Lecture 2: Homeostatis and Temperature Regulation Flashcards
variables that change to keep the regulated variables relatively constant
adjustable variables
pathway towards integrating center
afferent
pathway away from integrating center
efferent
something that makes changes in adjustable variables
effector
when inputs and outputs are balanced
steady state
What happens during the rising phase of a fever?
- set point is increased to facilitate recovery
- patient becomes “hypothermic”
- vasoconstriction and shivering
- temperature rises to meet new set point
What happens during a fever when patient reaches new set point?
patient is “normothermic” even though they are febrile
What happens during the falling phase of a fever?
- patient’s set point decreases back to normal
- patient is now “hyperthermic”
- vasodilation and sweating
- patient temperature returns to normal
What can interfere with maintenance of temperature?
- damage to the hypothalamus (integrating center)
- certain drugs interfere with body temp effectors
- conflicting regulatory systems
What happens during heat exhaustion?
- 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
heat exhaustion resulting from sweating without replacing lost salt (water is replaced though)
salt depletion
heat exhaustion resulting from loss of water; results in low BP and great temp elevation
water depletion
heat exhaustion resulting from drinking too much water and not replacing lost sodium
dilutional hyponaturemia
What happens during acclimatization to high temperatures?
- 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)
What happens during heat stroke?
- thermoregulatory systems are overtaxed
- distinguished from heat exhaustion by presence of neurological symptoms and a temp of +40 degrees C
heat stroke due to high environmental temperature in people who are more vulnerable (children and elderly)
classic heat stroke
heat stroke usually resulting from strenuous exercise in hot environments; more severe
exertional heat stroke
What happens during a heat stroke?
- 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
part of the coagulation pathway; leads to disseminated intravascular coagulation (DIC)
tissue factor
What role do heat shock proteins have in heat strokes?
- produced in response to hyperthermia
- act as chaperones to protect cells from injury
- trigger release of anti-inflammatory cytokines
How do you treat heat stroke?
- reduce body temp FAST
- provide support for affected organ systems and management of complications
variables that are kept the same in face of changing conditions
regulated variables
