endocrine Flashcards
1
Q
endocrine organs
A
- ductless glands
- usually secrete hormones into bloodstream via fenestrate capillaries
- generally have systemic effects
2
Q
systemic effects
A
endocrine cell releases hormone in blood capillary and then travels to distant target cells. hormone binds to its receptor on the distant target cells
3
Q
Paracrine hormones
A
–localized effect
paracrine cell releases hormone, paracrine hormone binds to its receptor on a nearby target cell
4
Q
autocrine hormones
A
–localized effect
autocrat cell releases hormone that binds to a receptor on its own cell
5
Q
localized effects
A
- paracrine
2. autocrine
6
Q
functions of hormones
A
regulation of:
- other endocrine organs (tropic hormones)
- metabolism and energy balance
- glandular secretions
- smooth and cardiac muscle contraction
- growth and development
- “flight or fight” responses and reproduction
7
Q
which endocrine functions are augmented by the ANS?
A
regulation of:
- smooth and cardiac muscle
- regulation of glandular secretions
- “flight or fight” responses
8
Q
in what “non-endocrine” organs is there endocrine tissue?
A
- EPO and renin secreting cells in kidney
2. enteroendocrine cells in gut, lung
9
Q
types of hormones
A
- protein
- peptide
- lipid-derived
- monamine
10
Q
protein hormones
A
bind to cell surface receptors, activate 2nd messengers, etc
exs:
1. prolactin
2. growth hormone
11
Q
peptide hormones
A
bind to cell surface receptors, activate 2nd messengers, etc
exs:
1. ADH
2. oxytocin (9AA each)
12
Q
lipid-derived hormones
A
diffuse through cell/nuclear membranes, bind to nuclear receptors to effect gene expression
- from cholesterol: steroid hormones (estrogen, glucocorticoids)
- from eicosinoids: prostaglandins
13
Q
monamine hormones
A
derived from AA: phenylalanine, tyrosine, tryptophan, thyroxine, melatonin, catecholamines [adrenaline/noradrenaline]
14
Q
pituitary gland
A
aka hypophysis (Gk, hypo, under, phyein to grow)
anterior and posterior lobes
15
Q
posterior lobe of pituitary gland
A
aka neurohypophysis
- pars nervosa
- infundibulum
16
Q
anterior lobe of pituitary gland
A
aka adenohypophysis
- pars distalis
- pars intermedia
- pars tuberalis
17
Q
pituitary development
A
- posterior lober–formed from neuroectoderm (from floor of 3rd ventricle)
- anterior lobe-grew from remnants of Rathke’s pouch and oropharnyx ectoderm
- -gland surrounded by developing sphenoid bone
18
Q
type of cells in pars distalis
A
anterior lobe of pituitary
- basophils
- chromophobes
- endothelial cells
- acidophils
- fenestrated capillary
2 classes of cells: acidophils and basophils
19
Q
acidophils
A
- somatotropes (50%)- growth hormone
2. lactotropes/mammotropes (15%) -prolactin
20
Q
growth hormone
A
released by somatotrope (acidophil- class cell type) cells in anterior pituitary -growth of muscle, cartilage, bone; liver, pancreas, immune system, etc. functions
21
Q
prolactin
A
released by lactotropes/mammotrope cells (acidophil class cell type) in anterior pituitary functions: 1. mammary gland development 2. milk production 3.modulates spermatogenesis 4. surfactant synthesis in fetal lung
22
Q
basophils
A
found in anterior pituitary tropic hormones: act on other endocrine organs cell types: 1. corticotropes (15%) 2. thryrotropes (5%) 3. gonadotropes (10%)
23
Q
corticotropes
A
anterior pituitary-basophils
adrenocorticotropic hormone- ACTH
target: adrenal cortex, production of corticosteroids
24
Q
thyrotropes
A
anterior pituitary-basophils
thyroid stimulating hormone- TSH
target: thyroid gland, production of thyroid hormones
25
gonadotropes
anterior pituitary-basophils
follicle stimulating hormone-FSH and luteinizing hormone-LH
target: female and male reproductive organs
26
chromophobes
found in anterior pituitary
- degranulated acidophils/basophils?
- stem cells?
- folliculostellate cells?
27
folliculostellate cells structure
found in anterior pituitary
- devoid of granules, occupy 10% of anterior pituitary
- form cell clusters ("follicles")
- dendritic morphology
- possess gap junctional connections to other FS cells and to acidophils/basophils/chromophobes
28
folliculostellate cells functions
1. paracrine regulation
2. neuro/immune regulation of inflammation
3. stem cells?
29
pars intermedia
- part of anterior lobe
- between pars nervosa and pars distalis
- consists mostly of basophils (corticotrophs)
- synthesizes proopiomelanocortin (POMC) which is cleaned to form: MSH, B-endorphins, ACTH
- contains colloid filled cysts/ remnants of rathke's pouch (identification/differentiation from pars nervosa and pars distalis)
30
pituitary portal system
aka hypothalamic-hypophyseal portal system
in pars tuberalis
transports neurosecretory cells from hypothalamus to endocrine cells of anterior pituitary
31
hormones released from pituitary to rest of body/tissues
1. TSH
2. ACTH
3. FSH AND LH
4. Growth hormone (GH)
5. Prolactin (PRL)
6. Endorphins
32
hormones released from hypothalamus via pituitary portal system
negative feedback mechanisms usually control hypothalamic secretions (e.g. high TSH levels inhibits TRH release)
1. TRH-thyrotropin releasing hormone
2. CRH- corticotropin releasing hormone
3. GnRH- gonadotropin releasing hormone
GHRH- growth hormone releasing hormone
33
TSH
released from portal system and targets thyroid
34
ACTH
released from portal system and targets adrenal cortex
35
FSH and LH
released from portal system and targets testes or ovaries
36
growth hormone (GH)
released from portal system and targets entire body
37
prolactin (PRL)
released from portal system and targets mammary glands (in mammals)
38
endorphins
released from portal system and targets pain receptors in the brain
39
posterior lobe components
neurosecretory organ
2 components:
1. pars nervosa
2. infundibulum
40
posterior lobe cell types
1. pituicytes (glia)
- -its cytoplasm surrounds axon terminals
2. unmylinated axons
3. capillaries
41
pars nervosa
component of posterior lobe
storage and release of ADH and oxytocin
42
neurosecretion of posterior pituitary
- hormones are stored (herring bodies--bulb-like projections of axon terminal)
- axons terminate near blood vessels
- hormones (9AA each) are coupled to neurophysin I and II
- calcium release stimulate exocytosis
43
hormones released via neurosecretion in posterior pituitary
1. oxytocin
| 2. ADH (Vasopressin)
44
oxytocin
released from posterior pituitary
1. smooth muscle contraction of uterus
2. myoepithelial cell contraction (mammary gland)
3. emotional (trust, calmness)
45
ADH
(vasopressin)
1. increases collecting duct permeability
2. vasoconstrictor (minor role)
--absence/deficiency leads to central diabetes insipidus
46
pineal gland: structure, cell types
-neuroendocrine gland-aka third eye
-contains calcifications
divided in lobules by CT
cell types:
1. pinealocyte--purple cells with clear purple nucleus
2. interstitial (glial) cells--dark purple-ovalish shape
47
pinealocyte
in pineal gland
| produces melatonin
48
melatonin functions
1. participate in circadian rhythms (sleep cycles)
2. role in puberty??
3. powerful antioxidant
49
production of melatonin pathway
pathway active in darkness and inhibited by light
- occurs in pinealocyte of pineal gland
1. tryptophan enters
2. conversion to 5-hydroxytryptophan
3. serotonin+NAT
4. N-acetylserotonin+HIOMT
5. Melatonin
melatonin released from pinealocyte's perivascular process into fenestrated capillary
50
pineal gland calcifications
2 types of calcifications
1. corpora arenacea (brain sand)
2. myeloconia (brain dust)
51
corpora arenacea structure/size, composition
aka brain sand
-mid-sagittal organ-deviation from center may be indicative of pathology --tumors
- one type of calcifications in pineal gland
- large mulberry-like concretions
- hydroxyapatite, protein, glycoprotein
- increases with age
52
myeloconia:
| shapes, structure/size, composition
```
aka brain dust
one type of calcifications in pineal gland
-small 10-20 um crystals
-100-300 micro crystals/mm3
-calcite (CaCO3), glycoprotein
-similar to otoliths of inner ear
```
shapes: cubic, hexagonal, cylindrical
53
pancreas
```
islets of Langerhans
beta cells
alpha cells
delta cells
gamma cells
epsilon cells
```
54
islets of Langerhans
in pancreas
- circular areas of lighter purple/pink areas with cells
- abundant supply of fenestrated capillaries
55
islet hormones
1. insulin
2. glucagon
3. somatostatin
4. pancreatic polypeptide
5. gherlin
56
insulin
islet hormone
- synthesized by beta-cells in islets
- 51 AA dimer (a-chain/ b-chain)
- released in responses to elevated blood glucose levels
- promotes glucose absorption in muscle and adipose tissue
57
glucagon
islet hormone
- synthesized by alpha-cells in islets
- 29AA polypeptide
- released in response to low blood sugar
- promotes glycogen conversion to glucose- gluconeogenesis
58
somatostatin
islet hormone
- synthesized by delta cells in islets
- 14 or 28 AA
- inhibitory actionsL pituitary, gastrointestinal hormones, endocrine and exocrine pancreas
59
pancreatic polypeptide
islet hormone
- synthesized by F-cells (gamma cells) in islets
- released in response to hypoglycemia and food ingestion
- regulated pancreas/GI functions
60
gherlin
islet hormone
- synthesized by epsilon cells in islets and GI cells
- "hunger hormone" (increasing hunger, opposite of leptin)
61
beta cells
islets
| insulin producing
62
alpha cells
islets
| glucagon producing
63
delta cells
islets
| somatostatin
64
gamma cells
islets
aka F cell
pancreatic polypeptide
65
epsilon cells
islets
| ghrelin
66
thyroid gland cell types
1. follicular cells
| 2. parafollicular cells
67
thyroglobulin
-iodainated glycoprotein (lots of tyrosine residues)
-comprises the major colloid component of thyroid
-extracellular storage form of thyroid hormone precursor
also present:
1. thyroid peroxidase
2. Iodine (I)
3. iodide (I-) --ion
68
T4
thyroxine
| -stable, long .5 life--one week
69
T3
triiodothyronine
aka thyroid hormone
-potent form
70
goiter
iodine-deficiency goiter
- -large/inflamed thyroid--can see in neck
- -iodized salt has all but eradicated these goiters in most parts of the world
71
goiter cycle
low thyroxine (hypothyroidism)--> increased TRH from hypothalamus--> increased TSH from pituitary--> hypertrophy and hyperplasia of thyroid cells and increased colloid--> return to low thyroxine (hypothyroidism)
72
graves disease
autoantibodies against TSH receptor (resulting in excess activation)
- hyperthyroidism
- goiter develops from follicle cell hyperplasia
- excess periorbital CT/fat deposition leads to exopthalamos (enlarged-staring eyes)
- -periorbital fibroblasts express TSH receptors
73
graves disease mechanism
1. TSH and ABs compete and ABs stimulates TSH receptors
| 2. follicular cells in thyroid are then stimulated and T3/T4 produced and released, and follicle cell hyperplasia occurs
74
parafollicular cells
clear cells
- reside within basal lamina
- neural crest-derived
- stores and produces calcitonin
75
calcitonin
-released and stored by parafollicular cells
- stimulated by high calcium
lowers blood calcium levels by
a. increases osteoblast activity
b. decreases osteoclast activity
c. decreases calcium absorption
-opposes parathyroid hormone
76
calcitonin
-released and stored by parafollicular cells
- stimulated by high calcium
lowers blood calcium levels by
a. increases osteoblast activity
b. decreases osteoclast activity
c. decreases calcium absorption
-opposes parathyroid hormone
77
parathyroid gland: cell types
4 parathyroid glands in the thyroid
1. principal cell
2. oxyphil cell
3. chief cells
78
chief cells
in parathyroid gland
-secretes parathyroid hormone (PTH)
smaller cells with large nucleus, little cytoplasm, lots of them
79
oxyphil cells
in parathyroid gland
-appear at puberty
-unknown function
look like egg cells--larger pink cell with purple nucleus in middle
80
Parathyroid hormone (PTH)
- secreted by chief cells in parathyroid gland
- 84 aa polypeptide
- opposes (opposite of) action of calcitonin but only PTH is vital
- functions:
1. increases blood calcium
a. increases osteoclast activity
b. stimulates vitamin D activation in kidney
c. vitamin D stimulates coliseum resorption in GI tract and kidney
81
exotic thyroid
remnant of thyroglossal duct outside of thyroid (thyroid tissue growth somewhere else in throat/mouth area
82
thyroglossal duct cyst
can see on neck--growth of cyst --fluid filled
83
adrenal gland composition/strucutre/components
-CT capsule
-cortex/medulla
-3 layers in cortex:
1. zona glomerulosa
(outer most part-near capsule)
2. zona fascuculata
3. zona retutcularis (inner most part-near medulla)
- cortex: steroid hormone synthesis
- medulla:catecholamine synthesis
84
steroid secreting cell features
released from adrenal cortex
| -lipid, smooth ER, mitochondria with tubular cristae
85
aldosterone
aka mineralocorticoid
released/made in zona glomerulosa of adrenal cortex
1. promotes Na resorption in kidney, increases b.p.
2. controlled primarily by angiotensin II-less so by K+ levels and ACTH
86
zona glomerulosa features
outer most layer of cortex in adrenal gland
- in picture--can see capsule wall
- produces/makes aldosterone
87
production of angiotensin 2 pathways
1. angiotensinogen is released from liver when pt has decreased b.p., fluid volume and increase Beta-1 sympathetic
2. increased renin from kidney makes angiotensin 1
3. ACE plus angiotensin 1 make angiotensin 2
88
angiotensin 2 effects
1. increased vasoconstriction
2. increased salt (NaCl) and water reabsorption in kidney
3. makes aldosterone via adrenal cortex--which increases Na resorption in DCT of kidney
all three together, increase bp, fluid volume
89
zona fasciculata:
cell type/shape
hormone produced?
middle layer of adrenal gland cortex
- -cells with purple nucleus, lighter cytoplasm filled with dots
- --elongated cords of cells
- -large cells, extracted lipid droplets
- -fenestrated capillaries (elongated endothelial nuclei)
- -makes cortisol (glucocorticoids)
90
glucocorticoids
```
aka cortisol
made in zona fasciculata layer of adrenal gland cortex
1. glucose metabolism (gluconeogenesis)
2. anti-inflammatory agent
3. controlled by ACTH
```
91
zona reticularis
inner most layer of adrenal gland cortex
| produces/makes androgens
92
gonadicorticoids
aka androgens
produced in zona reticular layer of adrenal gland cortex
1. precursor for sex hormones
--DHEA-dehydroepiandrosterone, converted to estrogen and testosterone in ovaries and testes
2. controlled by ACTH
93
adrenal medulla:
| cell types
1. chromaffin cells
production of catecholamines (epinephrine and norepinephrine and some dopamine)
94
chromaffin cells
neuroendocrine cells--modified, axonless neurons
-neural crest-derived
-synthesize catecholamines from phenylalanine and tyrosine
-80% epinephrine (adrenaline0
-20% noreepinephrine (noradrenaline)
plus small amounts of dopamine
95
chromaffin cells behave like what type of cells?
sympathetic neurons--2 neuron chain process
1. 1st nerve--releases cholinergic (acetylcholine) to chromaffin cells.
2. crhomaffin cells are postsynaptic neurons that then release adrenaline and noradrenaline (20:1) but released into blood stream and not onto target cell like sympathetic neurons.
- -this process is slower bc hormones have to travel through blood to arrive at its target cells
96
effects of adrenaline and noradrenaline on body?
increased HR
increased BP
dilate bronchioles
dilate coronary arteries
