The endocrine

The Endocrine System | Bachelor in Political Science II-1

ENDOCRINE GLANDS


• Glands - an organ in the human or animal body that secretes particular chemical substances for use in the body or for discharge into the surroundings.

• Target cells - a cell that bears receptors for a hormone, drug, or other signaling molecule, or is the focus of contact by a virus,

phagocyte, nerve fiber, etc.• Receptor - an organ or cell able to respond to light, heat, or other

external stimulus and transmit a signal to a sensory nerve.

• Corpus luteum - a hormone-secreting structure that develops in an ovary after an ovum has been discharged but

degenerates after a few days unless pregnancy has begun.

Definition of Terms


• Spermatogenesis - the production or development of mature spermatozoa.

• Ovarian follicles - a fluid-filled structure in the mammalian ovary within which an ovum develops before

ovulation.• Biorhythms - a recurring cycle in the physiology or functioning of an

organism, such as the daily cycle of sleeping and waking.

Definition of Terms


Posterior pituitary gland

• (or neurohypophysis) Comprises the posterior lobe of the pituitary gland which is part of the endocrine system.


Oxytocin

Secreted Hormones

Location:• Uterus• Mammary glandsFunction: • Stimulates contraction• Stimulates milk ejection


Antidiuretic hormone (ADH)

Secreted Hormones

Location: KidneysFunction: Stimulates re-

absorption of water; conserves water


Anterior Pituitary Gland

• Also called the adenohypophysis or pars anterior

• The glandular, anterior lobe that together with the posterior lobe, that makes up the pituitary gland .


Secreted Hormones

Growth hormone (GH) Function:• Stimulates growth

by promoting protein synthesis and fat breakdown


Secreted HormonesAdrenocorticotropic

hormone (ACTH) Location: Adrenal cortex

Function:• Stimulates secretion

of adrenal cortical hormones such as cortisol


Secreted Hormones

Thyroid-stimulating hormone (TSH) Location: Thyroid gland

Function:• Stimulates thyroxine

secretion


Secreted HormonesLuteinizing hormone

(LH)Location: GonadsFunction:• Stimulates ovulation

and corpus luteum formation in females; stimulates secretion of testosterone in males


Secreted Hormones

Prolactin (PRL) Location: Mammary glands

Function:• Stimulates milk

production


Secreted HormonesFollicle-stimulating

hormone (FSH)Location: GonadsFunction:• Stimulates

spermatogenesis in males; stimulates development of ovarian follicles in females


Secreted Hormones

Melanocyte-stimulating hormone (MSH)Location: SkinFunction:• Stimulates color

change in reptiles and amphibians; unknown function in mammals

Thyroid Gland

• The thyroid gland is found in the neck, below the thyroid cartilage (which forms the laryngeal prominence, or "Adam's apple")



Secreted Hormones

Thyroxine (thyroid hormone) Location: Most cells

Function:• Stimulates metabolic

rate; essential to normal growth and development


Secreted Hormones

CalcitoninLocation: BoneFunction:• Lowers blood calcium

level by inhibiting loss of calcium from bone

Parathyroid Glands

• Small endocrine glands in the neck that produce parathyroid hormone



Secreted HormonesParathyroid hormoneLocation:• Bone• Kidneys• Digestive tractFunction:• Raises blood calcium level by stimulating bone

breakdown; stimulates calcium reabsorption in kidneys; activates vitamin D

Adrenal Medulla

• Part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex.



Secreted Hormones

Epinephrine (adrenaline) and norepinephrine (noradrenaline)Location: Smooth muscle,cardiac muscle,blood vesselsFunction:• Initiate stress responses; raise heart rate, blood

pressure, metabolic rate; dilate blood vessels; mobilize fat; raise blood glucose level

Adrenal Cortex

• Mediates the stress response through the production of mineral ocorticoids and glucocorticoids, including aldosterone and cortisol respectively



Secreted Hormones

Aldosterone Location: Kidney tubulesFunction:• Maintains proper

balance of Na+ and K+ ions


Secreted Hormones

CortisolLocation: Many organsFunction:• Adaptation to long-term

stress; raises blood glucose level; mobilizes fat

Pancreas

• A glandular organ in the digestive system and endocrine system of vertebrates



Secreted Hormones

Insulin Location: Kidney tubules Function:• Lowers blood glucose level; stimulates storage of glycogen in liver


Secreted HormonesGlucagon Location: Liver, adipose

tissueFunction:• Raises blood glucose level; stimulates breakdown of glycogen in liver

Ovary

• An ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system



Secreted Hormones

Estradiol Location: GeneralFunctions:• Stimulates development of secondary sexcharacteristics in femalesLocation: Female reproductive structuresFunctions: • Stimulates growth of sex organs at puberty and monthly preparation of uterus for pregnancy


Secreted Hormones

Location: UterusFunction:• Completes preparation

for pregnancyLocation: Mammary

glandsFunction:• Stimulates

development

Progesterone

Testis

• The primary functions of the testes are to produce sperm(spermatogenesis) and to produce androgens, primarily testosterone.



Secreted Hormones

TestosteroneLocation: Many organsFunctions:• Stimulates development of secondary sexcharacteristics in males and growth spurt at pubertyLocation: Male reproductive structuresFunctions:• Stimulates development of sex organs; stimulatesspermatogenesis

Pineal Gland

• Also known as the pineal body, conarium or epiphysis cerebri

• A small endocrine gland in the vertebrate brain.



Secreted HormonesMelatoninLocation: Gonads, pigment cellsFunctions:• Function not well understood; influencespigmentation in some vertebrates; may controlbiorhythms in some animals; may influenceonset of puberty in humans

Target Cells


What is target cells?


Three actions are defined to be able to describe how the signal is distributed for a particular hormonal pathway:

• Endocrine action• Paracrine action• Autocrine action


Two important terms are used to refer to molecules that bind to the hormone-binding sites of receptors:

• Agonists• Antagonists


Education

The endocrine