Endocrine Flashcards
Endocrine system: The cells, tissues and organs are called endocrine ________ and the chemical messengers, _______ they secrete
glands
hormones
What are some examples of the most familiar hormone sources that are the endocrine glands
pituitary, thyroid, and adrenal gland
Hormones are also secreted by organs and tissues not usually thought of as glands like
the brain, heart, small intestine, bones, and AT
What is the classic distinction between endocrine and exocrine glands?
ducts
Most exocrine glands secrete their products by way of a ________ onto an epithelial surface
duct (exoskeletons hide in ducts)
do exocrine secretions have extracellular or intercellular effects?
exocrine = extracellular (altering cell metabolism)
which glands, in contrast, are ductless and release their secretions into the bloodstream
endocrine (en-do the bloodstream)
do endocrine have extracellular or intercellular effects?
intercellular
Endocrine glands have a high density of blood capillaries, which are highly permeable type called _____________ capillaries
fenestrated
what do fenestrated capillaries look like?
have patches of large pores on their walls
T or F: Some glands and secretory cells are not easily classified as one or the other type
T
what are some examples of organs that fall into the not easily identified category
- liver cells (secrete into bile and hormones into the blood)
- pancreas cells (secrete insulin / glucagon and dig enzymes that go thru a duct in the small intestine)
what are the two systems that complement each other rather than duplicate each others function
nervous and endocrine system
neurons release ________ into a synapse affecting postsynaptic cells
neurotransmitters
Endocrine glands release hormones into the bloodstream that bind to and affect specific target cell __________
receptors
Hormones are produced by one cell in an endocrine gland, is this designed to affect a cell close by or some distance away
some distance away (= target cell or target organ)
what is the difference of the NS vs hormone (endocrine) reponse
- NS: few milliseconds
- hormone: several seconds - days
what is the difference when stimulus ends?
- NS: stops response almost immediately
- Endocrine: may persist for several days/weeks
long term stimulation for both?
- NS: most neurons adapt and response declines
- endocrine: more persistent
so what can be said about the endocrine (hormone) response?
it may take longer to generate but it lasts longer and bigger effect
- An efferent nerve fiber innervates only one organ and a limited number of cells, so its effects are targeted, while in contrast, hormones circulate throughout the body and have more ____________ effects.
widespread
Some hormones, such as oxytocin and epinephrine, are secreted by ___________________ cells
neuroendocrine
what are neuroendocrine cells?
neurons that release secretions into the bloodstream
what is an example of hormones and neurotransmitters produce overlapping effects on the same targets
epi and noepi acting on the heart cells
How do the 2 systems regulate each other?
neurons can trigger hormone secretion, and hormones can stimulate or inhibit neurons
Both neurotransmitters and hormones depend on __________ on the receiving cells
receptors (specificity and target)
T or F: Hormones have powerful effects when present in very low concentrations (uL).
T
What are the 3 classes of hormones
- steroids
- peptides
- monoamines
what class? Lipid based hormones derived from cholesterol
steroid hormones
what is an example of a steroid hormone?
testosterone and estrogen
what class? Come from single amino acids which typically act on cell surface receptors
monoamines (biogenic amines)
example of monamines
epi and norepi
what class? Chains of AA that can not easily cross the cell membrane
peptide (protein) hormones
Example of a peptide hormone
insulin
rank the hormone classes from easily pass through cell membranes (1) to not easily crossing the cell membrane at all (3)
- steroid (easy)
- monoamine
- peptide (hard)
T or F Hormones stimulate ONLY those cells that have receptors for them
T
what is an analogy for a receptor ?
A switch - turns certain metabolic pathways on or off when the hormone binds to them
T or F: A receptor for one hormone will not bind other hormones.
True
Responsiveness of a target cell to a hormone depends on (2)
- hormones conc
- abundance of receptors
Hormones cause changes in cellular ___________
metabolism
how can hormones cause changes in the cellular metabolism of the target cell?
synth new molecules, cell membranes permeability will change, change rate of reactions
At liver cells— __________ stimulates glycogen synthesis
insulin
At adipocytes—________ stimulates triglyceride synthesis
insulin
Most hormone synthesis and release is regulated through (negative or positive) feedback mechanisms.
negative feedback mechanisms
Feedback from target organs also regulates the pituitary and hypothalamus through feedback loops. Regulated by signals from ________ ________ , chemical changes in the blood or by other hormones.
nervous system
- Most often, this regulation occurs by negative feedback __________, in which the hormone itself inhibits further secretion by binding to the pituitary or hypothalamus.
inhibition
________ feedback control: the change produced by the hormone causes more hormone to be released.
positive
what is an example of a positive feedback loop
labor and delivery - oxytocin
_________ involve either hyposecretion or hypersecretion of a hormone
disorders
Endocrine gland stimuli may be _________, ________, or __________
humoral, neural, or hormonal
CRITICAL IONS or nutrients that act as stimuli controlling the secretion of hormones are _________ stimuli.
humoral
If NERVE FIBERS stimulate hormone release, then the stimulus for release is ________
neural
If the secretion of a hormone is in response to HORMONES produced by other endocrine glands, it follows a _________ pattern of secretion.
hormonal
Ok, so what are the examples of “turn on” and “turn off” factors
- “turn on” = hormonal, humoral, and neural
- “turn off” = feedback inhibition
modulated by the activity of the NS
The ____________ is the major integrating link between the nervous and endocrine systems.
hypothalamus
Hypothalamus receives input from (4)
- cortex
- thalamus
- limbic system
- internal organs
Hypothalamus controls pituitary gland with ____ different releasing & inhibiting hormones.
9
The _________ _______ and ___________ have a more wide-ranging influence than any other part of the endocrine system
pituitary gland and hypothalamus
What do the pituitary gland and hypothalamus regulate?
all aspects of growth, development, metabolism, and homeostasis
The ___________ is shaped like a flattened funnel and forms the floor and walls of the third ventricle of the brain.
hypothalamus
- Anatomically, the pituitary is suspended from the floor of the hypothalamus by a stalk (infundibulum) and housed in a depression of the sphenoid bone, the ________ _________
sella turcica
T or F: The pituitary gland is roughly the size and shape of a kidney bean, usually about 1.3 cm wide; it grows 50% larger in pregnancy.
T
what 2 structures is the pituitary gland made up of?
- anterior pituitary (adenohypophysis)
- posterior pituitary (neurohypophysis)
what is the difference of composition of the ant vs post pit
- ant: glandular tissue (produces its own hormones)
- post: neural tissue and part of the brain (stores and releases)
specialized network of blood vessels that connect the hypothalamus to the pituitary gland
the hypophyseal portal system
The hypothalamus controls the anterior pituitary by secreting hormones into the ________
capillaries
___________ control enables the brain to monitor conditions within and outside the body and to stimulate or inhibit the pituitary anterior-lobe hormones appropriately.
hypothalamic
why is the anterior pituitary gland the MASTER gland
regulates the secretion of hormones from most other glands
It releases “________” hormones that stimulate other glands to release their hormones.
“tropic”
what are some of the hormones the ant pit releases
- growth hormone (GH)
- thryoid-stim hormone (TSH)
- gonadotrophins (FSH and LH)
- PRL
- ACTH
Excess GH: child grows exceptionally fast and becomes extremely tall (8 feet)
gigantism
Excess GH: (after epiphyseal plate have closed) bony areas that still have growth areas responsive to GH like hands, feet, and face
acromegaly
- GH HYPOsecretion in childhood or adolescence causes _________ ________
pituitary dwarfism
Thyroid gland: stimulates thyroid gland to release thyroid hormone (controls metabolic rate)
thyroid-stimulating hormone (TSH)
what makes up the gonadotrophins
FSH and LH
Ovaries and testes: in females, stimulates ovarian follicle maturation and estrogen production // in males, stimulates sperm production
follicle-stimulating hormone (FSH)
ovaries and testes: in females, triggers ovulation and stimulates ovarian production of estrogen and progesterone; in males, promotes testosterone production
Luteinizing hormone (LH)
Breast secretory tissue: promotes lactation
Prolactin (PRL)
Adrenal cortex: promotes release of glucocorticoids and androgens (helps body cope with stress)
Adrenocorticotropic hormone (ACTH)
Posterior pituitary hormones: Structurally consists of nerve fibers and neuroglia v. glandular epithelial cells of the anterior pituitary gland. The nerve fibers originate in the __________
hypothalamus
The two posterior pituitary hormones are ____ and _____, which are synthesized in the HYPOTHALAMUS and then transported to the POST PIT for storage
ADH and OT
Uterus – stimulates uterine contractions; initiates labor // breast: initiates milk ejection
Oxytocin (OT)
Kidneys: stimulates kidney tubule cells to reabsorb water
Antidiuretic hormone (ADH)
The ________ gland weighs about 25 g and is the largest endocrine gland in adults
thyroid
B. The thyroid gland has two lateral lobes and lies just below the larynx - base of throat, just inferior to the Adam’s apple. It is named for the __________ thyroid cartilage (Adam’s apple) of the larynx
shieldlike
what 3 hormones does the thyroid gland produce
T3, T4, and calcitonin
control conversion of glucose to energy or heat and regulate growth of reproductive and nervous tissue. They are collectively termed thyroid hormone (TH).
Thyroid Hormones: T3 (triiodothyronine) and T4 (tetraiodothyronine)
Increase basal metabolic rate (rate at which the body uses O to transform nutrients into E)
Thyroid hormone
Only hormones held in storage in quantity in body
thyroid
An enlargement of the thyroid gland (can occur from either hypo or hyperthyroidism)
Goiter
thyroid produces too little thyroid (sluggish and feel cold)
hypothyroidism
thyroid gland produces too much thyroid hormone, overreactive metabolism (high activity level, fidgety, hot, sweaty)
hyperthyroidism
Hormone released by the thyroid gland that promotes a decrease in calcium levels in the blood
calcitonin
The _________ glands are ovoid glands about 3 to 8 mm long and 2 to 5 mm wide. Four of them are found partially embedded in the posterior surface of the thyroid, separated by a thin fibrous capsule.
parathyroid
B. They secrete parathyroid hormone (PTH) in response to low blood _________
calcium
This increases when the blood conc of calcium whenever it falls below some threshold
parathyroid hormone (PTH)
The adrenal (suprarenal) glands sit like caps on the superior surface of each _______
kidney
T or F: The adult adrenal gland measures about 5 cm vertically, 3 cm wide, and 1 cm anterior to posterior. It weighs about 8 to 10 g in the newborn, but by the age of 2 years following involution of its outer layer, it becomes 4 to 5 g and remains this weight in adults.
T
The adrenal gland has two different functional areas:
- adrenal medulla (gray-dark red) 10-20% of gland
- adrenal cortex (yellowish) 80-90% of the gland
Are the medulla and the cortex functionally independent?
no, need each of them to stimulate the other
he adrenal cortex, which surrounds the medulla, produces more than 25 steroid hormones known as the __________ or _________
corticosteroids or corticoids
- These fall into three categories, which are produced in three layers of glandular tissue:
- mineralocorticoids: zona glomerulosa
- glucocorticoids: zona fasciculata
- sex steroids: zona reticularis
which contains cells arranged in spherical clusters (glomerulus = ball of yarn)
zona glomerulosa
what hormone is in the zona glomerulosa
aldosterone
hormone secreted by the adrenal cortex that stimulates reabsorption of sodium ions and water from the kidney
aldosterone
Aldosterone is controlled by…
Na+ levels, BP and blood volume. RAAS: Renin, Angiotensin, Aldosterone System.
whose cells are arranged in parallel cords (fascicle = bundle of parallel sticks) and contain an abundance of lipid droplets
zona fasciculata
what hormone and conditions are associated with zona fasciculata
cortisol, cushing syndrome, addision’s disease
A glucocorticoid hormone produced by the adrenal cortex (stress hormone)
cortisol
ACTH secreting pituitary tumor or (rarely) by a tumor o the adrenal cortex, high levels of glucose in the blood (swollen face and redist of fat to post neck -> buffalo hump)
cushing syndrome
deficiency in glucocorticoids and mienralocorticoids (low blood glucose)
addison’s disease
is the narrow, innermost layer, adjacent to the renal medulla.
zona reticularis
what is the zone reticularis
DHEA and estradiol
produced by adrenal glands, precursor hormone that is important to production of testosterone and estrogen
dehydroepiandrosterone (DHEA):
The main adrenal estrogen is ____________; this is of minor importance to women during reproductive years, but is it is the main source of estrogen after menopause.
estradiol
How does the adrenal medulla have a dual nature?
acts as both an endocrine gland and as a ganglion of the sympathetic NS
what fibers extend through the cortex to reach cells in the medulla
sympathetic preganglionic nervefibers
(AM)Upon stimulation by nerve fibers—usually under conditions of fear, pain or stress—the cells release ___________
catecholamines
The _________ is an elongated, spongy, primarily exocrine gland below and behind the stomach that secretes digestive enzymes—but scattered throughout its exocrine tissue are 1 to 2 million endocrine cell clusters called pancreatic islets (islets of Langerhans).
pancreas
Although they are less than 2% of pancreatic tissue, the _______ secrete hormones of vital importance to glycemia, the blood glucose concentration.
islets
Where are hormones secreted from in the pancreas?
islet cells
what cells secrete glucagon, a protein hormone that signals liver cells to release glucose from their glycogen stores, thus raising blood sugar levels whenever they fall too LOW
alpha cells
what cells secrete insulin, a protein hormone that signals most cells of the body to take up glucose from the blood and promotes storage of glucose as glycogen in the liver, lowering blood sugar (WHEN HIGH -> LOW)
Beta cells
________ _________ is the world’s most prevalent metabolic disease, occurring in about 7% of the U.S. population.
Diabetes mellitus
Diabetes mellitus (DM) can be defined as a disruption of carbohydrate, fat, and protein metabolism resulting from ___________ or inaction of insulin.
hyposecretion
T or F: (DM) Body cells are unable to take up and metabolize glucose.
True
Normally the kidneys remove glucose from the ________ and return it to the __________(reabsorption), via glucose transporters (carrier-mediated transport).
urine -> blood
In DM, the amount of glucose saturates the glucose transporters leading to what in the urine
excess glucose passes through the urine “sugar pee”
- Glucose and ketones in urine raise osmolarity, causing _______ __________ —water remains in the tubules.
osmotic diuresis
What are the 2 types of diabetes:
- type 1
- type 2
are older terms such as juvenile/insulin-dependent and adult/non-insulin-dependent still used?
NO, they are misleading
When a genetically susceptible individual is infected by certain viruses, the body produces autoantibodies that destroy insulin-producing pancreatic beta cells.
Type 1 DM
In type 1, insulin falls to a critically low level -> what occurs
hyperglycemia
T or F: Type 1 Victims require insulin to survive, usually by injection, and meal planning, exercise, and self-monitoring of blood glucose are aspects of treatment.
True
Type 2 DM accounts for what percentage of cases?
90-95%
What is the chief problem of Type 2 DM
INSULIN RESISTANCE
what is insulin resistance and what is it often due to?
unresponsiveness of the target cells to the hormones, often due to declining insulin receptor sensitivity
T or F: Type 2 DM develops slowly and is usually diagnosed after age 40, but is becoming more prevalent in young people because of childhood obesity.
True
True or false: Type 2 DM can often be successfully managed through a weight loss program of diet and exercise; if these prove inadequate, insulin therapy is also employed.
True
what are the 2 roles of the pineal gland
- secretes melatonin
- regulates circadian rhythms
what does the thymus gland secrete?
thymosins
what does the thymus gland do?
promote development of T lymphocytes and immunity
What do the ovaries produce?
estrogen, progesterone, and inhibin
what do the female gonadal hormones do?
development of the reproductive system, female physique, promoting growth, reg menstrual cycle, preg, mammary glands for lactation
what does the placenta product (basis of home pregnancy tests)
estrogen, progesterone, and human chorionic gonadotropin (hCG)
Testes produce _____________
testosterone
what does testosterone stimulate?
male reproductive system in fetus and adolescent, male physique, sex drive
_____________: produce hormones important to the coordination of digestive activities (gastrin, secretin, cholecystokinin).
Intestines
_________: Keratinocytes of the epidermis convert a cholesterol-like steroid into cholecalciferol using UV radiation from the sun
skin
_________: It converts cholecalciferol into calcidiol, the next step in calcitriol synthesis.
liver
___________: convert calcidiol to calcitriol (active form of vitamin D that aids calcium absorption in the intestines)
kidneys
Kidneys also synthesize and secrete ____________ (EPO) which stimulates RBC production.
erythropoietin (EPO)
Adipose Cells: - Hormone ________ which suppresses appetite
leptin
What does the heart produce when BP becomes high (lowers BP)
atrial natriuretic peptide (ANP)
Do endocrine glands grow or decrease in size over the lifetime
decrease
Muscular strength _______ as GH levels _________
decrease, decrease
ADH levels________ due to slower break down in liver and kidneys
increase
Calcitonin levels decrease; increase risk of ___________
osteoporosis
T or F: F. Insulin resistance may develop as you age
True
G. Changes in _________ secretion affect the body clock (aka circadian rhythm)
melantonin
Thymosin production declines increasing risk of __________
infections
