Skin and Temperature Regulation Flashcards
What is the normal body temperature?
37 degrees
AT what body temperature do proteins begin to denature?
41 degrees
Below what temperature is consciousness lost?
30 degrees
What four factors make up the thermal balance of the bosy?
Convection
Evaporation
Conduction
Radiation
What is the normal heat production of the body at rest?
80kcal/hour
What is the difference between convection and conduction?
They are essentially the same process except convection occurs when there is fluid contact with the body rather than solid objects
How is body temperature detected?
Multiple receptor throughout the body are receptive to heat but some are exclusive to cold or heat
What kind of receptors detect the extremes of temperature?
In effect, nociceptors
As cold and warm receptors can overlap and fire over the same part of a their temperature range, how does the body know which stimulus is correct?
The receptors have dynamic responses as well as static ones which allow their firing to be differentiated
Where are peripheral thermoreceptors concentrated?
In the skin, especially the face and scrotum
Where are central thermoreceptors concentrated?
In the spinal cord, abdominal organs and hypothalamus
What happens to the information coming in from the peripheral and central thermoreceptors?
They are relayed to the regulatory centre in the hypothalamus which analyses them and decides whether to change the body temperature
What are four mechanisms which increase the heat levels within the body?
General metabolism - oxidative phosphorylation and other chemical reactions are not 100% efficient give off heat
Voluntary muscle activity
Shivering thermogenesis (involuntary)
Non shivering thermogenesis - in humans this is only significant in babies due to their levels of brown adipose tissue which are very low in adults
What are two ways that heat loss from the body is reduced?
Vasomotor control - sympathetic arteriolar constriction in the periphery reduced delivery of blood to the skin and therefore reduces heat loss
Behavioural responses - reducing surface area, adding clothing, moving to warmer environment
What is the definition of hypothermia?
A fall in body temperature to below 35 degrees
Which groups of people are particularly at risk of hypothermia?
Neonates - do not detect temperature change well, not much fat, don’t shiver well
Elderly
Vagrants
What is the treatment for hypothermia?
Dry/insulate to prevent further heat loss
Slow re-warming with bag/blankets
Internal re-warming with hot drinks and/or warm air
Fast re-warming by immersion in water - not recommended
What are the vascular components of frost bite?
Vasoconstriction
Increase in viscosity
Promotes thrombosis
Causes anoxia
What re the cellular components of frost bite?
Ice crystals form in the extracellular space, increasing osmolality and causing the movement of water from the cell and resulting in dehydration death
What is the rate of excess mortality during winter in the UK?
40%
What are three factors that increase heat loss from the body?
Vasomotor control - arteriolar dilation increases delivery of blood to the skin
Sweating - sympathetic cholinergic fibres increase increase evaporative heat loss
Behavioural responses - increasing surface area, removing clothing, moving to shaded area
What is heat exhaustion? What are the effects? Is this heat illness or heat injury?
A body temperature raised in the range of 37.5-40
Causes vasodilation and a drop in central blood volume
Caused by a disturbance of the body’s fluid/salt balance due to excessive sweating
This is heat illness but may progress to injury
What are the symptoms of heat exhaustion?
Headache Confusion Nausea Profuse sweating Clammy skin Tachycardia Hypotension Weak pulse Fainting & collapse
What is heat stroke? Is this heat illness or injury?
A raise in body temperature above 40 degrees
This is heat injury, the control mechanisms have failed and the skin becomes hot and dry because sweating has ceased and circulatory collapse will occur
