5.1 Endocrine 1 Flashcards
What is the difference between endocrine and exocrine glands?
Endocrine vs exocrine:
1- Exocrine secretes into a lumen eg digestive enzymes, mucus
2- Endocrine- no ducts, secrete into the blood, and not the surface, the molecules then travel through the blood
Yes, hormones can travel through entire body, BUT, need a receptor, and need enough receptors to trigger a resonse
What are the 3 categories of endocrine disorder?
1-hormone deficiency
damage to glands due to autoimmune conditions (attacked by antibodies), infection, inflammation, infarction, or tumors
2- hormone excess
increased production by glandular cells due to tumors, autoimmune (activation by autoantibodies), genetic mutations
3–hormone resistance
lack of hormone receptor response due to genetic defects, down-regulation
What are the 2 major ways hormones interact with a receptor?
Second messenger system
Direct gene activation
What three classes of stimuli affect hormone release?
Blood: levels of molecules in the blood
Neural: stimulation by the nervous system
Hormonal: “management” by other glands, the hypothalamic/pituitary axis of control
What are the two types of receptors for hormones?
extracellular receptor: located on the plasma membrane, linked to the inside of the cell by second messenger system
intracellular receptor: located inside the cell, directly activate genes
What are the two structural types for hormones?
Amino-acid based hormones
Steroid-based hormones
Describe an amino-acid based hormone
Water-soluble
range in size from proteins, peptides or specific amino acids (tyrosine, amines)
cannot cross the plasma membrane, hydrophilic
require extracellular receptors
What is notable about thyroxine?
It’s AA based but lipid-soluble
Describe steroid hormones
Lipid-Soluble
derived from cholesterol in gonads, adrenal cortex
can cross the plasma membrane, hydrophobic
act via intracellular receptors, but can use extracellular receptors
Which 2 types of second messengers are used by hormones?
cAMP
PIP2
What are the steps in the cAMP pathway?
Hormone binds receptor: Receptor activates G-protein G-protein activates adenylate cyclase Adenylate cyclase makes cAMP cAMP activates protein kinases Protein Kinase causes changes inside the cell
What is the function of protein kinases within the cell?
cause changes inside the cell
via phosphorylation of cellular proteins downstream
can increase or decrease cell activities
examples: synthesis of molecules, breakdown of molecules, activation of enzymes, deactivation of enzymes, increase in receptors, decrease in receptors …
a single protein kinase can catalyze hundreds of reactions
AMPLIFICATION of response to a single hormone
What is the PIP2/Ca++ pathway?
Hormone binds receptor:
Receptor activates G-protein
G-protein activates Phopholipase C
Phospholipase C makes phosphatidyl inositol bisphosphate (PIP2)
PIP2 activates diaclyglycerol (DAG) and inositol triphosphate (IP3)
DAG activates Protein Kinases
AND/OR
IP3 releases Calcium
Calcium binds to Calmodulin and activates Protein Kinases
What are the steps of direct gene action for hormones?
Steroid hormone diffuses into cell
Receptor inside the cell forms a receptor-hormone complex
Receptor-Hormone Complex binds to DNA
DNA transcription to mRNA is activated
mRNA is translated into a protein
Protein changes activity within the cell
examples: synthesis of signaling molecules, synthesis of receptors, synthesis of structural proteins, synthesis of secretory proteins
What is the pathway of direct gene action?
Steroid hormone diffuses into cell Receptor inside the cell forms a receptor-hormone complex Receptor-Hormone Complex binds to DNA DNA transcription to mRNA is activated mRNA is translated into a protein Protein changes activity within the cell
