Lecture 1 Flashcards
1
Q
the endocrine system
A
- glands secreting directly into circulatory system
- regulates funciton of target organs
- affect metabolic and biochemical processes
- controlled by the hypothalamus and pituitary
- negative feedback system
- endocrine vs. exocrine
2
Q
the glands of the endocrine system
A
- thyroid
- parathyroid
- islet cells of pancreas
- adrenal glands
- gonads
3
Q
Hypothalamus location
A
- base of brain
- diencephalon
- superior to pituitary
4
Q
What does the hypothalamus regulate
A
- regulates homeostasis
- primary gland
5
Q
What hormones does the hypothalamus release
A
- thyrotropin releasing horone
- responding to T4 and T3 levels
- ## stimulates release and synthesis of thyrotropin from anterior pituitary gland
6
Q
how does the hypothalamus regulate hormones
A
- through down regulation of the pituitary through dopamine and somatostatin
- growth hormone
- increases trapping, synthesis, and release of hormones from thyroid
7
Q
pituitary size and location
A
- base mid-brain, inferior to hypothalamus
- 0.5 grams
- anterior and pasterior portions
8
Q
what does the pituitary release and its method of communication
A
- growth hormone
- gonadotropic hormones
- thyrotropin
- adenocorticotropic hormone ACTH (stress hormone)
- communicates with the hypothalamus via the rich anterior vascular system
9
Q
Where does the growth hormone go
A
- muscle
- bone
- organ growth
10
Q
What are the gonadotropic hormones
A
- FSH
- LH
- prolactin
11
Q
What is thyrotropin
A
- a glycoprotein that stimulates the thyroid gland
12
Q
What is adrenocorticotropic hormone
A
- stress hormone
- stimulates adrenal cortex receptor sites
13
Q
Thyroid location
A
- 2nd and 3rd tracheal ring
- 5th and 7th C-spine
14
Q
Thyroid shape and size
A
- bilobal
- butterfly shaped
- attached by the isthmus
- pyramidal lobe
- 15 to 25 grams, largest endocrine gland
- made up of thyroid follicles
15
Q
Hormones released by the thyroid
A
- calcitonin
- triiodothyronine T3
- thyroxine T4
16
Q
Explain the thyroid follicles
A
- follicular cells that release triiodothyronine T3 and thyroixine T4
- parafollicular cells that release calictonin for bone development
- colloid for storage
- epithelial cells
17
Q
What are the hormone actions of the thyroid gland
A
- stimulate metabolic activity in body tissue
- essential in normal growth and development
- affects carbohydrate metabolism
- increases actions on the nervous sytem
18
Q
explain the thyroid negative feedback loop
A
- Low T3 & T4 → Hypothalamus releases TRH (Thyrotropin-Releasing Hormone).
- TRH → Stimulates the pituitary to release TSH (Thyroid-Stimulating Hormone).
- TSH → Stimulates the thyroid to produce T3 (Triiodothyronine) & T4 (Thyroxine).
- T3 & T4 increase → Signal the hypothalamus & pituitary to reduce TRH & TSH.
19
Q
Explain T3 and T4
A
- iodine containing hormones
- functions in intake, trapping, iodination, coupling, and releasing
20
Q
Explain iodine trapping
A
- iodide extracted from plasma
- capillaries, epithelial cells, follicular cells
- can be blocked by monovalent anions (potassium perchlorate)
- during trapping thyroid produces thyroglobin
21
Q
Iodination and organification
A
- iodide oxidized to iodine by thyroid peroxidase enzyme
- occurs at follicular cell- colloid junction
22
Q
explain coupling
A
- iodine binds to tyrosine residues on thyroglobin molecule
- yields monoiodotyrosine
- MIT and DIT coupling catalyzed by TPO
- MIT + DIT= T3
- DIT + DIT= T4
- stores one months worth of hormone
23
Q
Explain releasing
A
- diffuse through plasma membrane
- enter interstitial fluid before entering blood
- bind to thyroxine binding proteins in blood
24
Q
Explain T3 vs. T4 in serum
A
- T4 levels greater than T3
- T3 is more metabolically active
- T4 is de-iodinated in peripheral tissues 1/3
- Thyroxine binding proteins
- Different half lives
25
Thyroxine binding proteins
- thyoxine binding globulin
- thyroxine binding pre-albumin
- albumin
26
Half-lives of T3 and T4
- T3= 1.5 days
- T4= 6.7 days
27
Primary, secondary, tertiary
- primary: functional issue with gland
- Secondary: functional issue with anterior pituitary
- Teritary: functional issue with hypothalamus
28
Thyrotoxicosis
- syndrome resulting from overproduction or release of thyroid hormone
29
Hyperthyrodism
- increased iodide trapping and overproduction of thyroid hormone
30
hypothyroidism
- underproduction of the thyroid hormone
31
Thyrotoxicosis associated with thyroid hyperfunction
- excess tsh produciton
- abnormal thyroid stimulator
- graves diease
- trophoblastic tumor
- intrinsic thyroid autonomy
- hyperfunctioning adenoma
- toxic multinodular goiter
32
Thyrotoxicosis not associated with thyroid hyperfunction
- disorders of hormone storage
- subacute thyroiditis
- chronic thyroiditis with transient thyrotoxicosis
- extr-thyroid source of hormone
- ectopic thyroid tissue
- carcinoma
33
hyperthyroidism signs and symptoms
- goitre
- exothalamus
- heat intolerance
- perspiration/sweating/moist skin
- nervous/irritable
- tremor
- tachycardia
- decreased appetite
- dysmenorrhea
- pretibial myxedema
- altered bowel activity
- low tsh, elevated T4 and T3
34
hypothyroidism pathologies
- grave's disease
- plummer's disease (multinodular goitre)
- ectopic thyroid
35
Hypothyroidism symptoms
- general hypoactivity
- cold intolerance
- cold, dry skin
- lethargic/fatigue
- amenorrhea
- increased weight
- decreased apetite
- possible goitre
- constipation
- High TSH, low T3, T4
36
Cretinism
- hypothyroidism during fetal development
- mental impairment
- dwarfism
37
Chronic thyroiditis
- hashimoto's
- organification defect, autoimmune disease
38
acute thyroiditis
- rare bacterial infection
- pain, fever, chills, hot + tender enlarged gland
39
subacute thyroiditis
- viral infection
40
Describe protection from iodine
- Regulatory bodies: CNSC, QEII HSC in uptakes, scanning, therapies, ablations
- thyroid screening
- bioassay
41
The thyroid in calcium regulation
- high levels of calcium:
- calcitonin released,
- increase deposition of calcium in bone matrix
42
Parathyroid in calcium regulation
- Low calcium level:
- release of PTH
- promotes release of calcium from bone
- increases blood levels
- encourages re-absorption of calcium by kidneys
- kidneys release calcitrol affecting GI absorption
- vitamin D activation promotes calcium absorption from food
43
43
Parathyroid feedback loop
- Low blood calcium (Ca²⁺) → Parathyroid glands release parathyroid hormone (PTH)
🦴 Bones: Stimulates osteoclasts to release calcium.
🟡 Kidneys: Increases calcium reabsorption & activates vitamin D.
🍽️ Intestines: Enhances calcium absorption via vitamin D.
- Calcium rises → PTH release decreases (negative feedback).
44
Pathologies causing primary hyperparathyroidism
- adenoma
- hyperplasia
- ectopic
- parathyroid cancer
45
Secondary hyperparathyroidism
- renal insufficiency
46
Tertiary hyperparathyroidism
- renal failure
- autonomous function
47
Hyperparathyroidism Signs and
Symptoms historically
- nephrolithiasis
- osteitis fibrosa cyticas
- osteoporosis
- pathologic fractures
- brown tumors
- GI symptoms
- neuropsychiatric symptoms
48
Hyperparathyroidism Signs and
Symptoms currently
- asymptomatic
- Dx with routine blood work
- increase serum calcium
- decrease serum inorganic phosphate
- PTH level then ordered
49
Describe the adrenal glands
- two
- located above and slightly medial to upper pole of both kidneys
- 5g each
- cortex vs medulla
- 90% cortex, 10% medulla
50
what does the cortex produce and release?
- Aldosterone
- Cortisol, Corticosterone, Cortisone
- Androgens/Dehydroepiandrosterone
51
What does the medulla produce and release
- epinephrine
- norepinephrine
52
adrenal gland cortex pathologies
- addison's disease
- cushings disease
53
adrenal gland medulla pathologies
- neuroblastomas
- insulinomas
- pheochromocytomas
54
