Feedback Control - Temperture And Other Vital Signs Flashcards
What is the maintained core body temperature
Normothermia
What is the core body temperature
Temperature of the blood and internal organs
What temperature is the core homeostatically maintained
37.8 degrees
Why is the skin/subcutaneous fat not a good site for monitoring tempreatures
Skin temperature varies widely
What is normothermia optimum for
Cellular function
Metabolism
What happens if body temperature is increased
Speeds up cellular metabolism
Causes overheating
Therefore proteins denature and nerve malfunction
What happens if body temperature is decreased
Slows down metabolism and cellular function
What temperature range is considered a fever
38-40
What temperature range is considered hyperthermic
40+
What temperature range is considered hypothermic
Below 35
Where are the sites for the direct estimate of body temperature
Rectal
Oesophageal
What is the term used to describe slightly varying core temperature throughout the day in the same individual
Diurnal variation
What can alter body temperature
Exercise
Exposure to extreme temperatures
When will the core temperature of a female vary
During the menstrual cycle and after ovulation
What is the main source of heat gain/production
Internal environment - metabolic heat gain
What are the sources of heat gain from the external environment
Radiation
Convection
Conduction
What are the ways heat is lost to the external environment
Radiation
Conduction
Convection
Evaporation
What is the Basal Metabolic Rate (BMR)
Minimum amount of energy required to sustain vital body function
How can the BMR be increased
Hormones
Adrenaline
Noradrenaline
Thyroxine
How does shivering increase heat production
By increasing muscle activity
How is heat lost through radiation
The human body emits and absorbs radiant heat depending on relative temperature of body and surrounding objects
How much of the bodys heat is lost through radiation
Half
How does the body lose heat through conduction
Heat moves warmer to cooler
Transfer of heat through direct contact
How does the body lose heat through convection
Transfer of heat energy by air/water currents which help to carry heat away from the body
How does convection and conduction work together to cool down the body
Conduction warms the skin
Warm air is less dense and rises away from skin, cool air collects on skin
What is the wind chill factor
Forced air movement (by fan) allows greater total amount of heat to be carried away from the body
How is heat lost from the body through evaporation
Energy used to convert water on the skin to vapour
This energy comes from the body
Passive and active evaporation
Humidity of atmosphere affects evaporation
What is passive evaporative heat loss
Occurs continuously
Water molecules continuously diffuse from skin and lining of resp airways
What is an active evaporative heat loss process
Sweating
Controlled
Sympathetic nervous system
How does the human body maintain its core temperature
At a set point
Homeostatic mechanisms involving negative feedback control system
What are the sensors involved for the negative feedback control of temperature control
Central thermoreceptors (hypothalmus)
Peripheral thermoreceptors (skin)
What is the control centre for the negative feedback control of temperature
In hypothalmus
What are the effectors for the negative feedback control of temperature
Skeletal muscles
Skin arterioles
Sweat glands
What are the neural inputs to the hypothalamus
Include those from the negative feedback receptors for temperature regulation
Which hypothalamic centre is activated by cold
Posterior
Which hypothalamic centre is activated by the warmth
Anterior
HOw does the hypothalamus interact with systems to have an affect on the bodys core temperature
Neural connections to motor neurons which control the skeletal muscle system
Connections to the sympathetic nervous system
What is the response of the skin arterioles to cold exposure
Vasoconstriction
Blood flow to skin surface is reduced
Conserve heat
What are the skeletal muscles respionse to cold exposure
Increased muscle tone
Shivering
Increases heat production
What other behavioural adaptations occur to conserve heat
Postural changes which reduced exposed surface area
What is the response of skin arterioles in response to heat exposure
Vasodilation
Blood flow to skinincreased
Increase heat loss
What is the sweat glands response to heat exposure
Sweating - evaporation increases heat loss
What are the skeletal muscles response to heat exposure
Decreased muscle tone
Decreased voluntary movement
Decrease heat production
What is the function of endogenous pyrogen
Stimulate the release of prostaglandins in the hypothalamus
What cell type can act as endogenous pyrogen response to inflammation of infection
Macrophages (release chemicals)
What happens when prostaglandins act on the hypothalamic thermo-regulatory centre
Reset the brains thermostat to a higher resting temperature
How is a fever achieved in response to the new set point
Hypothalamus initiates mechanisms to heat the body
How can the hypothalamic increased set point be reduced to normal
Pyrogen release is reduced/stopped
Prostaglandins synthesis is decreased/stopped
What happens after prostaglandin synthesis is decreased or pyrogen release is decreased
Hypothalamus initiates mechanisms to cool the body and return it to the reduced set point
