This is a comprehensive summary and study material that includes lecture notes, textbook and other resource information pertaining to animal metabolism, transport and thermoregulation. It includes relevant and useful pictures and diagrams for a detailed understanding. All pages are loaded as A4. Th...
Samenvatting Hoofdstuk 12 van Biology a Global Approach 11th edition
Samenvatting Hoofdstuk 8 van Biology a Global Approach 11th edition
Samenvatting Hoofdstuk 7 van Biology a Global Apprach 11th edition
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University of the Witwatersrand (wits)
Introductory Life Science (BIOL1000)
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KEY CONCEPTS Animal form and function are correlated at all levels
▪ Physiological effects of temperature change of organization
▪ Temperature limits → An animal’s size and shape are fundamental aspects of
▪ Tolerance to high temperatures form that significantly affect the way the animal interacts
▪ Heat death with its environment
▪ Tolerance to low temperatures → Physical laws that govern strength, diffusion, movement,
▪ The implications and solutions to freezing and heat exchange limit the range of animal forms.
▪ Body temperature and classification → Physical laws also influence animal body plans with
▪ Control of heat loss regard to maximum size.
▪ Heating and cooling rates → As body dimensions increase, thicker skeletons are
▪ Circulatory effects required to maintain adequate support
▪ Anabolism and catabolism → As bodies increase in size, the muscles required for
▪ Basal metabolism and the TNZ locomotion must represent an ever larger fraction of the
▪ Control of metabolism in endotherms total body mass.
Exchange with the Environment
• Animals must exchange nutrients, waste products, and gases with their environment, and this requirement
imposes an additional limitation on body plans.
• Exchange occurs as substances dissolved in an aqueous solution move across the plasma membrane of
each cell
• A single-celled organism has a sufficient membrane surface area in contact with its environment to carry
out all necessary exchange.
• An animal is composed of many cells, each with its own plasma membrane across which exchange must
occur.
• The rate of exchange is proportional to the membrane surface area involved in exchange, whereas the
amount of material that must be exchanged is proportional to the body volume
• A multicellular organization therefore works only if every cell has access to a suitable aqueous
environment, either inside or outside the animal’s body.
• Many animals with a simple internal organization have body plans that enable direct exchange between
almost all their cells and the external environment
• Our bodies and those of most other animals are composed of compact masses of cells, with an internal
organization much more complex
• Increasing the number of cells decreases the ratio of outer surface area to total volume
• The evolutionary adaptations that enable sufficient exchange with the environment are specialized surfaces
that are extensively branched or folded.
• In almost all cases, these exchange surfaces lie within the body, an arrangement that protects their delicate
tissues from abrasion or dehydration and allows for streamlined body contours.
• The branching or folding greatly increases surface area
• Internal body fluids link exchange surfaces to body cells. The spaces between cells are filled with fluid ~
interstitial fluid
• An animal can maintain a relatively stable internal environment despite
the fact that it is living in a changeable external environment
• complex body plans have distinct benefits: an external skeleton can protect
against predators, and sensory organs can provide detailed information on the
animal’s surroundings. Internal digestive organs can break down food gradually,
TJW NOTES
controlling the release of stored energy & specialized filtration systems can
adjust the composition of the internal fluid that bathes the animal’s body cells
, Metabolism Temperature
• Metabolism is defined as the sum total of all → Temperature has a profound effect on organisms
chemical reactions in body. and their metabolic processes.
• Divided broadly into two pathways: → Birds and mammals can be active over a wide
▫ Catabolism: break down complex molecules range of environmental temperatures (Te), but
with the release of energy only a narrow range of body temperatures (Tb).
▫ Anabolism: construction of complex molecules → Most other animals are active over a narrower
with input of energy range of Te, but can tolerate a wider range of Tb.
→ Some species can live in an inactive state outside
Physiological effects of Tb change of these temperatures.
→ Increase in Tb usually increases rates of → Adaptation to low Tbs is common, but rare for
physiological processes. high Tbs.
→ Change in rates due to temperature are described → Range of Tolerance:
by a coefficient called the Q10. • Range in Tb for active animal life from about -
→ In general, a 10 °C change causes a rise in the 2 °C to 80 °C.
rate of most processes 2 to 3 times. • Pompei worm can tolerate parts of its body
→ If the rate doubles, the Q10 is 2. being at 80 °C.
10/ T1 −T2 • Polar fish live permanently at Tbs of -2 °C.
R1 • Most organisms are generally limited to
Q10 =
R2 between 3 °C and 40 °C.
• Birds and mammals are active over a very
narrow range in Tb; ~3 °C
Tolerance to low Temperatures
→ The biggest problem with low Tb is cell damage
from freezing.
→ Some animals can tolerate freezing, but most are
‘freeze susceptible’.
→ There are two ways of dealing with freezing Tes:
1. Tolerance – adaptations to allow body to
freeze
2. Avoidance – adaptations to lower freezing
point or use behaviour to avoid.
1. Freeze Tolerance 2. Freeze avoidance
→ Few animals are freeze-tolerant because: → The body fluids of some cold-climate ectotherms
1. freezing causes mechanical cell damage contain antifreeze
2. freezing causes some organs to shut down → substances which lower the freezing point.
before others → Polar fish only freeze below -6 °C. They live
→ Freeze-tolerant animals prevent cell damage and permanently at -2 °C.
organs are frozen in a sequence (not such → Some insects contain glycerol which increases in
problem with small animals). concentration during winter. This acts as an
→ Wood frog tolerates freezing and can survive Tb antifreeze allowing Tb to go far below 0 °C
of -16 °C. without freezing.
→ In some species of beetles, only extracellular fluids
freeze.
TJW NOTES
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