ENDOCRINE SYSTEM Flashcards
What constitutes the Endocrine system?
Endocrine glands and hormone-secreting cells
A molecule that is released in one part of the body but regulates the activity of cells in other parts of the body
Hormones
Hormones delivered to tissues throughout the body by the blood
Mediator molecules characteristic of endocrine
Far from site of release; binds to receptors on or in target cells
Site of Mediator action characteristic of endocrine
Secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to the outer surface of the body.
Exocrine glands
Secrete their products into the interstitial fluid surrounding the secretory cells rather than into ducts
Endocrine glands
Science of the structure and function of the endocrine glands and the diagnosis and treatment of disorders of the endocrine system
Endocrinology
Enumerate the endocrine glands
Pituitary gland
Thyroid gland
Parathyroid gland
Adrenal gland
Pineal gland
The effect when a hormone is present in excess, and the number of target-cell receptors decreases; target cell becomes less sensitive to a hormone
Down-regulation
The effect when a hormone is deficient, and the number of receptors increase; target cells become more sensitive to a hormone
Up-regulation
Pass from the secretory cells that make them and released into the interstitial fluid, and then into the blood
Circulating hormones
Act locally on neighboring cells or on the same cell that secreted them without entering the bloodstream
Local hormones
Local hormones that act on neighboring cells
Paracrines
Local hormones that act on the same cell that secreted them
Autocrines
Derived from cholesterol; each is unique due to the presence of different chemical groups attached to various sites on the 4 rings at the core of its structure
Steroid hormones
Synthesized by attaching iodine to the amino acid thyroxine. Has only 2 types: T3 and T4
Thyroid hormones
Most of these hormone molecules circulate in the blood/watery blood plasma in a “free” form
Water-soluble hormone
Most of these hormone molecules are bound to transport proteins
Lipid-soluble hormone
Synthesized by the cells in the liver. They make lipid soluble hormones temporarily water-soluble, thus increasing their solubility in blood
Transport proteins
A mechanism of hormone action wherein a free lipid-soluble hormone molecule diffuses from the blood, through the interstitial fluid, and through the lipid bilayer of the plasma membrane, then into the cell.
Diffusion
A mechanism of hormone action wherein the activated receptor-hormone complex alters gene expression
Transcription
Types of water-soluble hormones
Amine Hormones
Peptide and protein hormones
Eicosanoid hormones
Integral transmembrane proteins in the plasma membrane
Receptors
A water-soluble hormone that binds to its receptor at the outer surface of the plasma membrane; it causes production of the second messenger inside the cell
First messenger
This is where specific hormone stimulated responses take place
Second messenger
Are the parathyroid glands posterior or anterior to the thyroid glands
Posterior
Are synthesized by decarboxylating and otherwise modifying certain amino acids
Amine hormones
Amino acid polymers
Peptide hormones and protein hormones
Protein hormones that have attached to carbohydrate groups
Glycoprotein hormones
Derived from arachidonic acid, a 20-carbon fatty acid.
Eicosanoid hormones
0.1-10% of the molecules of a lipid-soluble hormone that are not bound to a transport protein.
Free fraction
The hormone-receptor complex activates a membrane protein called?
G protein
The activated G protein activates what
Adenylyl cyclase
An enzyme that phosphorylates other cellular proteins
Protein kinase
An enzyme that inactivates cAMP(Cyclic adenosine monophosphate
Phosphodiesterase
A target cell responds more vigorously when the level of a hormone rises or when it has more receptors. In addition, the actions of some hormones on target cells require a simultaneous or recent exposure to a second hormone.
Permissive effect
When the effect of two hormones acting together is greater than the sum of their individual effects, the two hormones are said to have a
Synergistic effect
When one hormone opposes the actions of another hormone, the two hormones are said to have
Antagonistic effects
Was called the “master” endocrine gland because it secretes several hormones that control other endocrine glands
Pituitary gland
This small region of the brain below the thalamus is the major link between the nervous and endocrine systems
Hypothalamus
Secretes hormones that regulate a wide range of bodily activities, from growth to reproduction
Anterior pituitary(anterior lobe)
Larger portion of the anterior pituitary
Pars distalis
Forms a sheath around the infundibulum
Pars tuberalis
Does not synthesize hormones. Stores and releases two hormones. Consists of axons and axon terminals of more than 10000 hyopthalamic neurosecretory cells.
Posterior pituitary
Secrete growth hormone also known as human growth hormone
Somatotrophs
Secrete thyroid-stimulating hormone, also known as thryotropin
Thyrotrophs
In men, they stimulate the testes to produce sperm and to secrete testosterone. In women, they stimulate the ovaries to mature oocytes and to secrete estrogens and progesterone.
Gonadotrophs
Secrete prolactin which initiates milk production in the mammary glands
Lactotrophs
Secrete adrenocorticotropic hormones which stimulates the adrenal cortex to secrete glucocorticoids such as cortisol
Corticotrophs
Also known as growth hormone-releasing hormone, stimulates secretion of growth hormone
Somatocrinin
Stimulates secretion of thyroid-stimulating hormone
Thyrotropin-releasing hormone
Stimulates secretion of adrenocorticotropic hormone
Corticotropin-releasing hormone
Stimulates secretion of prolactin
Prolactin-releasing hormone
Stimulates secretion of follicle-stimulating hormone and luteinizing hormone
Gonadotropin-releasing hormone
Also known as growth hormone-inhibiting hormone, suppresses secretion of growth hormone
Somatostatin
Prolactin-inhibiting hormone, suppresses secretion of prolactin
Dopamine
In this system, blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries of the anterior pituitary.
Hypophyseal portal system
Branches of the internal carotid arteries, bring blood into the hypothalamus
Superior hypophyseal arteries
In the anterior pituitary, the hypophyseal portal veins divide again and form another capillary network
Secondary plexus of the hypophyseal portal system
Drain blood from the anterior pituitary
Hypophyseal veins
They synthesize the hypothalamic releasing and inhibiting hormones in their cell bodies and package the hormones inside vesicles, which reach the axon terminals by fast axonal transport
Neurosecretory cells
Anterior pituitary hormones that act on other endocrine glands
Tropic hormones or tropin
Growth hormones exert their growth-promoting effects indirectly through small protein hormones called
Insulin-like growth factors or somatomedins
Increases skin pigmentation in amphibians by stimulating the dispersion of melanin granules in melanocytes
Melanocyte-stimulating hormone
In females, stimulates secretion of estrogens and progesterone, ovulation, and formation of corpus luteum. In males, stimulates testes to produce testosterone
Luteinizing hormone
Stimulates secretion of glucocorticoids by adrenal cortex
Adrenocorticotropic hormone
These cells have a supporting role similar to that of astrocytes
Pituicytes
Blood is supplied to the posterior pituitary by what arteries
The inferior hypophyseal arteries
A capillary network that receives secreted oxytocin and antidiuretic hormone
Capillary plexus of the infundibular process
Is a substance that decreases urine production
Antidiuretic
What neuron is capable of detecting high blood osmolarity.
Osmoreceptor
Located just inferior to the larynx. It is composed of right and left lateral lobes, one on either side of the trachea
Thyroid gland
Microscopic spherical sacs that make up most of the thyroid gland
Thyroid follicles
Cells that constitute the wall of each follicle
Follicular cells
The follicular cells produce two hormones. Enumerate
Thyroxine
Triiodothyronine
A few cells which lie between follicles. They produce the hormone calcitonin, which helps regulate calcium homeostasis
Parafollicular cells or C cells
The thyroglobin with attached iodine atoms, a sticky material that accumulates and is stored in the lumen of the thyroid follicle
Colloid
As cells produce and use more ATP, BMR increases, more heat is given off, and body temperature rises, what is this phenomenon called?
Calorigenic effect
Can decrease the level of calcium in the blood by inhibiting the action of osteoclasts, the cells that break down bone extracellular matrix.
Calcitonin CT
Partially embedded in the posterior surface of the lateral lobes of the thyroid gland. Several, small, round masses of tissue
Parathyroid glands
Type of epithelial cell in the parathyroid gland. More numerous cells that produce parathyroid hormone.
Chief cells or principal cells
Type of epithelial cell in the parathyroid gland.
Its presence helps to identify the parathyroid gland histologically due to its unique staining characteristics
Oxyphil cell
Active form of vitamin D
Calcitriol
Produces steroid hormones that are essential for life.
Adrenal cortex
The outer zone, just deep to the connective tissue capsule, of the adrenal cortex
Zona glomerulosa
The middle zone of the adrenal cortex. Widest of the three
Zona fasciculata
The cells of the zona glomerulosa secrete what hormone
mineralocorticoids
Inner zone of the adrenal cortex.
Zona reticularis
What hormones do the cells of the zona reticularis synthesize
Androgens
What do the cells of the zona fasciculata secrete
Glucocorticoids
The major mineralocorticoid. Regulates homeostasis of two mineral ions
Aldosterone
Controls secretion of aldosterone
Renin-angiotensin-aldosterone pathway
Regulate metabolism and resistance to stress
Glucocorticoids
The breakdown of triglycerides and release of fatty acids from adipose tissue into the blood
Lipolysis
Conversion of a substance other than glycogen or another monosaccharide into glucose
Gluconeogenesis
Promotes the release of ACTH from the anterior pituitary.
Corticotropin-releasing hormone
The major androgen secreted by the adrenal gland
Dehydroepiandrosterone
Genetic disorder in which one or more enzymes needed for synthesis of cortisol are absent
Congenital adrenal hyperplasia
The inner region of the adrenal gland. Modified sympathetic ganglion of the autonomic nervous system
Adrenal medulla
Hormone-producing cells. Innervated by sympathetic preganglionic neurons of the ANS
Chromaffin cells
Two major hormones synthesized by the adrenal medulla
Epinephrine
Norepinephrine
Both an endocrine and exocrine gland. Endocrine controls blood sugar. Exocrine helps digestion.
Pancreas
Produce digestive enzymes, which flow into the gastrointestinal tract through a network of ducts
Acini
Tiny clusters of endocrine tissue scattered among the exocrine acini
Pancreatic islets
Constitute about 17% of pancreatic islet cells and secrete glucagon
Alpha or A cells
Constitute about 70% of pancreatic islet cells and secrete insulin
Beta or B cells
Constitute about 7% of pancreatic islet cells and secrete somatostatin
Delta or D cells
Constitute the remained of pancreatic islet cells and secrete pancreatic polypeptide
F cells
The neurotransmitter liberated from axon terminals of parasympathetic vagus nerve fibers that innervate the pancreatic islets
Acetylcholine
Organs that produce gametes
Gonads
Paired oval bodies located in the female pelvic cavity; produce several steroid hormones
Ovaries
A protein hormone that inhibits secretion of FSH. Produced by ovaries
Inhibin
Peptide hormone which increases the flexibility of the pubic symphysis during pregnancy and helps dilate the uterine cervix during labor and delivery
Relaxin
Oval glands that lie in the scrotum
Testes
Stimulates descent of the testes before birth, regulates production of sperm, and stimulates the development and maintenance of male secondary sex characteristics.
Testosterone
Small endocrine gland attached to the roof of the third ventricle of the brain at the midline.
Pineal gland
An amine hormone derived from serotonin. Secretion of pineal gland
Melatonin
A type of depression that afflicts some people during the winter months, when day length is short.
Seasonal affective disorder
Located behind the sternum between the lungs. Produces thymosin, thymic humoral factor, etc
Thymus
Hormone that plays a role in the synthesis of calcitriol, the active form of vitamin D
Cholecalciferol
A modified PG that constricts blood vessels and promotes platelet activation
Thromboxane
Hormone that promotes secretion of gastric juice
Gastrin
Hormone that stimulates release of insulin by pancreatic beta cells
Glucose-dependent insulinotropic peptide(GIP)
Hormone that stimulates secretion of pancreatic juice and bile
Secretin
Hormone that stimulates secretion of pancreatic juice; regulates release of bile from gallbladder
Cholecystokinin (CCK)
Hormone that stimulates corpus luteum in ovary to continue production of estrogens and progesterone to maintain pregnancy
Human chorionic somatomammotropin
Hormone that is a part of a reaction sequence that raises blood pressure by bringing about vasoconstriction and secretion of aldosterone
Renin
Hormone that increases rate of red blood cell formation
Erythropoietin
Hormone that aids in absorption of dietary calcium and phosphorus
Calcitriol
Hormone that decrease blood pressure
Atrial natriuretic peptide(ANP)
Hormone that suppresses appetite; may increase FSH and LH activity
Leptin
Hormones that play important roles in tissue development, growth, and repair. Are mitogenic
Growth factors
Stress that prepares us to meet certain challenges and thus is helpful
Eustress
Harmful stress
Distress
Any stimulus that produces a stress response is called
Stressor
First stage in stress response. Initiated by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system, including the adrenal medulla, quickly mobilizes the body’s resources for immediate physical activity
Fight-or-flight response
Second stage in stress response. Initiated in large part by hypothalamic releasing hormones and is a longer-lasting response
Resistance reaction
The resources of the body may eventually become so depleted that they cannot sustain the resistance stage, and this ensues
Exhaustion
Anxiety disorder that may develop in an individual who has experienced, witnessed, or learned about a physically or psychologically distressing event
Post-traumatic stress disorder
An outgrowth of ectoderm where the posterior pituitary is derived from
Neurohypophyseal bud
The anterior pituitary is derived from an outgrowth of ectoderm from the roof of the mouth cawlled
Hypophyseal pouch or Rathke’s pouch
The thyroid gland develops during the fourth week as a midventral outgrowth of endoderm called the
Thyroid diverticulum
The parathyroid glands develop during what week after fertilization
fourth
Disorder of the endocrine system. Inadequate release of a hormone
Hyposecretion
Disorder of the endocrine system. Excessive release of a hormone
Hypersecretion
Hyposecretion of growth hormones during the growth years slows bone growth, and the epiphyseal plates close before normal height is reached
Pituitary dwarfism
Hypersecretion of growth hormones during childhood causes an abnormal increase in the length of long bones
Giantism
Hypersecretion of growth hormones during adulthood is called
Acromegaly
This disorder is due to defects in antidiuretic hormone receptors or an inability to secrete ADH
Diabetes insipidus
Hyposecretion of thyroid hormones that is present at birth, has devastating consequences if not treated promptly
Congenital hypothyroidism
Hypothyroidism during the adult years. A hallmark of this disorder is edema that causes the facial tissues to swell and look puffy
Myxedema
An autoimmune disorder in which the person produces antibodies that mimic the action of thyroid-stimulating hormone
Graves disease
Graves patients often have a peculiar edema behind the eyes which causes the eyes to protrude.
Exophthalmos
Simply an enlarged thyroid gland
Goiter
normal secretion of thyroid hormone
Euthyroidism
Hyposecretion of glucocorticoids and aldosterone
Addison’s disease
Benign tumors of the chromaffin cells of the adrenal medulla. Causes hypersecretion of epinephrine and norepinephrine.
Pheochromocytomas
Too little parathyroid hormones. Causes neurons and muscle fibers to depolarize and produce action potentials spontaneously
Hypoparathyroidism
Elevated level of parathyroid hormone, most often is due to a tumor of one of the parathyroid glands
Hyperparathyroidism
Hypersecretion of cortisol by the adrenal cortex produces
Cusing’s syndrome
Caused by an inability to produce or use insulin
Diabetes mellitus
Occurs because the person’s immune system destroys the pancreatic beta cells
Type 1 diabetes
The by-products of fatty acid breakdown accumulate. Buildup of ketones causes blood pH to fall. What is this condition called?
Ketoacidosis
Most often occurs in obese people who are over age 35.
Type 2 diabetes
Most often results when a diabetic injects too much insulin
Hyperinsulinism
Decreased blood glucose level, which occurs because the excess insulin stimulates too much uptake of glucose by body cells
Hypoglycemia
Shock due to an insulin overdoes
Insulin shock
Excessive development of mammary glands in a male
Gynecomastia
Presence of excessive body and facial hair in a male pattern, especially in women
Hirsutism
Severe state of hyperthyroidism that can be life-threatening
Thyroid crisis(storm)
Tumor of the adrenal gland that liberates excessive androgens, causing virilism
Virilizing adenoma
Adrenal tumor cells liberate estrogens to the extent that a male patient develops gynecomastia
Feminizing adenoma