9.2 chemical control in mammals

Question 1

where are hormones produces?

Answer 1

endocrine glands

Question 2

how do hormones travel around the body?

Answer 2

in the bloodstream

Question 3

how do hormones have an effect?

Answer 3

they travel around the bloodstream until they reach receptor molecules on the surface of target organs

Question 4

what is the advantage of having ductless glands?

Answer 4

their effect comes about quicker

Question 5

what controls endocrine glands?

Answer 5

the pituitary gland

Question 6

what controls the pituitary gland?

Answer 6

the hypothalamus

Question 7

what are the two types of hormones?

Answer 7

• protein based hormones
• steroid based hormones

Question 8

how do protein based (non-steroid) hormones bring about change?

Answer 8

1- a non-steroid hormone (first messenger) binds to a surface receptor on a cell membrane
2- this activates an enzyme inside the cell membrane
3- The activated enzyme hydrolyses ATP, removing two of its phosphate groups to form a molecule of cyclic adenosine monophosphate (cAMP)
4- The cAMP acts as a second messenger and activates further enzymes that cause a cascade of reactions in the cell
5- this changes the cell activity/structure

Question 9

what is an example of a protein based hormone?

Answer 9

adrenaline

Question 10

how do steroid based hormones bring about change?

Answer 10

1- a lipid soluble hormone passes through the membrane and into the nucleus of a cell
2- the hormone binds to a hormone receptor complex
3- the hormone bound to the receptor acts as a transcription factor, regulating gene expression and switching sections of the DNA on and off
4- this creates mRNA that is transcribed into a protein that changes cell functions

Question 11

what is an example of a steroid based (lipid soluble) hormone?

Answer 11

oestrogen

Question 12

what are the differences between these two hormones?

Answer 12

• location of receptors
• only protein based uses second messenger
• only lipid based results in transcription + translation
• only lipid based produces activated enzyme wheras protein based activates an enzyme that is already present
• lipid based tend to have longer lasting effects

Question 13

what are the similarities between these two hormones?

Answer 13

• hormones are transported in the blood plasma
• they travel all around the body but only affect cells with complimenary receptor sites