Chp 16 Flashcards
The body’s second homeostatic control system is what system
endocrine sytem
what system uses hormones as control agents
endocrine system
how does the endocrine system secrete hormones
Hormones are secreted by endocrine (ductless) glands and tissues
what chemical messengers are released into the blood to regulate specific body functions and in what system?
hormones in the endocrine system
Endocrinology:
the scientific study of hormones and the endocrine organs
Hormones Regulate:
Volume & chemical composition of the extracellular fluid (ECF)
Metabolism and energy balance
Contraction of smooth and cardiac muscle fibers and many glandular secretions
Homeostasis during normal and emergency conditions
Some immune system activities
Coordinated, sequential growth, development, and maturation
Reproduction
Hormones Regulate Reproduction by regulating
- gamete production
- fertilization
- nourishment of the embryo and fetus
- labor and delivery
- lactation for nourishment of the infant
which system is rapid and which is slow
nervous rapid
endocrine is slow
What disease or condition is caused by unmyelination of mylin sheath
MS
multiple sclerosis
which system sends messages via nerve fibers and which sends messages through hormones released into body fluids in the blood
nerve fibers- nervous system
hormones- endocrine
which system has neurotransmitters released at specific effector(s)?
which system has all body cells exposed; only target cells with receptors respond?
nervous system- has neurotransmitters released at specific effector(s)
endocrine system-
all body cells exposed; only target cells with receptors respond
which system has nerve impulses are brief (msecs/seconds), although control can be sustained?
which system has hormones persist for seconds/hours/days?
nervous system has nerve impulses are brief (msecs/seconds), although control can be sustained
endocrine system has- hormones persist for seconds/hours/days
which system has responses of target cells may last seconds/hours/days, even weeks/months?
which system has response of effectors is of relatively short duration (seconds/minutes)?
endocrine system- responses of target cells may last seconds/hours/days, even weeks/months
nervous system has response of effectors is of relatively short duration (seconds/minutes)
what gland secrete hormones into surrounding tissue fluid by exocytosis and the blood transports them to target cells?
Endocrine glands
which glad secrete various compounds by exocytosis into a duct system
Exocrine glands
which glands have extensive capillary blood supply
which glands form a discrete structure/organ
all glands
exocrine and endocrine glands
what glands have both endocrine and exocrine functions?
mixed glands
Six Pure Endocrine Glands
pineal pituitary thyroid parathyroid adrenal cortex/medulla thymus
mixed glands:
- pancreas
- gonads: ovaries & testes
other endocrine tissue
- stomach and intestines
- skin and adipose tissue
- heart
- kidneys
- placenta
neuroendocrine “organs”
Hypothalamus/Pituitary gland
Two types of Chemical Regulators are
Circulating hormones (endocrines) Local hormones
Circulating hormones (endocrines) travel
travel via the blood to reach all tissues, and may affect distant target cells
Local hormones diffuse into
-diffuse into local interstitial fluid, reach and affect only local target cells
Types of local hormones
-paracrine - acts on target cells close to the site of release
-autocrine - acts on the same cell which secreted it
for the various immune system local hormones, see Chapter 21 (cytokines, lymphokines, etc.)
What hormone molecules are usually short lived, and inactivated quickly
local hormones
What hormone molecules linger in the bloodstream, and exert their effects for minutes or hours
Circulating hormones
what hormones are inactivated by enzymes in the target tissues or in the bloodstream or in the liver; some hormones are also eliminated by the kidneys
circulating hormones
what hormones cause kidney or liver disease – may cause problems due to increased hormone levels
circulating hormones
Two main chemical classes of circulating hormones
Amino acid based:
amines - from single amino acids
peptides – short sequences of amino acids
proteins - long chains of amino acids
Steroids: synthesized from cholesterol
end in
OL
or
ONE
lipid
steroid
End in
INE
or
IN
Amine or protien
A third category exists, if local hormones are included in the chemicals of circulating hormones
eicosanoids: synthesized from a cell membrane fatty acid (arachidonic acid)
synthesized from a cell membrane fatty acid (arachidonic acid)
eicosanoids
from single amino acids
amines
short sequences of amino acids
peptides
proteins
long chains of amino acids
Hormones may alter cell activities and metabolism by
Changing membrane permeability or membrane potential by opening or closing gated ion channels
Synthesis of proteins, lipids, or carbohydrates or certain regulatory molecules within the cell
Enzyme activation or deactivation
Induction or suppression of secretory activities
Stimulation of mitosis (and meiosis in the stem cells in the gonads)
Most amino acid, peptide and protein hormones are three things
Are water soluble/lipid insoluble (hydrophilic)
Cannot cross the cell membrane
Need a second messenger to exert their effects
Second Messenger Systems are
Most amino acid, peptide and protein hormones:
Cyclic AMP (cAMP) excitatory stages
1) Hormone A (excitatory) binds membrane receptor, activating Gs
2) Gs stimulates adenylate cyclase (AC)
3) AC forms cAMP from ATP
4) cAMP activates Protein Kinase A
5) PKA: activates/deactivates other enzymes; stimulates cell secretion; opens ion channels, etc.
Cyclic AMP (cAMP) inhibitory stages
1) Hormone B (inhibitory) binds its membrane receptor, activating Gi
2) Gi inhibits adenylate cyclase
3) Antagonistic control
Twice as much activation happens with
second messengers
Two second messengers may
work together (e.g., IP3 & Ca2+)
Activate enzymes and trigger other
intracellular activities
Hormones are in very low concentrations in
body fluids
Hormones they bind how to target cell membrane receptors
reversibly
Second messengers initiate what
a cascade of events (a “snowball” effect) because they activate enzymes that act on other enzymes
This cascade effect does what
amplifies the effect of small quantities of hormone binding to cells
For instance, consider a single hormone molecule binding to a specific receptor on a cell surface
It may activate 10 membrane proteins
Each membrane protein may activate 10 adenylate cyclase enzymes to produce 1000 cAMP’s
This produces a total of 100,000 second messengers in the cell which act on various cytoplasmic enzymes
Each enzyme may then activate hundreds/thousands of other protein molecules
Steroid hormones (derived from cholesterol) are
lipid soluble and penetrate the cell membrane
Bind to cytoplasmic receptors inside the cell
steroid hormones
Hormone-receptor (h-r) complex enters the nucleus, binds to a
DNA receptor protein
Hormone-receptor (h-r) complex enters the nucleus, binds to a DNA receptor protein
This causes
transcription of certain genes, and thus produces specific proteins
This direct gene activation is a slower process, but with longer lasting effects
steroid hormone
Target cells have specific
cell surface or cytoplasmic receptors which bind to a specific hormone
A target cell has how many receptors
2,000 to 100,000 receptors for each hormone to which they respond
target cells have what kind of regulation
down regulation and up regulation
down-regulation
reduction in the number of receptors when a hormone is present in excess so target tissues become less sensitive
up-regulation
increase in the number of receptors when hormone is deficient so that target tissues become more sensitive
Hormone Interactions at Targets are divided into what groups
permissveness
synergism
antagonism
Permissveness
one hormone allows another hormone to cause an effect
example of permissiveness
thyroid hormone permits reproductive hormones to cause their effects on reproductive development
Synergism
effect of two hormones acting together is greater than either acting alone
example of synergism
ex: glucagon and epinephrine together cause more increase in blood glucose than either alone
Antagonism
one hormone has an opposite effect to another hormone
example of antagonism
ex: glucagon elevates blood glucose, insulin lowers blood glucose
Humoral Control/Autocontrol of hormone release
levels of substances in the blood regulate the release of the hormone,
Ca2+ levels in blood regulate PTH release by the parathyroid gland
is an example of
Humoral Control/Autocontrol
Glucose levels in blood regulate insulin and glucagon release by the pancreatic islets
is an example of
Humoral Control/Autocontrol
Na+ and K+ levels in the blood regulate aldosterone release by the adrenal cortex
is an example of
Humoral Control/Autocontrol
Nervous System Control of hormone release
neural input stimulates the release of specific hormones.
what types of hormone release are there
Humoral Control/Autocontrol
Nervous System Control:
Hormonal Control
Sympathetic ANS stimulation of the adrenal glands cause them to release epinephrine and norepinephrine is an example pf
Nervous System Control of hormone release
Nerve impulses from the hypothalamus cause oxytocin release from the posterior pituitary during labor or breast feeding is an example of
Nervous System Control of hormone release
Nerve impulses from hypothalamus cause ADH release from the posterior pituitary when water concentration of blood declines is an example of
Nervous System Control of hormone release
Hormonal Control of hormone release
hormones stimulate the release of other hormones
Neurohormones from the hypothalamus stimulate the anterior pituitary to release hormones which, in turn, stimulate the thyroid gland, the adrenal cortex, and the gonads, respectively, to release their hormones
is an example of
hormonal control
Two structural components with different embryological origins is known as what gland
pituitary
The Master Gland
pituitary gland
how many functional components does the pituitary glands have
two
The pituitary gland has two functional components
anterior pituitary
and
posterior pituitary
Anterior pituitary
does what
- Adenohypophysis
- Primarily glandular tissue
- Synthesizes protein hormones
Posterior pituitary
does what
- Neurohypophysis
- Primarily neuosecretory cells (their cell bodies in the hypothalamus)
- Secretes peptide hormones
- Some support/glial cells
The Pituitary gland Connected to the hypothalamus by the
infundibulum
the pituitary gland vascular linkage
- hypothalamus to the anterior pituitary
- two capillary beds – the hypophyseal portal system
the pituitary gland nervous linkage
- hypothalamus to the posterior pituitary
- hypothalamic neuron axons
Regulation of Pituitary Hormone Release is by
the anterior pituitary gland and posterior pituitary gland
Anterior pituitary
hypothalamic releasing and inhibiting hormones/factors
transported via blood in the hypophyseal
portal system
Posterior pituitary
neuroendocrine release from neurosecretory cells
hormones produced in hypothalamus and
released from axon end bulbs in the posterior lobe
Growth Hormone =
human growth hormone (hGH)
Anterior Lobe / Adenohypophysis
produces what hormone
hGH
sweat glands are called
eccrine
what does the endocrine system do
releases hormones
what is a hormone
a chemical messanger
what other system has chemical messangers
nervous system
example of a nervous system chemical messenger
acetylcholine
what are chemical messengers doing
regulation (increase or decrease) or homeostasis
what are some things chemicals regulate
blood pressure temp cycles rate of metabolism sleep
endocrine system directly secretes hormones where
into the blood stream
endocrine tissue has that name because
is to secrete hormones
ductless system
endocrine system
humoral means
secreting something directly into the blood stream
if we are secreating something into the blod stream we know it is what system
circulatory traveling alongside everything going to the organ or cell its targeting
like boats that are secreted into the blood stream
humoral
key difference between chemical messengers in the endocrine system and nervous system
endocrine has to do with the blood stream nervous has to do with nueromuscular and neuron neuron junctions
which is faster acting and shorter lasting nervous or endocrine
nervous
which are longer lasting and slower to where they need to go? Nervous system, or endocrine
endocrine
Anterior Lobe / Adenohypophysis release stimulated by.... feedback... inhibited by...
- stimulated by GHRH from the hypothalamus
- negative feedback regulation by low blood levels of GH
- inhibited by GHIH (somatostatin) from the hypothalamus
Anterior Lobe / Adenohypophysis actions
targets. ..
stimulates. …
Actions
- targets especially liver, muscle, bone, cartilage; also most tissues
- stimulates growth, mobilizes fats, elevates blood glucose (insulin antagonist
two different types of hormones in relation to how they function
direct
tropic
example of a direct hormone
insulin- because it goes directly to the glucose and then the cell
tropic hormones have what
a middle man are also apart of hte endocrine system
example of a tropic hormone
TSH Thyroid stimulating hormone. Because it first goes to the thyroid gland
Where is TSH secreted
the anterior lobe of the pituitary gland
SH or RH on the end are…
always tropic
will release hormones to effect another endocrine gland /tissue
tropic
endocrine gland releases hormone that targets cells is what type of hormone
direct
endocrine gland releases hormone that targets another endocrine gland
tropic
Posterior lobe of the pituitary gland is what kind of tissue
Neurol tissue
stalk that is above the pituitary gland
infundibulum
anterior lobe of the pituitary gland is also known as
adenohypophysis
anterior lobe of the pituitary gland is also known as
adenohypophysis
posterior lobe of the pituitary gland is an extension of
hypothalamus
the storage spot and released for only two hormones oxytocin
posterior lobe of the pituitary gland or neurohypophysis
oxytocin is invloved and found
is involved in labor and milk let down
found in the posterior lobe if the pituitary gland or neurohypophysis
oxytocin is invloved and found
is involved in labor and milk let down
found in the posterior lobe if the pituitary gland or neurohypophysis
oxytocin has the ability to secrete
happy hormones
milk letdown needs what to happen
oxytocin
where is prolactin hormone (produces milk) produced
anterior lobe of the pituitary gland
ADH is
anti diuretic hormone or vasopressin (protein)
anti diuretics do what
retaining /reabsorption of H2O
where is retaining/reabsorption of h2o happening
in the kidneys
why and what instance would you need to secrete ADH (anti diuretic hormone or vasopressin)
dehydration
what inhibits ADH (anti diuretic hormone or vasopressin)
alcohol
reabsorption of water is caused by what hormone
ADH
storage site of two hormones
posterior lobe of the pituitary gland
the president of the body or the master endocrine gland
anterior lobe of the pituitary gland or adenohypophysis
gland that produces and secretes many tropic hormones
anterior lobe of the pituitary gland or adenohypophysis
Gland responsible for anything with tropic hormones . SH or RH and sometimes IH at the end. Stimulating and releasing
anterior lobe of the pituitary gland or adenohypophysis
Deals with TSH, FSH releasing TRH
anterior lobe of the pituitary gland or adenohypophysis
Two direct hormones of the anterior lobe of the pituitary gland or adenohypophysis
Growth Hormone
prolactin
regulates musculoskelatal growth
Growth Hormone
Not enough of this causes dwarfisim
Growth Hormone
determines how fast or slow and when your epiphyseal plates close
GH
pituitary adenoma
tumor of the anterior lobe of the pituitary
symptoms of pituitary adenoma for a female
producing milk when you aren't suppose to. vision problems. headaches crazy sluggish
FSH and LH are
tropic hormones that affect your ovaries messing up your ovaries progesterone and
Pineal gland secretes
melatonin (sleep cycle regulation)
melatonin is activated by ____ and secreted during ___
sunlight
stage two of REM sleep 2-4am
butterfly shaped organ surrounding the larynx (voice box)
thyroid gland
does TSH get secreted by the thyroid gland
no
where is TSH secreted? And what type of hormone is it? So where is it going?
anterior lobe of pituitary
tropic
the thyroid
thyroid gland secretes
calcitonin
thyroxin
-T3 or T4
if i was diagnosed with hypothyroidism? Would my levels of TH be increased or decreased?
decreased secretion of TH
TIH is what? Comes into play when?
Thyroid inhibiting hormone. If the president (anterior lobe of pituitary gland) talks to the ceo (hypothalamus)
hypothyroid is determined if you have
elevated TH levels. Anterior pituitary determines that
decreased tsh level and increased T3T4 you have
hyperthyroidism
feedback loop always includes the
hypothalamus
hypothalamus sends a signal to the ___ to release TIH
anterior pituitary
the parathyroid releases what hormone and where is it located
parathyroid hormone out of the thyroid gland
parathyroid regulates and increases
blood calcium. osteoclast
TSH stands for…. and is secreted by
Thyroid stimulating hormone
anterior lobe of the pituitary
TSH tropic or direct
tropic… targets thyroid
where is calcitonin secreated by?
thyroid
is there endocrine tissue in other organs?
yes
storage spot for oxytocin, ADH two hormones
posterior part of pituitary gland
ADH
Anti diuretic hormone/vasopressin
Anti diuretic means
reabsorption of h20 in the kidneys
what inhibits adh from being released
alcohol
The president of the body or mast
adenohypophysis
When would you need to secrete adh
dehydration
alcohol does what to adh
inhibits
produces and secretes many tropic hormones
anterior gland
if it has sh, rh or something with an IH at the end means
it is tropic, and from the anterior gland
sh- stimulating
rh- releasing
ih- inhibiting
sometimes IH is
inhibiting
two direct hormones from the anterior
growth hormone, prolactin
how is the growth hormone helping us grow?
it is regulating muscular skeletal growth. how fast or slow your epihyseal plates grow
the GH is from where and what type of hormone
anterior pituitary
and direct
what is a pituitary adenoma
tumor of anterior lobe of the pituitary lobe causing milk production `
FSH and LH are what
tropic hormones from the anterior lobe that affect your ovaries. Affect progesterone and estrogen
Pineal gland does what
secretes melatonin
Does TSH get secreted by the Thyroid gland
no
what secretes TSH and what kind of hormone is it
anterior, topic
what does the thyroid gland secrete
calcitonin and thyroxine (T3, T4)
if I was diagnosed with hypothyroidism would my levels of TSH be increased or decreased? and would the thyroid hormone be increased or decreased
thyroid hormone is low so the anterior lobe of the pituitary gland is increases TSH in an atempt to increase the thyroid hormone
if I was diagnosed with hyperthyroidism would my levels of TSH be increased or decreased?
decreased because there is already too much thyroid hormone in the blood
what two major hormones are involved in the pancreas
insulin and glucagon
what cells secrete the hormones in the pancreas
islets of longerhans
islets of the pancreas
pancreatic ilets
specifically alpha and beta
alpha and beta cells of the pancreas secrete what
alpha cells secretes glucagon
and
beta cells secrete insulin
what is the breakdown process when we eat
first: glucose
and bombarding the blood stream and that sends a message to the beta cells of the pancreas. Since beta cells are their carries they tag on to glucose and take them to the cells to convert that glucose into atp and to any kind of storage as glycogen.
why would glucagon (secreted by alpha cells in the pancreas) be released
in between meals
or in the absence of dietary glucose.
what does glucagon do and where does it get it from
its putting glucose back into the blood stream from stored places. First skeletal muscle then the liver.
the term Diabetes means
passing through
what is there to make sure we have a constant blood glucose level
glucagon
antagonist of insulin
glucagon
mellitus means
sweet
what is passing through in diabetes mellitus
glucose
what is happening in diabetes mellitus
not enough insulin, so the glucose isn’t being absorbed
if we don’t have enough insulin what are we not going to be able to do
store or carry glucose to all the cells. so our body determine
two reasons our body wouldn’t have enough insulin
type one and type two diabetes mellitus
how is type one diabetes mellitus different from type two
type one is an autoimmune disorder (beta cell of the pancreas or the immune system is attacking the beta cells, causing us to not be able to produce enough of it or faulty receptors)
type two is you did this to yourself (genetic predisposition, diet)
diabetes mellitus type one is considered what?
insulin dependent
insulin resistance
when your body is bombarded with sugar
how do you know if a patient is insulin resistant type 2 diabetes mellitus
exhausted
eat all the time still hungry (craving sweets)
Not within normal bmi
and can’t loose weight
non insulin dependent diabetes mellitus. why?
type 2
because it is reversible if you catch it in time. If you don’t change your lifestyle it will change to type 1.
what is prescribed for type two diabetes
glucophage
three cardinal signs of diabetes mellitus (one and two)
1) polydipsia (many thirst)
2) polyphagia (many hunger)
3) polyuria (many urination)
Diabetes insipidus has nothing to with and everything to do with
insulin, glucose, pancreas
and has to do with water
insipid means clear
if someone has diabetes insipidus their urine is
clear
diabetes insipidus is an absence of
ADH- anti diuretic hormone
If I don’t have the ability to release adh or enough of it then what is going to happen
more excreation of everything because it helps us have more water any thing you drink is passing through and not being retained
adh is stored where and made where
the stored in posterior pituitary gland and made in the hypothalamus
What Is an Antidiuretic Hormone (ADH)
is a hormone that helps your kidneys manage the amount of water in your body. It tells your kidneys how much water to conserve.
How does diabetes affect the kidneys?
Diabetes means passing through. So it’s going straight through the blood stream to the urinary system (kidneys).
One glucose molecule is what?
C6H12O6
It’s BIG!
Meaning that as it is going through our kidneys/tiny tubules and bursting the tubs… killing the kidneys causing renal failure
smallest functional unit of the kidney
nephrons
Number two drug in the world
metforman or glucophage
gonad hormone
testosterone
gland that synthesizes protein hormone
anterior pituitary
gland that secretes peptide hormones
posterior pituitary
The Pituitary Gland connected to the hypothalamus by the
infundibulum
Vascular linkage of the pituitary gland
- hypothalamus to the anterior pituitary
- two capillary beds – the hypophyseal portal system
Nervous linkage of the pituitary gland
- hypothalamus to the posterior pituitary
- hypothalamic neuron axons
anterior lobe releases what hormones
GH- Growth Hormone TSH- Thyroid stimulating hormone ACTH- Adrenocorticotropic Hormone FSH-follicle stimulating LH/ICSH- Luteinizing hormone/interstitial cell stimulating hormone Prolactin
posterior lobe releases what hormones
Oxytocin
ADH- Antidiuretic Hormone (vasopressin)
Thyroid Gland releases what hormones
Thyroxine (T4) Triiodothyronine (T3) Amine hormones Tyrosine (Thyro) calcitonin
Parathyroid glands releases what hormones
PTH- Parathyroid Hormone
hypothalamic releasing and inhibiting hormones/factors
transported via blood
in the hypophyseal
portal system
Anterior pituitary
hormones produced in hypothalamus and
released from axon end bulbs in the posterior lobe
Posterior pituitary
Growth Hormone release
- stimulated by GHRH from the hypothalamus
- negative feedback regulation by low blood levels of GH
- inhibited by GHIH (somatostatin) from the hypothalamus
hyposecretion of GH leads to
pituitary dwarfism (normal trunk/limb proportions)
hypersecretion of GH in children and adults leads to
childhood – pituitary gigantism
adulthood - acromegaly
inhibited by negative feedback from the thyroid hormones and GHIH (somatostatin)
TSH
stimulated by:
- TRH from hypothalamus
- indirectly by pregnancy and body temperature
Thyroid Stimulating Hormone (TSH)
targets thyroid gland
stimulates thyroid hormone release (T3 and T4)
Thyroid Stimulating Hormone (TSH)
stimulated by corticotropin releasing hormone (CRH) from hypothalamus
Adrenocorticotropic Hormone (ACTH)
inhibited by negative feedback by glucocorticoids from adrenal gland (and by chronic use of therapeutic anti-inflammatory steroids)
Adrenocorticotropic Hormone (ACTH)
targets adrenal cortex
stimulates release of glucocorticoids (and to a lesser degree – gonadocorticoids, and mineralocorticoids)
Adrenocorticotropic Hormone (ACTH)
hyposecretion of Adrenocorticotropic Hormone (ACTH) causes what dieses
Addison’s Disease
hypersecretion of Adrenocorticotropic Hormone (ACTH) causes what disese
Cushing’s Disease (pituitary tumor)
- stimulated by gonadotropin releasing hormone (GnRH) from hypothalamus
- inhibited by negative feedback
- estrogen and inhibin in females
- testosterone and inhibin in males
Follicle Stimulating Hormone (FSH)
targets ovaries and testes female stimulates ovarian follicle to mature stimulates production of estrogen male - stimulates sperm production
Follicle Stimulating Hormone (FSH)
-Release
-stimulated by GnRH
-inhibited by negative feedback
estrogen and progesterone in females (except during LH surge)
testosterone in males
Luteinizing Hormone (LH) [Interstitial Cell Stimulating Hormone (ICSH) in males]
targets ovaries and testes
- stimulates
- females - ovulation and production of estrogen and especially progesterone
- males – production of androgens, e.g., testosterone
Luteinizing Hormone (LH) [Interstitial Cell Stimulating Hormone (ICSH) in males]
targets breast secretory tissue
stimulates milk production for lactation
prolactin
targets smooth muscle of the uterus and the breast
stimulates uterine contractions and milk ejection/letdown
oxytocin
positive feedback
uterine stimulation (stretch) and suckling stimulate the hypothalamus to release oxytocin from the posterior pituitary
stimulates uterine contractions (labor) and milk letdown
increases feedback for more oxytocin release
inhibited by lack of these stimuli
Oxytocin
(1) targets kidney (ADH effect)
stimulates kidney tubule cells to reabsorb water
NaCl (salt) will be conserved passively to some degree
(2) targets vascular smooth muscle to constrict
elevates blood pressure (vasopressin effect)
Antidiuretic Hormone (ADH) or Vasopressin
stimulated by impulses from hypothalamus in response to:
increased osmolarity (dehydration)
decreased blood volume or blood pressure
stress
inhibited by adequate hydration or ethanol ingestion
Antidiuretic Hormone (ADH) or Vasopressin
Located in the anterior neck inferior to the larynx (“Adam’s apple”)
Thyroid Gland
The largest pure endocrine gland in the body
Thyroid Gland
Two lateral lobes connected by isthmus
Thyroid Gland
formed from an amino acid (AA) –
tyrosine
targets all tissues except adult brain, spleen, testes, uterus and thyroid gland
Thyroid Gland
important regulator of growth and development in conjunction with hGH
Thyroid Gland
stimulates glucose metabolism
increases basal metabolic rate
increases body heat = thermogenesis
Thyroid Gland
decreased levels of thyroid hormones stimulate
TRH and TSH
