Unit 1: Endocrine System

Endocrine System

Hormones that are directly secreted into the blood stream

Mechanisms of intracellular communication

Gap Junctions

Paracrine Communication

Autocrine Communication

Paracrine communication

cells talking to adjacent cells by using chemicals

Autocrine Communicationm

Cells talking within itself

Ex: Smooth muscle coordinating contraction

Nervous System Communication

neurons communication to effector cells through exocytosis

Mechanisms of Action

Alter genetic activity

Alter rate of protein synthesis

Change membrane Permeability

Alter genetic Activity

Turn off/on genes

Copies genetic code

DNA>mRNA=Transcription

Alter rate of protein synthesis

mRNA>Proteins=Translation

Changing genetic code

Quicker to make proteins

Change membrane permeability

Affect membrane channels

increase of permeability= more stuff goes through

decrease of permeability= less stuff goes through

Remove/Close membrane channels=less

Add/open membrane channels=more

Hydrophilic

mix well with H2O

travels freely in water

protein is made+ stored

released by exocytosis

1st messenger

Hydrophobic

does not mix well with H2O

protein needs to be made on demand

Diffuses through cell membrane

binds to receptors in cytoplasm (Inside cell)

Binds to nuclear membrane

activate specific genes

Steroid Hormones

Cholesterol based

lipid derived=hydrophobic hormone

found in: reproductive organs, adrenal cortex, kidneys

Peptide Hormones

hydrophilic hormone (non-steroid)

Contains ADH, Oxytocin, Prolactin, growth hormone found in the pituitary gland

Glycoproteins

type of peptide hormones

non-steroid

contains thyroid stimulating hormone, Luteinizing hormone, follicle stimulating hormone found in the pituitary gland

Tyrosine

type of Amino Acid Derivative

contains catecholamines, thyroid hormones, tryptophan

Catecholamines

Epinephrine + Norepinephrine

Dopamine

Hydrophilic (non-steroid)

Tryptophan

Hydrophobic

non-steroid

Melatonin

Thyroid Hormone

T3 + T4

steroid hormone

hydrophobic

Amplification

Taking a very small stimulus and producing a big response

Hormone Clearance

Degraded by liver and kidneys

Up-Regulation

Absence or low level of hormones

Adding more receptors

Down Regulation

High level of hormones

Acts as protection

Removing Receptors