Endocrine System Flashcards
mediator molecules that have effects on cells in the local area, or more distant part of the body
Hormones
secreted and bind to the same cell.
Autocrine hormones
secreted into interstitial fluid and act on nearby cells
Paracrine hormones
are secreted into interstitial fluid and then absorbed into the
bloodstream to be carried systemically to any
cell that displays the appropriate type of receptor
Endocrine hormones
Hormones can be divided into two broad_____
classes.
Chemical
This chemical classification is useful because the two classes exert their effects differently .
________ bind to receptors in the cytoplasm or nucleus of the cell (hydrophobic)
Lipid soluble hormones
This chemical classification is useful because
the two classes exert their effects differently. _____ bind to receptors on the surface of the cell
Water soluble hormones
consist of steroid hormones,
thyroid hormones, and the gas nitric oxide
Lipid soluble hormones
require a carrier protein for transport in the watery environment of the blood. Once they arrive at their destination, however, they are able to freely pass through the plasma membrane to bind to receptors located in the cytoplasm or the nucleus of the target cell
Lipid soluble hormones
consist of steroid hormones,
thyroid hormones, and the gas nitric oxide
Lipid soluble hormones
require a carrier protein for transport in the watery environment of the blood
Once they arrive at their destination, however, they are able to freely pass through the plasma membrane to bind to receptors located in the cytoplasm or the nucleus of the target cell
Lipid slub,e hormones
include peptide and protein
hormones (and others with an amine group), and a group
of local hormones derived from the arachidonic acid on
our cell membranes called eicosanoids
Water soluble hormones
are easy to transport in the
watery blood. The plasma membrane of target cells,
however, is impermeable to them.
Water soluble hormones exert their effects by binding to receptors exposed to the interstitial fluid on the surface of target cells
Water soluble hormones
the hormone binding to its receptor acts as_______ in a cascade of signal transduction
the first
messenger
The first messenger (the hormone) then causes production
of a _____ inside the cell, where specific
hormone-stimulated responses take place
second messenger
The _____ system does so through the action potentials travelling on neurons, and the neurotransmitters they secrete
Nervous
The_____ system uses hormones produced by endocrine structures to produce their effects
Endocrine
One common second messenger is_____ Neuro- transmitters, neuropeptides, and several sensory transduction mechanisms (vision) also act via second-messenger systems
Cyclic acid (cAMP)
Hormone secretion is regulated by signals from the_____ system,_____ changes in the blood, and other hormones
nervous, chemical
Most hormonal regulatory systems work via
_____feedback, but a few operate via______ feedback
negative, positive
Negative feedback system : Blood Ca2+ level is controlled by the
parathyroid hormone (PTH).
Negative feedback system :
High blood Ca2+ level -> the body will cease PTH production and secrete_____ causing the body to lower the Ca2+ levels.
calcitonin
Exclusively endocrine glands:
pituitary, thyroid, parathyroid, adrenal and pineal glands
Other important glands of the endocrine system are not
exclusively endocrine glands
hypothalamus, thymus,
pancreas, ovaries, and testes
The_____ is the major link between the nervous and endocrine systems
It receives input from several regions in the brain
hypothalamus
The hypothalamus mainly controls the_______,
which is also called the hypophysis
anterior adenohypophysis posterior neurohypophysis
pituitary gland
The anterior pituitary (adenohypophysis) is connected to the hypothalamus by the
hypophyseal portal system
Neurosecretory cells secrete
______ into the portal system that goes to the anterior pituitary
releasing hormones
secreted by the anterior pituitary, target other endocrine glands
(all anterior pitiutary hormones except hGH, Prolactin, and MSH, which directly target the end organs)
Tropic hormones
The_______ releases,
but does NOT synthesize any hormones • Hormones are produced in neurosecretory hypothalamus
cells • Travel down the axons • Released when cells are stimulated
posterior pituitary (neurohypophysis)
posterior pituitary (neurohypophysis) which hormones
oxytocin and ADH
causes uterine
contractions and “milk
letdown”.
Oxytocin
minimizes water
loss in kidney and sweat
glands. constricts
arterioles
ADH
inferior to the larynx and anterior to
the trachea. two laterally placed lobes separated by a
bridge-like isthmus
Thyroid gland
The Thyroid Gland
● Mostly composed of _____● spherical groups of follicular cells ● Store a 100-day supply
of its two hormones in_____
thyroid follicles, TGB (for thyroglobulin)
made from the oxidation and
iodination of the amino acid tyrosine
TGB
tetraiodothyronine
thyroxine or T4
triiodothyronine
T3
an enlargement of the thyroid gland and may be
associated with hyperthyroidism, hypothyroidism, or
euthyroidism
Goiter
In many third-word countries dietary_____ intake is inadequate; the resultant low level of thyroid hormone in the blood stimulates secretion of TSH, which causes thyroid gland enlargement
iodine
