Homeostatic regulation of body temperature Flashcards
what are ectotherms ?
- animals classified as cold blooded
- depend on external environment to survive
- e.g. reptiles
what are endotherms ?
- animals that use thermoregulation to manatin constant internal temperature, even when external temparature changes
- it is crucial for life
- e.g. humans
what are endotherms ?
- animals that use thermoregulation to manatin constant internal temperature, even when external temparature changes
- it is crucial for life
- e.g. humans
Why is temperature regulation important?
- for metabolic processes to occur
- these metabolic processes are responsible for energy production
what happens when someone has hypothermia ?
- decrease vital signs (lower heart rate, respiratory rate)
- drowsy (not feeling cold anymore, just sleepy)
- Coma (loosing consciouness)
- death
what is a Hypothalamus and what does it do ?
- Part of the brain
- Control centre for temeperaure regulation
- Ajjutonomic nervous system to stimulate various organs such as the skeletal muscle to generate heat
What is the range of normal body temperature ?
35.6 - 37.8 degrees
Homeostatic control – temperature regulation in cold environment
- Blood temperature drops
- a signal is sent to the hypothalamus
- signal stimulates skeletal muscles to shiver and constriction of BV in skin
How does skeletal muscle generate heat?
- muscle activity generates heat as a by product
- ATP is used to power muscle contraction - (75% of the energy used for the contraction escapes as heat)
- skeletal muscle is mist abundant muscle tissue in the body so it is responsible for the generation of most heat
How does skeletal muscle generate heat?
- muscle activity generates heat as a by product
- ATP is used to power muscle contraction - (75% of the energy used for the contraction escapes as heat)
- skeletal muscle is mist abundant muscle tissue in the body so it is responsible for the generation of most heat
How does the liver generate heat ?
- the liver is the primary site of metabolism
- Heat generated can be transferred to the rest of the body
- This happens because Liver has high blood supply which warms up by liver by conduction method.
- The warm blood then circulates round the rest of the body
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how does adrenalin generate heat ?
- produced by the adrenal gland
- Increased production of adrenaline increases the metabolic rate in different target tissues = increased heat !!!
how does adrenalin generate heat ?
- produced by the adrenal gland
- Increased production of adrenaline increases the metabolic rate in different target tissues = increased heat !!!
how do thyroid glands affect body temeparure ?
- internal temperature regulation
- When issues arise,perception may be altered – so person may feel cold/hot when they are not.
how do thyroid glands affect body temeparure ?
- internal temperature regulation
- When issues arise,perception may be altered – so person may feel cold/hot when they are not.
thyroid gland and the sympathetic nervous system when exposed to cold
- Glucose uptake by skeletal muscle is increased
- Glucogenesis by the liver is increased
- Thermogenesis occurs in Brown Adipose Tissue (brown fat)
- Lipolysis occurs in white adipose tissue (white fat)
And core body temperature is raised.
Other factors effecting Thyroids regulation of body temperature
- Low levels of seratonin and dopamine
- Low serotonin can lead to low TSH and low body temperature.
what are the stages that one can go through when they have hyperthermiab (heatstroke) ?
- Excessive heating caused by hot environment or intensive exercise
- Patient feels confused, has red skin, headache and is dizzy
- Patient can loose consciousness if not treated
- Can result in Death
Heat loss mechanisms
- Most heat loss occurs in the skin in 2 ways :
- radiation= when the body temeperature increases past the set point.
- evaporation = sweating
Heat loss mechanisms
- Most heat loss occurs in the skin in 2 ways :
- radiation= when the body temeperature increases past the set point.
- evaporation = sweating
why does fever occur ?
- infection
- cancer
- allergic reactions
- central nervous system injuries
therefore
Macrophages, white blood cells and injures tissue cells release PYROGENS.
what is the effect of pyrogens ?
- act on the hypothalamus to raise the set point (so body temperature can rise above 37 degrees)
- This causes blood vessels in skin to constrict (makes skin feel cold,clammy)
- new thermostatic “fever” setting - maintained until the natural body defences neutralise the threat or you are treated with a drug.
Why is mild/short term fever useful ?
- trigger the immune system
- Some immunological and biochemical pathways work more efficiently at slightly raised temperatures
how does aginig affect homeostasis / body temperature ?
- slower metabolic rate
- those above 65 tend to have lower baseline temperatures
name thigs that can affect body temepraure
- aging
- stress
- feeding
- smoking
- drugs
- Menopausal hot flashes
