Class Notes (836,290)
Canada (509,749)
Biology (1,284)
BIOL 103 (255)
Lecture 6

WEEK 6.docx

4 Pages
Unlock Document

BIOL 103
Virginia K Walker

WEEK 6: HORMONES + ENDOCRINE SYSTEM -amines and proteins/peptide hormones generally share similar chem. properties and actions; steroid hormones act differently 1. AMINES -small -water-soluble -derived from a.acid tyrosine ((nor)epinephrine) or tryptophan (melatonin) -target cell receptor on plasma membrane (except thyroid glands) -works as a secondary messenger 2. PEPTIDES/PROTEINS -small, water soluble -participates in numerous body f'ns -target cell receptor on plasma membrane -works as secondary messenger -eg. insulin, glucagon, leptin 3. STEROIDS -made from cholesterol lipids -insoluble in water -steroid hormones bound to large, soluble proteins in the blood that act as carriers -acts in cell cytosol or nucleus; stimulates gene transcription -eg. cortisol, testosterone, estradiol MEMBRANE RECEPTION -water-soluble hormones -ligand binds to a receptor protein on the plasma membrane -hormones diffuse from the blood into the interstitial fluid, binding to a specific receptor proteins on the cell surface -only cells w/ the proper receptors on their surfaces can respond to the hormone -->hormone activates only specific cells in the body -receptor interacts noncovalently + reversibly w/ hormone -initiates intracellular signalling -->1. cyclic AMP pathways --> 2. Ca2+/phosphatidylinositol pathway --> 3. tyrosine/kinase pathway -signal transduction can be rapid and involve enzymes -->enzymes can amplify the hormone signal -also leads to changes in cellular activities that occur more slowly -->usually requires activation/inhibition of various genes in the nucleus -isoforms: different receptors that can recognize the same hormone -->from different genes or alternative splicing of genes -->one hormone can perform 1+ actions in the body by binding to receptor isoforms that differ slightly from each other -->receptors have diff. affinities for the hormone: [hormone] binding affects action of cell INTRACELLULAR RECEPTION -w/ steroid hormones -receptors located within the cell (either cytosol or nucleus) -complex of steroid hormone + receptor f'ns as a transcriptional activator by binding to enhancers of a particular gene -->once bound, transcription is increased, which increases the amount of that gene's protein -single type of steroid hormone can have a variety of actions throughout the body -eg. changes in puberty [HORMONES] IN THE BLOOD -change in hormone amounts in the blood depend on: 1. changing the rate of hormone production by an endocrine 2. chang
More Less

Related notes for BIOL 103

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.