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Medical Physiology
The Regulation of Body Temperature
98
Health Care
Graduate
07/21/2007

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Term
Humans are _______ or warm-blooded animals.
Definition
Homeotherms
Term
Humans regulate their internal body temperatures within a narrow range near _______, in spite of wide variations in environmental temperature.
Definition
37 Degrees Celcius
Term
The body is divided into a _______ internal core and a _______ outer shell.
Definition
Warm; Cooler
Term
Heat is produced in _______ tissues of the body, but is lost to the environment only from tissues _______ with the environment.
Definition
ALL; In Contact
Term
Heat is lost from the body predominantly from _______, and to a lesser degree from _______.
Definition
The skin; The Respiratory Tract
Term
Heat flow by _______ varies directly with the thermal conductivity of the tissues.
Definition
Conduction
Term
Heat flow by _______ depends on the rate of blood flow and the temperature different between the _______ and the _______.
Definition
Convection; Tissue; Blood supplying the tissue
Term
Core temperature varies slightly fro one site to another depending on such local factors as _______, _______ and _______.
Definition
Metabolic rate; Blood supply; The temperatures of neighbouring tissues
Term
The effects of heavy exercise and fever are familiar, variation among individuals and such factors as _______, _______ and _______ to heat can also cause differences of up to 1 degree celcius in core temperature at rest.
Definition
Time of day; Phase of the menstrual cycle; Acclimatization
Term
The _______ is well insulated from the environment, its temperature is independent of environmental temperature.
Definition
Rectum
Term
The tongue is richly supplied with blood, oral temperature under the tongue is usually _______.
Definition
Close to blood temperature
Term
Cooling the _______, _______ or _______ can make oral temperature misleadingly low.
Definition
Face; Neck; Mouth
Term
Most heat is exchanged between the body and the environment at _______.
Definition
The skin surface
Term
Skin temperature is ________ than core temperature.
Definition
Much more variable
Term
Skin temperature is affected by thermoregulatory responses such as _______ and _______, _______ and environmental factors such as _______, _______ and _______.
Definition
Skin blood flow; Sweat secretion; The temperatures of underlying tissues; Air temperature; Air movement; Thermal radiation
Term
_______ is one of the majour factors determining heat exchange with the environment.
Definition
Skin Temperature
Term
The Calorie (capital C) used in physiology and nutrition is the quantity of heat that will raise the temperature of _______ of pure water by _______
Definition
1 kg; 1 degree Celcius
Term
Heat is a _______ of Energy-requiring Metabolic processes
Definition
By-Product
Term
About 70% of energy production at rest occurs in the body _______, (_______, and _______) even though they comprise only about 36% of body mass.
Definition
Core; Trunk viscera; The Brain
Term
As a by-product of their metabolic processes, these organs (Trunk viscera; brain) produce most of the heat needed to maintain _______ at comfortable environmental temperatures.
Definition
Heat Balance
Term
Only in the cold must such by-product heat be supplementeby by heat produced expressly for _______.
Definition
Thermoregulation
Term
Factors other than body size that affect metabolism at rest include _______ and _______ and _______ and _______.
Definition
Age; Sex; Hormones; Digestion
Term
The ratio of metabolic rate to suface area is _______ in infancy and _______ with age.
Definition
Highest; Declines (most rapidly in childhood and adolescence and more slowly thereafter.)
Term
A woman's metabolic rate _______ during pregnancy.
Definition
Increases
Term
The metabolic rate increase in pregnancy is need for _______.
Definition
The growth of the Fetus
Term
The _______ and _______ are the hormones that have the greatest effect on metabolic rate.
Definition
Catecholamines; Thyroxine
Term
_______ cause glycogen breakdown into glucose and stimulate many enzyme systems, _______ cellular metabolism.
Definition
Catecholamines; Increasing
Term
_______ is a clinical feature of some cases of pheochromocytoma, a catecholamine secreting tumor of the adrenal medulla.
Definition
Hypermetabolism
Term
_______ is a catecholamine secreting tumor of the adrenal medulla.
Definition
Pheochromocytoma
Term
_______ magnifies the metabolic response to catecholamines, _______ protein synthesis, and _______ oxidation by the mitochondria.
Definition
Thyroxine; Increases; Stimulates
Term
A resting person's metabolic rate increases 10 to 20% _______
Definition
After a meal
Term
The effect of food raising a person's metabolic rate is called the _______.
Definition
Thermic effect of food.
Term
The thermic effect of food is _______ after eating protein and _______ after carbohydrate and fat.
Definition
Greatest; Less
Term
The thermic effect of food lasts _______ and appears to be associated with _______.
Definition
Several hours; Processing the products of digestion in the liver
Term
Basal Metabolic rate is measured after fasting for _______, _______. beginning after the person has rested quietly for at least _______ and the air temperature must be _______.
Definition
12 Hours; in the morning after a good night's sleep; 30 Minutes; Comfortable
Term
_______ is a method of estimating metabolic rate which is based on measuring a person's rate of oxygen consumption.
Definition
Indirect Calorimetry
Term
Even during mild exercise the _______ are the principal source of metabolic heat, and during intense exercise they may account for up to _______.
Definition
Muscles; 90%
Term
_______ is the transfer of heat resulting from the movement of a fluid, either liquid or gas.
Definition
Convection
Term
_______ is the body's only means of losing heat when the environment is hotter than the skin.
Definition
Evaporation of water
Term
Evaporation must dissipate the heat produce by _______ and any heat gained from the environment by _______ and _______.
Definition
Metabolic processes; Convection; Radiation
Term
Animals exchange heat with their environment through both _______ and the _______, but only the _______ exchanges heat by radiation.
Definition
Skin; Respiratory passages; Skin
Term
The rate of _______ is the difference between heat production and net heat loss.
Definition
Heat Storage
Term
Storage of heat in the tissues changes their _______, and the amount of heat stored is the _______, the body's _______ and a suitable mean body temperature.
Definition
Temperature; Product of body mass; Mean specific heat
Term
The body's mean specific heat depends on its _______, especially the _______.
Definition
Composition; Proportion of Fat
Term
Evaporative heat loss is nearly _______ of ambien temperature below 30 degrees celcius.
Definition
Independent
Term
Heat produced in the body must be delivered to the _______ to be eliminated.
Definition
Skin surface
Term
Heat exchange with other tissues (those which it passes through on the way to the skin) is greates when skin blood flos is _______.
Definition
Low
Term
Blood flow in human skin is under dual _______ control.
Definition
Vasomotor
Term
When a person is _______ raising skin blood flow brings skin temperature nearer to blood temperature and lowering skin blood flow brings skin temperature nearer to ambien temperature.
Definition
Not Sweating
Term
In most of the skin, the vasodilation that occurs during heat exposure depends on _______ that cause the blood vessels to dilate.
Definition
Sympathetic Nerve signals
Term
Active vasodilation (sympathetically induced) occurs in almost all the skin except in so-called acral regions, _______, _______, _______, _______ and _______.
Definition
Hands; Feet; Lips; Ears; Nose
Term
Behavioural thermoregulation is governed by _______ and _______.
Definition
Thermal sensation; Comfort
Term
RAther than operating at only two levels, most physiological control systems produce a graded response according to the _______ in the regulated variable.
Definition
Size of the disturbance
Term
In many instances, changes in the controlled variables are _______ to displacements of the regulated variable from some threshold value.
Definition
Proportional
Term
Changes in controlled variable that are proportional to displacements of the regulated variable from some threshold vaule are called _______.
Definition
Proportional control systems
Term
Temperature receptors in the _______ and _______ transmit information about their temperatures through afferent nerves to the brainstem and especially to the _______.
Definition
Body Core; Skin; Hypothalamus
Term
The _______ is where much of the integration of temperature information occurs.
Definition
Hypothalamus
Term
The sensitivity of the thermoregulatory system to core temperature enables it to adjust _______ and _______ to resist disturbance in core temperature.
Definition
Heat production; Heat Loss
Term
_______ elevates the core temperature at rest.
Definition
Fever
Term
Heat acclimatization _______ the core temperature at rest.
Definition
Decreases
Term
Fever, Heat acclimatization, the circadian rhythm and the menstrual cycle change the core temperature at rest by changing the _______.
Definition
Thermoregulatory set point
Term
During prolonged heat exposure with high sweat output, sweating rates _______ and the response of sweat glands to local _______ drugs is _______.
Definition
Gradually decline; Cholinergic; Reduced
Term
The reduction of sweat gland responsiveness is sometimes called _______.
Definition
Sweat Gland Fatigue
Term
Wetting the skin makes the _______ swell, mechanically obstructing the sweat gland ducts and causing a reduction in sweat secretion called _______.
Definition
Stratum Corneum; Hidromeiosis
Term
Intense exercise may _______ heat production within the body 10-fold or more, requiring large increases in _______ and _______ to reestablish the body's heat balance.
Definition
Increase; Skin blood flow; Sweating
Term
Increased heat production during exercise causes an increase in _______, which in turn elicits _______.
Definition
Core temperature; Heat-loss responses
Term
Core temperature continues to rise until _______ has increased enough to match _______ and core temperature and the heat-loss responses reach new _______ levels.
Definition
Heat loss; Heat Production; Steady-state
Term
Prolonged or repeated exposure to stressful environmental conditions elicits significant physiological changes called _______, that reduce the resulting strain.
Definition
Acclimatization
Term
Some degree of heat acclimatization occures either by _______ alone or by _______, which raises _______ and provokes heat-loss responses.
Definition
Heat exposure; Regular strenuous exercise; Core temperature
Term
Most of the improvement in heat tolerance occurs within _______.
Definition
10 Days
Term
Heat Acclimatization includes adjustments in _______, _______ and _______.
Definition
Heart Rate; Temperatures; Sweat Rate
Term
Changes in _______ and _______ balance also occur with Heat acclimatization.
Definition
Fluid; Electrolyte Balance
Term
During the first week of heat acclimatization total body water and especially plasma volume _______.
Definition
Increase
Term
Especially in humid heat, the fraction of sweat secreted on the limbs _______ to make better use of the skin surface for evaporation.
Definition
Increases
Term
With acclimatization the sweat glands become able to _______ sodium, this effect is mediated through _______, which is secreted in response to sodium depletion and to exercise and heat exposure.
Definition
Conserve; Aldosterone
Term
Constriction of cutaneous arterioles reduces _______ and Shell _______. Constriction of superficial limb veins further improves heat conservation by diverting venous blood to the _______.
Definition
Skin Blood flow; Conductance; Deep Limb veins
Term
There are a few reports of increased ______ and sometimes _______ activity in the winter.
Definition
Basal Metabolic rate; Thyroid
Term
As the skin is cooled below 15 degrees celcius, its blood flow begins to increase somewhat, as response called _______.
Definition
Cold-induced vasodilation (CIVD)
Term
After repeated cold exposure, CIVD begins earlier during clod exposure, produces higher levels of blood flow, and takes on a rhythmic pattern of alternating vasodilation and vasoconstriction called the _______.
Definition
Lewis Hunting response
Term
_______ are substances that cause fecer and may be either exogenous or endogenous.
Definition
Pyrogens
Term
Exogenous pyrogens stimulate a variety of cells, especially _______ and _______ to release endogenous pyrogens, polypeptides that cause the thermoreceptors in the hypothalamus.
Definition
Monocytes; Macrophages
Term
The effect of endogenous pyrogens is mediated by the local synthesis and release of _______.
Definition
Prostaglandin E2
Term
Aspirin and other drugs that inhibit the synthesis of _______ also reduce fever.
Definition
Prostaglandins
Term
Many of the body's defenses against infection and cancer are elicited by a grop of polypeptides called _______.
Definition
Cytokines
Term
The group of endogenous pyrogens _______ commonly elicit the body's response agains infection and cancer.
Definition
Interleukin-1
Term
_______ is circulatory failure resulting from a pooling of blood in the peripheral veins, with a consequent decrease in venous return and diastolic filling of the heart, resulting in decreased cardiac output and a fall of arterial pressure.
Definition
Heat Syncope
Term
Heat syncope affects mostly those who are _______, presumably because the plasma-volume expansion that accompanies acclimatization compensates for the peripheral pooling of blood.
Definition
Not acclimatized to heat
Term
_______, also called heat collapse, is probably the most common heat disorder.
Definition
Heat Exhaustion
Term
Heat exhaustion represents a _______ of cardiovascular homeostasis in a hot environment.
Definition
Failure
Term
In _______ the patient has dilated pupils and usually sweats profusely.
Definition
Heat Exhaustion
Term
The most severe and dangerous of heat disorders, _______, is characterized by high core temperature, neurological disturbances with a loss of consciousness and frequently convulsions.
Definition
Heat Stroke
Term
In the classical form the primary factor is _______ that overwhelms an impaired thermoregulatory system, and most patietns have preexisting chronic disease.
Definition
Environmental heat stress
Term
In _______ heat stroke, the primary factor is high metabolic heat production.
Definition
Exertional
Term
Rhabdomyolysis, hepatic renal injury and disturbances of blood clotting are frequent accompaniments of ________.
Definition
Exertional Heat Stroke
Term
The traditional diagnostic criteria of heat stroke, _______, _______ and rectal temperature above 41.3 degrees celcius are characteristic of the _______ form.
Definition
Coma; Hot dry skin; Classical
Term
In exertional heat stroke patients may have a _______ rectal temperature and often _______.
Definition
Somewhat lower; Sweat Profusely
Term
The _______ is the cornerstone of treatment in heat stroke and it is most effectively accomplished by immersion in cold water.
Definition
Rapid lowering of core temperature
Term
_______ is a rare process triggered by deplarizing neuromuscular blocking agents or certain inhalational anesthetics.
Definition
Malignant Hyperthermia
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