HORMONES OF THE ENDOCRINE SYSTEM CONT Flashcards
Located below the larynx and consists of two broad lobes connected by an isthmus.
Thyroid Gland
Consists of secretory parts called follicles filled with hormonestoring colloid (thyroglobulin)
Thyroid Gland
Follicular cells produce two iodine-containing hormones,
thyroxine (T4 )/(tetraiodothyronine) and triiodothyronine (T3)
3 Types of Carriers protein of Thyroid hormones
TBG – thyroxine binding globulin
TBPA – thyroxine binding prealbumin or TTR transthyretin
TBA – thyroxine binding albumin
(70-75%)
TBG – thyroxine binding globulin
primary carrier protein of thyroid hormone
TBG – thyroxine binding globulin
synthesized and produced by the liver
TBG – thyroxine binding globulin
highest affinity to T3 and T4 = readily released
TBG – thyroxine binding globulin
(10- 25%)
(10%)
thyroxine binding prealbumin or TTR transthyretin
thyroxine binding albumin
Lowest affinity
TBPA – thyroxine binding prealbumin or TTR transthyretin
In the tissues, T4 is converted to T3 (physiologically active product);conversion of T4 to T3
Diiodination
takes place in liver and kidneys
Diiodination
99.97% : bound; 0.03% : free
T4
more abundant
T4
T4 NV
0.24 ug/dL
99.7% :bound
T3
T3 NV
7 ug/dL
0.3%: free
T3
more potent
T3
Biological Function of thyroid hormones
Calorigenic effects
Increase (?)
Stimulate synthesis of (?)
Increase (?) through the use of chemical energy for metabolic processes which is fueled mainly by (?)
basal metabolic rate
Na/K ATPase
body temperature; fatty acids
: enhances use of chem energy for MP
Calorigenic effects
Biological Function of thyroid hormones: Action of thyroid hormones
Stimulate (?)
Promote (?)
Increase (?)
Stimulate (?)
neural development
sexual maturation
adrenergic activity
protein synthesis and carbohydrate metabolism
adrenergic activity Aka
Sympathetic Nervous System Stimulation
1° Hypothyroidism
TT4 TT3 FT4 TSH
↓ ↓ ↓ ↑
2° Hypothyroidism
TT4 TT3 FT4 TSH
↓ ↓ ↓ ↓
1° Hyperthyroidism
TT4 TT3 FT4 TSH
↑ ↑ ↑ ↓
2° Hyperthyroidism
TT4 TT3 FT4 TSH
↑ ↑ ↑ ↑
1° Increased TBG
TT4 TT3 FT4 TSH
↑ ↑ N N
1° Decreased TBG
TT4 TT3 FT4 TSH
↓ ↓ N N
: Problem in the actual synthesis of T3 and T4 (thyroid gland)
Primary
: Problem in the actual synthesis of TSH (AP gland/hypothalamus)
Secondary
Produced by the C-cells (parafollicular) of the thyroid
Calcitonin
Lowers plasma Ca+2 level
Calcitonin
Opposes the effects of parathyroid hormones w/c acts primarily to increase blood level of calcium
Calcitonin
its production is stimulated by hypercalcemia
Calcitonin
promotes Ca+2 deposition in bones and urinary excretion of calcium
Calcitonin
Located at the posterior of the thyroid which consists of tightly packed secretory cells covered by thin connective tissue
Parathyroid Glands
consists of tightly packed secretory cells covered by thin connective tissue
Parathyroid Glands
Release is stimulated by hypocalcemia and increased plasma calcium levels
Parathyroid Hormone
responds to decrease in free calcium concentration within seconds.
Parathyroid Hormone
It stimulate bone resorption of osteoclasts and promotes tubular reabsorption of Ca+2 and intestinal absorption of calcium
Parathyroid Hormone
During a time of calcium deprivation, the increase in PTH rapidly alters both renal and skeletal metabolism
Parathyroid Hormone
2-3 cm wide, 4-6 cm long and 1 cm thick and situated on top of the kidneys enclosed in a layer of fat
Adrenal Glands
because each glands sits atop of the kidney, the adrenal glands are also referred to as the suprarenal glands
Adrenal Glands
Pyramid-shaped glands
Adrenal Glands
stores and secretes catecholamines
Adrenal medulla
Catecholamines:
Epinephrine, Norepinephrine, Dopamine
Adrenal Cortex - further divided into three layers:
- Zona glomerulosa (outermost)
- Zona fasciculata (middle)
- Zona reticularis (innermost)
Mineralocorticoid synthesis : (chief)
ALDOSTERONE
Glucocorticoid synthesis :
CORTISOL
Glucocorticoid and minimal Gonadal steroids :
ANDROGEN, ESTROGEN, PROGESTERONE
Adrenal steroid hormones:
Glucocorticoids, Mineralocorticoids, Sex steroids
The cells of the adrenal cortex produce over [?] different steroids
30
Release is stimulated by a decrease in serum SODIUM levels
Aldosterone
Promotes tubular reabsorption of sodium in the kidneys
Aldosterone
Promotes excretion of potassium and hydrogen
Aldosterone
Production is controlled by RAA (renin-angiotensin-aldosterone) system
Aldosterone
Dehydration = [?] = [?]
decreased blood volume = hypotension
Kidneys : produce
RENIN
Increased angiotensin I converted to angiotensin II in the presence of [?]
ACE
potent vasoconstrictor
Angiotensin II
stimulate adrenal cortex to release aldosterone
Angiotensin II
- potent vasoconstrictor =
Increases blood pressure
- stimulate adrenal cortex to release aldosterone =
increases Na+ and H2O reabsorption
A glucocorticoid, influences the metabolism of glucose, CHON, & fat
Cortisol
Has Anti-inflammatory and immunosuppressive effects
Cortisol
Produced in chromaffin cells
Catecholamines
Epinephrine,norepinephrine and dopamine
Catecholamines
– metabolite of dopamine
Homovanillic acid (HVA)
– epinephrine metabolite
Metanephrines and Vanillylmandelic acid (VMA)
Hormones of the Adrenal Medulla:
Epinephrine and norepinephrine
- Release is regulated by nerve impulses from the CNS
Epinephrine and norepinephrine
- Effects resemble those of the sympathetic division neurotransmitters
Epinephrine and norepinephrine
- Used in times of stress and for “fight or flight.”
Epinephrine and norepinephrine
- [?] promotes glycogenolysis
Adrenalin
Listen to music
DOPAMINE (The Reward Chemical)
Try something new
DOPAMINE (The Reward Chemical)
Do something creative
DOPAMINE (The Reward Chemical)
Tick something off your list
DOPAMINE (The Reward Chemical)
Hug someone you love
OXYTOCIN (The Love Hormone)
Spend time with friends
OXYTOCIN (The Love Hormone)
Show affection
OXYTOCIN (The Love Hormone)
Do something nice for someone
OXYTOCIN (The Love Hormone)
Exercise
SEROTONIN (For Good Moods)
Bask in the sun
SEROTONIN (For Good Moods)
Practice meditation
SEROTONIN (For Good Moods)
Eat a healthy meal
SEROTONIN (For Good Moods)
Take a hot bath
ENDORPHINS (The Pain Reliever)
Create music or art
ENDORPHINS (The Pain Reliever)
Try yoga
ENDORPHINS (The Pain Reliever)
Laughter
ENDORPHINS (The Pain Reliever)
Secretes hormones as an endocrine gland, and digestive juices to the digestive tract as an exocrine gland.
Pancreas
Posterior to the stomach
Pancreas
Endocrine cells : islets of Langerhans
- alpha cells - glucagon
- beta cells - insulin
- delta cells - somatostatin
- F cells – pancreatic polypeptide
- alpha cells -
glucagon
- beta cells -
insulin
- delta cells -
somatostatin
- F cells –
pancreatic polypeptide
Release is stimulated by hypoglycemia
Glucagon
Increases blood glucose levels by stimulating glycogenolysis & gluconeogenesis
Glucagon
Release is stimulated by hyperglycemia
Insulin
Decreases BGL by stimulating liver glycogenesis, increasing CHON synthesis, and stimulating adipose cells to store fat.
Insulin
coordinate to maintain a relatively stable blood glucose concentration.
Insulin and Blood Sugar glucagon
H. Other Endocrine Glands
- Pineal Gland
- Thymus Gland
- Reproductive Glands
- Digestive Organs
- 7 Reproductive Glands
Secreted by the ovarian follicles, corpus luteum & during pregnancy, the placenta
Estrogen
Adrenals & testes - small quantities
Estrogen
Dev’t & maintenance of the female sex organs & 2° female sex characteristics
Estrogen
With progesterone - the primary. secretory products of the ovaries
Estradiol
Secondary sexual characteristics
Estradiol
Most potent naturally occurring estrogen
Estradiol
Strongly bound to SHBG
Estradiol
2-3% unbound (biologically active)
Estradiol
Metabolite of estradiol
Estrone/Estrone sulfate
Circulate almost exclusively bound to albumin
Estrone/Estrone sulfate
Increased in obese, post-menopausal women
Estrone/Estrone sulfate
Estradiol Production Rate =
100 - 300 ug /dL
Estrone Production Rate =
100 - 200 ug /dL
Increased during fetal dev’t
Estriol
Steady increase should occur in the 3rd trimester
Estriol
24-H urinary maternal estriol monitors integrity of feto-placental unit
Estriol
Decline or sudden change indicates a complication of the pregnancy
Estriol
Pregnant women: major source of estrogens is the placenta (?)
estriol
Non-pregnant women: major source are the ovaries (?)
estradiol
Secreted by the corpus luteum in response to stimulation by LH from the AP gland
Progesterone
Promotes storage of glycogen and continued growth of blood vessels in the endometrium
Progesterone
Secreted by interstitial cells (Leydig cells) when stimulated by LH
Testosterone
Promotes maturation of sperm
Testosterone
Stimulates development of secondary sex characteristics in male
Testosterone
Secreted by sustentacular cells of the testes
Inhibin
Decreases the secretion of FSH from anterior pituitary gland
Inhibin
: synthesizes and secretes thyroid hormones; same structure stimulated by TSH; each follicle is surrounded by a layer of follicular cell
Thyroid follicles
: cavity
Colloid
Low blood levels of T3 and T4 (stimulation) or low metabolic rate stimulates release of:
TRH (Hypothalamus) → TSH (APG)
: ingested and absorbed; trapped by follicular cell
Iodide
Iodide is trasported from blood plasma by
Sodium-Iodide Simporter (NIS)
(located at the basolateral of follicular cell)
Sodium-Iodide Simporter (NIS)
Synthesis of Thyroglobin
: synthesized
: packaged
: transported
RER
Golgi complex
Secretory vesicle
: trasports iodide from the follicular cell to the colloid
Pendrin
: responsible for the conversion of iodide to iodine
Thyroid peroxidase
Binding of iodine to TGB
Iodination of tyrosine
Iodination of tyrosine of Products:
monoiodotyrosine (MIT) & diiodotyrosine (DIT)
Formation of T3 and T4
Coupling of T1 and T2
Lysosome cuts TGB to produce individual T3s and T4s
Pinocytosis and digestion of colloid
Secreted near the thyroid follicle
Calcitonin
From the same follicle but located at the periphery
PARAFOLLICULAR CELLS
Secretes calcitonin (C cells) by the thyroid gland
PARAFOLLICULAR CELLS
Isthmus: connected
Parathyroid Glands
Bean-shaped structure
Parathyroid Glands
Behind TG
Parathyroid Glands
: secretes calcitonin
Thyroid gland
: secretes PTH
Parathyroid gland
