Phys Test 2 Flashcards
Stimulating the enzyme adenylyl cyclase results in synthesis of the second messenger ________.
cAMP
The cAMP activates ____________, leading to _________________ that either activates or inactivates target enzymes.
protein kinase A; phosphorylation
What 2nd messenger mobilizes calcium from internal stores after being cleaved by phospholipase C?
Inositol triphosphate
As calcium enter the cell the concentration increases as calcium is released from what structure?
Sarcoplasmic reticulum
What will calcium bind to once it enters the cell?
Calmodulin
What happens to the half life when hormones bind to plasma proteins?
Steroids: Longer half life
Protein: shorter half life
What effect does a steroid hormone have on its target cells?
Increased protein synthesis
What effect does a protein hormone have on its target cells?
Increased cell metabolism
What is thought of as the “command center” of the endocrine system?
hypothalamus-pituitary complex
What structure controls the pituitary gland by both neural and hormonal mechanisms?
Hypothalamus
What pituitary is described below:
Epithelial component (glandular tissue)
Adenohypophysis
Vascular connection
Anterior Pituitary
What pituitary is described below:
Neural structure (neural tissue)
Neurohypophysis
Neural connection
Posterior Pituitary
Where are ADH and Oxytocin produced? Where are they stored?
Hypothalamus; Posterior pituitary:
What nuclei controls the production and release of antidiuretic hormone (ADH) [vasopressin]?
Supraoptic nuclei (SON)
What nuclei produce oxytocin?
Paraventricular nuclei (PVN)
ADH and oxytocin are released into the capillary plexus of the __________________________ artery.
inferior hypophyseal artery
What hormone stimulates contraction of smooth muscle of both the uterus during delivery and the breast to cause ejection of milk? (“Bonding Hormone”)
Oxytocin
Stimulates kidneys to reabsorb water, decrease urine output, stimulates thirst center to increase fluid intake, and in high doses it causes vasoconstriction?
Antidiuretic Hormone (ADH)
What cells within the hypothalamus produce hypophysiotropic (regulatory) hormones which control secretion of the anterior pituitary hormones?
Neuroendocrine cells
What blood vessel delivers hypothalamic hormones directly to the anterior pituitary?
hypothalamic-hypophyseal portal blood vessels
What will the hypothalamus secrete into the hypothalamic-hypophyseal portal blood vessels?
releasing hormones or inhibitory hormone
The hypothalamic hormones can be delivered to the anterior pituitary ____________ and in __________ concentration
directly
high
Cells from where receive high concentrations of the hypothalamic hormones?
anterior pituitary ONLY
The hypothalamic hormones ___________ appear in the systemic circulation. (Do or Do not)
do NOT
What is Growth hormone’s (GH) hypothalamic cell type?
Somatotrophs
What is Prolactin’s (PRL) hypothalamic cell type?
Lactotrophs
What is Follicle-stimulating hormone (FSH) and Luteinizing hormone’s (LH) hypothalamic cell type?
Gonadotrophs
What is Adrenocorticotropic hormone’s (ACTH) hypothalamic cell type?
Corticotrophs
What is Thyroid-stimulating hormone’s (TSH) hypothalamic cell type?
Thyrotrophs
Each of the anterior pituitary hormones is a ______________.
Peptide
What is synthesized and secreted by epithelial cells of the thyroid gland?
Thyroid hormone T3 and T4
What is the effect of thyroid hormone on the body?
Maintains metabolism
What is T3?
Triiodothyronine
What is T3?
What is T4?
Tetraiodothyronine, or thyroxine
The thyroid gland is composed of a large number of ______________.
follicles.
Each follicle is surrounded by a single layer of epithelial cells (________________) and filled with a proteinaceous material called ____________.
(thyrocytes)
colloid
What is the primary constituent of colloid that is a large glycoprotein?
thyroglobulin
What is thyroid hormone secretions primarily regulated by?
thyroid-stimulating hormone
(TSH) from the pituitary gland
What hormone will increase the secretion of TSH?
thyrotropin-releasing hormone(TRH)
What will inhibit the release of TSH?
Negative feedback fashion by circulating T3 and T4
TSH has a ______________ effect on the thyroid gland.
trophic
What leads to hypertrophy and hyperplasia of thyroid follicular cells and increased thyroidal blood flow?
sustained elevated levels of TSH
What inhibitory factor of TSH will inhibit the thyroid peroxidase enzyme?
Propylthiouracil(PTU)
What is Propylthiouracil(PTU) an effective treatment for?
Hyperthyroidism
Thyroid hormone contain a high amount of what element which must be adequately consumed through diet?
Iodide(Iodine)
hormone
What will tyrosine residues of thyroglobulin found in the follicular lumen be iodinated to form?
Precursors of thyroid
When there is a dietary deficiency of Iodine, the ____________ ________________ increases its activity, attempting to compensate for the deficiency.
Na+-I− cotransport
Iodide pump
What is the most important factor influencing the rate of iodide trapping by the thyroid?
Concentration of TSH
What enzyme will oxidize I- into I2?
thyroid peroxidase
Inside the lumen of the follicle, I2 combines with tyrosine of thyroglobulin to form?
monoiodotyrosine (MIT) and diiodotyrosine (DIT)
What will “salvage” I- and tyrosine after T3 and T4 have been delivered to systemic circulation?
Deiodinase enzymes
Thyroid hormones are __________ soluble, thus to circulate in blood, thyroid hormones must be associated with binding proteins.
lipid
What binding proteins will thyroid hormones use?
Thyroxine-binding globulin (TBG) ~ 70% “Resevoir”
Prealbumin (transthyretin) ~ 15%
Albumin~ 15%
Because of high affinity of the plasma-binding proteins for the T4 and T3, these substances are _________ released to the tissue cells.
slowly
T4(thyroxine) has a __________ latent period and a ____________ half life.
long
long
Structurally what hormone is thyroid hormone like? Characteristically what is it like?
Peptide hormone
steroid hormone
What enzyme converts T4(prohormone) into T3?
5’-iodinase
What are some main effects of thyroid hormone?
Increased BMR - Increased body heat - Increased O2 consumption Bone formation Increased glucose absorption Increased cardiac output
Thyroid hormone induces the ___________________ of cardiac β1-adrenergic receptors which mediate the effects of the sympathetic nervous system to _______________ heart rate and contractility. (Sympathomimetic)
up- regulation
increase
What hormones does thyroid hormone work with to promote bone growth(formation) and ossification?
growth hormone and somatomedins
In the perinatal period, what hormone is essential for normal maturation of the CNS?
Thyroid horme
What are some physiological effects of thyroid hormone?
Increased thermogenesis and sweating Increased rate and depth of respiration Increased cardiac output Increased pulse pressure Increased utilization of substrates for energy
Elevated T3 & T4
Decreased TSH
Hyperthyroidism
What would have the following symptoms:
What would have the following symptoms:
Elevated T3 & T4
Decreased TSH
Hyperthyroidism
What disease is a type of hyperthyroidism?
Grave’s disease
What would have the following symptoms:
Decreased T3 & T4
Elevated TSH
Hypothyroidism
In adults, what does thyroid hormone regulate?
metabolism
What are TSH secretions regulated by in the body?
Thyroid hormone levels in the blood
What symptoms
would be noticed in a dietary deficiency of iodine intake(hypothyroidism)?
Cold intolerance
Low BMR
Obese
Decreased sweating and enlarged goiter at first
Where is growth hormone secreted from?
anterior pituitary gland
Growth hormone exerts its effects _________ on all or almost all tissues of the body not a specific target gland.
directly
What are the effect of Growth hormone?
Promotes linear bone growth
Hypertrophy of skeletal muscles
Promotes fat utilization for energy
Inhibits actions of insulin
What are the effects of growth hormone on metabolism?
Promotes the use of lipids
Enhances the uptake of AA and protein synthesis
Regulation of blood glucose(anti-insulin effect)
Increases gluconeogenesis in the liver
Growth hormone acts ___________ on liver cells to stimulate the production of Insulin-like growth factor 1 (IGF-1)
directly
Growth hormone has an indirect effect on childhood growth and anabolic effect in adulthood by using?
Insulin Growth Factor (IGF-1)
How does IGF-1 have a direct effect on anabolic factors?
Stimulates increase bone and cartilage growth (epiphyseal cartilage)
Stimulates muscle growth
In skeletal muscle, IGF-1 promotes the differentiation and proliferation of what type of progenitor cell?
myoblasts
Where is IGF-1 primarily produced?
Liver
What will growth hormone directly cause?
Lipolytic effect
Ketogenic effect
Increase lean body mass (regulating body composition)
What is the name of GH’s ability to mobilize fatty acids from adipose tissue and then preferential utilize them for energy.
Lipolysis (lipolytic effect)
- GH increases lipolysis
How does growth hormone cause a ketogenic effect?
GH impairs glucose uptake into adipose cells
GH increases plasma levels of free fatty acids and ketoacids
What will occur as GH decreases the uptake and utilization of glucose by muscle and adipose tissue?
- Blood glucose concentration rise
- Insulin secretion increases to compensate for the GH-induced insulin resistance.
GH increases glucose production through gluconeogenesis and glycogenolysis from the _________ and __________.
liver; kidney
How are growth hormone secretions regulated?
negative feedback loop
What feed back loop involves IGF -1 inhibiting secretions of growth hormone by the anterior pituitary.?
Long Loop Feedback System
What feed back loop involves GHRH inhibits its own secretion from the hypothalamus?
Ultrashort-loop feedback
What type of regulation is the ultrashort-loop feedback?
Autocrine regulation
What feed back loop involves effects of GH on hypothalamic GHRH and somatostatin secretion?
Short-Loop Feedback System
Hypothalamic neuropeptides (______________ ___ _____________) are released and carried to the pituitary gland via the hypothalamic-pituitary portal system
GHRH and somatostatin
What will stimulate the secretion of somatostatin from the hypothalamus? What will inhibit the release?
IGF-1 and GH
GH
What factors affect the release of GHRH from the hypothalamus?
Age
Time of day
Nutrient levels in the blood
Stress, and Exercise
At what point in development is there an enormous secretory burst, induced in females by estrogen and in males by testosterone?
Puberty
When is GH the highest? When does it steadily decrease?
puberty
Adulthood
In what stage of a normal sleep cycle are GH concentrations the highest?
early stages 3 and 4
GH is secreted in the body in what type of pattern(roughly every 2 hours)?
pulsatile pattern
The largest secretory burst occurs within __ ________ of falling asleep.
1 hour
What type of sleep will decrease the secretion of GH?
REM sleep
GH is classified as one of the “___________” hormones and is __________ by neurogenic and physical stress
stress; increased
Growth hormone is classified as what type of hormone?
Hyperglycemic
What will cause a reduced mean GH concentrations, associated with decreased pulsatile GH secretion and a shorter GH half-life?
obesity
What can obesity induce that will inhibit GH secretions?
Hyperinsulinemia
Excess growth hormone in childhood before the growth plates have closed can cause?
Gigantism
Excess growth hormone in adulthood after the growth plates have closed can cause?
acromegaly
What are some characteristics of acromegaly?
Prominent Jaw line
Enlarged Brow
Thickening of Bone
GH is produced best when insulin levels are _________.
low
What are some anabolic effects of growth hormone?
Increased glucose and amino acid uptake by skeletal muscles
Stimulation of protein synthesis
Increase in bone length and density
Where does the adrenal medulla originate from?
neuroectodermal
Chromaffin cells of the adrenal medulla primarily secrete what catecholamines?
epinephrine and norepinephrine
What does the adrenal medulla mainly secrete?
Epinephrine (80%)
The adrenal medulla secretes catecholamines in response to?
sympathetic neural input
What will catalyzes the conversion of norepinephrine to epinephrine?
PNMT- phenylethanolamine-N-methyltransferase
What are the physiological responses to fight or flight?
increased cardiac output and BP
Redistribution of blood flow
Increased ventilation
Decreased GI motility and secretions Increased blood glucose
What are the 3 layers of the adrenal cortex?
zona glomerulosa (outer region) zona fasciculata zona reticularis (inner region)
What does the zona glomerulosa secrete?
Mineralocorticoids (aldosterone)
What does aldosterone have important effect on?
Sodium and potassium balance
What does the zona fasciculata secrete?
Glucocorticoids (cortisol)
What will glucocorticoids influence?
carbohydrate, fat, and protein metabolism
What does the zona reticularis secrete?
Androgens
What weak androgens contribute to secondary sex characteristics?
DHEA and androstenedione
Collectively what are the hormones from the adrenal cortex referred to as?
Corticosteroids
What are corticosteroids synthesized from?
Cholesterol
The rate-limiting step in the synthesis of adrenocortical hormones is the side-chain cleavage of cholesterol to form _____________.
pregnenolone
The principal regulators of the adrenals are?
CRH
corticotropin releasing hormone
ACTH
adrenocorticotropic hormone
Where is ACTH produced?
corticotroph cells of the anterior pituitary gland
What is the activation sequence for the release of Aldosterone, Cortisol & Androgens?
Hypothalamus activates CRH ——> tell Ant. pituitary to make ACTH —> send signal to adrenal cortex to make them
What single precursor is ACTH derived from?
pro-opiomelanocortin (POMC)
The synthesis and secretion of steroid hormones by the adrenal cortex depend on the stimulation of cholesterol ________________.
desmolase
Aldosterone will increase what in the kidneys?
Sodium Reabsorption & Potassium Secretion
What is the major stimuli(regulator) of aldosterone secretion?
Angiotensin II
Angiotensin II increases the synthesis and secretion of aldosterone by stimulating cholesterol desmolase and _____________ _________________.
aldosterone synthase
After synthesis what is aldosterone controlled by?
renin-angiotensin-aldosterone system. (RAAS)
What will be stimulated by a decrease in ECF volume causing a decrease in renal perfusion pressure?
Renin
What type of cells secrete renin?
juxtaglomerular cells of the kidney
Renin catalyzes the conversion of _________________ to angiotensin I
angiotensinogen
What will convert Angiotensin I to Angiotensin II?
ACE
How will aldosterone affect electrolyte transport in the colon?
increases sodium reabsorption from the colon and promotes potassium excretion in the feces.
How will aldosterone affect electrolyte transport in the sweat and salivary glands?
increases sodium reabsorption and promotes potassium excretion in sweat and salivary glands
Increase in plasma ______________ concentration increase aldosterone secretion, which in turn stimulates tubular secretion of potassium 🡪 _____ lost in the urine
potassium
K+
When is the highest secretory rates for cortisol noticed?
just before awakening in the morning
When is the lowest secretory rates for cortisol noticed?
during the evening hours and just after falling asleep
ACTH has a _________ and ____________ secretory pattern that drives a parallel pattern of cortisol secretion.
pulsatile
diurnal
What drives the diurnal pattern?
Your “internal clock” –> Hypthalamus
Overall, the effects of cortisol are __________ and Diabetogenic.
Catabolic
What is a catabolic example of cortisol?
Inhibition of inflammatory response
What does cortisol need in order to travel in the blood?
transport protein
What corticosteroid hormone will promote gluconeogenesis and storage of glycogen?
Glucocorticoids
How does cortisol promote gluconeogenesis?
- increases protein catabolism in muscle & decreases new protein synthesis
- increases lipolysis
- decreases glucose utilization by tissues
- decreases the insulin sensitivity of adipose tissue
What autoimmune disease has primary adrenocortical insufficiency?
Addison’s disease
What zones of the adrenal cortex does Addison’s diseases affect? What hormones are affect?
Destruction of all zones of the adrenal cortex
Decreased circulating levels of cortisol, aldosterone, and adrenal androgens
What physiological symptoms of Addison’s disease?
Hypoglycemia
Anorexia, weight loss, nausea, vomiting
Weakness
Hypotension
Hyperkalemia
Metabolic acidosis
Decreased pubic and axillary hair in females
decreased libido
Hyperpigmentation (α-MSH fragment)
How will addison’s disease affect ACTH levels?
Increased
- negative feedback loop effect of low cortisol
What disease is an example of hypercortisolism (hyperglycemia)?
Cushing’s syndrome
How does Cushing’s syndrome affect ACTH?
ACTH levels are low
the high cortisol levels feed back on the anterior pituitary and inhibits ACTH secretion.
How does Cushing’s disease affect ACTH?
primary defect is in the anterior pituitary, which is overproducing ACTH; ACTH levels are elevated
What can cause Cushing’s syndrome?
chronic excess of glucocorticoids
- tumor or meds
What are symptoms of Cushing’s syndrome?
Hyperglycemia
Muscle wasting
Central obesity
Round face, supraclavicular fat, buffalo hump
Osteoporosis
Striae
Hypertension
Virilization and menstrual disorders in females
How does cortisol have an anti-inflammatory effect?
induces the synthesis of lipocortin, an inhibitor of the enzyme phospholipase A2 which produces prostaglandins and leukotrienes.
inhibits the production of interleukin-2 (IL-2) and the proliferation of T lymphocytes
inhibits the release of histamine and serotonin from mast cells and platelets
Cortisol up-regulates what type of receptors found on arterioles that will vasoconstrict in response to catecholamines?
α1-adrenergic receptors
- Important for maintenance of BP
How will low cortisol affect the blood pressure? High cortisol?
Hypotension
Hypertension
Where are glucocorticoids found in the brain?
limbic system
When is a largest bursts of ACTH and cortisol noticed?
just before waking
In males, adrenal androgens play only a __________ role.
minor
In females, the adrenal cortex is the _________ source of androgenic compounds.
major
In females, what are adrenal androgens are responsible for?
development of pubic, axillary hair, and libido
What “stress” hormone will elevate blood sugar and suppress inflammation?
Cortisol
What corticoid will suppress the immune system?
Glucocorticoids
How does your body get fast energy in the fight or flight response?
Breakdown of glycogen
Glucose released from liver
Free fatty acids released from adipose
What processes are inhibited or decreased in the fight or flight response?
Inhibition of processes associated with growth and repair Inhibition of digestion Inhibition of reproduction Decrease in growth hormone Decrease in sex hormones levels
What are the 3 stages of the general adaptive syndrome
Alarm
Resistance
Exhaustion
Chronic stress response is _________________ to long term survival.
MALADAPTIVE
What affects are seen with chronic stress?
Elevation of glucose & FFA
Increased cardiovascular function
Inhibition of growth and repair
Nervous system changes
Chronic glucocorticoid (GC) exposure in humans can result in whole-body ____________ _______________ and obesity.
insulin resistance
Metabolic syndrome is linked with _________ ________________, cardiovascular risk, and decreased survival.
insulin resistance
What 3 tissues are involved in calcium regulation?
Bone (and teeth), Intestine and Kidney
What 3 hormones are involved in calcium regulation?
PTH, calcitonin and activated vitamin D3
What is parathyroid hormones function? Where is it released from?
Parathyroid gland: raises calcium in blood
What is calcitonin’s function? Where is it released from?
Thyroid gland: Lower calcium levels in blood
40 % of the calcium in the body is bound, what plasma protein is it mainly bound to?
Albumin
What form is unfilterable or not protein bound calcium in?
Free or ionized calciumm
Free, ionized Ca2+ is the only form of Ca2+ that is biologically ________.
active
Albumin has negatively charged sites, which can bind what ions?
H+ ions or Ca2+ ions
In acidemia, free ionized Ca2+ concentration _______________.
increases
In ____________, free ionized Ca2+ concentration decreases.
alkalemia
What structures inside the function in calcium balancing?
Kidneys - excrete Ca2+
GI tract - absorbs Ca2+
Bone does both
What hormone stimulates bone resorption (Increase in blood calcium)?
Parathyroid hormone
What vitamin stimulate bone absorption? What stops it from absorbing?
Vitamin D
Calcitonin
What type of cells within the parathyroid gland will secrete PTH?
Chief cells
How will PTH promote an increase in blood calcium levels?
Promotes the release of calcium from bone tissue
Stimulates kidneys to conserve calcium
- PTH acts direct and is mediated by cAMP;
What type of bone cell has receptors for PTH?
Osteoblasts
How does PTH act on the intestines (GI)?
PTH acts indirectly stimulating intestinal Ca2+ absorption , via activation of vitamin D
PTH secretion is regulated by the ________ ___________.
plasma [Ca2+]
What are PTH’s 2 actions on the kidneys?
inhibits phosphate reabsorption
- Inhibiting Na+-phosphate cotransport in the PCT of the nephron
stimulates Ca2+ reabsorption
What is the name for the phosphaturic action of PTH that causes the phosphate that was resorbed from bone to be excreted in the urine?
Phosphaturia
What will inhibition of Na+-phosphate cotransport cause?
Decreased phosphate reabsorption and phosphaturia
What is the flow of Vitamin D through the body?
Skin –> Liver –> Kidney
In the liver, what is vitamin D converted into?
25-hydroxycholecalciferol
*rxn stimulated and tightly controlled by PTH
In the cortex of the kidney’s, what enzyme will convert 25-hydroxycholecalciferol into 1,25-dihydroxycholecalciferol?
1 alpha hydroxlase
What is the physiologically active form of vitamin D?
1,25-dihydroxycholecalciferol
What will stimulate 1 alpha hydroxlase?
Increase in PTH
Decrease in free [Ca++]
Decrease in [calcium binding protein
calcium-stimulated ATPase
alkaline phosphatasePhosphate]
Vitamin D stimulates formation of what in the intestines?
calcium binding protein
calcium-stimulated ATPase
alkaline phosphatase
What is the overall role of vitamin D?
increase plasma levels of both Ca2+ and phosphate & to promote mineralization of new bone
What is secreted from the parafollicular cells (C cells) found in the thyroid gland?
CalcitoIn
What will stimulate the secretion of calcitonin?
in response to elevation of the extracellular calcium concentration
Calcitonin “tones down” [Ca++]nin
How does calcitonin differ from PTH?
calcitonin does not participate in the minute-to-minute regulation of the plasma [Ca2+]
What would cause increased calcitonin levels? Decreased levels?
Thyroid tumors
Thyroidectomy
What does the pineal gland release in the absence of light?
Melatonin
What is the function of melatonin in the body?
Regulation of circadian (or biological) rhythm
Promotion of sleep
?- Regulation of certain reproductive hormones (LH/FSH)
What will stop the release of melatonin?
light exposure
When are melatonin levels high or low?
Low during daylight hours
Higher during dark periods
What is a photoperiod?
the length of day versus night
What can melatonin block in smaller mammals?
Gonadotropins (LH and FSH)
ex) when melatonin is low, gonadotropins are high
What type of relationship does melatonin and gonadotropins(sex hormones) have in humans?
The are Inversely related
When are melatonin levels the lowest? Highest?
morning
evening
What is the brains master bio clock that receives light and dark cues from the retina through the optic nerve to update the circadian rhythm?
superchiasmatic nucleus of the hypothalamus
How does melatonin production shift throughout the year?
Summer: shorter daily periods
Winter: longer periods
