Endocrine i Flashcards
Chem messenges
- gap junctions
- chems secreted to interstitial fluid
- NTs
- Hormones
- cytoplasm to cytoplasm mvmnt of chem
- autocrine and paracrine
- released by synaptic cleft thru synaptic transmissino
- released into blood to affect more distant targets
Endocrine vs. Nervous system
Endocrine is:
- slower to respond
- longer duration
- signal intensity varies with concentration of hormone rather than frequency of APs
- amplitude modulated rather than frequency modulated
Nervous system prety much just affects other neurons, muscle cells, and gland cells
amount of hormone released
nanomolar 10^-9 to picomolar 10^-12
Diabetes Mellitus
Type I
- lack of insulin
- autoimmune disease that destroys insulin producing cells in pancreas
- treatment replaces insulin
Type II
- Lack of sensitivity to insulin (and lack of insulin)
- not enough receptors
- treatment increases sensitivity, up regulates receptors, increases insulin, and decreases glucose
3 methods of homonal release
- Hormonal stimuli: one hormone stimulates the release of another
- Humoral stimuli: change in blood levels stimulates release
- Neural stimuli: neurons stimulate release
Tropic hormone
- hormone that stimulates a release of another hormone at its target tissue
- if target of tropic hormone fails, system will usually be flooded with tropic hormone
3 types of hormone
steroid (lipid soluble)
protein (water soluble)
biogenic amines (usually altered tyrosine) –> water soluble except thyroid hormones
Responsiveness of target cell depends on:
- hormone concentration
- abundance of target cell receptors
- influence of other hormones (permissive, synergistic, and antagonistic)
eicosanoid
lipid soluble, but act like they’re water soluble
- deriitives of fatty acids, but use membrane surface receptors
Lipid soluble hormone binding to receptor
- travels thru blood with transport protein
- detaches and diffuses into target cell
- binds to receptor in cytoplasm or nucleus
- directly alters protein synthesis
Adenylate cyclase system
- ligand binds to receptor
- activates G protein
- G protein activates adenylate cyclase (amplifier enzyme)
- Converts ATP to cAMP (2 mess)
- cAMP ativates protein kinase A
- phosphorylation of proteins
- alters cell function
cAMP is degraded by phosphodiesterase
Who uses the adenylate cyclase system?
glucagon ADH epinephrine TSH FSH
Phospholipase C Signal Transduction Mechanism
-ligand binds to receptor
-G protein activated
-G protein activates phospholipase c
conversion of PIP2 –> DAG and IP3
-DAG activates protein kinase C which phosphorylates proteins
-IP3 opens calcium channels on ER or cell membrane increasing free calcium in cytosol
hormones that use phospholipase c
Oxytocin
ADH
epinephrine
Membrane receptor-enzyme
- extracellular receptor linked to intracellular enzyme
- ligand binds and activates protein kinase enzyme
- e.g. tyrosine kindase uses ATP to phosphorylate proteins
- e.g. guanlate cyclase turns GTP into cGMP which alters other proteins
phosphodiesterase turns cGMP into GMP
Effects of modifying proteins
-what usually modifies them?
- metabolic changes
- transportation changes
- dif gene expression
- changes protein func.
- causes muscle contraction
-calcium or phosphate
What are the purely endocrine glands?
- pituitary
- thyroid
- parathyroid
- adrenal
- pineal
what separates the adenohypophysis from the neurohypophysis
pars intermedia
Hormones of anterior piuitary
Which are tropic?
-human growth hormone thyroid stimulating hormone prolactin follicle simulating hormone luteinizing hormone adrenocorticotropic hormone
all except prolactin and growth hormone
Growth hormone effects
- lipolysis = release of fatty acids for energy
- AA uptake/ protein synthesis
- gluconeogenesis and glycogenolysis in liver
-stimulates liver to release IGFs to stimulate growth of cartilage, bone, and (proteins in skeletal muscles)
Factors affecting GH release
- Age –> less
- Time –> more in morning
- blood levels –> increases with AA and decreases if glucose/fatty acids in blood
- emotion –> stress
Posterior Pituitary
doesn’t synthesize hormones
- stores and releases oxytocin and ADH
- via hypothalamohypophyseal tract
oxytocin
- made in paraventricular nucleau
- during and after delivery of baby
- stimulates smooth muscle contraction of uterus and mammary glands
- Mile EJECTION
ADH
- made in supraoptic nucleus
- decreases urine production
- causes kidneys to return more water to blood
- constriction of arterioles to increase BP
- stops water loss thru sweat
-stimulated by high blood osmotic pressure
Thyroid gland
- anatomy
- cells
- hormones
- 2 lobes with isthmus inferior to larynx
- Follicular cells make thyroid hormones (T3 and T4)
- parafollicular (C) cells make calcitonin
Thyroid hormone function
- increases metabolism
- uses glucose and oxygen to make energy and heat
- lipolysis
- gluconeogenesis and glycogenolysis
- increases oxygen delivery
- works with growth hormone to promote tissue growth and development
- BP maintenance
stimulated by situiations that require ATP
T4 is inactive
Production of thyroid hormone
- iodine from blood is trapped in colloid space as I2
- thyroglobulin is created (nucleus - RER- golgi- secratory vessicles- colloid)
- iodine is oxidized
- tyrosines on thyroglubulin are iodinied
- coupling of T2 and T1
- pinocytosis and digestion of colloid
- secretion of thyroid hormone through exocytosis to blood
calcitonin
- involved in calcium metabolism, but not significant in humans
- inhibits osteoclast activity
Parathyroid glands
- 4 in thyroid
- make parathyroid hormone
Parathyroid hormone
- increases osteoclast activity
- makes kidney return calcium to blood
- stimulates kidneys to release calcitriol which is the active form of vit D, which allows calcium to be absorbed by food
Adrenal glands
-anatomy / labels
Cortex
- zona glomerulosa = mineralocorticoids
- zona fasciculata = glucocorticoids
- zona reticulata = gonadocorticoids
Medulla
-chromaffin cells which make catecholamines
Aldosterone
- Regulates ion concentration in kidneys
- reabsorbs Na and water
- excretes potassium and hydrogen
- works with adh
- affects water balance and ph
triggered by low blood pressure and high K+ (a little bit by ACTH)
How is aldosterone secreted?
Renin-Angiotensin-Aldosterone Mechanism
- low BP stimulates kidneys to release renin
- triggers formation of angiotensin I from angiotensinogen from liver
- ACE in lungs convert A I to A II
- stimulates aldosterone release and vasoconstriction of arterioles
Atrial natriuretic peptide (ANP) blocks renin and aldosterone to decrease BP
Cortisol
- last hormone of HPA axis
- response to stress
- reduces inflammation
- aids thyroid hormones in gluose metabolism
Androgens
- stimulated by ACTH
- mostly DHEA
- causes male secondary sex characteristics and pubic/axillary hair in females
- causes sex drive in females –> insignificant in males bc of testosterone
- levels rise from ages 7-13
Pancreas
1% endocrine, 99% exocrine
- pancreatic islets (of langerhans)
- alpha cells = glucagon
- beta cells = insulin
insulin secretion
- Beta cells have GLUT2 which is insulin independant
- glucose enters beta cell thru Glut2 transporters
- glucose is phosphorylated and turned into pyruvate
- pyruvate enters mitochondria and metabolized via citric acid cycle
- ATP from this blocks K channels, depolarizing the cell
- depolarization opens Ca channels
- Ca stimulates the release of insulin by exocytosis
insulin effect
- binds to receptor
- causes GLUT4 on secratory intracellular vessicle to join membrane
- glucose enters through GLUT4
lowers blood sugar by increasing uptake of glucose
Diabetes Mellitus
- types
- symptoms
(I) = lack of insulin (cured by giving insulin) (II) = low sensitivity to insulin (cured by increasing sensitivity and insulin --> aerobics help)
polyurea – bc osmotic diuresis
polydipsia – bc peeing all the time
polyphagia – bc cell hunger
Glucagon
- targets liver and skeletal muscle
- gluconeogenesis = glucose from lactic acid and AAs
- glycogenolysis = break down glycogen
Insulin
- glycogenesis = builds glycogen
- increases AA uptake and protein synthesis
- lipogenesis = synthesis of fatty acids
Ovaries
- makes gametes and hormones
- make 2 estrogens (estradiol and estrone) and progesterone
- regulate menstral cycle, pregnancy, lactation, and female sex characteristics
- inhibin inhibits FSH
- relaxin loosens pelvic girdle during pregnancy and some of cycle
Testes
- makes gametes and hormones
- makes testosterone –> regulates sperm production and meintains sex characteristics
- inhibn inhibits FSH
Pineal gland
- on roof of 3rd ventrical at midline in epithalamus
- masses of neuroglia and pinealocytes
- melatonin = amine hormone derived from serotonin
- biological clock
- more melatonin when its dark
acts on reticular formation in brain
Thymus
- where?
- hormones?
- function?
- behind sternum; between lungs
- thymosin, thymopoietin, thymic factor, thymic humoral factor
- involved in T lymphocyte maturation
Progesterone
- preps for pregnancy
- aids in fetal development
Adipose tissue
- leptin targets brain
- promotes satiety
heart
- Atrial Natriuretic Peptide
- targets smooth muscle cells in blood vessel walls and kidney tubules
- vasodilation
- natriuresis and fluid loss in kidneys
- decreases BP
Kidneys
Erythropoietin
-increases rate at which erythrocytes are made in red bone marrow
Renin
-part of RAA system
Calcitriol
-stimulates small intestine to absorb calcium
Stages of stress response (and name of it)
GAS = general adaptation syndrome
- initial fight or flight
- slower resistance reaction
- exhaustion
results of prolonged stress
- muscle deterioration
- immune system suppression
- ulcers
- failure of beta cells in pancreas
short term vs long term stress respons
Short:
- increased heart rate, blood flow, metabolism
- glygogenolysis
- dilation of bronchiles
- change in bloodflow patterns
- EPI and NE
Long:
- increased BP
- retention of salt
- gluconeogenesis
- suppression of immune system
- cortisol, hGH, T3 and T4
