Pathopyhsiology of fever
concept of homeostatic control loops using temperature regulation
Homeostasis = a physiological process in which internal body systems are maintained at equilibrium despite differing external conditions
3 components for control
control centre (our brain) to define our equilibrium e.g. a core temperature of 36 - 38 degrees celsius
An effector - to bring about a change that will maintain our equilibrium
A receptor or sensor - detects/responds to external change
Temperature regulation is a negative feedback loop i.e. changes are counteracted and returned to the set level
Controlled by the thermoregulatory centre (in Hypothalamus)
hypothalamus thermoreceptors measure blood temperature as it passes through the hypothalamus - Core temperature
Skin thermoreceptors (specialised nerve cells) monitor the temperature of the external environment and send impulses - external temperature
2 types of receptors in the pre-optic area of the anterior hypothalamus
One stimulated in colder external environments
One stimulated in warmer external environments
----------- = hairs on the body erect = insulating layer (trap heat)
Vasoconstriction = reduced blood flow to the skin = reduced heat loss through radiation
Hypothalamus releases t------ r------- h------
Shivering = generates metabolic heat
acts on anterior pituitary gland causing it to release thyroid stimulating hormone
TSH binds to the thyroid to produce thyroxin
Thyroxin increases the rate of cellular metabolism = more heat generated
Increased sweating = increased rate of evaporation of water from the skin (absorbs heat from the skin to enable it to evaporate)
decreased metabolic rate = less heat produced
------------ = blood vessels closer to the skin = increased heat loss via radiation
caused by micro-organisms secreting substances into the blood (endogenic/exogenic pyrogens)
inflammatory response releases --------- in the body to combat viral or bacterial infections
---------- stimulate the release of prostaglandins from the thermoregulatory region in the hypothalamus (They also cause a decrease in appetite )
Prostaglandins increase the set temperature point in our hypothalamus = inducing a fever
Purpose
causes our metabolic rate to be increased
kill of the bacteria and viruses ( However if temperature gets too high it could damage the protein complexes in our body )
produce a faster rate of healing