BioL Exam 3 Ch 9: Endocrine System

pituitary gland

hypertrophy of what gland would result in an abnormally high level of growth hormone (GH)

chemical/ electrical

what two types of intercellular communication does the nervous system use as signaling mechanisms

chemical

what type of intercellular communication does the endocrine system use as a signaling mechanism

hormones

what is the primary chemical signal of the endocrine system

neurotransmitters

what is the primary chemical signal of the nervous system

long or short

what is the distance traveled of endocrine hormones

relatively short

what is the distance traveled of signals in the nervous system

fast or slow

what is the response time of the endocrine system

always fast

what is the response time of the nervous system

internal

what is the environment targeted in the endocrine system

internal and external

what is the environment targeted in the nervous system

endocrine system

consisting of cells, tissues, and organs that secrete hormones as a primary or secondary function

endocrine glands

what are the “major players” of the endocrine system

endocrine gland

tissue or organ that secretes hormones into the blood and lymph without ducts such that they may be transported to organs distant from the site of secretion

ductless endocrine/ exocrine glands containing ducts

what are the two types of endocrine glands

ductless endocrine glands

secrete hormones directly into the bloodstream

hypothalamus, pituitary, pineal glands

3 primary endocrine system organs

release digestive enzymes

exocrine function of the pancreas

regulate blood glucose levels

endocrine function of the pancreas

thyroid gland

• butterfly-shaped gland that wraps around the trachea within the neck

• large endocrine gland responsible for the synthesis of thyroid hormones

parathyroid gland

• small, round glands embedded in the posterior thyroid gland that produce parathyroid hormone (PTH)

adrenal glands

glands located on top of the kidneys

epinephrine

what is the primary neurotransmitter in the nervous system; aka adrenaline

circulating hormones

hormones secreted into the extracellular fluid and diffuse into the blood or lymph, where they can be carried throughout the body

local hormones

hormones that act upon neighboring cells or the original cell that secreted them

autocrine signaling

chemical signal that elicits a response in the same cell that secreted it

interleukin-1

a signaling molecule that plays a primary role in the inflammatory response

paracrine signaling

chemical signal that elicits a response in neighboring cells

amine/ peptide/ protein hormones

three types of water-soluble hormones

amine hormones

hormones that are made from amino acids and contain a −NH3+ chemical group

• epinephrine/ norepinephrin

• dopamine

• melatonin

epinephrine/ norepinephrine

• amine hormone causing fight or flight response

• made from tyrosine is secreted by adrenal medulla

dopamine

• amine hormone that inhibits release of certain anterior pituitary hormones

• made from tyrosine is secreted by hypothalamus

melatonin

• amine hormone that regulates circadian rhythm

• made from tryptophan is secreted by pineal gland

adrenal medulla

inner layer of the adrenal glands that plays an important role in the stress response by producing epinephrine and norepinephrine

anterior pituitary gland

anterior lobe of the pituitary gland that secretes hormones in response to releasing hormones from the hypothalamus (also called adenohypophysis)

posterior pituitary gland

posterior portion of the pituitary gland made up of neural tissue (also called neurohypophysis)

peptide hormones

• short chains of amino acid

• Oxytocin is synthesized by the hypothalamus and released by the posterior pituitary

protein hormones

• longer polypeptide chains

• growth hormone is produced by pituitary gland

• insulin is produced by pancreas

• thyroid-stimulating hormones

lipid soluble hormones

• hormones derived from lipids or have lipid-like characteristics

• hydrophobic

water soluble hormones

• hormones derived from amino acids

• hydrophilic

• must bind to transport proteins to travel to target cells

• circulates in body longer

steroids, thyroid hormones, nitric oxide, eicosanoids

4 lipid soluble hormones

steroid

• lipid soluble hormone derived from cholesterol

• testosterone and estrogen produced by the gonads

• aldosterone produced by adrenal glands → regulate electrolyte concentrations

• cortisol produced by adrenal glands → regulate metabolism

thyroid hormones

• lipid-soluble hormones

• synthesized by attaching iodine to the amino acid tyrosine

• have two hexagonal benzene rings, and these structures make them very lipid-soluble

nitric oxide

• lipid soluble hormones

• a gas that acts as a hormone and neurotransmitter plays a critical role as a vasodilator that relaxes the smooth muscle in blood vessels, causing them to widen

eicosanoids

• lipid soluble hormone

• derived from arachidonic acid, a 20-carbon fatty acid

• act more as paracrine factors and local hormones as they tend to travel limited distances in the body

• prostaglandins and leukotrienes

hormone receptor

protein within a cell or on the cell membrane that binds a hormone, initiating the target cell response

feedback loops/ chemical changes in blood/ signals from nervous system

three main ways to control hormone secretion

cyclic adenosine monophosphate

the second messenger used by most hormones (cAMP)

calcitonin/ glucagon/ thyroid stimulating hormone

three hormones that use cAMP as a secondary messenger

positive feedback loop

• mechanism that intensifies a change in the body’s physiological condition in response to a stimulus

• the release of additional hormones in response to hormone release

• ex: the release of oxytocin during childbirth

negative feedback loop

• more common

• homeostatic mechanism that tends to stabilize an upset in the body’s physiological condition by preventing an excessive response to a stimulus, typically as the stimulus is removed

• ex: the release of glucocorticoid hormones such as cortisol from the adrenal glands

humoral stimuli

• related to body fluids

• changes in blood levels of non-hormone chemicals, such as nutrients or ions

• change in the chemical composition of the blood causes the release or inhibition of a particular hormone

high blood glucose levels

what causes a release of insulin from the pancreas

neural stimuli

• signal from the nervous system

• ex: activation of fight-or-flight response

hypothalamus

region of the diencephalon inferior to the thalamus that functions in neural and endocrine signaling

pituitary gland

bean-sized organ suspended from the hypothalamus that produces, stores, and secretes hormones in response to hypothalamic stimulation (also called hypophysis)

hypophyseal portal system

network of blood vessels that enables hypothalamic hormones to travel into the anterior lobe of the pituitary without entering the systemic circulation

oxytocin

hypothalamic hormone stored in the posterior pituitary gland and important in stimulating uterine contractions in labor, milk ejection during breastfeeding, and feelings of attachment (produced by males and females)

osmoreceptors

hypothalamic sensory receptor that is stimulated by changes in solute concentration (osmotic pressure) in the blood

growth hormone

anterior pituitary hormone that promotes tissue building and influences nutrient metabolism (also called somatotropin)

thyroid stimulating hormone

anterior pituitary hormone that triggers secretion of thyroid hormones by the thyroid gland (also called thyrotropin)

adrenocorticotropic hormone

anterior pituitary hormone that stimulates the adrenal cortex to secrete corticosteroid hormones (also called corticotropin)

follicle stimulating hormone

anterior pituitary hormone that stimulates the production and maturation of sex cells

luteinizing hormone

anterior pituitary hormone that triggers ovulation and the production of ovarian hormones, and the production of testosterone

prolactin

anterior pituitary hormone that promotes development of the mammary glands and the production of breast milk

trophic hormones

hormones that affect growth, function, or nutrition of other endocrine cells

tropic hormones

hormones that have other endocrine glands as their target