Download Hormonal Control

Hormonal Control
Option H1
The basics…
Hormones are chemical messengers
 Secreted by endocrine glands into the
blood
 Transported to specific target cells
 Binds to a matching receptor that sends
a signal inside the cell
 Can cause the cell to make a protein or
divide or …..

Different types of hormones
STEROIDS – eg progesterone
 Produced by ovary/placenta, acts on the
uterus to maintain endometrium during
pregnancy.
 PROTEINS – eg leptin
 Produced by adipose tissue, acts on the
hunger centre of the hypothalamus to
signal to the brain that body has eaten
enough.

TYROSINE DERIVATIVE – eg thyroid
hormone
 Produced by thyroid gland, acts in many
areas to determine basal metabolic rate
 AMINE – eg adrenalin (epinephrine)
 Produced by adrenal glands, acts on
heart, eyes, muscles, digestive system to
prepare body for “fight or flight” response

Steroids and Proteins act differently

Steroid hormones [estrogen/testosterone] pass
directly across the plasma membranes of
target cells.
 They bind to receptor proteins inside the
cytoplasm of these cells for form a hormonereceptor complex.
 This complex regulates gene transcription –
for some it is promoted and others inhibited.

http://highered.mcgraw-hill.com/olc/dl/120109/bio46.swf
Protein or peptide hormones [insulin /
TRH / ADH] do not enter cells.
 They bind to receptors on the plasma
membrane.
 This causes the release of a secondary
messenger inside the cell, which in turn
changes the activities of the cell.

Now for the thinking part of the
lesson…..
Get into groups of 3
 Decide on a scribe and a timekeeper
 Answer the two questions on the next
slide as fully as you can
 Include diagrams in your answers
 Put it on a piece of poster paper


Outline the relationship between the
hypothalamus and the pituitary gland

Explain the control of ADH (vasopressin)
secretion by negative feedback
And now….
One person – NOT the scribe – stay
where you are
 The other 2 group members move
around so that you are totally mixed and
not with anyone you were with before
 The person who stayed, explain the
answers to the new group members
 ANY QUESTIONS?
