Endocrine System Flashcards
Exam 1
Endocrine System
system of glands secreting hormones into the blood stream
What are the types of glands?
Endocrine gland: without duct, secretes hormones into blood
Exocrine gland: has duct for non-hormonal secretion
Gland
specialized group of cells capable of producing and secreting its substances into the blood stream or to the outside
Hormone
chemical messengers that are released by cells and transported in the blood stream to alter activities of specific cells and other tissue
Diffusion
movement of particles from higher to lower concentration
Negative Feedback Systems
Control hormone levels by inhibiting further release when target hormones are affected
Humoral Stimuli
caused by altered levels of critical ions or nutrients
Ex: declining blood Ca2+ concentration stimulates parathyroid glands to secrete PTH
Neural Stimuli
Stimulate hormone release through neural input
Ex: sympathetic nervous system fibers stimulate adrenal medulla to secrete catecholamines
Hormonal Stimuli
caused by another hormone (tropic hormones)
Ex: hypothalamic hormones stimulate release of most anterior pituitary hormones
Nervous System Modulation
Ability of the nervous system to make adjustments to hormone levels and override normal endocrine controls
Ex: under severe stress
Cyclic AMP Signaling
Hormone binds to receptor, activates G protein, leading to protein kinase (enzyme) activation
PIP2-calcium signaling
Hormone-activated G protein splits membrane protein into second messengers, leading to Ca2+ release
cGMP
Second messenger for selected hormones
Intracellular Receptors
bind with lipid-soluble hormones, initiate DNA transcription
mRNA
produced from DNA transcription, translated into specific proteins
Target Cell Specificity
cells must have specific receptors for hormone binding
ACTH Receptors
found only on certain cells of adrenal cortex
Thyroxin receptors
found on nearly all cells of the body
Target Cell Activation
depend on blood hormone levels, receptor numbers, and binding strength
Up-regulation
target cells form more receptors in response to low hormone levels
Down-regulation
Target cells lose receptors in response to high hormone levels
Half-Life of Hormone
time for hormone blood level to decrease by half
Hormone Removal
can be removed from blood by degrading enzymes, kidneys, or liver
Dermis
layer of skin, avascular with blood in epidermis via diffusion
Vasopressin
lipid-soluble hormone, stimulates smooth muscle contraction (oxytocin, ADH)
Examples of exocrine glands
sebaceous (oil), sudoriferous (sweat), ceruminous (wax), mammary
List hormones produced by anterior and posterior pituitary glands (give organ examples)
Growth Hormone (AKA somatotropin; bone)
Adrenocorticotropic Hormone (ADH; adrenal cortex)
Thyroid Stimulating Hormone (TSH; thyroid gland)
Follicle Stimulating Hormone and Luteinizing Hormone (FSH & LH; testis and ovaries)
Prolactin (PRL; production of milk in mammary glands)
Oxytocin (ejection of milk in mammary glands & uterus smooth muscle)
Anti-Diuretic Hormone (ADH; kidney tubules)
Where is Melanocyte Stimulating Hormone produced?
pars intermedialis
What is the function of FSH?
Males: stimulate production of sperm
Females: stimulates growth of ovarian follicles and production of estrogens
What is the function of LH?
gonad dropping hormone;
Males: produce testosterone
Females: release of estrogen and progesterone, causes ovulation and stimulates and maintains the corpusluteum (CL)
Ovary
produces gametes, stimulated by FSH and LH
Estrogen
hormone softening cells for ovulation, produced by growing follicle
Progesterone
hormone maintaining pregnancy, produced by corpus luteum
Lipid-soluble hormones
(steroid and thyroid hormones) act on receptors inside the cell, which directly activate genes
List 5 Steroid Hormones
testosterone, estrogen, progesterone, aldosterone, cortisol
Water-soluble hormones
(all amino acid-based hormones except thyroid hormone)
enter cell via plasma membrane receptors (lipoproteins); Act via G protein second messengers (require energy)
Site of sperm production
seminiferous tubules of the testes via FSH
Interstitial Cells of Leydig
produce testosterone via LH
Definition of Local Hormone
produced and entered into blood in search of target cells/tissues/organs
Types of Local Hormones
Autocrine: used by the same cell that produced it
Paracrine: used by cells adjacent to site of production
Types of capillaries
Continuous: big space, found in brain
Finestrated: bigger space, found in kidney nephron
Sinusoid: biggest space, found in liver
Circulating Hormones
blood carries them around
List Types of Hormonal Interactions
Permissive effect
Synergistic effect
Antagonistic effect
Permissive Hormone Effect
second hormone strengthens effect of first hormone
Ex: thyroid and epinephrine
Synergistic Hormone Effect
two hormones acting together for greater effect
Ex: Estrogen and LH
Antagonistic Hormone Effect
two hormones with opposite effects
Ex: insulin and glucagon
Catecholamines
epinephrine and norepinephrine
Thyroid Gland
butterfly-shaped gland in anterior neck, consists of isthmus, follicles, colloid, and parafollicular cells
Thyroid Gland Hormones
T3 (triiodothyronine)
T4 (thyroxine)
Calcitonin
T3
Triiodothyronine, form with 3 bound iodine atoms, affects tissue growth and development
T4
thyroxine, major thyroid hormone form with 4 bound iodine atoms, affects metabolic rate and heat production
Calcitonin
Produced by parafollicular cells; Lowers blood calcium levels, increases bone calcium levels
Thyroglobulin
glycoprotein produced by epithelial follicular cells in thyroid gland
Adrenal gland layers
capsule > glomerulosa > fascuilata > reticulata > adrenal medulla (stimulated by ACTH)
Zona Glomerulosa
mineralocorticoids (aldosterone)
What is the function of aldosterone?
help control the balance of salts and water in the kidneys by keeping sodium in and releasing potassium from the body
Zona Fascuilata
glucocorticoids (cortisol)
Zona reticularis
gonadocorticoids/androgens (testosterone and estrogen)
Adrenal Medulla
epinephrine and norepinephrine (chromaffin cells) (nervous area directly connected to hypothalamus)
Infundibulum
stalk connecting hypothalamus to pituitary gland
Hypothalamus Hormones
A neural structure lying below the thalamus;
Growth hormone-releasing hormone (GHRH)
Growth hormone-inhibiting hormone (GHIH)
Thyrotropin-releasing Hormone (TRH)
Corticotropin-releasing hormone (CRH)
Gonadotropin-releasing hormone (GnRH)
Prolactin-inhibiting hormone (PIH; AKA Dopamine)
Nephron Tubules
permeable to water; Open to let water out into body/kidneys
What is another name for Anterior Pituitary Gland?
adenohypophysis; consists of glandular tissue
What is another name for Posterior Pituitary Gland?
neurophypophysis; composed of neural tissue and secretes neurhormones
What is another name for Pituitary Gland?
hypophysis
Name for hormones that regulate secretion of other hormones
tropic hormones
Insulin-like Growth Hormones (IGFs)
stimulated by GH, promote cellular uptake of nutrients and bone growth
Parathyroid Gland
secretes Parathyroid hormone (PTH), increases blood calcium levels
Atrial natriuretic peptide (ANP)
secreted by heart in response to high blood pressure; Blocks renin and aldosterone secretion to decrease blood pressure (decrease salt absorption)
Pineal Gland
secretes melatonin (circadian rhythm)
Pancreas Hormones
alpha cells: glucagon
beta cells: insulin
somatostatin
What is the function of somatostatin
inhibit the release of other hormones, regulate the activity of gastrointestinal tract, prevent rapid reproduction of cells
Acinar Cells
enzyme-secreting cells of the pancreas, for digestion
What does the placenta secrete?
estrogens, progesterone, and human chorionic gonadotropin (hCG)
Human Chorionic Gonadotropin (hCG)
maintains corpus luteum in pregnancy, produced upon implantation; Simile to LH
Islets of Langerhans
alpha cells: glucagon (increase blood sugar)
beta cells: insulin (decrease blood sugar)
Hormones secreted by adipose tissue
Leptin: appetite control; stimulates increased energy expenditure
Resistin: insulin antagonist
Adiponectin: enhances sensitivity to insulin
Hormones secreted by gastrointestinal tract
Gastrin: stimulates release of HCl
Ghrelin: from stomach, stimulates food intake
Secretin: stimulates liver and pancreas
Cholecystokinin (CCK): activates pancreas, gallbladder, and hepatopancreatic sphincter
Incretins: enhance insulin release and inhibit glucagon
Hormones secreted by heart
Atrial Natriuretic Peptide (ANP): decreases blood sodium concentration, and blood pressure and blood volume
Hormones secreted by Kidneys
Erythropoietin: production of red blood cells
Renin: initiates the renin-angiostensin-aldosterone mechanism
Hormones secreted by skeleton
Osteocalcin: secreted by osteoblasts in bone
Hormones secreted by skin
Cholecalciferol: precursor of vitamin D
Calcitriol: active form of vitamin D that helps absorb calcium from intestine
Hormones secreted by thymus
Thymulin, Thymopoietins, and Thymosisns may all be involved in normal development of T-lymphocytes in immune response
Autoimmune Disease
condition where immune cells attack good cells
Diabetes Mellitus
inability to produce or use insulin, leading to high blood sugar;
Type 1: caused by deficiency of insulin
Type 2: caused by deficiency of insulin receptors
Polyuria
excessive urine production
Polydipsia
excessive thirst
Polyphagia
excessive hunger
Hormone produced by duodenum and stimulates pancreas and gall bladder
cholecystokinin
Which hormone would increase in blood as a result of stretching the cervix during labor?
oxytocin
Destruction of the beta cells of the pancreas results in what metabolic disorder that is characterized by hyperglycemia, polyuria, polydipsia, and polyphagia?
diabetes mellitus
Which hormone is detected in the urine in most common pregnancy tests?
human chorionic gonadotropin (hCG)
The Substances that are excreted from the Hepatopancreatic Ampulla
bile and pancreatic juice
The Characteristics of Steroid Hormones
- derived from cholesterol
- lipid-soluble, influence cell activity by acting on DNA
- require protein transport molecule to get through blood
How does the Hypothalamus control the Hypophysis?
secretes releasing hormones
Where is the Hypothalamus located? Where is the Hypophysis located?
Hypothalamus is located in the ventral brain, above pituitary gland and below third ventricle; Hypophysis is located below hypothalamus
What would most likely result when aldosterone secretion from adrenal cortex is impaired?
- hyperkalemia: high potassium levels
- hyponatremia: low sodium levels
- metabolic acidosis: too much acid
Which blood glucose lowering hormone is produced by the Pancreatic islet cells (Islet of Langerhans)?
insulin
Which hormone promotes an increased metabolic rate?
thyroid hormone
Definition of Amine Hormone
hormone synthesized from the amino acids tryptophan or tyrosine
Name an amine hormone derived from serotonin
melatonin
Hormones that act on neighboring cells without entering bloodstream
paracrine (local hormone)
What are the lipid-soluble hormones derived from cholesterol?
steroid hormones are derived from cholesterol
Which anterior pituitary hormone stimulates growth of bones?
growth hormone (GH)
What are Gonadotropin Hormones (GnH)? Give examples
Luteinizing Hormone, Follicle Stimulating Hormone (FSH): make the sex hormones testosterone, estrogen, and progesterone
Which hormone stimulates proliferation of red blood cells in red bone marrow?
erythropoietin
What is the determining factor that stimulates erythropoietin release from the kidney?
low hemoglobin levels
If you were to investigate the level of hormones in an individual, what’s the most common test?
blood test is most common, sometimes urine test
Parathyroid hormone is the major regulator of the concentration of which ions in the blood?
calcium
Which anterior pituitary hormone stimulates cortisol production?
ACTH Adrenocorticotropin Hormone
Which hormones are secreted by the hypothalamus and stored at the neurohypophysis?
oxytocin and ADH (vasopressins)
Characteristics of Hyperthyroidism?
elevated metabolic rate, goiter, rapid weight loss despite increased appetite, sweating, rapid and irregular heart beat, nervousness
Where are the target cells for follicle-stimulating hormone?
ovaries and testes
The disease called ________ is caused by excessive secretion of glucocorticoids and is characterized by redistribution of body fat to produce characteristic features such as “moon face”
Cushing syndrome
Which gland is called the “emergency gland” and helps the body adjust to stress?
adrenal gland
Which hormones have additive effects?
synergists
Hormones that stimulate endocrine glands to release other hormones are called? Give examples.
trophic hormones: ACTH, GnRH, gonadotropins, TSH
Which hormone has an opposite action of calcitonin?
parathyroid: increases blood calcium levels
