32-BodyTemp

Question 1

homeothermic

Answer 1

organism that regulates body temperature internally (eg humans)

Question 2

poikilothermic

Answer 2

organism that regulates body temperature externally (eg reptiles)

Question 3

primary source of heat loss

Answer 3

skin

Question 4

secondary source of heat loss

Answer 4

lungs

Question 5

primary source of heat production

Answer 5

cellular metabolism

Question 6

sympathatic vasomotor response to decrease in environmental temperature

Answer 6

NE -> alpha adrenergic R -> vasoconstriction of cutaneous arterioles

Question 7

sympathatic vasomotor response to increase in environmental temperature

Answer 7

ACH ->
-> vasodilation of cutaneous arterioles
VIP ->

Question 8

VIP

Answer 8

vasoactive intestinal peptide

Question 9

sympathetic effector of sweating

Answer 9

ACH -> incr sweat production

Question 10

endocrine effector of cellular metabolism

Answer 10

thyroid hormone -> incr cellular metabolism -> incr heat production

Question 11

neural effector of shivering-induced thermogenesis

Answer 11

ACH (not sympathetic) -> asynchronous skeletal muscle contraction (both extensors and flexors)

Question 12

neural effector of BAT thermogenesis

Answer 12

postganglionic sympathetic: NE -> beta-3 adrenergic R -> incr in UCP

Question 13

endrocrine effector of BAT thermogenesis

Answer 13

thyroid hormone

Question 14

UCP

Answer 14

uncoupling protein

uncouples glucose oxidation from ATP production, produces heat instead

Question 15

fiber type of cold receptors

Answer 15

A-delta

Question 16

fiber type of warm receptors

Answer 16

C

Question 17

cold transient receptor potential (TRP) channel in periphery

Answer 17

TRPM8 - DRG and trigeminal, menthol, <27 deg C

Question 18

heat transient receptor potential (TRP) channel in periphery

Answer 18

TRPV3 - keratinocytes, DRG (low), brain and tongue, 33-40 deg C

Question 19

Peripheral pathway of pain and temperature

Answer 19

spinothalamic tract

Question 20

Peripheral pathway for thermoregulation

Answer 20

spino-parabrachial pathway

Question 21

Site of thermoregulation control in hypothalamus

Answer 21

Anterior hypothalamus/preoptic area

Question 22

heat transient receptor potential (TRP) channel in hypothalamus

Answer 22

TRPV4 - found in OVLT and medial preoptic; responds to 25-35 deg C, osmolality

Question 23

Fever produced by

Answer 23

endogoneous pyrogens, released by macrophages in response to bacterial or viral particles

Question 24

endogenous pyrogens - examples

Answer 24

cytokines: interleukin-1,-6, and tumor necrosis factor alpha

Question 25

Endogenous pyrogens act on

Answer 25

neurons in anterior hypothalamus / preoptic area

Question 26

Mechanism of action of pyrogens

Answer 26

act on cytokine receptors in AH/POA -> incr. induction of COX-2 -> incr. formation of prostaglandins (esp. PGE_2)

Question 27

COX-2

Answer 27

cyclooxygenase-2, induced by pyrogens acting on cytokine receptors, leads to prostaglandin formation

Question 28

Mechanism of NSAIDs in reducing fever

Answer 28

NSAIDs = non-steroidal anti-inflammatory drugs | Block COX-2 activity -> decr. PGE_2

Question 29

Cytokines cross blood brain barrier via

Answer 29

circumventricular organs: - median eminence - area postrema - pineal - subfornical organ * -* organum vasculosum of the lamina terminals (OVLT) - located near POA of hypothalamus

Question 30

OVLT

Answer 30

organum vosculosum of the lamina terminals (OVLT) - site of BBB crossing of cytokines

Question 31

Site of action of PGE in POA

Answer 31

temperature-insensitive (I) neurons and warm (W) neurons

Question 32

Role of DMH in thermoregulation

Answer 32

``` DMH=dorsal medial hypothalamus Receives inhibitory (GABAergic) projections from warm neurons in AH/POA Sends excitatory (glutaminergic) projections to sympathetic premotor neurons in raphe nucleus ```

Question 33

Role of raphe pallidus in thermoregulation

Answer 33

Raphe pallidus neurons in medulla Receive direct inhibitory (GABAergic) input from warm neurons in AH/POA Send excitatory project to IML of spinal cord -> activate sympathetic vasomotor response