Thermoregulation

Question 1

endotherms

Answer 1

generate own body heat

Question 2

homeotherms

Answer 2

able to maintain core body temperature within narrow range despite large fluctuations in the environment

Question 3

core body temperature

Answer 3

37 Celsius. varies with time of day, stage of menstrual cycle, level of activity, age.

Question 4

radiation

Answer 4

transfers heat as electromagnetic waves between objects that are not in contact

Question 5

conduction

Answer 5

intermolecular thermal transfer between solid objects in direct contact

Question 6

convection

Answer 6

loss or gain of heat by movement of air or water over the body

Question 7

evaporation

Answer 7

of water from skin and respiratory tract can carry large amounts of heat generated by the body

Question 8

where is most body heat generated?

Answer 8

deep organs (liver, brain, heart, active skeletal muscles) by cellular metabolism

Question 9

rate of heat production

Answer 9

similar to metabolic rate

Question 10

sympathetic nervous system (SNS) supplying the skin vasculature

Answer 10

inhibited (less vasoconstriction = vasodilation + active vasodilation) when body temp rises and activated (more vasocontriction) when body temp falls

Question 11

acclimatization to hot weather

Answer 11

involves a change in the sweat glands to increase sweating capacity (up to 2-3L/hr, 1 to 6 weeks)

decrease in loss of NaCl in the sweat to conserve body salt, result of aldosterone secretion from adrenal cortex

Question 12

congenital anhidrosis

Answer 12

genetic inability to secrete sweat

Question 13

acetycholine secreting sympathetic nerve

Answer 13

innervates sweat glands. a primary protein free secretion is formed by the glandular portion but most of the electrolytes are reabsorbed in the duct, leaving a dilute, watery secretion.

Question 14

increased body temperature

Answer 14

engages skin vasodilation, sweating, and decreased heat production to reduce body heat

Question 15

decreased body temperature

Answer 15

engages skin vasoconstriction, piloerection, and thermogenesis/heat production (shivering, etc).

in infants there is sympathetic/chemical excitation involving epinephrine and norepinephrine.

Question 16

lethal hypothermia

Answer 16

caused by immersion in cold water for an extended period

Question 17

hypothalamic integrating center

Answer 17

specific neurons in brain, compare to set point, alter rates of firing

Question 18

exercise induced hyerthermia

Answer 18

due to initial imbalance between rates of heat production and dissipation.

Question 19

fever

Answer 19

is an increase in temp set point and core temp and is usually due to a pathological process such as infection.

mechanisms for raising body temp are engaged