BIOLOGY OF BEHAVIOR
JANE MAELYNE LOPEZ
RYAN MATTHEW CASTILEJO
ELIZA LORAINE BERJA
ROB BENEDICT REFORSADO
The endocrine system is made up of the endocrine glands
that secrete hormones. Although there are scattered throughout
the body, they are still considered to be one system because
they have similar functions, similar mechanisms of influence,
& many important interrelationships.
Some glands also have non-endocrine regions that have
functions other than hormone secretion. For example, the
pancreas has a major exocrine portion that secretes digestive
enzymes & an endocrine portion that secretes hormones. The
ovaries & testes secrete hormones & also produce the ova &
sperm. Some organs, such as the stomach, intestines, & heart,
produce hormones, but their primary function is not hormone
1) Glands – Are special secreting organs which pour their secretions
either directly or indirectly into the bloodstream.
Kinds of Glands:
a) Duct Glands or Exocrine Glands – Have ducts or canals through
which they pour out their secretions. These include lacrimal (tear)
glands, sebaceous (sweat), salivary, gastric, mammary glands.
b) Ductless or Endocrine Glands – Pour their secretions called
hormones directly into the bloodstream.
2) Endocrine System - A set of glands that produce hormones-chemical messengers that circulate in the blood. One of the body’s two
communication systems (Nervous & Endocrine System). Derives its
name from the fact that various glands release hormones directly into
the blood, which in turn transports the hormones to target tissues via
ducts. Secretes hormones that coordinate slower but longer-acting
responses including reproduction, development, energy metabolism,
growth, & behavior.
3) Hormone - Chemical messengers produced by the endocrine glands
& circulated in the blood. Chemical messengers carried by blood. May
stimulate other glands. Regulate growth, development, metabolism,
sex processes. “Messenger Molecules.” Reach all parts of the body,
but only target cells are equipped to respond.
Classification of Hormones:
a) Protein Hormones – (comprising small peptides, proteins &
glycoproteins) Are water-soluble thus (1) they don’t require carrier
proteins for circulatory system transport but (2) do require cell
membrane receptors to enter their target cells.
b) Steroid Hormones – Are cholesterol-derived compounds. They are
water insoluble thus (1) don’t require cell membrane receptors but (2)
do require carrier proteins for transport through the circulatory system.
c) Amino Acid Analogues & Derivatives – Include (1) catecholamines
that act like the protein hormones & (2) thyroid hormones that act like
Actions of Hormes: (based on target cells & working distance)
a) Autocrine – Hormone acts locally on the releasing cell & adjacent
b) Paracrine – Hormone acts locally or within an organ system on nonlike cells.
c) Endocrine – Hormone acts distantly via fluid transport on non-like
Mechanisms of Hormone Release:
a) Humoral - In response to changing levels of ions or nutrients in the
b) Neural - Stimulation by nerves.
c) Hormonal - Stimulation received from other hormones.
4) Target Cells – Are cells responding to the hormones for which they
have receptors. Only cells possessing the proper receptors will respond
to hormones; this is what gives the endocrine system its specificity.
5) Homeostasis – Is the (unconscious) maintenance of a constant
internal environment by the organism. Homeostasis is accomplished
by two interconnected systems: (1) the Autonomic Nervous System
(sympathetic, parasympathetic & enteric) which communicates via
nerve impulses resulting in rapid, but typically short-lived responses;
& (2) the Endocrine System which communicates via hormones
resulting in a slower, but more prolonged response.
ELEMENTS OF ENDOCRINE
1) Endocrine cells & glands
2) Hormones – 100+ chemical messengers secreted by endocrine cells
into the intercellular (extracellular) space where they may act locally
(autocrine & paracrine) or be transmitted by adjacent circulatory
systems to act distantly (endocrine).
3) Target cells
A part of the forebrain that sits below (hypo) the thalamus & is
responsible for orchestrating several behaviors that are considered
"maintenance" behaviors such as eating, drinking, sleeping, & body
temperature. In addition, the hypothalamus helps govern the endocrine
system (glands that produce hormones) using the pituitary gland, & is
also involved in feeling emotions & perceiving things are rewarding
(for example, being in love is perceived as a good & rewarding
feeling/emotion & something worth trying to obtain more of). All
vertebrate brains contain a hypothalamus. In humans, it is roughly the
size of an almond.
Uterine contraction & Lactation
Increase in the permeability to
water of the cells of distal tubule
& collecting duct in the kidney &
thus allows water reabsorption &
excretion of concentrated urine
Known as the master gland because part of its function is to control
the endocrine glands. Located near the hypothalamus, the pituitary
gland secretes the most number of hormones. It is divided into two
parts: the posterior pituitary & the anterior pituitary.
As its names suggests, the hypophysis is found beneath the brain
resting within a bony crypt formed by the sphenoid bone.
Anatomically & functionally it is divided into an posterior
neurohypophysis & anterior adenohypophysis.
Causes the uterus to contract
Regulates the amount of urine
being released by the bladder.
Growth hormone or Somatotropin Regulates the amount & tiring of
Is a hormone that stimulates the
thyroid gland to produce thyroxine,
& then triiodothyronine which
stimulates the metabolism of
almost every tissue in the body.
growth, pubertal maturation, &
reproductive processes of the body.
Is a protein that in humans is
probably best known for its role in
enabling female mammals to
Arguably the phylogenetically oldest of the endocrine organs, the
thyroid gland is a bi-lobed gland lying ventral to the (gasp!) thyroid
cartilage of the larynx. It is a compound gland containing 2 sets of
endocrine producing cells: (1) Follicular cells that produce thyroid
hormones & (2) parafollicular cells that secrete calcitonin.
The thyroid gland is a very vascular organ that is located in the
neck. It consists of two lobes, one on each side of the trachea, just
below the larynx or voice box. The two lobes are connected by a
narrow band of tissue called the isthmus. Internally, the gland consists
of follicles, which produce thyroxine & triiodothyronine hormones.
These hormones contain iodine.
It affects almost every physiological process in
the body, including growth & development,
metabolism, body temperature, & heart rate.
Increases cardiac output. Increases heart rate.
(Tetraiodothyronine) Increases ventilation rate. Increases basal
metabolic rate. Potentiates the effects of
catecholamines. Potentiates brain development.
Thickens endometrium in females. increase
metabolism of proteins & carbohydrates.
This protein hormone acts via membrane
receptors to lower blood calcium levels by (1)
suppressing osteoclast activity (bone resorption
& release of calcium) & (2) promoting osteoid
Calcitonin secretion is
regulated by serum levels of calcium.
The suprarenal glands are bilateral, triangular shaped glands
positioned over the superior pole of the kidneys. A thick connective
tissue capsule invests each gland & the parenchyma is divided into
two regions, cortex & medulla.
The orange-colored 2 adrenal glands are located just above both
kidneys. It consists of two parts: the outer cortex & the inner medulla.
The adrenal cortex produces steroids that plays important role in
maintenance of blood pressure & regulation of the breakdown of
secretes hormones that help in the body’s reaction to stress.
Situated along the perimeter of the adrenal gland, the adrenal
cortex mediates the stress response through the production of
mineralocorticoids & glucocorticoids, including aldosterone & cortisol
respectively. It is also a secondary site of androgen synthesis.
The suprarenal cortex is divided into 3 zones based on the
arrangement of their cells. The zona glomerulosa is the most
superficial & its cells are arranged in ovoid clusters surrounded by
sinusoidal capillaries. The zona fasciculata is the middle cortical layer
& its cells are arranged in long straight cords surrounded by sinusoidal
capillaries. The zona reticularis is the deepest layer of the cortex & its
cells are arranged in interwoven cords separated by capillaries.
The adrenal medulla (Latin: suprarenal medulla) is part of the
adrenal gland. It is located at the center of the gland, being surrounded
by the adrenal cortex. It is the innermost part of the adrenal gland,
consisting of cells that secrete epinephrine (adrenaline),
norepinephrine (noradrenaline), & a small amount of dopamine in
response to stimulation by sympathetic preganglionic neurons.
These hormones, such as Aldosterone
controls the body’s sodium, potassium &
Are steroids, like cortisone & cortisol,
which aids carbohydrates, fat & protein
metabolism in the body.
Are responsible for the secondary sex
Regulates the sympathetic nervous
system, such as making the heart beat
fast, increase blood pressure, dilation of
pupils & other involuntary body
functions during stress.
Maintains normal blood circulation &
increases blood pressure by constricting
the blood vessels.
(OVARIES & TESTES)
The gonad is the organ that makes gametes. The gonads in males
are the testes, & the gonads in females are the ovaries. The product,
gametes, are haploid germ cells. For example, spermatozoon & egg
cells are gametes.
Are the reproductive glands – testes or testicles in male & ovaries
in female. The testes & ovaries have the main function of stimulating
the reproductive organs to become mature & produce the sperm cells
for males & egg cells for females.
Testosterone/Androgen The principal male hormone which is
responsible for the appearance of
secondary sex characteristics such
as growth of beard & public hair,
deepening of voice & increased in
Female sex hormone that regulates
the secondary sex characteristics –
development of the breast, widening
of pelvic bones & growth of public
Another female sex hormones,
menstruation & lactation in pregnant
Hypothal- Hypopituitar Hypothalamic disease may cause insufficient
or inhibited signalling to the pituitary
leading to deficiencies of one or more of the
following hormones: thyroid-stimulating
hormone, adrenocorticotropic hormone,
follicle-stimulating hormone, & melanocyte–
Neurogenic Neurogenic diabetes insipidus may occur
due to low levels of ADH production from
the hypothalamus. Insufficient levels of
ADH result in increased thirst & urine
output, & prolonged excessive urine
excretion increases the risk of dehydration.
Secondary hypothyroidism occurs
Hypothyroidism when TSH secretion from the
pituitary is impaired, whereas
tertiary hypothyroidism is the
deficiency or inhibition of TRH.
Developmental Insufficient GH production may
cause poor somatic growth,
gonadotropin deficiency, failure to
initiate or complete puberty, & is
often associated with rapid weight
gain, low T4, & low levels of sex
A condition where there is
excessive amount of urine excreted
in the body making the individual
dehydrated & weak, which
increased thirst & urination
of A condition cause by the water
intoxication due to the retention of
fluid in the body.
A condition when there is too little
growth of hormones during
childhood characterize by being
miniature. It is mark by
Occurs when the deficiency of
growth hormones is after puberty
resulting to having small bones of
Cause by excessive growth
hormones during childhood that
leads to over growth of skeletal
A condition due to excessive
production of growth hormone in
adults mark by overgrowth of
extremities (hands, feet & face).
Hyperthyroidism, or overactive thyroid, is
due to the overproduction of the thyroid
hormones T3 & T4, which is most
commonly caused by the development of
Graves' disease, an autoimmune disease in
which antibodies are produced which
stimulate the thyroid to secrete excessive
quantities of thyroid hormones The disease
can result in the formation of a toxic goiter
as a result of thyroid growth in response to
a lack of negative feedback mechanisms.
Hypothyroid- Hypothyroidism is the underproduction of
the thyroid hormones T3 & T4.
Thyroid neoplasm is a neoplasm or tumor
of the thyroid.
Thyroid cancer is a malignant neoplasm
parafollicular thyroid cells.
Inflammation of the thyroid.
A goitre or goiter, is a swelling of the neck
or larynx resulting from enlargement of
the thyroid gland, associated with a
thyroid gland that is functioning properly
It is characterize by moon-shaped face,
obesity, easily bruised skin & poor healing
Adrenogenital Cause by excessive adrenal androgen &
more mark in women than in men
symptoms include hirsutism, amenorrhea,
deepening of voice & decrease breast size.
Undersection of glucocorticoids could
result to this disorder. The symptoms
exhibited are weakness, fatigue, weight
less, low blood pressure & tanning
without exposure to the sun or
A syndrome characterize by
Sterility, Diminishes Sexual drive & Amenorrhea
Failure of sexual characteristics to develop