endocrine system

gap junctions

avenue of communication from cell to cell; enable cells to pass nutrients, electrolytes, and signaling molecules directly from the cytoplasm of one cell to the cytoplasm of the next through pores in their plasma membranes

neurotransmitters

avenue of communication from cell to cell; released by neurons, diffuse across a narrow synaptic cleft, and bind to receptors on the surface of the next cell

paracrines

avenue of communication from cell to cell; secreted by one cell, diffuse to nearby cells in the same tissue, and stimulate their physiology

hormones

chemical messengers that are transported by the bloodstream and stimulate physiological responses in cells of another, often distant, tissue or organ

endocrine system

the glands, tissues, and cells that secrete hormones

endocrinology

the study of the endocrine system and the diagnosis and treatment of its disorders

endocrine glands

a ductless gland that secretes hormones into the bloodstream

neuroendocrine cells

cells that act like neurons in many respects, but release their secretions into the bloodstream like endocrine cells

target organs

organs that respond to a particular hormone

pituitary gland

The endocrine system's most influential gland. Under the influence of the hypothalamus, regulates growth and controls other endocrine glands.

infundibulum

A stalk that attaches the pituitary gland to the hypothalamus.

anterior pituitary

constitutes about three-quarters of the pituitary as a whole (orange one)

hypophysial portal system

a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is to transport and exchange hormones between the two glands.

posterior pituitary

constitutes the posterior one-quarter of the pituitary (*)

hypothalamo-hypophysial tract

the neural tracts the hypothalamus uses to communicate with the posterior pituitary

releasing hormones

hormones that stimulate a gland to release hormones of its own

inhibiting hormones

hormones that inhibit the release of other hormones

paraventricular nuclei

Hypothalamic nuclei that play a role in eating and synthesize hormones released by the posterior pituitary; releases oxytocin

supraoptic nuclei

hypothalamic nuclei in which the hormones of the posterior pituitary (antidiuretic hormone) are synthesized

gonadotropins

a pituitary hormone that stimulates the gonads

follicle-stimulated hormone (FSH)

anterior pituitary hormone secreted by gonadotropic cells; in the ovaries, it stimulates the secretion of ovarian sex hormones and the development of the follicles that contain the eggs; in the testes, it stimulates sperm production

luteinizing hormone (LH)

anterior pituitary hormone secreted by the gonadotropic cells. in females, it stimulates ovulation and stimulates the corpus luteum to secrete progesterone, a hormone important in pregnancy. in males, it stimulates the testes to secrete testosterone

thyroid-stimulated hormone

anterior pituitary hormone secreted by thyrotropic cells; it stimulates growth of the thyroid gland and the secretion of thyroid hormone, which has widespread effects on metabolic rate, body temperature, and other functions

adrenocorticotropic hormone

anterior pituitary hormone secreted by corticotropic cells; its target organ is the adrenal cortex; stimulates the cortex to secrete cortisol and glucocorticoids which regulate protein, glucose, and fat metabolism and are important in the body's response to stress

prolactin

anterior pituitary hormone that rises proportionately in pregnancy and stimulates the mammary glands to synthesize milk after a woman gives birth

growth hormone

anterior pituitary hormone secreted by somatotropic cells; stimulates mitosis and cellular differentiation and thus promotes tissue growth throughout the body

axis

the anterior pituitary is involved in a chain of events linked by hormones; the hypothalamus secretes a releasing hormone... this induces a type of pituitary cell to secrete its hormone... that hormone is target to another endocrine gland elsewhere... and that gland secretes a hormone with an effect of its own. this relationship is called what?

6; follicle stimulating hormone, luteinizing hormone, thyroid stimulating hormone, adrenocorticotropic hormone, prolactin, growth hormone

how many anterior pituitary hormones are there and what are they?

two; antidiuretic hormone and oxytocin

how many posterior pituitary hormones are there and what are they?

antidiuretic hormone

hormone secreted by the posterior pituitary that increases water retention by the kidneys, reduces urine volume, and helps prevent dehydration; also functions as a brain neurotransmitter and can cause vasoconstriction

oxytocin

a hormone released by the posterior pituitary that has a variety of reproductive functions in situations ranging from intercourse to breast-feeding; it surges in both sexes during sexual arousal and orgasm, functions in feelings of sexual satisfaction and emotional bonding between partners, stimulates labor contractions and flow of milk in pregnant women

neuroendocrine reflexes

the release of hormones in response to nerve signals; controls the posterior pituitary

negative feedback inhibition

the pituitary stimulates another endocrine gland to secrete its hormone, and that hormone feeds back to the pituitary or hypothalamus and inhibits further secretion of the pituitary hormone. this is...

insulin-like growth factors

Anabolic hormone produced by the liver, which is responsible for growth and development; these hormones prolong the action of growth hormone

half-life

the time required for 50% of the hormone to be cleared from the blood

pineal gland

gland responsible for the secretion of melatonin; the size of this gland regresses rapidly and is no mor than a tiny shrunken mass of fibrous tissue in the adult (involutes)

involution

the shrinkage of an organ

melatonin

A hormone manufactured by the pineal gland that produces sleepiness.

thymus

Gland in the thoracic cavity above the heart where T lymphocytes mature.

thyroid gland

the largest adult gland to have a purely endocrine function

thyroid hormone

thyroid gland hormone; secreted or inhibited in response to fluctuations in metabolic rate

parathyroid glands

small pea-like organs that regulate calcium and phosphate balance in blood, bones, and other tissues

parathyroid hormone

hormone of parathyroid glands that regulates blood calcium levels

adrenal glands

a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

adrenal medulla

the inner core of the adrenal gland; secretes epinephrine

adrenal cortex

outer section of each adrenal gland; secretes cortisol, aldosterone, and sex hormones

epinephrine

Neurotransmitter and hormone secreted by the adrenal medulla in response to stress; inhibits the secretion of insulin

stress

any situation that upsets homeostasis and threatens one's physical or emotional well-being

stressors

things that trigger the stress response

stress response

the physical and emotional reactions to a stressor

epinephrine and norepinephrine

what two hormones are involved in the alarm reaction of the stress response?

norepinephrine

hormone released by adrenal medulla that increases alertness and prepares the body in several ways for physical activity

glycogenolysis

hydrolysis of glycogen to glucose

gluconeogenesis

conversion of fats, amino acids, and other noncarbohydrates to glucose

increase

adrenal catecholamines to what to the heart rate and blood pressure, pulmonary airflow, and metabolic rate?

steroids

what type of hormones does the adrenal cortex produce?

angiotensin II

a widespread vasoconstrictor that is activated by a sympathetic reflex when the major arteries detect falling blood pressure

angiotensinogen

a plasma protein produced by the liver that eventually becomes angiotensin I

angiotensin I

Renin converts angiotensinogen into...

angiotensin-converting enzyme

What converts angiotensin I to angiotensin II?

aldosterone

angiotensin II stimulates the adrenal cortex to secrete what hormone?

aldosterone

hormone secreted by the adrenal cortex that stimulates the kidneys to retain sodium which helps to maintain blood pressure and volume

cortisol

stress hormone released by the adrenal cortex; stimulates fat and protein catabolism, gluconeogenesis, and the release of fatty acids and glucose into the blood

pancreas

a gland located behind the stomach that produces insulin and juices that assist in digestion of food in the duodenum of the small intestine

pancreatic islets

parts of the pancreas that have endocrine functions

alpha cells

pancreatic cells that secrete glucagon between meals when the blood glucose concentration falls

glucagon

a hormone secreted by the pancreatic islets that exerts glycogenolysis and gluconeogenesis on the liver

beta cells

pancreatic cells that secrete insulin during and immediately following a meal when blood nutrient levels are rising

insulin

a hormone produced by the pancreas that stimulates cells to absorb glucose, fatty acids, and amino acids and to store or metabolize them, lowering the level of blood glucose and other nutrients; promotes the synthesis of glycogen, fat, and protein, thereby promoting the storage of excess nutrients for later use and enhancing cellular growth and differentiation

delta cells

pancreatic islet cells that secrete somatostatin

somatostatin

hormone secreted by the pancreatic islets that helps to regulate the speed of digestion and nutrient absorption

gonads

ovaries and testes

steroid hormones

hormones that are derived from cholesterol; they include sex steroids produced by the testes and ovaries (estrogens, progesterone, and testosterone)

monoamines

hormones that include dopamine, epinephrine, norepinephrine, melatonin, and thyroid hormone; made from amino acids and retain an amino group

peptide hormones

hormones that are chains of 3 to 200 or more amino acids (the posterior pituitary hormones)

iodine

Which element is needed in the process of synthesizing the thyroid hormone (the only place where this is used)?

thyroglobulin

glycoprotein found in the thyroid that is converted into thyroid hormone; follicle cells synthesize this

no

are hormones secreted at steady rates?

hydrophobi

are steroid hormones hydrophilic or hydrophobic?

transport proteins

to travel in the bloodstream, steroids and thyroid hormone must bind to what?

bound hormone

a hormone attached to a transport protein

unbound hormone

a hormone that is not attached to a transport protein; only this type of hormone can leave a blood capillary and get to a target cell

prolong it

what effect to transport proteins have on the half-lives of hydrophobic hormones?

peptides and catecholamines

what type of hormones cannot penetrate a target cell's plasma membrane and must stimulate its physiology indirectly though second-messenger systems?

steroids

which hormones can pass easily through the plasma membrane of a target cell and mostly go directly into the nucleus and bind to a receptor there?

TH (thyroid hormone)

which hormone enters a target cell by means of an ATP-dependent transport protein?

signal amplification

one hormone molecule triggers the synthesis of not just one enzyme molecule but an enormous number

up-regulation

a cell increases the number of receptors and becomes more sensitive to a hormone

down-regulation

the process in which a cell reduces its receptor population and thus becomes less sensitive to a hormone

synergistic effects

in which two or more hormones act together to produce an effect that is greater than the sum of their separate effects

permissive effects

in which one hormone enhances the target organ's response to a second hormone to come later

antagonistic effects

in which one hormone opposes the action of another

metabolic clearance rate

the rate of hormone removal

alarm reaction

the initial response to stress mediated mainly by norepinephrine from the SNS and epinephrine from the adrenal medulla

angiotensin and aldosterone

what other hormones rise during the alarm reaction?

raises blood pressure

what is the effect of angiotensin in the alarm reaction?

sodium and water conservation

what is the effect of aldosterone in the alarm reaction?

stage of resistance

the body enters this stage of stress if the situation isn't resolved before the glycogen is gone, in which the first priority is to provide alternative fuels for metabolism

cortisol

which hormone promotes the breakdown of fat and protein into glycerol, fatty acids, and amino acids, providing the liver with raw material for gluconeogenesis and inhibiting glucose uptake by most organs? (dominates the stress stage of resistance)

stage of exhaustion

stress stage when fat is depleted and stress overwhelms homeostasis and the body now relies on protein breakdown to meet its energy needs?