THE ENDOCRINE SYSTEM Flashcards
the endocrine system
a complex and critical regulatory system in the human body, responsible for controlling and coordinating various physiological processes through the secretion and circulation of hormones
the endocrine system is often referred to as a ductless system, true or false
true
endocrine glands are ductless, true or false
true
the pancreas has endocrine and exocrine functions, true or false
true
name some purely endocrine glands
Pituitary gland
Pineal gland
Thyroid gland
Parathyroid glands Adrenal: 2 glands(medulla and cortex)
name some endocrine cells that are also found in other cells
Pancreas
Thymus
Gonads
Hypothalamus
what are the components of the endocrine system
endocrine glands
hormones
how does the endocrine system act as a communication system
through hormonal signalling(chemical systems)
through remote communication systems, which provide the means to control a huge number of physiological processes
endocrine glands
ductless glands comprised of endocrine cells
endocrine glands release hormones directly into the blood stream, true or false
true
pheromones
chemical substances produced and released by animals and even some plants to communicate with others of the same species. They are released outside of the body
hormones can act on both local and distant target cells, true or false
true
autocrine signalling
this is when hormones are released by a cell to activate the same cell
paracrine signalling
when hormones are released by a cell to activate neighbouring cells
target cells
Target cells refer to cells that contain specific receptors (binding sites)for a particular hormone.
all cell types respond in the same way to the same hormone, true or false
false
which 3 types of hormones are typically considered as the most important
Peptide Hormones
Amino Acid Derivatives
Steroid Hormones
what are some actions carried out by hormones
Fetal development and differentiation
Cell growth and cancer Metabolism
Cardiovascular function Renal function
Skeletal function Reproductive function Immune function
Central nervous system function
lipophilic hormones
examples
which receptors do they bind to
fat-soluble hormones
steroid hormones, thyroid hormones
intracellular receptors
hydrophilic hormones
examples
what receptors do they bind to
water- soluble hormones
all other hormones apart from steroid and thyroid hormones
binds to extracellular receptors
peptide hormones
where are they synthesized
where are they stored
lipophilic or hydrophilic
where are receptors found on target cells
hormones that are comprised of chains of amino acids
Synthesized on ribosomes of the (rough) ER of endocrine cells
Can be stored in vesicles in endocrine cells
water soluble
Receptors are found on the cell surface of their target cells.(extracellular)
vasopressin hormones are also known as
antidiuretic hormones
the types of amino acid derivative hormones
tyrosine derivatives
tryptophan derivatives
the two most important tyrosine-derived hormones
Catecholamines, e.g, epinephrine(adrenaline), norepinephrine(noradrenaline), and dopamine
Thyroid Hormones, e.g, T4(Thyroxine) and T3(Triiodothyronine)
the two most important examples of tryptophan-derived enzymes
melatonin
serotonin
steroid hormones
produced by?
derived from?
can they be stored in vesicles?
where are it’s receptors located on target cells?
a class of hormones that are derived from cholesterol and have a characteristic chemical structure
the gonads, the adrenal cortex, and the kidneys.
cholesterol
no
inside the target cells
why can steroid hormones not be stored in vesicles
because;
they are highly lipid soluble, and can therefore easily diffuse through the cell membrane, without needing any vesicular storage
they are also produced on demand, and are synthesised only when needed, rather than being synthesised and needing to be stored in vesicles for later release
homeostasis
a fundamental biological concept that refers to the body’s ability to maintain a stable and balanced internal environment despite changes and challenges in the external environment.
negative feedback
turns off a signal in response to a change in the body. it is homeostatic
positive feedback
where a signal amplifies a signal (vicious cycle).I.e. Child birth. Not homeostatic
chromaffin cells
are neuroendocrine cells found in the medulla of the adrenal glands
Adrenal gland functions?
neurohormones
a special category of hormones that are produced and released by nerve cells (neurons) rather than endocrine glands
examples of neurohormones
oxytocin
vasopressin
Corticotropin-Releasing Hormone (CRH)
Thyrotropin-Releasing Hormone (TRH)
etc
where are neurohormones released into
the bloodstream, instead of the synaptic cleft
which type of cells synthesise and release catecholamines
chromaffin cells
the neurohormones, oxytocin and vasopressin are stored where?
in the posterior pituitary gland
where particularly in the brain are neurohormones produced
hypothalamus
where are releasing hormones produced
where do they exert their hormonal action
hypothalamus
in the anterior pituitary gland
the mechanisms of hormone release(and their description)
humoral(in response to changing levels of ions or nutrients in the blood)
neural( in response stimulation by nerves)
hormonal(in response to stimulation received from other hormones)
which components of the brain work together as the main regulators of the endocrine system
hypothalamus and pituitary gland
what is the size of the pituitary gland, and where is it located
it is pea-sized, and located in the base of the skull(sella turcica), underneath the brain and behind the bridge of the nose.
the anterior pituitary gland is aka
adenohypophysis
the pituitary gland is also known as the
hypophysis
the posterior pituitary gland is aka
neurohypophysis
name five functions(or more) of the hypothalamus
Regulation of Body Temperature
Control of Hunger and Satiety:
Sleep-Wake Cycle Regulation
Water Balance and Thirst
Endocrine Function via Pituitary Gland
Emotional and Behavioral Responses
Control of Autonomic Nervous System
Reproduction and Sexual Function
Integration of Neuroendocrine Responses
which part of the brain is the Posterior pituitary gland attached to
the hypothalamus
briefly describe what you know about the anterior pituitary gland
The anterior of the pituitary gland is composed of six distinctive endocrinocytes (one for each hormone)
Under control by the hormones released by the hypothalamus
function of the hypophyseal portal system
serves as a specialized vascular connection that enables precise and rapid communication between the hypothalamus and the anterior pituitary.
where are peptide hormones synthesized and stored in the posterior pituitary gland
Peptide hormones are synthesized in the cell bodies of hypothalamic neurons
they are stored in the axon terminals of these neurons
where in the brain do cell bodies and axon terminals of the hypothalamic neurons lie
cell bodies lie within the hypothalamus and axon terminals lie within the posterior pituitary gland
when activated, where are hormones released from the axon terminal of hypothalamic neurons into
the hypophyseal vein
functions of trophic hormones
they regulate the functions of other hormones
hormones found in the posterior pituitary gland
ADH and oxytocin
hormones found in the anterior pituitary gland
TSH: thyroid-stimulating hormone
ACTH: adrenocorticotropic hormone
FSH: follicle-stimulating hormone
LH: luteinizing hormone
PRL: prolactin
GH: growth hormone
which hormones in the anterior pituitary gland are classified as trophic hormones
TSH
ACTH
FSH
LH
function of prolactin and in which gender it is found
breast development and milk production
found in males and females
function of GH
growth and puberty. Levels decrease throughout the lifespan
function of ACTH
stimulates the adrenal gland to release corticosteroids. Important for responding to stress
function of LH
Triggers ovulation (f)and stimulates androgen (m)secretion by the testis
function of FSH
Stimulates growth and maturation of ovarian follicles, and oestrogen production from ovaries (f) and FSH stimulates the testes, specifically the Sertoli cells within the testes, to support spermatogenesis (m)
function of TSH
stimulates thyroid to release thyroid hormone. Thyroid hormones involved in regulating metabolism
function of ADH
water retention and vessel constriction
function of oxytocin
uterine contraction ,milk ejection during breast feeding, fosters social interaction
what are the two classes of hormones secreted by the hypothalamus
releasing hormones(RH)
inhibiting hormones(IH)
functions of the releasing hormones
stimulate the synthesis and secretion of one or more hormones at the anterior pituitary
functions of IH(inhibiting hormone)
prevent the synthesis and secretion of hormones from the anterior pituitary
the hypothalamus receives input from?
the cortex
thalamus
limbic system
what are some examples of stimulating hormones and their functions (at least three)
Thyrotropin-releasing hormone (TRH)- release of TSH
Gonadotropin-releasing hormone (GnRH)- release of FSH and LH
Growth hormone-releasing hormone (GHRH)- release of GH
Corticotropin-releasing hormone (CRH)- release of ACTH
Prolactin-releasing hormone (PRH)- release of prolactin
some examples of inhibiting hormones and their functions
Growth hormone-inhibiting hormone GHIH- inhibit GH
Dopamine – inhibit prolactin
what would happen if the pituitary gland fails
Diabetes insipidus due to too little ADH
Acromegaly due to too much GH in adulthood Gigantism due to too much GH in childhood
what are the two hormones produced by the thyroid gland
Thyroid hormone(TH)
Calcitonin
what causes gigantism and acromegaly
tumours of the anterior pituitary gland
cells that produce calcitonin
Parafollicular “C” cells
cells t produce thyroglobulin
follicle cells
prohormone
a substance that the body can convert into a hormone. prohormones have minimal hormonal effects by themselves
which one between the thyroid hormones T4 and T3 is a prohormone
T4
which is more stable, T3 or T4
T4 is more stable than T3. T3 has a vey shore half life
which between T3 and T4 acts as a reservoir for the other
T4
primary action of T3 and T4
to increase body BMR (Basal metabolism rate)
how is calcitonin release related to calcium ions
they are released when calcium levels are high
function of calcitonin
involved in calcium and phosphorus metabolism
