Phys II- Endocrine II Flashcards
Follicular Cells
- functional unit of thyroid
- lumen filled with colloid (stores TH)
Describe TH
- T4 (thyroxine) or T3
- made of tyrosine (made by body) and iodine (from diet), amine
- lipophilic
- tropic
C Cells
- secrete calcitonin
- peptide hormone
TH Synthesis (4 steps)
- thyroglobulin uses exocytosis to move from follicular cells to colloid)
- Iodine to colloid from blood via pump
- Iodine attaches to tyrosine
- iodinated tyrosine molecules couple up to form TH
TH Storage
- in colloid until secretion
- usually enough for several months
TH Secretion
- follicular cells phagocytize thyroglobulin colloid
2. T3 and T4 are now free to diffuse across plasma mem into blood using plasma protein (thyroxine-binding globulin)
Is T3 or T4 more potent? How much?
T3 (4x)
How is TH used?
- target cells cleave iodine
- liver/kidney
- long term but slow acting
3 Effects of TH
- Metabolic
- Permissive
- Developmental
Metabolic Effects of TH
- basal metabolic rate
- stimulates Na/K+
- heat generation
- calorigenic
Permissive Effects of TH
- works w SNS
- increase target cells responsiveness toE and NE
- increase HR and force by increasing beta-adrenoreceptors on heart
Developmental Effects of TH
- normal NS development
- essential for normal growth
- stimulates release of GH
- stimulates IGF-1 production
- enhances effect of GH and IGF-1
Congenital Hypothyroidism
- absence of TH in fetus
- poorly developed NS (compromised intellectual function)
What is the one condition resulting from hypothyroidism?
atrophy
What are the three conditions resulting from hyperthyroidism?
- Hypertrophy
- Hyperplasia
- Goiter
Hyperthyroidism
- primary failure of thyroid
- secondary to deficiency of TRH, TSH or both
- too much iodine in diet
- low TSH in blood
- high T4/T3 in blood
- often caused by Graves (autoimmune)
- often goiter present
Cretinism
hyperthyroidism at birth causing CNS effects
How is Hyperthyroidism treated?
- surgical removal
- radioactive iodine
- antithyroid
Symptoms of Hyperthyroidism
- weight loss
- heat intolerance
- increased appetite
Hypothyroidism
- high TSH
- low T4 and T3
Symptoms of Hypothyroidism
- weight gain
- cold sensitivity
- fatigue
- slow weak pulse
- impaired mental function
Treatment of Hypothyroidism
- replacement therapy
- dietary iodine
Myxedema
- hypothyroidism in adults
- edema
- sugar related
Goiters
- over stimulated thyroid
- mostly hypo but can be hyper
- treat with exogenous TH or dietary Iodine
Grave’s Disease
- improper TSI production
- goiter
- decreased TSH in blood
Adrenal Medulla
- inner
- E , NE
Adrenal Cortex
- outer
- steroid hormones (cholesterol)
Three Divisions of the Adrenal Cortex
- Zona Glomerulosa
- Zona Fasciculata
- Zona Reticularis
Zona Glomerulosa
- outer
- aldosterone
Zona Fasciculata
- middle/largest
- cortisol
- DHEA
Zona Reticularis
- innermost
- DHEA
- cortisol
- DHEA
- Cortisol
- Aldosterone
Triggers…
- albumin
- corticosteroid-binding globulin
- albumin
Three Adrenal Steroids
- Mineralcorticoids
- Gluticocorticoids
- Sex Hormones
- What are Mineralcorticoids?
- What do they do?
- What happens when they are lacking?
- What stimulates their release?
- aldosterone
- influence NA+/K+ balance
- action site on distal and collecting tubules of kidney
- decreases Na+,
- increases plasma K+
- lowers BP
- independent of ant pit 3.
- w/o aldosterone you die within 2 days from shock
- secretion increased by renin-angiotensin-aldosterone system
Hypersecretion of Mineralcorticoids
- adrenal tumor
- chron’s
- inipropriate increased activity of renin-angio… (secondary hypersecretion)
- excessive Na+ retention or K+ depletion
- high BP
- What are Gluticocorticoids?
- What do they do?
- How are they regulated?
- cortisol
- glucose, lipid&protein metabolism
- stimulates hepatic gluconeogenesis (glucose from non-carb)
- inhibits glucose uptake
- increase plasma glucose
- stimulates protein degeneration (esp. in muscles)
- lipolysis
- adaptation to stress
- anti-inflammatory
- immunosupressive
- diurnal rhythm (increased when awake)
- negative feedback (CRH, ACTH)
What organ does Gluticocorticoids not effec t?
brain
What can supplementary gluticocorticoids be used to treat?
- inflammatory conditions
2. transplants
Describe the Tropic Effects of Cortisol
- permissive
- permit (E) to induce vasoconstriction
- prevents circulatory shock in stress
Hyper-secretion of Cortisol
- overstimulation of adrenal cortex by CRH, ACTH
- tumors
Cushing’s
- hyper-secretion of cortisol
- buffalo hump
- moon face
- skinny arms and legs
- thin/brittle skin
- muscle weakness
- immunosupressin
- osteoperosis
- striations
- hyperglycemia
- hypertension
- adrenalectomy needed
Sex Hormones
- identical/similarf to gonad hormone s
- DHEA
- ACTH NOT FSH or LH
- overpowered by testosterone
- responsible for hair in women, growth spurt, and development/maintenance of sex drive
DHEA Hyper-Secretion
- Arenogenital Syndrome
- male-like body hair
- deepening of voice
- muscular arms and legs
- small breasts
- no menstruation
- cortisol insufficiency increases ACTH therefore DHEA
- inhibits gonadotropins making women sterile
- treated with glucorticoid therapy
DHEA Hyper-secretion in newborn females
- male external genetalia
DHEA Hyper-Secretion in Pre-Pubertal Males
- prepubertal males (pseudopuberty)
The Adrenal Medulla can be described as…
- modified SNS
Epinephrine
- fight or flight
- helps SNS
- maintenance of BP
- increases blood glucose
- increases blood fatty acids
- gluconeogenesis (liver)
- glycogenolysis (liver/ skeletal muscles)
- inhibits insulin
- increased glucagon secretion
Stress and Hormones
- coordinated by hypothalamus
- activates SNS (and E)
- activates CRH-ACTH-cortisol system
- increase blood glucose and fatty acids
- decreases insulin
- increases glucagon
- increases RAAS
- increases vasopressin
- no effect on BP or blood volume
- ACTH helps with learning and behaviour
Anabolism
- build up/synthesis of larger macromolecules from smaller subunits
- require ATP
- excess stored for later
Catabolism
- breakdown of large energy rich molecules
1. hydrolysis of larger into smaller
2. oxidation of smaller to yield energy for ATP
Pancreatic Hormones (from Islets of Langerhans)
- Beta- Cells
- insulin
- Alpha-Cells
- glucagon
- PP Cells
- pancreatic polypeptide
Insulin
- anabolic
- uptake of glucose (glycogen), fatty acids(triglycerides) , AA (proteins)
- secretion increases in absorptive state
- stimulated by blood glucose
Diabetes Mellitus
- increased blood glucose
- glucose in urine
- Type 1 (10%)- lack of secretion
- Type 2 (90%)- reduced sensitivity in target cells, more insulin than normal
Polyuria
extra glucose not reabsorbed by nephron is secreted and water is secreted as well (osmotic diuresis), sweet urine
