Endocrine Flashcards
1
Q
What does the endocrine system do?
A
Maintain the body’s homeostasis
2
Q
Hormones are […]
A
Chemical messengers from ductless glands
3
Q
Endocrine hormones travel in […]
A
blood
4
Q
Hormone effect is determined by […]
A
The hormones binding and activating their specific receptors in the target cell
5
Q
A hormone circulates in the blood at […] concentration but their target cells contain the specific […] able to respond to the hormone
A
Very low
High affinity receptor
6
Q
Hormones may be removed/cleared by […]
A
Binding their receptors in target cells
7
Q
1° endocrine glands
A
Main job is to secrete a hormone
8
Q
2° endocrine glands
A
Main job is not hormone secretion
9
Q
Hydrophilic Hormones
A
- travel free of proteins in plasma
- short half life in plasma –> higher clearance
- stored in secretory vesicles
- bind/activate trans-membrane (inegreal) receptor proteins
- catecholamine & peptide hormones
10
Q
Catecholamine Hormones
A
- synthesized by enzymatic reactions
tyrosine –> DOPA –> DA –> NE –> Epi - tyrosine hydroxylase: rate-limiting enzyme for tyrosine –> DOPA
- PNMT required for NE –> Epi
- circulate free in plasma
- short-half life
- bind/activate GPCRs
11
Q
Epi –> B-adrenergic –> cAMP –> PKA –> […]
A
Muscle relaxation/vasodilation
12
Q
Epi –> a-adrenergic –> Ca2+/calmodulin –> […]
A
Muscle contraction/vasoconstriction
13
Q
Indoleamines from tryptophan bind/activate […]
A
melatonin & serotonin
14
Q
Peptide/Protein Hormones
A
- made via transcription –> translation
- stored in secretory vesicles together & secreted together (hormone & co-peptide)
- circulate free (except GH, IGFs)
- short half-life
- ex: insulin
15
Q
Peptide hormones bind specific trans-membrane receptor proteins […]
A
- GPCR
- Intrinsic kinase activity
- JAK kinase
16
Q
Hydrophobic Hormones
A
- not stored
- circulate protein-bound in plasma
- free hormones diffuse into cells & bind their specific intracellular receptor proteins
- long half-life
- thyroid hormones, steroid hormones, Vit D
17
Q
2 Common characteristics for all hydrophobic hormones
A
1.) hydrophobic hormones circulate in the plasma bound to binding proteins
2.) free H enters a cell where it binds its intracellular receptor proteins
18
Q
Thyroid Hormones (T3 & T4)
A
- secreted by thyroid gland
- made from tyrosine & requires iodine ingestion
- in plamsa: bind thyroxine-binding globulin
- in target cells: bind intracellular thyroid hormone receptors (T3R)
- in liver: thyroid hormones are modified
19
Q
T3
A
- most potent
- active hormone
20
Q
T4
A
- most abundant
- most stable
- pro-hormone form
21
Q
Steroid Hormones
A
- secreted by: adrenal glands, ovaries, testes
- made from cholesterol
- rate limiting enzymes: P450 scc
- in plasma: binding globulins –> long half life
- in target cells: bind intracellular receptor proteins
- in liver: are modified
22
Q
C19 compounds
A
androgens (testosterone)
23
Q
C18 compounds
A
estrogens (estradiol)
24
Q
1,25-(OH)2-vitamin D (calcitriol)
A
- supply of precursor vitamin D
- 2 step activation:
liver
kidneys with 1-hydroxylase - in plasma: binding globulins –> long half life
- in target cells: bind intracellular receptors
- in liver: calcitriol is modified
25
Hormone levels reflects the [...]
secretion rate
26
secretion rate is modulated by [...]
- ions
- nutrients
- neurotransmitters
- hormones
27
glucose stimulates [...] secretion from the pancreas
insulin
28
[...] inhibits PRL secretion from the [...]
- dopamine
- anterior pituitary gland
29
[...] stimulates cortisol secretion from the [...]
- ACTH
- adrenal cortex
30
Max Response
related to # of functionally available receptors
31
Up-regulation
caused by prolonged exposure to LOW levels of hormone
32
Down-regulation
caused by prolonger exposure to HIGH levels of hormones
33
Physiological dose
normal/typical concentrations in the body, leads to normal effects
34
Pharmacological dose
abnormally high concentrations that leads to abnormal effects
35
Sensitivity
hormone that elicits half-maximal response
36
Insensitivity
requires more hormone for the same response
37
Hypersensitivity
requires less hormone for the same response
38
Permissiveness
hormone A cannot exert its full effects in absence of hormone B (no effect by itself)
39
Syngerism
hormones A & B individually exert effects
effects together > effects of A + effects of B
40
Antagonism
hormone opposes effect of another
41
3 organs for energy storage & release
1.) liver
2.) fat
3.) skeletal muscle
42
Carbohydrate
stored as glycogen in liver
43
Fat
- stored as triglycerides
- most abundant
- most efficient energy reserve
44
Protein
- stored in muscle
- major source of glucose during long-fasting
45
Absorptive Phase
- fed state
- < 4 hrs
- high insulin, low glucagon
- low counter-regulatory hormones
- used by all cells
- store extra via anabolism
46
Glucose enters liver via [...]
GLUT2
47
Insulin [...] activity of [...]
increases
glucokinase
48
glucose enters skeletal muscle & fat through [...]
GLUT4
49
Glycogen production
increase glycogensis in liver & muscle
50
Protein production
increase proteogenesis in muscle
51
Triglyceride production
increase lipogenesis in fat
52
Insulin promotes [...] and inhibits [...]
anabolism
catabolism
53
Triglycerides are packaged as [...]
chylomicrons
54
Post-Absorptive Phase
- fasting state
- > 4 hrs
- low insulin
- high counter-regulatory hormones
- mobilize stored energy from liver, fat, skeletal muscle
- all cells must use energy substrates resulting from catabolism
55
[...] and [...] are main regulators
glucagon
sympathetic output (epi)
56
[...] and [...] are modifiers
cortisol
GH
57
Liver
- glycogenolysis: glycogen --> glucose
- gluconeogenesis: aa --> glucose
- ketogenesis: ketone
58
Muscle
- incomplete glycogenolysis: glycogen --> lactate
- proteolysis: protein --> aa
59
Adipocyte
- lipolysis: TG --> FFA & glycerol
60
[...] cells use [...] & [...] for energy production
Peripheral
FFA
Ketones
61
Central Nervous Tissues use [...] preferentially
glucose
62
Sources of glucose for blood glucose
- 0-4 hrs: ingested glucose
- 4-24 hrs: glycogenolysis of liver glycogen is main source of blood glucose
- 24+ hours: hepatic gluconeogenesis
- on 2nd day of fasting gluconeogenesis is main source of blood glucose
63
Fat (TG) content
chylomicron > VLDL > LDL > HDL
64
Protein content
chylomicron < VLDL < LDL < HDL
65
Homeostasis of Cholesterol
- controlled by in vivo synthesis by liver
- VLDL & chylomicrons deliver TG to cells
- LDL is a main source for cholesterol delivery to cells
- HDL transports cholesterol back to liver
66
[...] for intense exercise
carbohydrates
67
[...] for prolonged exercise
fat
68
Hormonal responses to exercise [...]
all insulin-opposing hormones & GH increase
69
Training enhances [...]
insulin sensitivity
70
Basal Metabolic Rate (BMR)
energy required for an individual @ rest
71
BMR depends on [...]
Genetics
Physiological status
Environment
72
Hypothalamic integrating center controls [...]
hunger & satiety
73
When blood glucose levels cannot be controlled [...]
diabetes mellitus
- elevated blood glucose
- decreased glucose tolerance
74
Hyperglycemia
- 3 ps: polyphasic, polyuria, polydipsia
- some symptoms develop fast (hunger, fatigue, ketoacidosis) TYPE 1
- others develop slowly (slow-healing, neuropathy) TYPE 2
75
Type 1 Insulin Dependent Diabetes
- too little insulin
- genetic component
- rapid onset
- ketoacidosis
- insulin therapy
76
Type 2 Insulin Independent Diabetes
- majority of diabetes
- associated with obesity
- insulin insensitivity
- darkening in the skin folds
- can be reserved with life style change
- treatment: metformin
77
[...] enhances glucose uptake from plasma as insulin does
intense exercise
78
[...] increases the body's insulin sensitivity
intense exercise
79
[...] controls the activity of the pituitary gland
hypothalamus
80
[...] is a master gland that controls several target glands
pituitary gland
81
[...] secretes worker hormones which provides the homeostatic negative feedback
target gland
82
Hypothalamus & posterior pituitary are derived from [...]
neural tissues
83
Anterior pituitary gland is derived from [...]
endocrine tissues
84
Posterior Pituitary
- arterial blood supply: yes
- hypothalamic neurons: send axons through pituitary stalk & terminates @ posterior pituitary
85
Anterior Pituitary
- arterial blood supply: no
- hypothalamic neurons: terminates @ median eminence, releases factors carried to AP in portal blood
86
Hypothalamic factors that affect release of anterior pituitary hormones
GnRH: gonadotropin-releasing hormone
TRH: thyrotropin-releasing hormone
CRH: corticotropin-releasing hormone
GHRH: growth hormone-releasing hormone
DA: dopamine
SST: somatostatin
87
Anterior Pituitary Hormones
LH: luteinizing hormone
FSH: follicle-stimulating hormone
TSH: thyroid-stimulating hormone
ACTH: adrenocorticotropic hormone
GH: growth hormone
PRL: prolactin
88
Prolonged elevation in AP hormone causes
hypertrophy
89
Prolonged deficiency in an AP hormone causes
atrophy
90
Tertiary Dysfunction
occurs @ hypothalamus
91
Secondary dysfunction
occurs @ AP
92
Primary dysfunction
occurs @ target gland
93
Panhypopituitarism
- loss of all anterior pituitary function
decrease AP hormones --> hypothalamic RH increases, IH decreases
- ex: Sheehans syndrome
blood clots blocking the hypothalamic-pituitary portal vessel
94
Isolated pituitary hormone deficiency or excess
- loss of only 1 hormones function
- Kallmans syndrome: no GnRH --> deficient LH/FSH --> hypogonadism
95
Acromegaly
- GH secreting tumor
- exaggerated growth effects of IGF1
- exaggerated metabolic effects of GH: insulin insensitivity
96
Posterior Pituitary Gland
- ADH & oxytocin
- synthesized in soma in hypothalamus
- action potential needed for neurotransmitter release
97
[...] stimulates water-reabsorption by the kidney
ADH
98
[...] stimulates smooth muscle contraction & modulates neuronal activities
oxytocin
99
Thyroid Gland
- thyroid follicle makes thyroid hormones
- parafollicular C cells btwn follicles secrete calcitonin
100
Thyroid Hormone Synthesis
1.) thyroid follicular cell
actively transports iodide & makes everything else necessary for synthesis of thyroid hormones
2.) in colloid
oxidation of iodide
formation of T3 & T4
3.) in follicular cell
endocytosis & hydrolysis of T3 & T4
4.) in the plasma
free T3 & T4 bind to carrier proteins
101
Free T3 activates nuclear T3R for modulating transcription
- increase BMR
- potentiate sympathetic responses
- required for complex processes
neuron development
102
The presence of a [...] indicates [...]
Goiter = high TSH
Thyroid problems
103
Hyperthyroidism
- TH secreting tumors
decrease TRH & TSH
increase TH
- TSH secreting tumors
decrease TRH
increase TSH & TH
- Graves disease
decrease TRH & TSH
increase TH
104
Symptoms of Hyperthyroidism
- exophthalmos
- sweating
- heat intolerance
- weight loss
- pretibial myxedema
- hair loss
- tachycardia
105
Hypothyroidism
- death of AP thyrotropes
decrease TSH & TH
increase TRH
- chronic iodine deficiency
decrease TH
increase TRH & TSH
- hashimotos thyroiditis: autoimmune destruction of follicles
106
Symptoms of Hypothyroidism
- cretinism: congenital deficiency
- growth stunt
- cold intolerance
- bradycardia
- weight gain
- brittle hair
107
Bone Components
- bone cells
- organic matrix
- bone marrow
- hydroxyapatite crystals
108
2 types of bone tissue
Compact (cortical) bone
Spongy (cancellous) bone
109
2 types of bone marrows
Red: site of hematopoiesis
Yellow: fat & stem cells for cartilage, fat or bone cells
110
Spongy Bone
made of red bone marrow
111
Compact Bone
made of osteons
112
What are responsible for direct bone formation & bone repair/remodeling
osteoblasts & osteoclasts
113
[...] of the epiphysis becomes a scaffold for long bone growth
chondrocytes
114
Long bones grow by [...]
endochondral bone formation
- bone formation @ epiphyseal growth plate
- stimulated by GH --> IGF
- pubertal growth spurt
- closure (ossification) by sex steroid hormones
115
GH/IGF-1 [....] bone thickness by [...]
increases
stimulating bone-remodeling processses
116
at [...] bone resorption equals bone formation
calcium homeostasis
117
PTH
- bones: stimulates bone resorption
- kidneys: stimulates reabsorption of Ca2+ & PO42- excretion
118
Calcitriol stimulates absorption by the [...]
gut
119
Estrogen
decreases activity of osteoclasts
120
Calcitonin
decreases activity of osteoclasts
121
High Cortisol
increases activity of osteoclasts
122
Hypocalcemia
symptoms:
- tetany (increased muscular activity)
- Trousseaus sign
- Chvostek sign
- weak bones: osteomalacia
causes:
-1° hypoparathyroidism
- vit D deficiency
- renal failure
123
Hypercalcemia
symptoms:
- predisposition to kidney stones
- muscle weakness, fatigue, lethargy
- calcification of soft tissues
causes:
- 1° hyperparathyroidism
- certain types of cancer
124
The [...] secrete cortisol, aldosterone, &. fight-or-flight hormones
adrenal glands
125
What does the adrenal medulla secrete
catecholamines: Epi > NE
126
The "neural" adrenal medulla is a [...] of the sympathetic nervous system
modified ganglion
sympathetic drive stimulates it
127
Secretion of catecholamines
- tyrosine hydroxylase is the rate-limiting enzyme
- PNMT is required for NE --> Epi
128
Metabolic effects of catecholamines
- increased glycogenolysis
- increased lipolysis
129
Cardiovascular & Respiratory Effects
- decreased fatigue of skeletal muscle
- increased cardiac function
- increased lung ventilation
130
Pheochromocytoma
- catecholamine-secreting tumor
symptoms:
- severe hypertension
- headaches
- heart palpitations
- pallor (paleness)
131
Mineralocorticoids
secrete aldosterone
- in zona glomerulosa
132
Glucocorticoids
secretes cortisol
- in zona fasciculata
133
Adrenal Androgrens
secretes adrenal androgens (DHEA)
- in zona reticularis
134
Zona glomérule
produces aldosterone in response to angiotensin II
- angiotensin II stimulates aldosterone secretion
- no 17 hydroxylase
135
[...] controls the body's homeostasis of ECF volume
aldosterone
136
Major effects of aldosterone
- increase Na+ reabsorption
- increase K+ excretion
137
Zona fasciculata & Zona reticularis
- ACTH stimulates secretion of glucocorticoids & adrenal androgens
- no aldosterone synthase (P450scc) --> no corticosterone or aldosterone
138
ACTH stimulates
secretion of:
- cortisol
- adrenal androgens
139
Physiological Functions of Cortisol
- permissive to catecholamines
- increase blood glucose & blood pressure
- induces differentiation of type II pulmonary alveoli that secret surfactant
140
Cortisol puts a [...] on the hypothalamic pituitary axis
negative feedback
CRH --> ACTH --> cortisol
141
CRH secretion is controlled by the [...]
circadian rhythm
142
Circadian rhythm during stress
rhythm is maintained @ elevated levels
143
Circadian rhythm in disease states
the rhythm disappears
144
Adrenal Androgens
- adrenarche: puberty @ young age
- adrenal androgens are weak androgen
145
Addisons Disease
- hypocortisolism
- cause: destruction of adrenal cortex
- symptoms:
hypotension
hypoglycemia
muscle weakness
salt craving
- treatment: lifelong hormone replacement therapy
146
Aldosterone, Cortisol, DHEA, & ACTH in Addisons
- aldosterone decreases
- cortisol decreases
- DHEA decreases
- ACTH increases
147
Congenital Adrenal Hyperplasia
- hypocortisolism
- cause: deficiency in 21-OHase
increased ACTH & androgens
- in men: precocious puberty
- in women: amenorrhea, virilism, hirsutism
- masculinization of female genitalia if enzyme defect is complete
148
Cushing's Disease
- hypercortisolism
- symptoms due to excess cortisol when not stressed
- metabolic:
hyperglycemia
moon face
buffalo hump
- cardio: hypertension
- immune: poor wound healing & infections
- skeletal: back pain
149
Adrenal Cushing's
primary
increased cortisol
150
Pituitary Cushing's
secondary
increased ACTH
151
Ectopic Cushing's
extra-pituitary source of ACTH (tumor)
increased ACTH
