Chapter 13 Study Questions Flashcards
A homeostatic system involves regulation of the , , or systems.
TEMPERATURE; WATER BALANCE; FOOD INTAKE
A modern classification of animals reflects the source from which they derive warmth. actively generate warmth internally in order to regulate their body temperature, whereas gain their heat from the environment. Animals in both classes actively regulate their temperature, but do so through metabolism, whereas do so behaviorally (such as by sitting on a hot rock).
endotherms; ectotherms; ENDOTHERMS; ECTOTHERMS
One advantage of endothermy is greater from environmental conditions. By producing a constant internal temperature, endothermy allows an animal to forage in a wider variety of environments. Also, in order to produce the chemical reactions necessary to produce heat, endothermy has allowed animals a capacity for utilization. Ectotherms are typically capable of only bursts of high-intensity activity.
INDEPENDENCE; GREATER; OXYGEN; short
The top level of control in a negative feedback control system is a comparator. In the case of body temperature regulation, this works like a : it contains a reference value, or “set ,” and it compares the present temperature of the body to the desired temperature. The system operates by means of feedback from the body—that is, when the desired temperature is reached, feedback information acts to shut the system off, and it remains off until the temperature deviates from the desired level. In mammals, this optimal level is usually in the range of °C.
THERMOSTAT; POINT; negative; “36 to 38”
Mammals can increase heat generation in response to a drop in body temperature in two ways, one involving a specialized type of tissue, and the other involving a specialized type of behavior. In the first case, the nervous system signals fat, which is full of , to metabolize molecules to produce heat. In the second case, the nervous system activates muscle fibers to cause heat-producing .
SYMPATHETIC; BROWN; MITOCHONDRIA; SHIVERS
Birds incubate eggs by keeping them in contact with a special, highly area of the skin known as the . A rat mother’s own thermoregulation compensates for the needs of her pups, which are born without and cannot regulate their own body temperatures until they are old enough to stray from the nest.
VASCULARIZED; brood patch; fur
Early experiments with local heating and cooling (via implanted wires) implicated a particular brain structure, the , in the control of temperature. Subsequent work demonstrated that neurons located in subregions of this structure, namely the area and the , change their rate of firing depending on body temperature, suggesting that this is the location of the “thermostat.”
hypothalamus; PREOPTIC; ANTERIOR HYPOTHALAMUS
Recent lesion experiments have suggested that in mammals, different brain sites are responsible for two main kinds of thermoregulation. thermoregulation (e.g., locomotion) is abolished by lesions of the , whereas (e.g., autonomic) thermoregulation is abolished by lesions of the
BEHAVIORAL; LATERAL HYPOTHALAMUS; PHYSIOLOGICAL; PREOPTIC AREA
Some basic cellular processes common to all animals evolved first in marine organisms and have persisted in that form up to the present day. These include expression and . A more watertight body has not evolved because we need to surrender water on occasion for purposes of elimination. We also use up and must actively replenish water and
GENE; METABOLISM; WASTE; SALT
The two main fluid compartments of the body are the intracellular compartment and the compartment. Fluid of the intracellular compartment is located (not surprisingly) within . Fluid of the compartment is located in two places: the fluid (the fluid that surrounds and bathes the cells of the body) and the blood .
extracellular; CELLS; extracellular; interstitial; plasma
- Semipermeable membrane—
- Physiological saline—
- Water—
- Concentration gradient—
- Salt—
- Saltier than body fluid—
- Passive movement of molecules from one location to another—
- Less salty than body fluid—
- cell membrane
- ISOTONIC
- solvent
- OSMOTIC PRESSURE
- solute
- hypertonic
- OSMOSIS
- hypotonic
A cell that comes into contact with a hypotonic solution has a higher concentration of molecules on its inside and a higher concentration of molecules on the outside. Because the cell membrane is , but not ions move into the cell faster than they leave, causing the cell to swell and eventually rupture
Na+; water; SEMIPERMEABLE; water; NA+
The extracellular fluid acts as a in the sense that it both provides and water, allowing the cell to maintain the correct internal concentration for the operation of cellular mechanisms.
RESERVOIR; accepts
Hypovolemic thirst can be triggered by , vomiting, or diarrhea. The word “hypovolemic” is a clue to the property of the external fluid that is monitored by the brain in this kind of thirst, namely blood . Since both solvent and are lost, the overall concentration of the fluid does not change.
HEMORRHAGE; VOLUME; solute; EXTRACELLULAR
Hypovolemia is detected by located in the heart and major blood vessels, and the brain responds by triggering both thirst and hunger. This extra is required to prevent the extracellular fluid from becoming .
BARORECEPTORS; salt; salt; HYPOTONIC
In addition to triggering the behavioral reactions to hypovolemia, the nervous system also mediates two physiological responses, one of which is vascular and one of which is hormonal. The nervous system mediates a constriction of the walls of blood vessels, which raises blood to compensate for the lost volume. The brain also mediates the release of the hormone , which further causes vessels to constrict and also instructs the to reduce the release of water into the urine.
SYMPATHETIC; pressure; VASOPRESSIN; KIDNEYS
Angiotensin II affects brain function by triggering the release of and also directly causes blood vessels to . It enters the brain via the “leaky” portion of the blood–brain barrier, where it binds to receptors within the and the organs and leads to pronounced thirst.
vasopressin; constrict; CIRCUMVENTRICULAR; SUBFORNICAL
