m7 + 8 lecture - endocrine system Flashcards
what organs are involved in the endocrine system?
- hypothalamus
- pineal gland
- pituitary gland
- thyroid gland
- parathyroid gland
- thymus
- adrenal glands
- pancreas
- ovary (female)
- testis (male)
what are hormones?
- chemical messengers
- amino acid or cholesterol based
what are target tissues?
- tissues containing receptors that are activated by specific hormones
what is a steroid hormone?
- made from cholesterol
- lipid-soluble
ex.) testosterone, estrogen, progesterone, aldosterone, cortisol
how do steroid hormones move?
direct gene activation
what is direct gene activation?
- can move thru membrane + into the nucleus
- attaches to receptor in nucleus
- activates an enzyme which will target a specific gene on a chromosome
- results = protein synthesis
what are amino acid based hormones?
- water soluble
- need surface membrane receptor
how do amino acid based hormones move?
second messenger systems
what are second-messenger systems?
- hormone attaches to a surface receptor
- surface receptor stimulates G-proteins along membrane
- activating cyclic AMP (triggers a change)
– cAMP activates any number of different enzymes called Protein Kinase = these creates changes inside the cell
what happens during the positive feedback loop?
- happens with oxytocin release during labor and delivery ONLY
what is the negative feedback loop cycle?
repeated cycle
1) stimulus
2) control center
3) hormone
4) action
5) negative impact
what is a humoral stimulus?
- stimulus is determined by blood levels of certain chemicals
- glucose => insulin/glucagon
- Ca+ –> parathyroid hormone = 9-11 mg/100ml
- O2 –> erythropoietin
what is the negative feedback loop?
- one way that the endocrine system tries to keep homeostasis (stability) in the body
- if an endocrine gland senses that there is too much of one hormone in the body, it will initiate changes to decrease production of that hormone.
what is erythropoietin?
- produced by kidneys
- a hormone that tells the bone marrow to produce more red blood cells in response to low oxygen levels
what is a neural stimulus?
- where the ANS system initiates a hormone be released
— epinephrine - SNS
— stomach hormones - m/c
what is a hormonal stimulus? m/c
- begins at hypothalamus
- pituitary gland stimulates release of other hormones
what is hypophysis? (pituitary gland)
- hangs below the hypothalamus from the infundibulum
- controls many other endocrine glands = called master gland
what are the two parts of the hypophysis? (pituitary gland)
- anterior (adenohypophysis)
- posterior (neurohypophysis)
what does the adenohypophysis do? (anterior pituitary gland)
- produces 6 types of hormones
–> release regulated by hypophyseal portal system
what happens in the neurohypophysis? (posterior pituitary gland)
- stores hormones secreted by hypothalamic neurosecretory cells that extend down through the infundibulum
anterior pituitary gland hormones: name and action
GHRH –> growth hormone (GH) - achondroplasia, gigantism, acromegaly
TRH –> thyroid-stimulating hormone (TSH) - thyroid
ACTRH –> adrenocorticotrophic (ACTH) - adrenal cortex
GnRH –> LH + FSH - gonads
PRH - Prolactin - milk production
posterior pituitary hormones: name + action
oxytocin - 1) uterine contractions 2) milk letdown 3) emotional bonding
anti-diuretic hormone (ADH) - increases permeability of the collecting duct to water = decreased urine loss (less water loss)
what causes diabetes insipidus?
- when the body doesn’t make enough anti-diuretic hormone (ADH) - hyposecretion
thyroid gland: location + action
- two main portions on either ride of the larynx - connected by isthmus
- action of hormone: establishes core body temp.
ex.) “furnace” of the body, runs more in winter than summer bc of the cold - to maintain body temp
what is the hormone produced in thyroid gland?
thyroxine (T3 or T4)
– is produced with iodine combined with tyrosine (amino acid)
- increases metabolic activity in all tissue cells
- important for normal growth in childhood
what are the sx for hypothroidism? (cretinism, myxedema, hashimoto’s dz)
- low thyroxine
- low vital signs
- low temp.
- low appetite
- lethargic
- increased weight
- increased TSH
what are the sx for hyperthyroidism? (grave’s dz, exophthalates)
- increased thyroxine
- increased temp.
- increased appetite
- decreased TSH (can’t sleep)
- decreased weight
what do the adrenal glands do?
- sit on top of each kidney
contain two secretory areas:
– cortex
– medullary area
what happen in the cortex of the adrenal gland?
- responds to hormonal stimuli
- produces hormones called corticosteroids
ex.) cortisol, aldosterone
what happens in the medullary area of the adrenal gland?
- responds to neural stimuli through the SNS
- produces catecholamines
ex.) epinephrine
what is aldosterone (anti-diuretic)?
- mineralocorticoid - regulates salt and water balance in the body
- secretion stimulated by dehydration and drop in BP –> leads to kidney’s production of renin
- regulator of extracellular minerals = Na + K
- renin-angiotensin-aldosterone system (RAAS) –> aldosterone –> increased Na/H2O reabsorption
- Na retention lead to decrease in K
ex.) extended process = cramping
what is the renin-angiotensin-aldosterone system (RAAS)?
- a hormone system that regulates blood pressure, blood volume, and electrolyte balance
- by increasing sodium and water reabsorption, and vascular tone
- three main substances: renin, angiotensin II, and aldosterone
what are the glucocorticoids?
- cortisol = produced in long-term stress situations (physical or emotional)
what happens with glucocorticoids?
- these influence the cells metabolism of glucose
- stimulated by release of ACTH
- stimulates process of gluconeogenesis
- is anti-inflammatory + used medicinally
ex.) cortisone, prednisone
what is gluconeogenesis?
- production of glucose from non-carbohydrate sources to provide more energy for activity
what side effects happen during extended cortisol secretion?
- decreased protein formation - affects hair, muscles, nails
- decreased healing rates
- suppressed immune reaction
- high BP
- decreased mental functions
what is cushing’s syndrome?
- hypersecretion of cortisol, due to over secretion of ACTH
cause: usually tumor on pituitary or adrenal gland
sx: buffalo hump, moon face, red cheeks
what are gonadocorticoids?
- cortex of adrenal gland produces both types of sex hormones
ex.) testosterone and estrogen - may help start puberty and maturation of gonads
what happens in the medullary area of the adrenal gland?
- produces catecholamines
ex.) epinephrine, nor-epinephrine
chromaffin cells:
- produce the hormones
- short term stress hormones - deal with fight or flight situations
what is the pancreas?
- location: just below stomach
- both an exocrine (enzymes) and an endocrine (hormones) gland
what is the endocrine function of the pancreas?
islets of langerhan’s:
- pockets of glandular tissue in pancreas
hormones produced:
- insulin
- glucagon
what does insulin do?
- produced in the beta cells of the islets
- stimulation: high blood glucose levels
- stimulates body tissue cells to absorb glucose to lower blood sugar levels, stimulating protein synthesis, lipogenesis, and glycogenesis
what does glucagon do?
- secreted by the alpha cells
- stimulation: low blood glucose levels
- effects the liver to release stored glucose in glycogen
diabetes mellitus type one: cause, age, and treatment?
cause - autoimmune
age- childhood
treatment - insulin injections
diabetes mellitus type two: cause, age, and treatment?
cause - poor diet
age - adult
treatment - meds, diet, exercise
what causes diabetes insipidus?
low ADH
what happens in the testes?
- controlled by FSH and LH
- release testosterone and produce sperm
- control growth in stature, muscle, and promotes male sexual characteristics
what happens in the ovaries?
- controlled by FSH and LH
- regulates ovarian cycle and production of estrogen and progesterone
- promotes female sexual characteristics and uterine cycle
other hormone producing organs, their hormones and their actions:
– skin - vitamin D3 –> serotonin –> :)
– heart - atrial natriuretic peptide (ANP) - regulates blood pressure and salt-water balance –> diuretic, blocks aldosterone
– placenta –> progesterone, HCG
– kidney –> EPO, renin
– adipose –> leptin
