Endocrine system Flashcards
Bootcamp
what are the ways hormone can be secreted?
Endocrine, Paracine, autocrine
Endocrine
through the blood stream
Paracrine
to neighboring cells
autocrine
onto the same cell that is secreting the hormone
what are the three types of hormones
Peptide hormone, steroid hormone, and amino acid derived hormone
peptide hormone
(protein hormone)
- produced in the Rough ER and made of amino acid connected peptide bonds
what action does peptide hormone perform
binds to cell surface receptors because they cannot pass freely through the cell membrane as a result of being water-soluble (and not soluble).
- indirect stimulation
what are two ways the peptide can receive a signal
Secondary messenger and ligand-gated io channels
what are some common secondary messengers
- cAMP (cyclic AMP)
- IP3 (inositol triphosphate)
- DAG (diacylglyercol)
- Calcium ions (CA+2)
G protein coupled receptors (GPCRs)
are cell surface receptors that can initiate a secondary messenger response after binding to a peptide hormone extracellularly
Receptor Tyrosine Kinases
are another cell surface receptor that dimerizes and intimates secondary messenger responses upon binding to a peptide hormone
Signal amplification
the second messenger system of peptide hormone signaling allows for quick and immediate pychsiological changes
ligand-gated ion channels
change the shape upon binding to peptide hormones allowing ions to flow across the cell membrane
- no secondary messenger involved
steroid hormones
produced in the smooth ER and made up of a fused 4-ring structure
- all steroid hormones are derived from cholesterol
what action does steroid hormone perform
requires a protien carrier to travel through the blood stream due to being lipophilic
- Freely crosses the cell membrane and binds to receptors either int he cytoplasm or the nucleus to form molecule-receptor complexes that bind to DNA and influence gene transcription
direct stimulation
Freely crosses the cell membrane and binds to receptors either int he cytoplasm or the nucleus to form molecule-receptor complexes that bind to DNA and influence gene transcription
amino acid derived hormones
can have both properties of peptide hormones and steroid hormones
- produced in rough ER and cytosol
- mainly derived from the amino acid tyrosine
hypothalamus
coordinates the bodies internal enviorment and maintains homeostasis
pituitary gland (hypophysis)
is under the hypothalamus and is composed of tow lobes: Anterior pituitary and posterior pituitary
posterior pituitary
known as neurohypophysis because it was made of neuronal tissue and a direct neuronal extension of the hypothalamus
what are the two hormones that are stored and released by the posterior pituitary (and produced by the hypothalamus)
Antidiuretic hormone (ADH aka vasopressin) and Oxytocin
Antidiuretic hormones (ADH aka vasopressin)
decreases urination by increasing water retention
- targets nephrons increasing the number of aquaporins for water reuptake
oxytocin
causes uterine contraction during child labor and the release of milk during breastfeeding (mammary gland)
- also plays a important role in facilitating maternal behavior )drive to be a good parent)
anterior pituitary
- Known as the adenohypophysis, it is made of glandular tissue, and produces its own hormones.
- It is connected to the hypothalamus through a hypophyseal portal system, which allows for quick diffusion of hormones through a portal vein.
- Hypothalamic-releasing hormones are released by the hypothalamus to stimulate the
anterior pituitary to release other hormones.
GnRH (gonadotropin-releasing hormone)
causes release of luteinizing hormone (LH) and follicle stimulating hormone (FSH).
TRH (thyrotropin -releasing hormone)
causes
release of thyroid stimulating hormone (TSH).
CRH (corticotropin-releasing hormone)
causes release of adrenocorticotropic
hormone (ACTH).
GRH (growth hormone-releasing hormone)
causes release of growth hormone (GH).
Hypothalamic-inhibiting hormones
are released
by the hypothalamus to inhibit the release of other
hormones by the anterior pituitary.
tropic hormones
- anterior pituitary then produces its own hormones
- target other endocrine glands
for further hormone release.
what are some Important
examples released from the anterior pituitary
FSH, LH, ACTH, and TSH
FSH (follicle stimulating hormone)
follicle growth (females) and sperm maturation (males) in the gonads.
LH (luteinizing hormone)
stimulates
ovulation, corpus luteum formation (females), and testosterone production (males) in thegonads.
ACTH (adrenocorticotropic hormone)
stimulates release of glucocorticoids from the adrenal gland to fight stress. This also leads to an increase in glucose levels in the body.
TSH (thyroid stimulating hormone)
stimulates
T3 and T4 production by the thyroid gland to increase metabolism.
Direct hormones
target organs directly for effects.
what are some important examples released from the anterior pituitary
Prolactin and Growth Hormone
Prolactin
stimulates mammary gland development and increases milk production after childbirth.
Growth Hormone (somatotropin)
stimulates body cells to grow and divide.
pineal gland
in the brain produces
melatonin, which regulates circadian rhythm.
thyroid gland
is the largest endocrine organ
and is located in front of the trachea.
what are the three main hormones of the thyroid
triiodothyronine (T3) Thyroxine (T4), and Calcitonin
Triiodothyronine (T3)
released in response
to TSH and increases metabolism in the
body. Has a negative feedback effect on
TSH secretion.
Thyroxine (T4)
- performs the same actions as T3 above. However, T4 has one more iodine and gets converted into T3 upon cell uptake. It is much less potent than T3 but is more stable in the blood.
Calcitonin
secreted by parafollicular
thyroid cells (C cells) to decrease blood
calcium levels. Stimulates osteoblasts to use
up blood calcium to build bone and inhibits osteoclasts. Also decreases calcium uptake in
intestines and kidneys.
Hypothyroidism
describes the under-secretion of T3 and T4, resulting in reduced levels of
metabolism in the body.
Hyperthyroidism
describes the over-secretion of T3 and T4, resulting in increased levels of
metabolism in the body.
goiter
physical enlargement of the thyroid gland
- Iodine deficiency is the most common cause of a goiter.
parathyroid gland
secretes parathyroid
hormone (PTH) which performs in the opposite way as calcitonin
- It stimulates osteoclasts and
decreases calcium uptake by bones.
parathyroid
hormone (PTH)
increases blood calcium levels.
pancreas
is a gland that contains exocrine
and endocrine tissue.
Exocrine tissue
secretes digestive enzymes through the pancreatic duct to the small intestine.
endocrine tissue
secretes glucagon, insulin and somatostatin.
glucagon
secreted by Alpha (α) cells in response
to low blood glucose levels.
- Glucagon raises
glucose levels by stimulating the liver and fat
tissue to release their glucose storages.
insulin
secrete by Beta (β) cells in response to
high blood glucose levels.
- Insulin lowers
glucose levels by stimulating the liver,
muscle, and fat tissue to store glucose.
somatostatin
secrete by Delta (δ) cells which
inhibits growth hormone
- It also inhibits the
secretion of glucagon and insulin.
what are the two types of Adrenal glands
Adrenal Cortex and Adrenal Medulla
adrenal Cortex
Deals with longer term stress.
● Stimulated by secretion of ACTH from the anterior pituitary.
● Releases steroid hormones.
● Produces glucocorticoids (i.e. cortisol) to raise blood glucose levels for immediate fuel
during periods of long-term stress. However, this also lowers our immune response.
● Produces mineralocorticoids (i.e. aldosterone) to increase blood volume and
blood pressure by raising reabsorption of Na+. Water passively gets reabsorbed with
Na+ due to osmosis.
● Produces a small amount of male sex
hormones (androgens).
Adrenal medulla
● Deals with short-term stress.
● Stimulated by the sympathetic nervous
system.
● Releases amino-acid derived hormones.
● Produces catecholamines (epinephrine and
norepinephrine) to initiate “fight or flight”
response by increasing heart rate and the breakdown of glycogen into glucose. Epinephrine binds both alpha (α) and beta (β) adrenergic receptors to cause vasoconstriction (alpha) and vasodilation beta).
what hormone does Ovaries produce
progesterone and estrogen
what hormone does testes produce
androgens and testosterone
Female hormone process with LH and FSH
● LH - during menstrual cycle, the LH surge causes ovulation. This results in the formation of a corpus luteum, which
produces progesterone and estrogen.
● FSH - stimulates follicle growth in ovaries, which results in the increased production of
progesterone and estrogen.
male hormone process with LH and FSH
● LH - triggers testosterone production by
Leydig cells.
● FSH - stimulates sperm maturation.
Positive feedback
- the change causes the amplification of itself, forming a loop that continues to intensify. You can think of it as promoting exponential growth.
Negative feedback
the change causes the inhibition of itself, forming a loop that
prevents hormone overproduction. You can think of it as promoting stability in the body.
feedback systems
- Hormonal control relies on
- which fall under positive and negative feedback
loops.
