Lecture 2: Homeostatis and Temperature Regulation

Question 1

variables that change to keep the regulated variables relatively constant

Answer 1

adjustable variables

Question 2

pathway towards integrating center

Answer 2

afferent

Question 3

pathway away from integrating center

Answer 3

efferent

Question 4

something that makes changes in adjustable variables

Answer 4

effector

Question 5

when inputs and outputs are balanced

Answer 5

steady state

Question 6

What happens during the rising phase of a fever?

Answer 6

• set point is increased to facilitate recovery
• patient becomes “hypothermic”
• vasoconstriction and shivering
• temperature rises to meet new set point

Question 7

What happens during a fever when patient reaches new set point?

Answer 7

patient is “normothermic” even though they are febrile

Question 8

What happens during the falling phase of a fever?

Answer 8

• patient’s set point decreases back to normal
• patient is now “hyperthermic”
• vasodilation and sweating
• patient temperature returns to normal

Question 9

What can interfere with maintenance of temperature?

Answer 9

• damage to the hypothalamus (integrating center)
• certain drugs interfere with body temp effectors
• conflicting regulatory systems

Question 10

What happens during heat exhaustion?

Answer 10

• high temperature leads to sweating, vasodilation, and water loss
• BP drops
• BP has a higher priority
• less sweat is produced and body temp rises
• can lead to fatigue, fainting, and weakness

Question 11

heat exhaustion resulting from sweating without replacing lost salt (water is replaced though)

Answer 11

salt depletion

Question 12

heat exhaustion resulting from loss of water; results in low BP and great temp elevation

Answer 12

water depletion

Question 13

heat exhaustion resulting from drinking too much water and not replacing lost sodium

Answer 13

dilutional hyponaturemia

Question 14

What happens during acclimatization to high temperatures?

Answer 14

• CV systems becomes more efficient – blood shunted to skin w/o jeopardizing brain supply
• fat loss and muscle gain - body moves more efficiently while creating less heat
• heat loss mechanisms kick in more rapidly (earlier and more sweating)

Question 15

What happens during heat stroke?

Answer 15

• thermoregulatory systems are overtaxed

- distinguished from heat exhaustion by presence of neurological symptoms and a temp of +40 degrees C

Question 16

heat stroke due to high environmental temperature in people who are more vulnerable (children and elderly)

Answer 16

classic heat stroke

Question 17

heat stroke usually resulting from strenuous exercise in hot environments; more severe

Answer 17

exertional heat stroke

Question 18

What happens during a heat stroke?

Answer 18

• heat exhaustion leads to dehydration and high body temperature
• blood is shunted away from GI tract for extended period of time
• inflammatory response is triggered due to GI tissue damage and increased permeability (bacteria get into bloodstream)
• septic shock
• leads to systemic inflammatory response syndrome (SIRS)
• immune response triggers release of cytokines and tissue factor
• increases clotting which interferes with organ function
• multi-organ failure

Question 19

part of the coagulation pathway; leads to disseminated intravascular coagulation (DIC)

Answer 19

tissue factor

Question 20

What role do heat shock proteins have in heat strokes?

Answer 20

• produced in response to hyperthermia
• act as chaperones to protect cells from injury
• trigger release of anti-inflammatory cytokines

Question 21

How do you treat heat stroke?

Answer 21

• reduce body temp FAST

- provide support for affected organ systems and management of complications

Question 22

variables that are kept the same in face of changing conditions

Answer 22

regulated variables