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120 Cards in this Set

  • Front
  • Back
Compare the ES to the nervous system and the exocrine
gland system
Compared to the nervous system communication by the ES is
-slow
-effects on target cells often last longer
-not targeted to specific individual cells
Name the chemical messengers produced by endocrine
glands and how they reach their target cells.
hormones are secreted into blood circulation which carries them to target cells
*How many hormones can be produced by a single
endocrine gland or cell type? How many glands can
produce a particular hormone?
-a single gland can secrete multiple hormones
-a hormone may be produced by more than one gland
*What roles in other systems are played by the chemicals
that act as hormones in the ES
a chemical acting as a hormone in the ES may serve as a neurotransmitter in the nervous system or an autocrine/paracrine agent
Name the amino acid from which all amine hormones are produced.
amino acid: tyrosine
Amine Hormones Sources
thyroid hormones:
-triiodothyronine T3
-tetraiodothyronine T4 (thyroxine)

catecholamines:
-made in adrenal medulla
-epinephrine E
-norepinephrine NE

hypothalamus:
-dopamine

-serotonin 5-HT
Amine Hormones
T3
T4
epinephrine
norepinephrine
dopamine
serotonin
What is the size range of the peptide hormones?
3 amino acids to small proteins
Using all the proper terms, list the steps in peptide hormone synthesis.
Synthesis
-synthesized on ribosomes as inactive preprohormones
-cleaved to prohormones in rough ER
-packaged in vesicles in Golgi and cleaved to active form


ribosomes to rough ER to Golgi
How are peptide hormones released?
exocytosis
Name the molecule from which all steroid hormones are synthesized
cholesterol
List the basic steps in the synthesis of a steroid hormone by a cell.
1. Synthesis is triggered by binding of tropic factors from pituitary to receptors on target endocrine cells

2. cAMP is produced as second messenger

3. cAMP activates PKA --> phosphorylation of cholesterol esterase

4. cholesterol esterase releases cholesterol from lipid stores

5. mitochondria and smooth ER convert free cholesterol into hormones
Describe how steroid hormones are released from cells.
Steroid hormones leave cells by diffusing across membranes into the blood.

They are transported in blood bound to carrier proteins.
Steroid Hormones
Adrenal Cortex
-Aldosterone
-Cortisol
-Corticosterone
-Androstenedione
-Dehydroepiandrosterone (DHEA)

Gonads
-Androstenedione (testes)

Skin
-calcitriol
Steroid Hormones
Adrenal Cortex Hormones Functions
Aldosterone
-important for regulation of Na+, K+, and H+ by kidneys
-produced in zona glomerulosa (outer layer)

Glucocorticoids (cortisol and corticosterone)
-important for metabolism of glucose and other organic nutrients
-produced in zona fasciculata and zona reticularis (middle and inner layers)

Androgens (androstenedione and DHEA)
-less potent than androgen testosterone (from testes)
-not important in adult male
-has roles in adult female, in fetus and at puberty
-produced in zona fasciculata and zona reticularis (middle and inner)
Steroid Hormones
Gonads Functions
-in testes androstenedione is precursor of major male androgen testosterone

-in ovaries enzyme aromatase converts testosterone to major female sex hormone estradiol
Steroid Hormones
Skin Functions
Vitamin D
-denotes a group of compounds
-calcitriol is the active form that stimulates calcium absorption from the gut
List the types of water soluble hormones.
catecholamines and most peptides
How are water soluble hormones transported in the blood?
water soluble hormones are dissolved in plasma
List the types of non-water soluble hormones.
steroid hormones and thyroid hormones
How are non-water soluble hormones transported in the blood?
-non-water soluble hormones are transported bound to proteins in blood
-a small amount of these hormones is free in plasma
Explain what is meant by bound, free, and total hormone.
non-water soluble hormones

bound: bound to protein in blood
free: free in plasma
total = free + bound
Explain the importance of the free hormone.
the concentration of the free hormone is more important than the amount of total hormone as only the free hormone can diffuse across capillary walls and reach target cells
Describe the factors that control the elevation of hormone levels in the blood.
rate of secretion by endocrine gland
and
rate of "clearance" from the blood by
-excretion
-metabolic transformation
Describe the routes/mechanisms of hormone removal from the blood.
-excreted or metabolized by kidney or liver

-target cells can also metabolize peptide hormones by endocytosis and catabolism of hormone-receptor complexes

-catecholamines and peptide hormones in blood tissues are also removed by enzymatic degradation
What are the major organs involved in hormone excretion and metabolism?
kidneys and liver
Compare the length of time water soluble and nonwater soluble hormones remain elevated in the blood.
water soluble: removed quickly (minutes to an hour)

non-water soluble: removed slowly (hours to days)
Describe the role of metabolism by target cells in hormone activation.
-metabolism may be necessary for activation of some hormones

-metabolism in target cells converts some hormones to their active state
Compare the locations of the receptors for water soluble (peptide and catecholamine) and nonwater soluble (steroid and thyroid) hormones.
water soluble: on cell membranes

non-water soluble: intracellular
Using all the appropriate terminology, explain how hormone levels can affect receptor density.
low levels may cause increased receptor density = up-regulation

high levels may cause decreased receptor density = down-regulation
Explain what is meant by "permissiveness."
some hormones can up-regulate or down-regulate the density of receptors for other hormones

-"permissiveness" refers to situation where one hormone must be present for another hormone to have its full effect

-example: epinephrine + thyroid hormone
List/describe the effects of the binding of water soluble hormones to their receptors.
-usually rapid actions

-influence enzyme activity of receptors
-influence activity of cytoplasmic JAK kinases associated with receptor
-influence activity of G proteins coupled to effector proteins (ion channels and enzymes) that generate second messengers

-in some cases may activate/inhibit transcription of particular genes --> more long term responses
Describe the effects of the binding of non-water soluble hormones to their receptors.
-usually binding of hormones to receptors results in transcription of particular genes and increased synthesis of particular proteins

-ultimate effect is enhancement or inhibition of particular cell processes or secretion of particular proteins by cells

-some of these hormones also mediate rapid responses through plasma membrane receptors
*How are high concentrations of hormones sometimes used pharmacologically?
high concentrations can have effects not seen nomally = "pharmacological effects"

example: adrenal cortisol used to suppress inflammation and allergic reactions
Give a general description of rates of hormone secretion.
-usually secreted in short bursts
-may fluctuate with circadian rhythms
List/describe the inputs to endocrine cells that influence hormone secretion.
Inputs:
-changes in plasma levels of mineral ions or organic nutrients
-neurotransmitters from neurons acting on endocrine cells
-other chemical signalling agents, including hormones (tropic hormones)

-rate of hormone secretion is result of integration of multiple (sometimes conflicting) inputs
What is a tropic hormone?
a tropic hormone is a hormone that stimulates secretion of another hormone
*Give examples of some of the varied effects of endocrine disorders.
-imbalance in metabolism (weight loss or gain)
-failure to grow or develop normally in early life
-abnormally high or low blood pressure
-loss of reproductive fertility
-changes in mental or emotional state
What is hyposecretion?
too little hormone
What is hypersecretion?
too much hormone
What is hyporesponsiveness?
reduced response of target cells
What is hyperresponsiveness?
increased response of target cells
*What is primary, secondary, and tertiary hyposecretion?
primary hyposecretion
-occurs when gland is secreting too little hormone
-examples: destruction of adrenal cortex leads to decreased cortisol secretion; dietary iodine deficiency leads to decreased thyroid hormone secretion

secondary hyposecretion:
-occurs when not enough tropic hormone to stimulate gland

tertiary hyposecretion:
-rare
-occurs when factors from the hypothalamus that stimulate the tropic hormone-producing gland are absent
*How is hyposecretion treated?
treatment of hyposecretion is generally by giving hormone injection or by oral or nasal administration
*What are examples of hypersecretion?
Pheochromacytoma
-tumor of adrenal medulla
-unregulatedsecretion of catecholamines
-symptoms: tachycardia, hypertension, headache, episodes of sweating, anxiousness, tremor

Tumor of endocrine gland
-Treatments: removal or irradiation of tumor; drugs that block hormone's synthesis; drugs that block hormone's action on target cells
*What is hyporesponsiveness? Give examples.
-target cells do not respond normally to hormone
-caused by low density of receptors for hormones, abnormal receptors for hormones, or abnormal response to hormone

example: diabetes mellitus (type 2)
-target cells are hypresponsive to insulin

example: androgen insensitivity syndrome (or testicular feminization)
-target cells don't bind to androgens in genetic males --> failure to develop male sex characteristics
*What is hyperresponsiveness? Give examples.
-increased response to hormones by target cells

example: hypersecretion of thyroid --> increased synthesis of receptors for epinephrine --> hyperresponsiveness to epinephrine
Describe the location in the brain of the pituitary and the hypothalamus.
pituitary protrudes from base of brain and lies in a pocket of sphenoid bone

-pituitary is connected to anterior hypothalamus by infundibulum
Using all of the correct anatomical terms, describe in detail the anatomy of the pituitary.
pituitary has two lobes: anterior & posterior

Anterior (Adenohypophysis)
-derived from same tissue as roof of mouth
-special capillary circulation allows chemical signaling agents from neurons in the hyptholamus to circulate into the anterior pituitary

Posterior (Neurohypophysis)
-derived from neural tissue
-axons from neurons in hypothalamus project to capillaries in the posterior pituitary and release their chemical signaling agents
Describe the source of the hormones of the posterior pituitary and how they are transported into the posterior pituitary.
-synthesized by neurons in the hypothalamus

-axons carry hormones to posterior pituitary and release them into blood circulation

-posterior pituitary hormones are also produced in other parts of brain where they act as neurotransmitters
What is the posterior pituitary hormone? Describe its function.
posterior pituitary hormone: Oxytocin

-stimulates secretion of milk from breasts during lactation

-stimulates contraction of uterine smooth muscle during labor
Describe the role of releasing and inhibitory factors from the hypothalamus on the anterior pituitary.
specific releasing factors stimulate release of specific anterior pituitary hormones

specific inhibiting factors inhibit release of specific anterior pituitary hormones
Describe how releasing and inhibitory factors from the hypothalamus reach the anterior pituitary.
factors are carried from the hypothalamus to the anterior pituitary through the hypothalamo-pituitary portal vessels
Give a general description of the cascade of events that occurs when a releasing factor goes from the hypothalamus to the pituitary.
stimulus --> hypothalamus (hormone 1 secretion) --> anterior pituitary (hormone 2 secretion) --> third endocrine gland (hormone 3 secretion)

-target cells respond to hormone 3
List the major hormones released from the anterior pituitary.
FSH: follicle-stimulating hormone
LH: luteinizing hormone
GH: growth hormone, somatotropin
TSH: thyroid stimulating hormone
Prolactin
ACTH: adrenocorticotropic hormone
FSH & LH Function
-gonadotropic hormones

-germ cell development
-production of estrogens/progesterone in females
-production of testosterone in males
Growth Hormone Function
-stimulates protein synthesis and lipid/carbohydrate metabolism in many tissues

-stimulates secretion of insulin-like growth factor 1 (IGF-1) from liver and other cells
TSH Function
-stimulates thyroid to secrete triiodothryonine T3 and thyroxin T4
Prolactin Function
-breast development and milk production
-decreases female fertility during breast feeding
Adrenocorticotropic (ACTH) Function
-secretion of cortisol from adrenal cortex
Name and describe the functions of all of the know hypophysiotropic hormones.
CRH, GHRH, SS, TRH, GnRH, DA

CRH (corticotropin-releasing hormone) --> stimulates release of ACTH

GHRH (growth hormone-releasing hormone) --> stimulates secretion of GH

SS (somatostatin) --> inhibits release of GH

TRH (thyrotropin-releasing hormone) --> stimulates secretion of TSH

GnRH (gonadotropin-releasing hormone) --> stimulates secretion of LH and FSH

DA (dopamine or prolactin-inhibiting hormone, PIH) --> tonically inhibits the secretion of prolactin
Describe the neural controls of hypophysiotropic hormone release.
Many excitatory and inhibitory neural inputs to hypothalamic neurons that release hypophysiotropic hormones.
Describe the long-loop and short-loop negative feedback control of hypophysiotropic hormone release.
Long-Loop Negative Feedback
-third (final) hormone in sequence
-acts back on hypothalamus to inhibit secretion of hypophysiotropic hormone
-acts back on anterior pituitary to inhibit secretion of second hormone in sequence

Short-Loop Negative Feedback
-second hormone (from anterior pituitary) in sequence acts back on hypothalamus to inhibit secretion of hypophysiotropic hormone
State the importance of thyroid hormones to life.
NOT essential for life, but have widespread and diverse effects throughout the body
Name the two iodine-containing hormones of the thyroid. Tell which one is the major one and why.
T3 & T4

T4 is major form in blood but T4 is converted to T3 in target cells

Thus, T3 is considered the major thyroid hormone
Describe the location and structure of the thyroid gland.
-bilobed and wrapped around trachea

-tissue consists of follicles which are structures consisting of cells surrounding a protein-rich core
Describe in detail the steps in thyroid hormone synthesis.
1. Iodide trapping: iodide is carried into follicular cells by a unidirectional Na+ contransport mechanism

2. Iodide diffuses to luminal side of cells

3. Thyroid peroxidase oxidizes the iodide to an iodine free radical and binds it to tyrosine residues of a thyroglobin protein synthesized by the follicular cells
-if 1 iodine attached forms monoiodotyrosine (MIT)
-if 2 iodines attached forms diiodotyrosine (DIT)

4. The phenolic ring of tyrosine is cleaved from a MIT or DIT and coupled to another DIT of the thyroglobin to form either T3 or T4 (still contained within the thyroglobin)

5. When thyroid hormone is needed, the iodinated thryoglobin is brought back into the follicular cells by endocytosis

6-7. The endocytotic vessels merge with lysosomes and proteolytic enzymes digest the thryoglobin to release the T3 and T4 which are then released into the blood.
What is the basic mechanism that controls thyroid function?
basic mechanism: long-loop negative feedback loop of TH (thyroid hormone) acting on anterior pituitary and hypothalamus
Describe the general and specific actions of the thyroid hormones.
General
-nuclei of most cells in body have thyroid hormone receptors that bind both T3 & T4
-hormones act by inducing gene transcription and protein synthesis

2. Metabolic Actions
-TH stimulates carbohydrate absorption from intestine and fatty acid release from adipocytes
-provides energy for the activity of the Na+/K+ ATPases throughout the body
-major effect of TH on the body is heat production = calorigenic effect

3. Permissive Actions
-TH upregulates beta-adrenergic receptors in tissues, especially heart and nervous systems
-thus, excess TH action can resemble symptoms of excess sympathetic nervous system activity (thyroid + epinephrine)
-patients with hyperthyroidism are often treated with beta-adrenergic receptor blockers

4. Growth and Development
-TH required for production of GH and absense retards growth in children
-especially important in nervous system development
-absence in fetal development can result in congenital hypothyroidism (formerly "cretinism")
-also required for normal nerve/muscle reflexes and cognition in adults
What is calorigenic effect and cretinism?
heat production = calorigenic effect of TH

Cretinism
-congenital hypothryoidism
-absense of TH in fetal development, results in poorly developed nervous system
-results in mental retardation
-most commonly caused by iodine deficiency
-can be at least partially corrected by administering TH and iodine to newborn
*Define hypothyroidism.
plasma TH below normal levels
*List categories/types of hypothyroidism, frequency of each, and cause of each type.
Primary
-defect in thyroid gland
-95% of all cases
-caused by loss of functional thyroid tissue or inadequate iodine
-iodine-deficiency primary hypothyroidism common worldwide
-stimulation of thyroid growth: goiter
-reversible with addition of iodine to diet

-autoimmune thyroiditis most common form of primary hypothyroidism in US
-autoimmune destruction of thyroid gland
-Hashimoto's disease
-more common in women
-goiter can occur
-treated with T4


Secondary
-defect in anterior pituitary
-defect in hypothalamus
*What is a goiter?
enlarged thyroid
-can be caused by iodine-deficiency primary hypothyroidism or autoimmune thyroiditis
*Symptoms of hypothroidism
-decreased BMR
-fatigue
-weight gain
-cold intolerance
-reduced HR and blood pressure
-decreased concentration

Myxedema
-accumulation of hydrophilic glycosaminoglycans in intracellular space
-causes puffiness of face and other areas
*What is another term for hyperthyroidism?
thyrotoxicosis
*Name the conditions that can cause hyperthyroidism
hormone-secreting tumors (rare)

Graves' disease
-autoimmune disease
-more common in women with onset at 20-40 years of age
-produce antibodies that activate TSH receptor
-result is hypertrophy of thyroid
-increased T3 and T4
-goiter
*Symptoms of hyperthyroidism
-increased BMR
-weight loss + increased appetite
-heat intolerance
-often increased sympathetic nervous system activity especially with stress of cardiovascular system

exophthalmos or proptosis
-bulging eyes
-1/3 cases
-due to immune attack on structures between eyes
*Treatment of hyperthyroidism (thyrotoxicosis)
-drugs that inhibit TH synthesis
-surgical removal of thyroid
-destruction of thryoid using radioactive iodine followed by TH supplementation
Describe the terms "stress" and "stressor"
Stress is an environmental change that must be adapted to if life and health are to be maintained

Stressors include physiological challenges and harmful or potentially harmful conditions
List the common physiological stressors.
-trauma
-prolonged exposure to cold
-prolonged heavy exercise
-infection
-decreased oxygen supply
-sleep deprivation
-fright
-pain
Describe the element that is common to ALL stress responses.
responses to different stressors vary but one element common to all:


increased secretion of the glucocorticoid hormone CORTISOL by adrenal cortex

thus, "stress" has come to mean any response in which cortisol levels are raised
What is another characteristic response to stress?
activation of the sympathetic nervous system including increased release of epinephrine from adrenal medulla is often a characteristic of "stress"
List the actions of sympathetic nervous system during stress.
1. increased hepatic and muscle glycogenolysis (provides a quick source of glucose)
2. increased breakdown of triglyceride (provides a supply of glycerol for gluconeogenesis and of fatty acids for oxidation)
3. decreased fatigue of skeletal muscle
4. increased cardiac function
5. diverting blood from viscera to skeletal muscles
6. increased lung ventilation
Describe the hormonal stress response and list the hormones or other signaling agents that may be involved.
-the hormonal stress response is triggered by neural inputs to the hypothalamus
-activates the CRH/ACTH/cortisol system

hormones other than CRH which are released during stress can also stimulate ACTH secretion:
-vasopressin
-cytokines (chemical singalling agents secreted by immune cells; link the endocrine stress respone to immune system activation)
What is the role of cytokines the stress response?
cytokines are chemical signalling agents secreted by immune cells

cytokines link the endocrine stress response to immune system activation
Describe in detail the physiological functions of cortisol.
1. Basal cortisol levels required to maintain
-blood pressure
-cellular concentrations of enzymes required for metabolic homeostatis (located primarily in liver)

2. Cortisol has systemic anti-inflammatory and anti-immune functions
-inhibits production of leukotrienes and prostaglandins that promote inflammation
-acts as brake on immune system which would otherwise overreact to minor infections
-cortisol reduction may be a cause of autoimmune disorders

3. in development cortisol plays a role in the differentiation of many tissues including brain, lungs, intestine, etc.
Describe the functions of cortisol in stress.
In stressful situations organism may have to fast or may be injured
-cortisol increases plasma concentrations of amino acids, glucose, glycerol, and free fatty acids
-provides fuel when fasting
-amino acids can be converted to glucose or used for tissue repair
Describe the implications of cortisol's actions on recovery from surgery and growth/development in children.
-patients who are ill or recovering from surgery catabolize significant amounts of body protein
-children subjected to severe stress of any kind may exhibit retarded growth
Describe the effect of cortisol on responsiveness to epinephrine and the consequences of low cortisol for blood pressure and circulation.
cortisol also acts during stress to increase responsiveness of vascular smooth muscle to norepinephrine to maintain blood pressure
-if cortisol levels are insufficient a patient may exhibit hypotension
-persons exposed to extreme stress can die of circulatory failure if plasma cortisol levels don't increase above basal levels
Functions of cortisol in stress.
stress --> immune cell secretion of cytokines --> increased secretion of ACTH --> increased secretion of cortisol

elevation of plasma cortisol dampens immune response in which cytokines play a role
Describe the interaction of cortisol with cytokines and the implications for immune system function during stress.
interaction between cortisol and cytokines insures that stress does not cause excessive immune or inflammatory reactions
Make a list of the hormones other than cortisol that are released during stress and briefly describe the function of each.
aldosterone, vasopressin, glucagon, GH, insulin, beta-endorphin

-aldosterone and vasopressin help maintain blood pressure
-aldosterone retains sodium
-vasopressin (ADH) retains water

-glucagon, GH, and insulin play role in metabolization of energy stores

-beta-endorphin release may relate to pain relief
List and describe the deleterious effects of a chronic stress response.
-reduced fertility
-deterioration bone and muscle
-compromised immune system function
-development of atherosclerosis (hardening of arteries) and hypertension

true for psychological as well as physical stress
*Define adrenal insufficiency and list the symptoms of this condition
-cortisol is absolutely essential for life

-adrenal insufficiency refers to a condition of chronically low cortisol levels

symptoms:
low blood sugar
weakness
lethargy
loss of appetite
low blood pressure
*Describe the causes of primary and secondary adrenal insufficiency.
Primary Adrenal Insufficiency (Addison's Disease) cause by destruction of adrenal gland tissue by
-tumors
-diseases
-autoimmune attack (most common)

often also affects aldosterone levels --> imbalances of water, K+, Na+ in blood --> hypotension

Secondary Adrenal Insufficiency is caused by deficiency of ACTH
*What is another name for primary adrenal insufficiency?
Addison's Disease
*What is Cushing's Syndrome?
chronically elevated cortisol levels in nonstressed individual
-may be primary or secondary as with ACTH secreting tumor of pituitary (most common)
*Describe the symptoms of Cushing's syndrome.
uncontrolled catabolism of bone, muscle, skin, etc.

catabolism --> precursors for gluconeogenesis --> increased blood sugar --> symptoms like diabetes

cortisol-mediated immune suppression

redistribution of body fat --> "moon face"

increased appetite --> obesity

hypertension
*Describe a common cause of Cushing's syndrome.
prolonged clinical use of glucocorticoids to reduce inflammation can cause Cushing's syndrome
List the 3 general factors in growth.
genetics
environment
endocrine function
What kind of growth detemine's height?
bone growth
Describe the basic structure of bone.
collagen matrix in which calcium salts are deposited

ends of bone called epiphyses and rest is the shaft

epiphyseal growth plate is cartilage junction between ends and shaft
Using the proper terms describe the process of growth of immature long bones.
-cartilage proliferates in growing bone
-osteoblasts convert cartilage to bone on side of plate next to shaft
-new cartilage put down by chondrocytes in interior of plate
-epiphyseal closure occurs when hormones of puberty convert plates to bone and stop growth
Name the two postnatal development periods in which the greatest changes in height occurs.
first two years of life
&
puberty
What occurs at the epiphyses to stop growth of long bones?
epiphyseal closure occurs when hormones of puberty convert epiphyseal plates to bone and stop growth
Name the two environmental factors that influence growth.
adequate nutrition
&
freedom from disease
Describe the adverse effects of malnutrition in fetal and early child development.
can inhibit physical growth and intellectual development
How many growth/growth-inhibiting factors influence growth?
60
List the major hormones/growth factors that influence growth.
-growth hormones
-thyroid hormones
-testosterone
-estrogen
-insulin
-cortisol
-peptide growth factors including insunlin-like growth factors I and II
*Briefly describe the relationship between growth factors, oncogenes, and some cancers.
Some cancers are caused by oncogenes which produce growth factors, factors similar to growth factors, growth factor receptors, or intermediates in growth factor signal transduction pathways
Describe in detail when and how growth hormone influences growth.
GH has no effect on fetal growth but most important hormone for postnatal growth
-stimulates cell division in many tissues such as chondrocytes in epiphyseal tissues
-acts mostly indirectly by stimulating synthesis and release of the mitogen, insulin-like growth factor 1 (IGF-1)
-IGF-1 from liver released into blood as hormone
-IGF-1 from other tissues act as autocrine/paracrine agent
*What causes dwarfism?
dwarfism can be caused by low GH, low IGF-1, or lack of tissue response to IGF-1
Other GH effects
increased amino acid uptake by cells
stimulates ribosome synthesis and activity
stimulates growth in other organs, especially muscle
Describe the feedback control of GH release through the hypothalamus and anterior pituitary.
hypothalamus secretes GHRH and SS

GHRH stimulates GH release from anterior pituitary
SS inhibits GH release from anterior pituitary

when GHRH is released SS is not
What causes the diurnal fluctuations of GH in the blood?
diurnal rhythm of GH: GH elevated in sleep but low when awake

negative feedback of GH and IGF-1 on hypothalamus and anterior pituitary regulate GH secretion
Describe in detail the influence of sex hormones, insulin, and thyroid hormones on GH and growth.
result is age-related rates of growth
-highest in adolescence
-next highest in children
-lowest in adults
-in older adults get loss of bone and muscle and increased adipose tissue

IGF-1 (but not GH) is necessary for fetal growth and nervous system development
IGF-II is necessary for postnatal growth and throughout life (not dependent on GH)

thryoid hormone influences synthesis of GH

Insulin
-anabolic actions prevent protein degradation
-directly influences fetal cell differentiation and division


Sex hormones start to increase at ages 8-10 and plateau at 13-20
-stimulate GH and IGF-1 secretion
-stop growth by closing epiphyses
-higher testosterone in males causes increased muscle mass
*Describe the use of anabolic steroids by athletes and the dangers of steroid use.
testosterone-like compounds used by athletes to increase muscle mass

can also cause infertility, liver damage, and increased risk of prostate cancer
*List the effects of prolonged cortisol elevation in illness/stress or prolonged glucocorticoid therapy.
-can inhibit growth
-decreases DNA synthesis
-stimulates protein catabolism
-inhibits bone growth and degrades existing bone
-inhibits GH secretion
*What is compensatory growth?
specific type of regeneration that can occur in many human organs

example is enlargement of one kidney after other is removed
*Compare acromegaly and gigantism.
usually caused by slow-growing tumors of anterior-pituitary --> excess GH

get gigantism if tumor active before puberty when epiphyses still open

get acromegaly if tumor active after epiphyses close

in both get bone broadening and enlargement of many internal organs

usually treated by tumor removal