Chapter 18 - Endocrine System Flashcards
Which two body systems act together to coordinate functions of all body systems?
Nervous System
Endocrine System
How does the nervous system act on other body systems?
Generates action potentials (nerve impulses) conducted along axons of neurons that trigger the release of neurotransmitters
What is a hormone?
A mediator molecule that is released in one part of the body but regulates the activity of cells in other parts of the body
How do hormone travel throughout the body?
Hormones enter the interstitial fluid, then the blood stream
- circulating blood delivers hormones throughout the body
How does an endocrine response differ from a nervous system response?
Endocrine system is often slower
- some hormones act within seconds, others take minutes
Nervous system effects are more brief
Nervous system acts of specific muscles or glands
Endocrine system effect are much more broad
What are exocrine glands?
Glands that secrete their products into ducts that carry the secretions into body cavities
What are some examples of exocrine glands?
Sudoriferous (sweat) glands, sebaceous (oil), mucous & digestive glands
What are endocrine glands?
Glands that secrete their products into interstitial fluid surrounding the secretory cells rather than into ducts
What are some examples of endocrine glands?
Pituitary, thyroid, parathyroid, adrenal and pineal glands
What are some examples of ORGANS that secrete hormones?
Hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, small intestine, skin, heart, adipose tissue and placenta
What constitutes the endocrine system?
All of the endocrine glands & hormone secreting cells (organs)
What are the functions of hormones?
- Regulate chemical composition & volume of interstitial fluid
- Regulate metabolism & energy balance
- Regulate contraction of smooth & cardiac muscle fibres
- Regulate glandular secretions
- Regulate immune system activities
- Control growth & development
- Regulate operation of reproductive systems
- Help establish circadian rhythms
What is the function of hormone receptors?
Bind to specific hormones
- specific hormone affects only specific target cells b/c of hormone receptors
What is the target cell?
The cell(s) that a specific hormone will influence
What is down-regulation?
If a hormone is present in excess, the number of target-cell receptors may decrease
- makes target cells LESS SENSITIVE to the hormone
What is up-regulation?
If a hormone is deficient, the number of receptors may increase
- makes target cells MORE SENSITIVE to the hormone
What happens if a hormone is prevented from interacting with its receptors?
The hormone cannot perform its normal functions
What are circulating hormones?
Hormones that pass from the secretory cells into interstitial fluid, & then into the blood
What are local hormones?
Hormones that act on neighboring cells or on the same cell that secreted them without first entering the bloodstream
What are paracrines?
Local hormones that act on neighboring cells
What are autocrines?
Local hormones that act on the same cell that secreted them
What are the two kinds of local hormones?
- Paracrines
2. Autocrines
Which kind of hormones is inactivated quickly, which linger longer?
(Circulating vs. Local)
Local are inactivated quickly
Circulating linger in the bood
What are the two broad classes of hormones?
- Lipid-soluble hormones
2. Water-soluble hormones
What are the three kinds of lipid-soluble hormones?
- Steroid hormones
- Thyroid hormones
- Nitric oxide (NO)
Describe steroid hormones.
Each steroid hormone is unique due to the presence of different chemical groups attached at various sites on the 4 rings at the core of its structure
- small differences allow for large diversity
- derived from cholesterol
Describe thyroid hormones.
Synthesized by attaching iodine to the amino acid tyrosine
- presence of two benzene rings makes it very lipid-soluble
Describe nitric oxide (NO).
Both a hormone & a neurotransmitter
- synthesis is catalyzed by the enzyme nitric oxide synthase
What are the three kinds of water-soluble hormones?
- Amine hormones
- Peptide & protein hormones
- Eicosanoid hormones
Describe amine hormones.
Called amines b/c they retain an amino group (NH3+)
- synthesized by decarboxylating (removing a molecule of CO2) & otherwise modifying certain amino acids
Describe peptide & protein hormones.
They are amino acid polymers
- smaller peptide chains of 3-49 amino acids
- larger peptide chains of 50-200 amino acids
Describe eicosanoid hormones.
Derived from arachidonic acid, a 20-carbon fatty acid
- important local hormones
- may act as circulating hormones
What are the two major types of eicosnoid hormones?
- Prostaglandins
2. Leukotrienes
What are the three functions of transport proteins?
- Make lipid-soluble hormones temporarily water-soluble (increase solubility in blood)
- Slow passage of small hormone molecule through kidneys (slows rate of hormone loss)
- Provide a ready reserve of hormone, already present in the bloodstream
Which hormones (water-soluble or lipid-soluble) are bond to transport proteins?
Lipid-soluble
- (water-soluble hormones circulate freely in blood plasma)
What is the “free-fraction” of lipid-soluble hormones?
- 1% - 10% of lipid-soluble hormones are NOT bound to transport proteins
- diffuse out of capillaries, bind to receptors, and trigger responses
Describe the action of lipid-soluble hormones.
- Lipid-soluble hormone diffuses into cell
- Activated receptor-hormone complex alters gene expression
- Newly formed mRNA directs synthesis of specific proteins on ribosomes
- New proteins alter cell’s activity
Describe the action of water-soluble hormones.
- Binding of hormone (first messenger) to its receptor activates G protein, which activates adenylate cyclase
- Activated adenylate cyclase converts ATP to cAMP
- cAMP serves as a second messenger to activate protein kinases
- Activated protein kinases phosphorylate cellular proteins
- Millions of phosphorylated proteins cause reactions that produce physiological responses
- Phosphodiesterse inactivates cAMP
What is a first messenger?
When a water-soluble hormone binds to its receptor at the outer surface of the plasma membrane, it acts as a first messenger
What is a second messenger?
The first messenger causes production of the second messenger inside the cell
- where specific hormone-stimulated responses take place
What is cyclic AMP?
A common second messenger
What is a G protein?
Hormone receptor complex
- acts like a switch
- activates adenylate cyclase
What does adenylate cyclase do?
Converts ATP into cyclic AMP
Why can hormones that bind to plasma membrane receptors be effective at very low concentrations?
B/c they initiate a cascade or chain reaction, each step of which multiplies or amplifies the initial effect
What does the responsiveness of the target cell to a hormone depend on?
- Hormone concentration in the blood
- Abundance of the target cell’s receptors
- Influences exerted by other hormones
What is the permissive effect?
The actions of some hormones on target cells require a simultaneous or recent exposure to a second hormone
- the second hormone is said to have a permissive effect
- without the second hormone, the first hormone is typically very weak
How does the permissive effect work?
The permissive hormone will either:
- Increase the number of receptors for the first hormone
- Promotes the synthesis of an enzyme required for the expression of the first hormone’s effect
What is the synergistic effect?
When the effect of two hormones ACTING TOGETHER is greater or more extensive than the effect of each hormone acting alone
What is the antagonistic effect?
When one hormone opposes the actions of another hormone
How is hormone secretion regulated?
- By signals from the nervous system
- By chemical changes in the blood
- By other hormones
How do most hormone regulatory systems work?
Positive or negative feedback
Negative feedback
- except for childbirth
What is the master endocrine gland?
Hypothalamus
- major link between nervous system & endocrine system
Why is the hypothalamus the master endocrine gland?
B/c it secretes several hormones that control other endocrine glands
How does the pituitary gland attach to the hypothalamus?
By the Infundibulum
What is the infundibulum?
A stalk that connects the pituitary gland to the hypothalamus
Where is the pituitary gland located?
In the hypophyseal fossa of the sella turcica of the sphenoid bone
What are the two portions of the pituitary gland called?
- Anterior pituitary (anterior lobe)
- pars distalis
- pars tuberalis
- Posterior pituitary (posterior lobe)
- pars nervosa
- infundibulum
* third section the pars intermedia atrophies during fetal development (non-existant in adults)
What does the anterior pituitary (adenohypophysis) secrete?
Secretes hormones that regulate a wide range of body activities
- from growth to reproductions
What controls the release of hormones from the anterior pituitary?
Stimulated by releasing hormones and suppressed by inhibiting hormones from the hypothalamus
How does blood flow in the hypophyseal portal system?
Blood flows from capillaries in the hypothalamus into portal veins that carry blood to capillaries of the anterior pituitary
What is the function of neurosecretory cells?
They synthesize the hypothalamic releasing & inhibiting hormones in their cell bodies & package hormones inside vesicles, which reach the axon terminals by axonal transport
- nerve impulses stimulate the vesicles to undergo exocytosis
What is the human growth hormone (hGH)?
Where it is secreted from?
hGH stimulates several tissues to secrete insulinlike growth factors
- hormones that stimulate general body growth & regulate aspects of metabolism
- secreted by anterior pituitary (somatotrophs)
What is GHRH?
Where is it produced?
Growth hormone-releasing hormone (somatocrinin)
- hypothalamus
- stimulated hGH
What is GHIH?
Where is it produced?
Growth hormone-inhibiting hormone (somatostatin)
- hypothalamus
- suppresses hGH & TSH
What does the thyroid-stimulating hormone (TSH) control?
Thyrotropin
Controls the secretions & other activities of the thyroid gland
- anterior pituitary
What is TRH?
Where is it produced?
Thyrotropin-releasing hormone
- hypothalamus
- stimulates TSH
What are the two types of gonadotrophins?
- Follicle-stimulating hormone (FSH)
2. Luteinizing hormone (LH)
What does FSH act on?
The gonads
- initiates development of ovarian follicles & the secretion of of estrogens
- stimulates sperm production
What does LH act on?
The gonads
- triggers ovulation, secretion of progesterone, stimulates formation of corpus leteum
- stimulates cells in testes to secrete testosterone
What is GnRH?
Where is it produced?
Gonadotropin-releasing hormone
- hypothalamus
- stimulates secretion of FSH & LH
What does prolactin (PRL) initiate?
Initiates milk production in the mammary glands
- anterior pituitary
What is PRH?
Where is it produced?
Prolactin-releasing hormone
- hypothalamus
- Stimulates secretion of PRL
What is PIH?
Where is it produced?
Prolactin-inhibiting hormone
- hypothalamus
- suppresses secretion of PRL
What does adrenocorticotropic hormone (ATCH), also known as corticotropin stimulate?
Stimulates the adrenal cortex to secrete glucocorticoids such as cortisol
- anterior pituitary
What is CRH?
Where is it produced?
Corticotropin-releasing hormone (CRH)
- hypothalamus
- stimulates secretion of ATCH & MSH
What is MSH?
Melanocyte-stimulating hormone
- anterior pituitary
- involved in pigmentation changes
How is the secretion of anterior pituitary hormones regulated?
- Neurosecretory cells in the hypothalamus secrete 5 releasing hormones, which stimulate secretion of anterior pituitary hormones, & two inhibiting hormones, which suppress secretion of anterior pituitary hormones
- Negative feedback in the form of hormones released by target glands decreases secretions of three types of anterior pituitary cells
What is the most plentiful anterior pituitary hormone?
hGH
What are the functions of the IGFs (insulin-like growth factors)?
- Cause cells to grow & multiply
- Increased use of fatty acids in ATP production
- Decrease use of glucose for ATP production
What is hypoglycemia?
Abnormally low blood glucose levels
What is hyperglycemia?
Abnormally high blood glucose levels
What is the function of the posterior pituitary (neurohypophysis)?
Stores & releases two hormones
What is the hypothalamohypophyseal tract?
Axons of the cell bodies of the neurosecretory cells of the hypothalamus for the hypothalamohypophyseal tract
What are pituicytes?
Specialized neuroglia
- assist in storage & release of neurohypophysial hormones
- have a supporting role similar to that of astrocytes
What is oxytocin (OT)?
What controls its secretion?
Stimulates contraction of smooth muscle cells of uterus during childbirth
Stimulates contraction of myoepithelial cells in mammary glands
- hypothalamus secretes in response to uterine distention & stimulation of nipples
What is antidiuretic hormone (ADH) or vasopressin?
What controls its secretion?
Conserves body water by decreasing urine volume
Decreases water loss through perspiration
Raises blood pressure by contricting arterioles
- hypothalamus secretes in response to elevated blood osmotic pressure, dehyrdation
What are some inhibitors of ADH?
Low blood osmotic pressure, high blood volume & alcohol
Where is the thyroid gland located?
Just inferior to the layrnx
- composed of left & right lobes on either side of the trachea
What is the isthmus?
how the left & right lobes of the thyroid connect to each other
What are thyroid follicles?
Microscopic spherical sacs that make up most of the thyroid gland
What two hormones do the follicular cells produce?
- Thyroxine (tetraiodothyronine or T4)
2. Triiodothyronine (T3)
What kind of cell lies between the follicular cells?
Parafollicular cells
- produce hormone calcitonin, which helps regulate calcium homeostasis
What are the principal actions of T3 & T4?
Increase basal metabolic rate
Stimulate synthesis of proteins
Increase use of glucose & fatty acids for ATP production
Increase lipolysis
Enhance cholesterol excretion
Accelerate body growth
Contribute to development of nervous system
What is the principal action of calcitonin?
Lowers blood levels of CA2+ amd HPO4 by inhibiting bone resorption by osteoblasts and by accelerating uptake of calcium & phosphates into bone extracellular matrix
- produced by parafollicular cells of thyroid
What are the steps in the synthesis & secretion of thyroid hormones?
- Iodide trapping
- Synthesis of TGB
- Oxidation of iodide
- Iodination of tyrosine
- Coupling of T1 & T2
- Pinocytosis & digestion of colloid
- Secretion of thyroid hormones
- Transport in blood
Which endocrine gland stores large quantities of its secretory product?
(100 day supply)
Thyroid gland
What is thyroglobulin (TGB)?
A large glycoprotein that is produced in the rough endoplasmic reticulum
- used in the synthesis of thyroid hormones
What are the effects of thyroid hormones?
- Increase basal metabolic rate (BMR)
- Stimulate synthesis of additional sodium-potassium pumps
- Stimulate protein synthesis & increase the use of glucose & fatty acids for ATP production
- Enhance some actions of norepinephrine & epinephrine
- Accelerate body growth
What is the calorigenic effect?
As cells produce & use more ATP, more heat is given off & body temperature rises
- b/c of this, mammals can survive in freezing temperatures
What is basal metabolic rate (BMR)?
The rate of oxygen consumption under standard or basal conditions (awake, at rest, & fasting) by stimulating the use of cellular oxygen to produce ATP
What are the steps involved in controlling thyroid hormone secretion?
- Low blood levels of T3 & T4 or low metabolic rate stimulates release of TRH
- TRH (carried by hypophyseal portal veins to anterior pituitary) stimulates release of TSH by thyrotrophs
- TSH released into blood stimulates thyroid follicular cells
- T3 & T4 released into blood by follicular cells
- Elevated T3 inhibits release of TRH & TSH (negative feedback)
What are the conditions that increase ATP demand that also increase the secretion of the thyroid hormones?
Cold environment
Hypoglycemia
High altitude
Pregnancy
Where are the parathyroid glands located?
Partially embedded in the posterior surface of the lateral lobes of the thyroid gland
How many parathyroid glands are there?
4
- one superior & inferior to each lateral lobe of the thyroid
What kinds of cells make up the parathyroid glands?
- Chief (principal) cells
2. Oxyphil cell
What do chief (principal) cells produce?
Produce parathyroid hormone (PTH)
Also called Parathormone
What is parathormone?
Parathyroid hormone, PTH
Increases blood calcium & magnesium levels and decreases blood HPO4 level
- increases bone resportion by osteoclasts
- increases calcium reabsorption & HPO4 excretion by kidneys
- promotes formation of calcitriol
What is calcitriol?
An active form of vitamin D
- increases rate of dietary calcium & magnesium absorption
Where are the adrenal glands located?
Lie superior to each kidney
What are the two distinct regions of the adrenal glands?
- Adrenal cortex
2. Adrenal medulla
What does the adrenal cortex produce?
Produces steroid hormones that are essential to life
What does the adrenal medulla produce?
Three catecholamine hormones:
- Norepinephrine
- Epinephrine
- Small amounts of dopamine
What are mineralocorticoids?
Adrenal cortex hormones
- affect mineral homeostasis
- increase blood levels of sodium & water
- decrease blood levels of potassium
What zone of the adrenal cortex secretes mineralocorticoids?
Zona glomerulosa
- outer zone
What is aldosterone?
The major mineralocorticoid
- regulates homeostasis of sodium & potassium
- helps adjust blood pressure & blood volume
What is the renin-angiotensin-aldosterone (RAA) pathway control?
Controls secretion of aldosterone
What are the steps involved in controlling aldosterone?
- Dehydration, sodium deficiency, or hemorrhage
- Decrease in blood volume
- Decrease in blood pressure
- Low blood pressure stimulates kidneys to secrete renin
- Increased renin
- Renin converts angiotensinogen into angiotensin I
- Increased levels of angiotensin I in blood
- Enzyme angiotensin-converting enzyme (ACE) converts angiotensin I into hormone angiotensin II
- Blood levels of angiotensin II increase
- Angiotensin II stimulates adrenal cortex to secrete aldosterone
- Aldersterone circulates to kidneys
- Aldersterone increases reabsorption of sodium (less water is lost through urine)
- Increased water resorption, blood volume increases
- Blood pressure returns to normal
What is renin?
An enzyme secreted by and stored in the kidneys that promotes the production of the protein angiotensin
What is angiotensinogen?
A plasma protein
What is angiotensin II?
- Hormone that causes vasoconstriction and a subsequent increase in blood pressure.
- Stimulates the release of aldosterone, from the adrenal cortex.
What do glucocorticoids regulate?
Regulate metabolism & resistance to stress
- includes cortisol, corticosterone & cortisone
What is cortisol?
A steroid hormone produced by the adrenal cortex and used medicinally to treat inflammation resulting from eczema and rheumatism.
What is corticosterone?
A steroid hormone, secreted by the adrenal cortex, that is involved in regulation of the water and electrolyte balance of the body
What is cortisone?
A hormone produced by the adrenal cortex. One of the glucocorticoids, it is also made synthetically for use as an anti-inflammatory and anti-allergy agent
What are the steps involved in controlling glucocorticoid secretion?
- Stimulus disrupts homeostasis by decreasing glucocorticoid level in blood
- Stimulate neurosecretory cells in hypothalamus to secrete CRH (corticotropin-releasing hormone)
- CRH promoes release of ACTH from anterior pituitary
- ACTH flows in the blood to adrenal cortex, stimulates secretion of glucocorticoid
- Increased levels of glucocorticoid levels in blood
- Return to homeostasis
What effects do glucocorticoids have?
- Protein breakdown
- Glucose formation
- Lipolysis
- Resistance to stress
- Anti-inflammatory effects
- Depression of immune resonses
What are androgens secreted by?
Adrenal cortex
What are the principal actions of androgens?
- assist in early growth of axillary & pubic hair in both sexes
- in females - contribute to libido & are a source of estrogens after menopause
What are chromaffin cells?
Hormone producing cells of adrenal medulla
- norepinephrine & epinephrine
What are norepinephrine & epinephrine?
Noradrenaline & adrenaline
- intensify sympathetic responses that occur in other parts of the body
- increase output of heart
- increase blood pressure
- dilate airways
- increase blood levels of glucose & fatty acids
What is the pancreas?
Both an endocrine & exocrine gland
Where is the pancreas located?
In the curve of the duodenum, the first part of the small intestine
What are acini?
Clusters of exocrine cells in the pancreas
What do acini produce?
Produce digestive enzymes
What are pancreatic islets?
Tiny clusters of endocrine tissue scattered among the exocrine acini
What are the 4 types of hormone-secreting cells are found in the pancreatic islets?
- Alpha (A) cells (17%)
- Beta (B) cells (70%)
- Delta (D) cells (7%)
- F cells (6%)
What do A cells secrete?
Secrete glucagon
What do B cells secrete?
Secrete insulin
What do D cells secrete?
Secrete somatostatin
What do F cells secrete?
Secrete pancreatic polypeptide
What is the principal action of glucagon?
Raises blood glucose level by accelerating breakdown of glycogen into glucose in liver, release glucose into blood
What is the principal action of insulin?
Lowers blood glucose levels by accelerating transport of glucose into cells, converting glucose into glycogen
What is the principal action of somatostatin?
Inhibits secretion of insulin & glucagon
- slows absorption of nutrients from gastrointestinal tract
What are the steps involved in regulating glucagon & insulin secretion?
- Low blood glucose (hypoglycemia) stimulates A cells to secrete glucagon
- Glucagon accelerates the conversion of glycogen into glucose
- Blood glucose level rises
- If blood glucose continues to rise, high blood glucose level (hyperglycemia) inhibits relase of glucagon
- High blood glucose (hyperglycemia) stimulates secretion of insulin by B cells
- Insulin accelerates diffusion of glucose into cells & speeds conversion of glucose into glycogen
- Blood glucose level falls
- If blood glucose level drops below normal, low blood glucose inhibits release of insulin & stimulates release of glucagon
What are gonads?
Organs that produce gametes
- sperm & oocytes
What hormones do the ovaries produce?
- Two estogrens (estradiol & estrone)
2. Progesterone
What is inhibin?
Hormone produced by ovaries
- inhibits secretion of follicle-stimulating hormones (FSH)
What is relaxin (RLX)?
Peptide hormone produced by ovaries & placenta
- increases the flexibility of the pubic symphysis during pregnancy
- helps dilate the uterine cervix during labor & delivery
What are the principal actions of estrongens & progesterone?
- regulate female reproductive cycle & oogensis
- maintain pregnancy
- prepare mammary glands for lactation
- promote development & maintenance of female secondary sex characteristics (breast enlargement & hip widening)
What is the main hormone secreted by the testes?
What are the principal actions of this hormone?
Testosterone (an androgen)
- stimulates the descent of testes before birth
- regulates production of sperm
- stimulates the development & maintenance of male secondary sex characteristics (beard growth, deepening of voice)
What other hormone is produced by the testes?
What is it’s principal action?
Inhibin
- inhibits secreation of FSH from anterior pituitary
What is the pineal gland and where is it located?
Small endocrine gland
- attached to the roof of the third ventricle of the brain at the midline
What are pinealocytes?
Secretory cells and masses of neuroglia of the pineal gland
What hormone does the pineal gland secrete?
Melatonin
- an amine hormone derived from serotonin
What does melatonin contribute to?
Contributes to the setting of the body’s biological clock
- thought to promote sleepiness
Where is the thymus located?
Behind the sternum between the lungs
What hormones are produced by the thymus?
- Thymosin
- Thymic humoral factor (THF)
- Thymic factor (TF)
- Thymopoietin
What is the principal action of the hormones produced by the thymus?
Promote the maturation of T cells (a type of white blood cell that destroys microbes & foreign substances) & may slow the aging process
What are the two families of eicosanoid molecules?
- Prostaglandins
2. Leukotrienes
What do eicosanoid molecules do?
Act as local hormones in response to chemical or mechanical stimuli
- found in virtually all body cells (except red blood cells)
How do eicosanoid molecules exert their effects?
- Eicosanoids bind to receptors on target-cell plasma membranes
- Stimulate or inhibit the synthesis of second messengers such as cyclic AMP
What do leukotrienes stimulate?
Stimulate chemotaxis (attactration to a chemical stimulus) of white blood cells & mediate inflammation
What do prostaglandins do?
Alter smooth muscle contraction, glandular secretions, blood flow, reproductive processes, promotoing inflammation & fever, & intensify pain
What role do growth factors play?
Roles in tissue development, growth & repair
- cause growth by stimulating cell division
What are some examples of growth factors?
- epidermal growth factor
- platelet-derived growth factor
- fibroblast growth factor
- nerve growth factor
- tumor angiogenesis factors
- transforming growth factors
What are two different kinds of stress?
- Eustress - prepares us to meet certain challenges
2. Distress - harmful
What is a stressor?
Any stimulus that produces a stress response
heat, cold, environmental poisons, toxins, bleeding, strong emotional reaction
What are the three stages of stress response?
General Adaptation Syndrome, GAS
- Initial fight-or-flight response
- Slower resistance reaction
- Exhaustion
What is the fight-or-flight response?
A physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival
What body functions are inhibited during fight-or-flight?
Nonessential body functions
- digestive, urinary, reproductive systems
Which hormones are involved in the resistance reaction?
Corticotropin-releasing hormone (CRH)
Growth hormone-releasing hormone (GHRH)
Thyrotropin-releasing hormone (TRH)
What does the resistance reaction help us to do?
Helps the body continue fighting a stressor long after the fight-or-flight response dissipates
What happens during exhaustion?
The resources of the body may eventually become so depleted that they cannot sustain the resistance stage, and exhaustion ensues
What role does stress have in contributing to human disease?
Exact role is unclear
- but it is clear that stress can lead to particular diseases by temporarily inhibiting certain components of the immune system
What are the three pituitary gland disorders?
- Pituitary dwarfism
- Giantism
- Acromegaly
What is Pituitary dwarfism?
Hyposecretion of hGH during the growth years slows bond growth, and the epiphyseal plates close before normal height is reached
- treatment requires administration of hGH during childhood before epiphyseal plates close
What is giantism?
Hypersecretion of hGH during childhood
- abnormal increase in the length of the long bones
- very tall, but proportions are normal
What is acromegaly?
Hypersecretion of hGH during adulthood
- long bones do not growth (plates are sealed)
- bonds of the hands, feet, cheeks & jaws thicken & other tissues enlarge
- skin thickens & develops furrows especially on the forehead & soles
What is diabetes insipidus?
Dysfunction of the posterior pituitary gland
- due to defects in antidiuretic hormone (ADH) receptors or an inability to secrete ADH
- bed-wetting is a common affliction in children
- individual may die from dehydration
- needs hormone replacement for life
What is congenital hypothyroidism?
Hyposecretion of thyroid hormones that is present at birth
- causes severe mental retardation & stunted bone growth
- thyroid treatment must be given for life
What is myxedema?
Hypothyroidism during the adult years
- edema - accumulation of interstitial fluid that causes the facial tissues to swell & look puffy
- has a slow heart rate, low body temperature, sensitivity to cold, dry hair & skin, muscular weakness, general lethargy & tendency to gain weight easily
What is Graves’ disease?
Hyperthyroidism
- autoimmune disorder in which the person produces antibodies that mimic the action of thyroid-stimulating hormone (TSH)
- primary sign is enlarged thyroid
- very common to have an edema (swelling behind the eyes)
What is a goiter?
Enlarge thyroid gland
- may be associated with hyperthyroidism, hypothyroidism or euthyroidism
- in some places of the world, iodine intake in inadequate which causes the thyroid to enlarge
What is Cushing’s syndrome?
Adrenal gland disorder
Hypersecretion of cortisol by the adrenal cortex
- characterized by breakdown and redistribution of muscle and fat
- “moon face”, “buffalo hump” and “hanging abdomen”
- bruise easily & healing is poor
What is Addison’s disease?
Adrenal gland disorder
Hyposecretion of glucocorticoids & aldosterone
- mental lethargy, anorexia, nausea & vomiting, weight loss, hypoglycemia, muscular weakness
- skin may have bronzed appearance
What is diabetes mellitus?
Pancreatic islet disorder
- inability to produce or use insulin
- 4th leading cause of death by disease in US
- blood glucose level is HIGH
What is hypoglycemia?
Decreased blood glucose level, which occurs b/c excess insulin stimulates too much uptake of glucose by body cells
What is hyperglycemia?
Abnormally high blood glucose concentration
