Intro to Endocrine Flashcards
1 cell type sends hormones to itself or another cell of the same type
Autocrine
1 cell type sends hormones to a different cell type
Paracrine
1 cell type sends hormones into the blood stream to affect a different cell type
Endocrine
A neuron releases hormones into the blood to affect a certain cell type
Neuroendocrine
List the classical endocrine glands (9)
Hypothalamus Anterior/Posterior pituitary Thyroid Parathyroid Adrenal cortex/medulla Pancreas Placenta Gonads
Major hormones released by Hypothalamus
ADH, oxytocin, anything ending in “RH”
Major hormones released by Anterior pituitary
ACTH, FSH, LH, TSH, GH
Major hormones released by Posterior pituitary
ADH, oxytocin
Major hormones released by thyroid gland
T4, T3, Calcitonin
Major hormones released by parathyroid gland
Parathyroid hormone (PTH)
Major hormones released by adrenal medulla
NE and Epinephrine
Major hormones released by adrenal cortex
Cortisol and Aldosterone
Major hormones released by pancreas
Insulin and Glucagon
Major hormones released by gonads
Testosterone and Estrogen
What are the 3 classes of hormones?
Protein/peptide
Amines
Steroids
What are protein/peptide hormones synthesized from and what are they stored in?
DNA and stored in vesicles
What is the half life and clearance rate like for protein/peptide hormones?
Short half life and fast clearance rate
What are the 2 types of amine hormones?
Catecholamines and Thyroid hormones
What are amine hormones synthesized from?
Tyrosine
What is the half life and clearance rate like for amine hormones?
Long half life and slow clearance
What are steroid hormones derived from?
Cholesterol
From short half life and fast clearance rate to long half life and slow clearance rate, rank the 3 hormone classes from fastest to slowest
PSA
proteins/peptides
Steroids
Amines
What is positive feedback?
When a downstream hormone further stimulates the releasing organ to release more of the same hormone
What is an example of positive feedback?
Estradiol stimulating the anterior pituitary to release more during female ovulation
What is negative feedback?
When a downstream hormone inhibits the releasing organ to release less of the same hormone
What is an example of negative feedback?
Testosterone inhibiting the signal to release more at the level of the anterior pituitary
Endocrine axis for bones/organs/muscles
Hypothalamus
Anterior pituitary releases GH
Endocrine axis for ovaries/testes
Hypothalamus
Anterior pituitary releases FSH and LH to both
Endocrine axis for adrenal cortex
Hypothalamus
Anterior pituitary releases ACTH
Endocrine axis for thyroid gland
Hypothalamus
Anterior pituitary releases TSH
Endocrine axis for kidneys
Hypothalamus
Posterior pituitary releases ADH
Endocrine axis for breasts/uterus
Hypothalamus
Posterior pituitary releases oxytocin
Describe 1st tier regulation
Regulating the hypothalamus:
Light - eyes - LGN/Retinohypothalamic tract => Suprachiasmatic Nucleus (SCN)
- SCN controls circadian rhythm at pineal gland to release melatonin and controls coordinated endocrine/metabolic and behavioral rhythms at the hypothalamic level
What are 2 ways to change responsiveness of hormone receptors?
Changing number of receptors
Changing affinity of receptors for the hormone
What is responsiveness of the target tissue expressed by?
Dose-response relationship
What is the adenylyl cyclase mechanism?
Hormone binds and activates G protein
G protein activates adenylyl cyclase to create cAMP
cAMP activates protein kinase A
What are some hormones that use the adenylyl cyclase mechanism?
ACTH, LH, FSH, TSH
What is the phospholipase C mechanism?
Hormone binds and activates G protein
G protein activates phospholipase C to create DAG/IP3
DAG/IP3 activate protein kinase C
What are some hormones that use the phospholipase C mechanism?
Oxytocin, TRH, GnRH
What is the steroid hormone mechanism?
Diffuse across cell membrane and bind intracellular receptors and then bind to DNA to activate/repress genes
What is the Guanylyl Cylcase mechanism?
Guanylyl cyclase converts GTP to cGMP
cGMP activates cGMP kinases
What is an example of the guanylyl cyclase mechanism?
NO relaxing smooth muscle
Receptor Tyrosine Kinases directly phosphorylate targets when what is bound?
Insulin
Tyrosine Kinase associated receptors are associated with proteins that have kinase ability when what is bound?
GH
