L23. Endocrine System 1 Flashcards
What is the function of the pituitary gland
- provides a functional connection between the CNS and the periphery NS
- regulates every cell in the body
How many lobes does the pituitary gland have, what are it’s lobes called?
- 2 lobes anterior and posterior
Where does the direct pathway occur
posterior lobe of the pituitary
Where does the indirect pathway occur
anterior lobe of the pituitary
Describe the function of hormones
- circulate in the blood
- can be lipophilic or hydrophilic ( depending on whether it is a steriod or peptide hormone)
What classes of hormones are there
- monoamines
- lipophilic
- peptide
What is the function of sex steroid hormones
- regulate reproductive and cognitive function
- regulate emotions and feelings
What are the 3 different signaling parameters?
- autocrine
- endocrine
- paracrine
What is an autocrine signaling pathway
hormones produced by a cell binds to the receptors on the same cell
What is a paracrine signaling pathway
hormones produced by cells binds to receptors close to the hormone-producing cell
What is an endocrine signaling pathway
hormones produced by the cell can enter the bloodstream and travel great distances
Describe peptide hormones
- composed of amino acids
- it is hydrophilic and is soluble in the blood stream
- arranged as a complex chain or simple string of amino acids
How many amino acids is oxytocin composed off
9
What are monoamine hormones
contain one amino acid connected to an aromatic ring
Describe steroid hormones
composed of 4 fuse chains and 1 side ring
activity varies with functional group
lipophilic
circulate in the blood only after when attached to a transporter
Describe monoamines
hydrophilic
what amino acid is part of the hormone adrenaline?
tyrosine
Describe the thyroid hormone
- derived from 2 amino acids (tyrosine)
- bound to transport proteins so it can circulate the blood
- lipophilic
draw the mode of amine and peptide hormones (pg 8b
pg 8b L 23
Draw the mode of action for steriods and thyroid hormones ( pg 9a)
pg 9a
Where are the receptors for peptides and monoamine hormones found?
cell surface (membrane) receptor
Where are the receptors for thyroid hormones found?
have nuclear receptors
Where are receptors for steroid hormones found?
nuclear receptors
membrane receptors
What is the difference between the function between the anterior pituitary and posterior pituitary?
the anterior pituitary both synthesizes and secretes the hormone
the posterior pituitary only secretes the hormone ( the hormones are produced elsewhere)
What are the hormones produced by the anterior lobe ?
FLAT P(E)G FSH, LH , ACTH, TSH, Prolactin, Growth hormone
What are the hormones secreted by the posterior lobe of the pituitary?
ADH
Oxytocin
What is the function of the anterior pituitary
- contains several different cell type that secretes a unique stimulating hormone
- different cell types in the anterior pituitary are regulated by different hypothalamic nuclei
What are corticotropes
they are one of the unique cell types on the anterior pitutary that secretes the stimulating hormone ACTH
Describe the capillary endothelium in the CNS
- forms a tight continuous junction
- known as the blood brain barrier
What is median eminence
a specialized region that circumvents the blood brain barrier
where neurons can either exit or terminate
- nerual axons to the posterior pituitary project through the ME
- neural axons towards the anterior pituitary terminate at the ME
where is the ME located?
located below the 3rd ventricle
describe the indirect pathway
- CRH or TRH producing cells secrete hormones/ have their neurons terminate in the median eminence
- there are nerve terminals near the hypophyseal artery
- the chromophil cell in the anterior pituitary produces (ACTH)
- ACTH is then released into the hypophyseal vein
what hormones are secreted through the indirect pathway
all hormones secreted by the anterior pituitary ( FLAT PEG)
describe the direct pathway
- AVP or OT producing cells have their tracts passing through the median eminence and the hormones are secreted directly to the herring body
- hormones from the herring body are then released to the hypophyseal vein
Draw the direct and indirect pathway (pg 14b and pg 15a)
pg 14 b and pg 15a
what does a nucleus mean in the CNS
group or cluster of cell bodies in the CNS
Where is the paraventricular neuron located
It is located beside the 3rd ventricle
Where is the supraoptic nucleus located
on top of the optic tract
In the paraventricular nucleus , what are the 2 types of cells where are they in terms of medial/ lateral positions
parvocllular ( medial)
magnocellular ( lateral)
Where do the substrates of parvocellular cells end up ?
They pass through the median eminence and enter the anterior pituitary
Where do the substrates of magnocellular cells end up?
They go directly to the posterior pituitary
What is the zona interna of the Median eminence
fibers en passage to the posterior pituitary
What is the zona externa of the median eminence
it integrates with the pituitary portal system ( needed for indirect pathway)
Describe the similarities/difference between the paraventricular nerves ( PVN) and the SON
- PVN and SON synthesize polypeptides
- unlike SON, PVN also contains neurosecretory neurons that terminate within BOTH the posterior pituitary and median eminence
- the peptide synthesizing neurons occupy different regions of the nucleus
How are the brain and the pituitary connected
through direct and indirect pathway
