Chapter Forty
Explain the difference between animals that are regulators and those that are conformers.
(for a particular environmental factor) regulator: uses internal control mechanisms to regulate internal change in the face of external fluctuation conformer: allows internal condition to conform to external changes of that variable.
Animals need to exchange materials with their environment. This process occurs as substances dissolved in an aqueous medium move across the plasma membrane of each cell. For each of the following organisms, explain how this is possible:
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What is the relationship between BMR and body mass?
Basal metabolic rate is the amount of energy needed to keep all of your cells just barely alive. If you have more body mass, you have more cells, and you need more energy to keep them alive. Therefore the higher Body mass you have, the higher BMR you have usually. metabolic rate=mass^(3/4)
There are four types of tissues. For each, give examples, the general function, and where you would find each type.
Epithelial Connective Muscle Nervous
Connective: examples, function, location
Function: binds and supports other tissues in the body. consists of sparse population of cells scattered through an extracellular matrix. Examples: cartilage adipose blood bone fibrous connective loose connective
Epithelial: examples, function, location
Function: covers the outside of the body and lines organs and cavities within body. Barrier against mechanical injury, pathogens and fluid loss. also exchange w/ environment Examples: cuboidal simple columnar simple squamous stratified squamous
Muscle: examples, function, location
Function: nearly all body movement. Examples: skeletal smooth cardiac
Nervous: examples, function, location
Function: sense stimuli and transmit signals in the form of nerve impulses from one part of the animal to another Examples: neurons glial cells
Heat loss in extremities is reduced by countercurrent exchange. How does countercurrent exchange work?
In many birds and mammals, reduction of heat loss relies on countercurrent exchange, the flow of adjacent fluids in opposite directions that maximizes transfer rates of heat or solutes. IE antiparallel arrangement of blood vessels
What is meant by a set point?
Maintaining homeostasis of a variable at or near one particular value. (ie temp) usually a normal range
What are the four processes by which heat is exchanged with the environment?
Radiation: emission of electromagnetic waves by all objects warmer than absolute zero. (absorbing heat from sun) Evaporation: removal of heat from the surface of a liquid that losses some of heat to molecules as gas. Convection: transfer of heat by the movement of air or liquid past a surface (breeze, blood) Conduction: direct transfer of thermal heat between objects in direct contact with each other. (sitting on a hot rock)
adipose tissue and thermoregulation
body fat. insulation. important with marine mammals.
The example in the text is related to temperature regulation. Would ectotherms be regulators or conformers?
conformers
Describe the difference between endothermy and ectothermy, and give an animal that exhibits each.
endothermy: warmed mostly by heat generated from metabolism (mammals and birds) ectothermy: gain most of their heat from external sources (amphibians, lizards, snakes, turtles, many fish and most invertebrates)
panting/sweating and thermoregulation
evaporation cools. heat is carried away from body with water vapor.
Describe an example of a negative feedback loop. Clearly identify the set point, the stimulus, and the response.
excersize--get hot--sweat--cool off
how whales exchange materials with their environment.
extensively branched and folded surfaces inside body allow for sufficient exchange with environment
What is a tissue?
groups of cells of similar appearance and a common function. can be organized into organs.
If a mouse and a small lizard of the same mass (both at rest) were placed in experimental chambers under identical environmental conditions, which animal would consume oxygen at a higher rate? Explain.
lizard?
vasodilation/vasoconstriction and thermoregulation
many animals alter amount of blood (and heat) flowing between body core and skin in response to changes in temp. vasodilitation: increase in diameter of superficial blood vessels (blood flow increases, warms skin) vasoconstriction: reduces blood flow and heat transfer by decreasing diameter of superficial blood vessels.
What is the metabolic rate? In what units is it usually measured?
metabolic rate: the amount of energy an animal uses in a unit of time; the sum of all energy-requiring biochemical reactions over a given time interval. mesured in joules or calories/kilocalories.
how hydra exchange materials with their environment.
multicell sac-like body plan, direct exchange with environment. body wall is only two cell layers thick.
We sometimes say that in negative feedback "more gets you less," and in positive feedback "more gets you more." Describe an example of a positive feedback loop.
pressure of a baby's head on on receptors at opening of uterus stimulates uterus to contract. contractions result in greater pressure against uterus opening, heightening contractions until baby is born.
fur/feathers and thermoregulation
provide insulation to reduce flow of heat between animal and environment. react to cold by raising fur or feathers, increasing insulation.
burrowing/sunning and thermoregulation
seek warm places. Conduction (ectotherms): direct transfer of thermal heat between objects in direct contact with each other. (sitting on a hot rock) Radiation: emission of electromagnetic waves by all objects warmer than absolute zero. (absorbing heat from sun)
how amoeba exchange materials with their environment.
single-celled has sufficient membrane surface area in contact with environment for all necessary exchanges
What is interstitial fluid?
spaces between cells are filled with this fluid. exchange between this and circulatory fluid (blood) allows cells to get nutrients and get rid of waste
What is basal metabolic rate (BMR)?
the minimum metabolic rate of a nongrowing endotherm that is at rest, has an empty stomach, and is not under stress vs standard metabolic rate: metabolic rate of a fasting, non-stressed ectotherm at rest at a particular temp
What is thermoregulation?
the process by which animals maintain an internal temperature within a tolerable range.
What is the role of the hypothalamus in temperature regulation?
the sensors that control thermoregulation are concentrated in the hypothalamus, a region of the brain near the ears. Contains group of nerve cells that function as a thermostat, responding to body temperatures outside of normal range.
how tapeworm exchange materials with their environment.
thin, flat body shape. most cells have direct contact with environment
What are the evolutionary advantages of torpor and hibernation?
torpor: physiological state in which activity is low and metabolism decreases. enables animals to save energy while avoiding difficult and dangerous conditions hibernation: long-term torpor. adaptation to winter cold and food scarcity. body temperature decreases
goose bumps and thermoregulation
vestige of hair raising inherited from furry ancestors.
