Endocrine 1 Flashcards
The major glands (pppta) (me at the pta)
The major glands: Pituitary, thyroid, parathyroid, adrenal and pancreas
The endocrine system has five general functions: (me and children)
reproductive and CNS development in the fetus
Stimulation of growth and development during childhood and adolescence
Hormones have specific rates and rhythms of secretion (circadian rhythm of cyclic pulsating hormones)
Circadian or diurnal pattern
Pulsatile and cyclic pattern
A pattern that depends on circulating substrates (circle the milk - think)
Ca+, K+, Na+, glucose, etc.
hormones
They operate on a feedback system: negative or positive
They affect only the cells with the appropriate receptors
hormones are eliminated (2 main places)
by the kidneys or metabolized in the liver into water soluble compound ready for renal excretion
HORMONE CLASSIFICATION
Water soluble
Lipid soluble
Water soluble hormones - where are the receptors? (receptive water)
-circulate freely in blood to act on target tissues. Receptors on cell membrane
Lipid soluble hormones - where is the receptor? Andhow does it cross membranes?
(fat is bound and diffues)
Lipid soluble
- bound by plasma proteins; cross membranes through diffusion
-receptor inside cell
Hypothalamus – The Master Gland - what are the cells called? (hippo has a secretary)
Located superior and anterior to the brain stem
Responsible for the direct control of the endocrine system through the pituitary gland
Contains special cells called neurosecretory cells—neurons in the hypothalamus receive input from the CNS then coordinates release of hormones
The Hypothalamus-pituitary Axis (HPA) - what 2 systems work together? (you know this)
Forms the structural and functional basis for the central
integration of the nervous and endocrine systems
The Neuro and Endocrine systems work together to maintain homeostasis in response to internal and external demands
In the HPA a number of releasing/inhibitory hormone as well as *tropic hormones are produced that affect body function:
Corticotropic releasing hormone (CRH) (cort sneezes in the tropics)
→ anterior pituitary (ACTH- Adrenocorticotropic hormone)→ adrenal glands
Prolactin releasing hormone (PRH) → (pro mammary)
Prolactin releasing hormone (PRH) → anterior pituitary (Prolactin) → mammary glands
Thyrotropin releasing hormones (TRH)→ (TRH is tsh)
Thyrotropin releasing hormones (TRH)→ anterior pituitary (TSH) → thyroid gland (thyroxine)
Gonadotropic releasing hormone →(fish for gonads)
Gonadotropic releasing hormone → anterior pituitary (gonadotropic hormones FSH and LH) → testes and ovaries
Growth hormone releasing/inhibitory hormone (growth everywhere)
Growth hormone releasing/inhibitory hormone → anterior pituitary (GH or GIH) →all body tissue
Prolactin releasing hormone →
Prolactin releasing hormone → anterior pituitary (PRL or PIH) →mammary glands
Hormones secreted by the hypothalamus and stored in the Posterior Pituitary (just 2)
Antidiuretic hormone (ADH):
Oxytocin:
ADH - what does it do to urine?
Regulates fluid volume by acting on collecting renal tubules to reabsorb water → concentrated urine
oxytocin does 2 things (you know this)
Stimulates uterine contraction and milk production
THE ADRENALS - do the medulla and cortex work together?
Located in the upper portion of both kidneys
Consists of the adrenal medulla and adrenal cortex both acting independently
Adrenal MEDULLA “Fight or Flight response” (fight medusa)
Inner part of adrenal gland
Makes up 10 to 20 % of the mass of adrenal gland
Secretes catecholamines: Epinephrine (75%) and Norepinephrine (25 %) and dopamine
Adrenal CORTEX - what does it secrete?
(cotex is on steroids)
Outer part of adrenal gland
Makes 80 to 90 % of the mass of adrenal gland
Secretes over 50 steroids (need cholesterol to make steroids)
corticosteriods - 2 types
glucocorticoids
mineralcorticoids
androgrens
convert testosterone in men and estrogen in women in the peripheral tissue
Cortisol released in response to (too much or too little sugar)
stressful situations: hypoglycemia, burns, infection, fever, anxiety, surgery
cortisol (cort is not inflammed when he eats sugar)
Anti-inflammatory properties
Glucose metabolism
ADRENAL CORTEX HORMONE: MINERALOCORTICOID (Aldosterone) - when is it released - relationship btwn aldosterone and K+
Released in response to low plasma volume and high serum osmolarity, hyperkalemia (aldosterone releases K+ out of the body), angiotensin II
ADRENAL CORTEX HORMONE: (cotex is a man) Androgens
The adrenal cortex secrets small amounts of androgens
Stimulates pubic and axillary hair growth and libido in females
Androgens are converted into estrogen in the peripheral tissue
After menopause, the adrenal cortex is the major source of endogenous estrogen
In men, adrenal secretion of androgen is minimal compared to testicular production of testosterone
THE PINEAL GLAND (pictures of pineal)
Composed of photosensitive cells
Secretes Melatonin
Stimulated by exposure to dark and inhibited by light exposure
THE THYROID GLAND
- Two encapsulated lobes connected by the isthmus
Regulated by TSH from the Anterior Pituitary
Iodine is needed for the synthesis of these hormone
FUNCTION OF THYROID GLAND - just salt
To take in iodine found in many foods and converts it into thyroid hormones
Release is controlled by a feedback mechanism
FUNCTIONS OF THE THYROID HORMONES (2 things)
(fat and hot thyroid)
Metabolic rate
Temperature regulation
PARAFOLLICULAR CELLS : CALCITONIN - produced by what? (c for calcitonin)
Produced by the C cells of the parafollicular cells of the thyroid gland
It is a “ weak” regulator of calcium
thyroid assessment - Posterior approach
Stand behind the patient
Place thumbs on the back of the neck (the sternocleidomastoid muscle) with fingers curved around the front of the neck on either side of the trachea
Locate the isthmus and ask the patient to swallow to feel the thyroid rising
thyroid assessment - anterior approach
Stand in front of the pt with the pt’s neck flexed
Place thumb on lower boarder of cricoid cartilage. Move thumb over isthmus while pt swallows
Place fingers along sternocleidomastoid muscle and palpate each lobe as pt swallow
Have pt turn head toward the lobe to be palpated
*Normal thyroid size often
not palpable. If thyroid enlarged, avoid pressing too aggressively as that will release more unnecessary thyroxine
parathyroid glands - located where? (para behind)
Located behind the thyroid glands (usually 4 but may range from 2-6 glands)
parathyroid glands - In the bones (parrot bones)
it acts on osteoclast to breakdown and release Ca into blood stream and inhibit bone formation (process called bone *resorption) * The process by which osteoclasts break down the tissue in bone and release Ca, resulting in increase circulating Ca in the blood
THE PANCREAS: As an exocrine gland: what does it break down?
(everything)
Pancreas excretes enzymes through ducts to the gut to break down proteins, lipids, carbohydrates, and nucleic acids in food.
the pancreas - what is the active area?
The islet of Langerhans is the active area
The islet accounts for < 2% of the gland:
PANCREATIC HORMONE: GLUCAGON - when is it released? (3 times)
Released in response to low blood glucose, exercise and protein ingestion
Stimulates glycogenolysis; gluconeogenesis and ketogenesis in fasting states
PANCREATIC HORMONE: INSULIN - when is it stimulated?
Stimulated in response to high blood glucose
ATRIAL NATRIURETIC FACTOR - what does it do to the kidneys?
Produced by the right atrial myocytes in response to atrial wall stretch (high plasma volume)
Acts on the kidneys to inhibit sodium reabsorption
endocrine - 5 general functions
Sexual reproduction
Maintenance of internal homeostasis
Adaptive responses to emergency demands
ex of water soluble hormones (PIG in the water)
-Insulin, growth hormone, prolactin
ex of lipid soluble hormones
-T3 and T4, steroids (Estrogen, Cortisol, Testosterone, Aldosterone)
ADH - Release is stimulated by
↑ plasma osmolality and hypovolemia
ADH - where do pressure changes occur? (4 places) (ADH CAAV)
Feedback from osmoreceptors in the hypothalamus and pressure changes in veins, arteries, atria and carotid arteries stimulates ADH release
A potent vasoconstrictor
glucocorticoids - ex (cort has glue)
cortisol
mineralcorticoids - ex
aldosterone
cortisol - what happens when fasting? (stops glucose uptake)
Inhibits protein synthesis and decreases peripheral glucose uptake in fasting states
cortisol - contributes to the metabolism of what? (cort eats fat and acid)
lipid and nucleic acid metabolism
cortisol - liver? (does it release glucose?)
Stimulates hepatic glucose production (gluconeogenesis)
aldosterone
Decreased renal perfusion and hyponatremia stimulates RAAS (Rennin-angiotension system)
aldosterone - what makes it stop? (relationship btwn ANF and alden)
Inhibited by Atrial natriuretic factor (ANF) and hypokalemia
Goal is to maintain extracellular fluid volume
pineal gland - melatonin (one surprising thing)
Melatonin is involved in regulating circadian rhythm and the reproduction system including puberty onset
Therapeutically, melatonin is used to help with sleep disturbances and jet lag
thyroid gland - what does it secrete? (not T3 here) (calcium thyroid)
Secretes 2 forms of thyroxine and calcitonin:
thyroid gland - T4- what does it get converted to?
80-90% is in form of thyroxine (T4) which is precursor to T3. > 90 % of T4 bound to protein. Gets converted to T3 after its release into bloodstream
thyroid gland - T3 - is it potent?
20% Triiodothyronine (T3) is more potent and is the biologically active form
thyroid gland - Calcitonin - where is it secreted? (calcium parasailing)
Calcitonin is secreted in the parafollicular cells of the thyroid gland
thyroid gland - Low thyroxine levels stimulates
the hypothalamus (TRH) → anterior pituitary (TSH) → thyroid gland (thyroxine)
function of thyroid hormones
Caloric requirement
O2 uptake and consumption
Carbohydrates and lipid metabolism
function of thyroid hormones (mom’s brain and nervous system)
Brain function and nervous system activity
Growth and development
calcitonin - Released in response to (remember, calcitonin lowers ca)
Released in response to ↑ levels of serum calcium
calcitonin - where does it go? (2 places) - think, where is Ca+?
Its site of action is the osteoclasts and the kidneys:
calcitonin - what does it do? (reabsorb, stores, and excretes)
Inhibits bone resorption → lowers serum Ca
Increases Ca storage in bone
Increases renal excretion of Ca+ and phosphate
parathyroid glands - regulate what? (parrot)
Regulates serum calcium levels
Stimulates renal conversion of vitamin D to its most active form
parathyroid glands - positive or negative feedback? (the usual)
Regulated by a negative feedback system
parathyroid glands - In the kidneys (Parrot loves vitamin D)
it promotes Ca reabsorption from renal tubules and excretion of phosphate.
Stimulates renal conversion of Vit D to its most active form (1,25 –dihydroxyvitamin D) which promotes absorption of Ca and Phos from the GI tract
the pancreas - As anendocrine gland:
Pancreassecretes the hormones insulin and glucagon into blood stream to target cells in order to control blood sugar
pancreas - Alpha cells (glu the alpha’s mouth shut)
synthesize glucagon
pancreas - Beta cells (beta has insulin, amy)
synthesize insulin and amylin
pancreas - Delta cells (delta loves somas)
secretes somatostatins
pancreas - PP cells (pp is full)
PP cells (Pancreatic Polypeptides), formerly F cells: Produced in response to food intake. Acts onsatietyhormone, regulation of exocrine function and possibly in slowing gastric emptying
glucagon - in a fasting state when glucose is not available…
epinephrine, cortisol, and glucagon break down free fatty acids and glycerol
insulin - Inhibited by
Inhibited by ↓ blood glucose, glucagon, somatostatin, catecholamines and hypokalemia (insulin drives K+ back into cells → ↓K+ )
insulin - Facilitates transport of- what about amino acids?
Facilitates transport of glucose into cells, amino acids into muscles, and synthesis of amino acids into protein in peripheral tissue
Tissues that do not require insulin to transport glucose for energy
cells of intestinal mucosa, renal tubules, brain
The major effect of insulin is where? (just think where is glucose stored)
in the liver where insulin enhances glucose storage into glycogen and triglycerides
ANF - inhibits which hormone? (think bp)
Inhibits ADH, renin-angiotensin II pathway thereby suppressing aldosterone
ANF - vasodilate or constrict?
ANF also causes vasodilation
GOAL is to decrease Blood Pressure!
aldosterone - what part of the kidneys does it work on? and what ions?
Acts on the renal distal tubules to reabsorb Na+ and secrete K+ and H+ (remember water follows Na+)
tissues that don’t need insulin to get glucose (what about blood?)
lens of the eyes, hepatocytes, and RBCs
