Mar22 M2-Fever

Question 1

normal body temperature range

Answer 1

35.6 to 38.5

Question 2

extremes of temperature at what time of the day + one thing that makes it higher

Answer 2

• lowest at 6 am
• highest at 4-6 pm
• 0.6 degrees higher after ovulation

Question 3

temp measurement methods

Answer 3

• IDEAL = core temperature = RECTAL OR ESOPHAGEAL
• oral = 0.6 lower
• axillary = 1 lower

Question 4

fever is part of what process in inflammation

Answer 4

acute phase response: neutrophilia, change in serum proteins, hormones, intermediary metabolism, sickness behavior, anorexia, lethargy

Question 5

fever definition and max value

Answer 5

increase in core temperature due to a change of the hypothalamic set point. *rarely goes over 41.1

Question 6

hyperpyrexia def

Answer 6

FEVER that is over 41.5

Question 7

hyperthermia def

Answer 7

when the body temperature overrides the hypothalamic set point that is still normal. For ex, may go over 41.5

Question 8

mechanisms we use to increase temp

Answer 8

• vasoconstriction
• thermogenesis in brown fat
• shivering (striated muscle)
• behavioral changes
• piloerection (weak)

Question 9

mechanisms we use to decrease temp

Answer 9

• vasodilation
• evaporation (insensible water loss, sweating)
• behavioral changes

Question 10

causes of fever

Answer 10

• infections
• rheumatic diseases (autoimmune for ex)
• autoinflammatory diseases
• immune reactions (to transfusion or drug)
• malignancies
• tissue damage (trauma, MI, etc.)

Question 11

steps before ‘‘end cytokines of fever’’ are released

Answer 11

1. macrophages see PAMPs wth their TLRs specific to LPS and other stuff.
2. cascade of IC events leading to NF kappa beta translocating in nucleus: stim release of pro inflam cytokines

Question 12

consequence of NF kappa beta activation

Answer 12

secretion of IL-1, TNF-a and possibly IFN-a and IFN-gamma

Question 13

consequence of the secretion of IL-1, TNF-a and possible IFN-a and IFN-gamma

Answer 13

secretion of IL-6 end cytokine

Question 14

3 main cytokines found in circulation during fever

Answer 14

• TNF, IL-1 in nanogram qts

- IL-6 (FINAL CYTOKINE)** (microgram qts)

Question 15

effect of IL-1, TNF-a and IL-6 act where (for fever) and do what

Answer 15

-anterior hypothalamus
-stim increase in PGs, PGE2**
(hypoth center ablation or PGE2 knockout or ASA, NSAIDs (blocks PG) = no febrile resp)

Question 16

probable cause of peripheral symptoms that accompany fever (muscle aches, malaise, etc.)

Answer 16

PGE2 produced peripherally

Question 17

probable site of PGE2 production in the brain

Answer 17

vascular endothelium

Question 18

protein translocated in vascular endothelium cells nucleus as a response to IL-6

Answer 18

STAT3

Question 19

name of brain regions activated in fever that are highly vascularized, fenestrated endoth, activated by injection of LPS and that have microglia with TLRs that can resp to LPS directly

Answer 19

circumventricular organs (brain). (*main thing is highly vascular + fenestrated endoth, unlike rest of brain with BBB)

Question 20

consequence of PGE2 injection in mouse ventricle or anterior hypothalamus

Answer 20

fever in minutes

Question 21

COX-2 knockout mice consequence

Answer 21

• NO fever when infection

- still regulate temperature normally

Question 22

alternate pathways leading to fever (causing fever before high cytokines in the blood)

Answer 22

PG produced peripherally lead to vagal stim of hypothalamus

Question 23

how conserve heat in fever

Answer 23

• less blood to extremities (feel cold bc of that)
• shivering
• thermogenesis in brown fat

Question 24

how lose heat in fever

Answer 24

• more blood to skin
• more water loss (skin and lungs)
• behavioral changes

Question 25

what’s used to raise temp in experimental animals + causes cold-blooded animals to seek hot environment if injected to them

Answer 25

LPS

Question 26

advantages of fever

Answer 26

• some bacteria grow more slowly
• less availability of Fe to bacteria
• PMNs fight bacteria better
• activated dendritic cells reach regional lymph node more rapidly
• sickness behavior limits spread of infection

Question 27

bad things in fever: increases what

Answer 27

• *increases O2 requirement** so get more
• CO2 prod
• water loss
• cerebral injury
• discomfort
• seizure activity

Question 28

people with weakest immune system

Answer 28

newborns and elderly, immunosuppressed

Question 29

82 year old with a stroke: possible cause of fever in this individual

Answer 29

primary CNS damage due to hypoxia, ischemia, reperfusion, blood in brain, compression or damage to hypothalamus (pathogenesis poorly understood)

Question 30

consequences of fever in someone with brain injury

Answer 30

exacerbates injury

• more toxic ntr release
• higher O2 free radical production
• disrupts BBB
• increased zone of injury

Question 31

recurrent fevers in a child probable cause and treatment

Answer 31

periodic fever syndromes. treat with IL-1 blockers.

Question 32

military recruit with temp over 42 after running a lot dx

Answer 32

heat stroke. (over 42, irreversible damage to liver, brain, vascular endothelium)
*nothing wrong with his hypothalamic control
(HYPERTHERMIA)

Question 33

when is there a real necessity to treat fever and what about the rest

Answer 33

• temp over 42 (becomes dangerous), or see it going towards such a high temp
• below that, it just causes anxiety for nothing

Question 34

why is it thought that fever causes discomfort?

Answer 34

• hard to know if fever or the disease causes discomfort so think it’s fever
• some antipyretics are good analgesics too so discomfort relief associated with drop in temp