16 Endocrine Flashcards
What are the 6 main endocrine glands
Pituitary Thyroid Parathyroid Adrenal Pineal Thymus
What organs have both endocrine and exocrine functiona
Pancreas
Gonads
What other tissues and organs produce hormones
Adipose Pockets of Cells in : small intestine Stomach Kidney Heart
What are hormones
Chemical substances secreted by cells into extra cellular fluid
- end up in blood
What is the main function of hormones
To regulate the metabolic function of other cells
What are the two classifications of hormones
Amino acid based
Steroids
List some amino acid hormones
Amines Thyroxine Peptide Protein hormones Insulin
List some steroid hormones
Gonadal
Adrenocortical
What are steroid hormones synthesized from
Cholesterol
What cells respond to hormones
Target cells
What are 5 responses to hormones
Alter plasma membrane permeability Stimulate protein synthesis Activate or deactivate enzyme systems Induce secretory activity Stimulate mitosis
What are the 2 ways that hormones alter cell activity
Bind to receptor on membrane
Directly activate gene
What hormone type can directly activate a gene
Only steroid hormones
Lipid soluble
How do amino acid hormones initiate cell response
Bind to receptor
Intracellular response via second messengers
cAMP
What 3 factors does target cell activation depend on
Blood levels of hormone
Relative number of receptors on target cell
Affinity of those receptors for the hormone
Describe up regulation
Target cells form more receptors in response to hormone
Describe down regulation
Target cells lose receptors in response to hormone
Desensitize
What are the forms that hormones circulate in blood
Free
Bound
What hormone type is must be bound to plasma protein
Steroids and thyroid
What do the concentrations of circulating hormones reflect
Rate of release
Speed of Inactivation and removal from body
How are hormones removed from the blood
Degrading enzymes
Kidneys
Liver enzyme systems
What type of control system controls blood levels of hormones
Negative feedback systems
What are the 3 stimuli types
Humoral
Neural
Hormonal
Describe humoral stimuli
Secretion or hormones in direct response to changing blood levels of ion and nutrients
Describe neural stimuli
Nerve fibers stimulate hormone release
Describe hormonal stimuli
Release of hormones in response to hormones produced by other endocrine organs
Example of humoral stimuli
Concentration of calcium in blood
Decline in Ca stimulates parathyroid gland to secrete PTH
PTH causes Ca concentration to increase
Stimulus is now removed
Example of neural stimuli
Preganglionic sympathetic fibers stimulate adrenal medulla to secrete catacholamines
What are catacholamines
Epinephrine
Norepinephrine
Example of hormonal stimuli
Hypothalamic hormones stimulate the anterior pituitary
Pituitary hormones then stimulate targets to secrete more hormones
What is nervous system modulation
The nervous system can override normal endocrine controls
Example of nervous system modulation
Control of blood glucose levels
Under stress need more glucose
Hypothalamus and SNS are activated to supply more glucose
Another name for the pituitary
Hypophysis
Another name for anterior pituitary
Adenohypophysis
Another name for posterior pituitary
Neurohypophysis
What is posterior pituitary made of
What is it’s function
Neural tissue
Receives, stores, and releases hormones from hypothalamus
What is anterior pituitary made of
What is its function
Glandular tissue
Synthesize and secretes a number of hormones
Which pituitary lobe is a downgrowth of hypothalamic tissue
Posterior
Describe the hypothalamic hypophyseal tract
Neural connection between hypothalamus and posterior pituitary
What hormones do nuclei of hypothalamus synthesize
Oxytocin
Antidiuretic hormone
What is stored in posterior pituitary
Oxytocin
Antidiuretic hormone
What portion of pituitary is epithelial tissue
Anterior lobe
How is anterior pituitary connected to the hypothalamus
Vascular connection
Hypophyseal portal system
Describe hypophyseal portal system
Primary capillary plexus
Hypophyseal portal veins
Secondary capillary plexus
What type of hormones in hypothalamus send stimuli to anterior pituitary
Releasing hormones
Inhibiting hormones
Name the hormones of the adenohypophysis
Growth hormone GH Prolactin PRL Thyroid stimulating TSH Adrenocorticotropic ACTH Follicle stimulating FSH Luteinizing LH
Name the tropic hormones
TSH
ACTH
FSH
LH
Name the gonadotropins
FSH
LH
Describe function of growth hormone
Stimulate most cells
Target bones and skeletal muscle
Promote protein synth
Encourage use of fat as fuel
What is stimulated by GH to produce insulin like growth factors
Liver
Skeletal muscle
Bone
Cartilage
What are somatomedins
Insulin like growth factors
What do insulin like growth factors do
Indirectly mediate the effects of GH
Promote protein synth
skeletal muscle and bone growth
What are the direct effects of GH
Use fats for fuel - lipolysis
Inhibit glucose uptake by tissue cells
Release glucose from liver - elevate blood glucose
What does lipolysis do
Elevate blood fatty acid levels
What are glycogenolysis and gluconeogenesis
Break down glycogen to glucose
Synth glucose from lactic acid and noncarb
Both elevate blood glucose levels
What hormones regulate secretion of GH
Where do they come from
Growth hormone releasing hormone GHRH
Growth hormone inhibiting hormone
GHIH
Hypothalamus
Hyper secretion of GH in children
Gigantism
Hypersecretion of GH in adults
Acromegaly
Overgrowth of areas still responsive to GH
Hyposecretion of GH in adults
No problem
Hyposecretion of GH in children
Pituitary dwarfism
Small kid
What is thyrotropin
Thyroid stimulating hormone
What does thyroid gland control
Metabolism
What is function of Thyrotropin
Stimulate normal development and secretory activity of thyroid
What triggers thyrotropin TSH
Hypothalamic peptide
Thyrotropin releasing hormone TRH
What blocks the release of TRH and TSH
Rising blood levels of thyroid hormone
GHIH inhibits TSH
Not growing turn down metabolism
What is another name for corticotropin
Adrenocorticotropic hormone ACTH
What is function of ACTH
Stimulate adrenal cortex to release corticosteroids
What triggers the release of ACTH
Hypothalamic corticotropin releasing hormone CRH
What blocks release of CRH and ACTH
Rising blood levels of cortisol
When is CRH released
In daily rhythm- high morning, dropping
Stress: blood loss, low blood glucose, happiness, anxiety
Basic Function of gonadotropins
Regulate function of ovaries and testes
FSH stimulates gamete production
When are gonadotropins absent
Prepubertal
What triggers gonadotropins
Hypothalamic gonadotropin releasing hormone GnRH
Function of gonadotropins in females
LH/ FSH maturation of ovarian follicle
LH trigger ovulation
LH promote synth/ release of estrogen/ progesterone
Function of gonadotropins in males
LH stimulate interstitial cells of testes to produce testosterone
What is another name for LH in males
Interstitial cell stimulating hormone ICSH
Function of prolactin PRL
Stimulates mammary gland development
Milk production
Unknown in males
What 3 hormones control prolactin release
Prolactin inhibiting hormone PIH
Prolactin releasing factors PRF
Estrogen
Describe what occurs to prolactin release before menstruation
Estrogen stimulates PRF, PRL
Inhibits PIH
What occurs to prolactin when placental estrogen, progesterone, and lactogen are present
Stimulate PRF, PRL
Inhibits PIH
How are mechanoreceptors involved in PRL release
Mechanoreceptors send afferent impulses to hypothalamus
Stimulate PRF
Inhibit PIH
What is prolactin inhibiting hormone
Dopamine
From hypothalamus
What is function of ADH
Influence water balance
What is function of oxytocin
Stimulate smooth muscle contractions of uterus and breasts
Triggers milk ejection reflex
What monitors the solute concentration of the blood
Osmoreceptors in hypothalamus
If solute levels are high ADH…
ADH preserves water
If solute levels are low ADH…
ADH is not released
Water loss
What inhibits ADH release
Alcohol
Copious urine
What occurs with inadequate ADH how is it caused
Diabetes insipidus
From head injury damaging hypothalamus of posterior pituitary
What is the largest endocrine gland
Thyroid
Connected by isthmus
What do thyroid follicles produce
Glycoprotein thyroglobulin
Describe colloid
Thyroglobulin + iodine
Precursor of thyroid hormone
What do para follicular cells secrete
Calcitonin
What does thyroid hormone consist of
2 iodine containing thyroglobulin compounds
T4- thyroxine
T3- triiodothyronine
What occurs when iodine attaches to thyroglobulin
Forms T1 and T2
What forms T3 and T4
T1 and T2 linked together
When are T3 and T4 release into the bloodstream
When colloid is endocytosed and combined a lysosome, where T3 and T4 are cleaved and diffuse into blood
What does TSH bind to
Follicle cells of thyroid gland
Which is released more from follicle T3 or T4
T4
Is T3 or T4 primarily responsible for effects of TH
T3
Enzymes in liver and other tissues can convert T4 to T3
What cells respond to thyroid hormone
Virtually all cells in body increase metabolic rate
How is TH release stopped
Negative feedback
High TH, shut off TSH
TRH can override this is necessary- during pregnancy
What is target of TRH
Anterior pituitary
What are the effects of TH
Elevate rates of oxygen and energy consumption
Heat production
Increase HR and force of contraction- increase BP
Regulate tissue growth
Develop skeletal/ nervous systems
Maturation
Reproduction
What causes hypothyroid
Too little TSH or TRH
Iodine deficiency- lack of TH
Thyroid gland removed
Describe hypothyroid in adults
Myxedema Low metabolic rate Chilled Thick dry skin Lethargy Mental sluggishness Puffy eyes
Hypothyroid in children
Cretinism
Mental retardation
Disproportionate body
Thick neck and tongue
What causes goiter
Enlarged thyroid
From lack of iodine
Symptoms of Hyperthyroid
Graves disease Elevated metabolic rate Nervousness Sweating Weight loss Exophthalmos from tissue getting edematous/ fibrous
Describe graves disease
Hyperthyroid Autoimmune disease Serum has abnormal antibodies against follicle cellar Antibodies mimic TSH Continuous TH release
Why are plasma Ca levels closely regulated
To prevent changes in neuromuscular excitability
Why is intracellular Ca important
For excitation contraction coupling
Why is extra cellular Ca important
Neuromuscular excitability
What happens with low extracellular Ca
Na influx is higher
Cell closer to threshold
Muscle may spasm randomly
In diaphragm causes asphyxiation
What happens with high extra cellular Ca
Decrease Na influx
Hyper polarize- depress excitability
Cause increased cardiac contractions
What is the function of calcitonin
Lowers blood Ca levels in children
What is the antagonist to parathyroid hormone
Calcitonin
What is calcitonin target
What action occurs
Targets skeleton
Inhibits osteoclasts- ca not released from bone
Stimulates Ca uptake/ incorporation into bony matrix
What regulates calcitonin levels
Negative feedback
Humoral
Ca ion concentration in blood
What is another name for PTH
Parathormone
What is function of parathyroid hormone
Increase Ca levels Stimulate osteoclasts Enhance reabsorption of Ca by kidneys Secretion of phosphate by kidneys Increase absorption of Ca by intestinal mucosa by activating Vit D
What hormone is most important for controlling calcium levels
Parathyroid hormone
What inhibits release of PTH
High blood Ca levels
What are symptoms of hyperparathyroid
Bones soft and deformed- Ca leached out
Elevated blood Ca- hypercalcemia
Depression of nervous system
Formation of kidney stones from Ca in kidneys
What causes hyperparathyroid
Tumor
What are symptoms of hypoparathyroid
Increased excitability of neurons
Respiratory paralysis
What causes hypoparathyroid
Gland trauma
Removal
Mg deficiency- needed for PTH
What is inner adrenal medulla made of
Neural tissue
Part of SNS
What is outer adrenal cortex made of
Glandular tissue
How rapidly can catecholamines be released
Peak at 30 seconds
Roles of epinephrine
Dilate bronchioles
Dilate coronary and skeletal muscle vessels
Increase HR and force
Spare glucose
Inhibit insulin release, promote glucagon
Promote lipolysis, glycogenolysis, and gluconeogenesis
Roles of norepinephrine
Peripheral vasoconstriction
Raise BP
What area of the adrenal gland secretes catecholamines
What triggers secretions
Adrenal medulla
SNS responds to short term stress
Describe Hyposecretion of catecholamines from adrenal medulla
None
Not problem because of SNS
Describe hyper secretion of adrenal medulla
Tumor called pheichromacytoma
Symptoms: hypertension, hyperglycemia, excessive sweating
What does the adrenal cortex secrete
Corticosteroids
What are the three layers of the adrenal cortex
Zona glomerulosa
Zona fasciculata
Zona reticularis
What does zona glomerulosa produce
Mineralcorticoids
Mainly aldosterone
What does zona fasciculata produce
Glucocorticoids
Mainly cortisol
What does zona reticularis produce
Gonadocorticoids
Mainly androgens
What is role of mineralcorticoids
Regulate electrolytes in extra cellular fluids
What does aldosterone do
Maintain Na balance by reducing excretion
Stimulates reabsorption of Na by kidneys
Secretion of K
What stimulates aldosterone secretion
Rising K levels
Low Na levels
Decrease BP/ volume
What are the major mechanisms for aldosterone secretion
Renin-angiotensin mechanism
Plasma concentration of Na/ K
ACTH
Atrial natriuretic peptide ANP
Describe how renin angiotensin mechanism works
Kidneys release renin when blood volume drops
Leads to angiotensin 2
Stimulates aldosterone release
How do plasma concentrations influence secretion of aldosterone
By directly influencing the zona glomerulosa
How does the ACTH aldosterone secretion mechanism work
By causing small increases of aldosterone during stress
What does ANP do for aldosterone secretion
Inhibits activity of zona glomerulosa
What is the roll of cortisol
Help body resist stress
How does cortisol reduce stress
Sparing glucose for brain Promote gluconeogenesis Promote fatty acid release from adipose Amino acid release from cells Suppress the immune system
Important details about gonadocorticoids
Small amount of androgens and estrogen secreted
Contribute to onset of puberty and female sex drive
What are the 3 disorders of the adrenal cortex
Adrenogenital syndrome
Cushings disease/syndrome
Addison’s disease
Important details about androgenital syndrome
Tumor of zona reticularis
Masculation of females
Femalization of dudes
What causes cushings disease
Excess levels of glucocorticoid
Difference between cushings disease/ syndrome
Disease- ACTH releasing tumor
Syndrome- glucocorticoid drugs, like cortisol
Symptoms of cushings disease
Immune system depressed Protracted/ exaggerated stress response Lipid reserves mobilized Peripheral proteins broken down Adipose redistribution- moon face
What causes Addison’s disease
Too little mineralcorticoids/ glucocorticoid
- ACTH deficiency
Symptoms of Addison’s
Weak
Loose weight
Low BP/ volume
Can’t tolerate stress
What do alpha cells produce
Glucagon
What do beta cells produce
Insulin
What is glycogenolysis
Glycogen to glucose
What is gluconeogenesis
Synth of glucose from lactic acid and noncarbohydrates
What is glucagon
28 amino acid polypeptide hormone
Potent hyperglycemia agent
What does glucagon target and promote
Liver
Release of glucose to blood
Glycogenolysis
Glyconeogenesis
What is insulin
51 amino acid protein
With 2 amino acid chains linked by disulfide bonds
How is insulin made
Synth as part of proinsulin then excised by enzyme
Released as insulin
What are functions of insulin
Lower blood glucose levels Enhance transport of glucose into cells Catalyzes oxidation of glucose for ATP Polymerizes glucose into glycogen Converts glucose to fat
Hyperglycemic effects…
Glucagon
Hypoglycemic effects of…
Insulin
What causes diabetes mellitus
Hyposecretion
Hypo activity
Of insulin
What are 3 signs of DM
Polyuria
Polydipsia
Polyphagia
Describe polyuria
Huge urine output
Describe polydipsia
Excessive thirst
Describe polyphagia
Excessive hunger and food consumption
Describe hyperinsulinism
Excessive insulin secretion
Results in hypoglycemia
What causes type 1 DM
Autoimmune disease
What causes type 2 DM
Down regulation of insulin receptors
What is the function of metatonin
Day/ night cycles
Physiological processes that show rhythmic variations
What hormone does heart produce what does it do
Atrial natriuretic peptide ANP
Reduce BP/ volume
Reduce blood Na concentration
What hormone is produce by gastrointestinal tracts
Enteroendocrine cells release local acting digestive hormones
What hormones are produced by kidneys
What do they do
Renin and EPO
Regulate aldosterone- blood volume
Production of red blood cells
What hormone does skin produce
What is its function
Cholecalciferol
The precursor of Vit D
What hormone does adipose issue release
Function
Leptin
Satiety
Increased energy expenditure
