3.5 - Thyroxine and Adrenaline

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What is the hormone secreted by the thyroid gland?

thyroxine

What is the effect of thyroine on the body?

control basal metabolic rate

What is the basal metabolic rate?

the rate at which the body uses energy while at rest to maintain vital functions

What organs does thyroxine target?

most tissues

What are the functions of thyroxine in the body?

• stimulates the basal metabolic rate

• involved in the the formation of glycogen/proteins

• involved in regulating respiration rate

• involved in regulating brain development in children

What is the effect of adrenaline on the body?

prepares the body for stressful situations - “fight or flight”

What are the target organs for adrenaline?

most tissues

What are the functions of adrenaline in the body?

• prepares body for fight or flight

• increase a heart rate to get more oxygen and glucose delivered to the brain and muscles 

• breathing rate increases

• pupils dilate (lets more light in)

• glycogen converted to glucose in the liver to be used for respiration

What is the effect of TSH on the body?

stimulates thyroid gland to produce thyroxine

What is negative feedback?

a process that reverses a change in the internal environment

Why does negative feedback occur?

to bring the change back to optimal conditions and maintain a steady state in the body

How does the feedback loop between TSH and thyroxine work?

• If thyroxine levels fall this is detected by the pituatay gland which will release TSH in response

• This tells the thyroid gland to release more thyroxine

• If thyroxine levels are high this is detected by the pituatay gland which will stop the release of TSH which turn tells the thyroid gland to stop releasing thyroxine