan or design) affect the way it interacts with its environment.

Physical Laws

Physical laws and the need to exchange materials with the environment place certain limits on the range of animals forms. Examples: Aquatic animals (sleek

streamlined body forms) and flying animals (bones that allow for the organism to generate enough lift to become air born)

Exchange with the environment Living cells must be bathed in a

aqueous medium to keep the plasma membrane intact Single celled organisms – Surface-to-

volume ratio Fig. 40.3a

Multicellular organisms

Composed of numerous cells which also must be in water Saclike body plan Hydra Fig. 40.3b Flat body plan – tapeworm

Both of these put a large surface area in contact with the environment but do NOT allow for complexity in internal organization

Complex body forms allow for: outer coverings to protect against predators, large muscles for fast movement internal digestive organs to break down food gradually, maintaining relatively stable internal environment, and for living on land.

Animal form and function are correlated at all levels of organization.

Tissues are classified into 4 main categories –

Epithelial

Sheets of tightly packed cells Where is it found? Epithelial tissue

covers the outside of the body and lines organs and cavities within the body

Form & function? Closely joined (tight junctions between them) so epithelium functions as a barrier against mechanical injury, microbes, and fluid loss.

Types? Stratified columnar Simple columnar Pseudostratified ciliated columnar Stratified squamous Simple squamous Cuboidal

All have slightly different volumes of cytoplasm which allow them to perform different functions.

Connective Tissue

Sparse population of cells scattered through an extracellular matrix.

Where is it found? Everywhere Form & function? Bind and support

other tissues

Types? Loose connective tissue – holds organs

in place Fibrous connective tissue – tendons &

ligaments Cartilage Bone – mineralized connective tissue Blood Adipose tissue – stores fat

Muscles tissue

Long cells called muscle fibers Where is it found? Everywhere!!

Most abundant tissue in most animals

Form & function? Contraction brings about movement

Types? Skeletal – attaches to bones – voluntary

movement Cardiac – striated – involuntary Smooth – lacks striations - involuntary

Nervous Tissue

Nerve cells Organs & organ systems – see table

40.1 pg. 827

Animals use the chemical energy in food to sustain form and function

Bioenergetics – limits the animal’s behavior, growth, and reproduction and determines how much food it needs.

– After the energetic needs of staying alive are met any remaining molecules from food can be used in biosynthesis (body growth & repair, storage material such as fat and production of gametes)

Metabolic rate – the sum of all the energy-requiring biochemical reactions occurring over a given time interval. Energy measured in Calories (cal) or

kilocalories (kcal) Unit Calorie with a capital C is actually a

kilocalorie Energy appears as heat so metabolic rate

can be determined by measuring heat.

2 Bioenergetic Strategies Endothermic – bodies are warmed

mostly by heat generated by matabolism and body temperature is maintained within a relatively narrow range.

Ectothermic – meaning that they gain their heat mostly from external sources

Endo or Ectothermic?

Endo or Ectothermic?

Endo or ectothermic?

Influences on metabolic rate Size and metabolic rate: amount of

energy it takes to maintain each gram of body weight is inversely related to body size. (Example – each gram of a mouse requires about 20 times more calories than a gram of an elephant)

Activity and metabolic rate: every animal experiences a range of metabolic rates. Basal Metabolic rate (BMR) – metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not experiencing stress. 1,600-1,800 kcal per day for adult male 1,300-1,500 kcal per day for adult

female

Standard Metabolic rate (SMR) – metabolic rate of a resting, fasting, nonstressed ectotherm at a particular temperature.

Maximum potential metabolic rates and ATP sources

Energy budgets – pg. 831 Fig. 40.10

40.4

Many animals regulate their internal environment within relatively narrow limits

Interstitial fluid (Bernard more than a century ago) – internal environment of vertebrates – today homeostasis – steady state

Regulators vs. Conformers Regulators – animal is a regulator for

a particular environmental variable is it uses internal control mechanisms to moderate internal change in the face of external fluctuation

Conformer – an animal is said to be a conformer for a particular environmental variable if it allows its internal condition to vary with certain external changes

Regulators and conformers are extremes and no animal is a perfect regulator or conformer

Some animals may regulate some internal conditions and conform to external conditions for others.

Mechanisms of Homeostasis Negative feedback – thermostat in

your house pg. 832 Fig. 40.1 Positive feedback – amplify rather

than reverse the change (child birth)

Thermoregulation – process by which animals maintain an internal temperature within a tolerable range. Critical because most biological processes work best at optimal conditions (plasma membrane)

Ectotherms vs. Endotherms Ectotherms include invertebrates,

fishes, amphibians, lizards, snakes, and turtles The amount of heat they generate has

little effect on body temperature Bask in the sun to warm Seek shade to cool Can tolerate greater variation in internal

temperature than endotherms Not “cold-blooded”

Endotherms include mammals, birds, some fish, and numerous insect species Can use metabolic heat to regulate body

temperature Sweating to cool Not “warm-blooded”

Advantages & Disadvantages Advantages – able to generate a large

amount of heat metabolically – can perform vigorous activity for much longer than is possible for most ectotherms, can tolerate extreme temperatures

Disadvantages – energetically expensive – requires more food

Modes of heat exchange

Conduction Convection Radiation Evaporation

Balancing heat loss & gain Insulation Circulatory adaptations Cooling by evaporative heat loss Behavioral responses Adjusting metabolic heat production

Insulation

Skin, hair, nails, fur Skin houses nerves, sweat glands,

blood vessels, and hair follicles

Insulation

Circulatory adaptations

Vasodilation (warms skin) – increases in diameter of superficial blood vessels

Vasoconstriction (cools skin) – reduces blood flow and heat transfer by decreasing the diameter of superficial blood vessels

Countercurrent heat exchanger – important for reducing heat loss in many endotherms

Cooling by evaporative heat loss Water absorbs considerable heat

when it evaporates Panting Sweat glands Spreading saliva on body surface

Roxy panting!!

Behavioral responses

Both ecto and endotherms Hibernation Migration Huddling in cold weather

Adjusting metabolic heat production Endotherms must counteract

constant heat loss Heat production is increased by

shivering NST – nonshivering thermogenesis

(produce heat instead of ATP)

Feedback mechanisms controlled by hypothalamus in the brain

Acclimatization – both ectotherms and endotherms can adjust to new range of environmental temperatures. Shedding, growing a thicker coat Heat shock proteins – help maintain

integrity of cell’s proteins when exposed to extreme heat so they don’t denature

Torpor & energy conservation Torpor – a physiological state in

which activity is low and metabolism decreases Hibernation – long term torpor to winter

cold and food scarcity Estivation – summer torpor Daily torpor – adapted to feeding

patterns