Histology: Endocrine System Flashcards
(130 cards)
1
Q
Glands are classified as either _______ or _______. What is the difference.
A
Either exocrine or endocrine
Exocrine = secrete onto surface either directly or through a duct
Endocrine - secrete internally, ductless glands, secrete hormones, utilize cardiovascular system for distribution
2
Q
Hormones can be broken up into two types: __ and __.
A
Circulating Hormones and Local Hormones
3
Q
What are the two types of local hormones/what do they do?
A
Paracrine hormones = hit neighboring cells
Autocrine hormones = hit themselves
4
Q
What is the main visceral control center for the body to maintain homeostasis?
A
Hypothalamus
5
Q
What are examples of how the hypothalamus controls /maintains homeostatis?
A
regulates body temperature, food intake, water balance, thirst, sleep-wake cycles, sexual behavior, endocrine system function!
6
Q
What is the “command center for the endocrine system” and why?
A
Hypothalamus
Because it’s secretions regulate other glands
7
Q
The hypothalamus connects to the pituitary gland via ____
A
infundibulum
8
Q
Wha tis the “master gland for endocrine system”?
A
Pituitary gland
9
Q
Together, what do hypothalamus adn pituitary gland regulate?
A
virtually all aspects of growth, development, metabolism and homeostasis
10
Q
The hypothalamus produces/releases __(#) hormones
A
9
11
Q
How are the # of hormones released/produced from hypothalamus categorized?
A
9 hormones
5 are releasing hormones
2 are inhibiting hormones
12
Q
Pituitary gland aka _____
A
hypophysis
13
Q
Infundibulum aka ____
A
Stalk
14
Q
Describe the location of the pituitary gland
A
Sits in the sella turcica of sphenoid bone
or
Sits in the hypophyseal fossa of the sphenoid bone
15
Q
What are the 2 functional components of the pituitary gland?
A
anterior pituitary gland and posterior pituitary gland
16
Q
Anterior pituitary gland aka ____ or _____
A
anterior pituitary gland
aka anterior lobe
aka adenohypophysis
17
Q
Posterior pituitary gland aka ____ or ____
A
posterior pituitary gland
aka posterior lobe
aka neurohypophysis
18
Q
How many/what are the parts of the anterior pituitary gland?
A
- Pars Distalis
- Pars Intermedia
- Pars Tuberalis
Pars NERVosa is in the NEUROhypophysis
19
Q
How many/what are the parts of the posterior pituitary gland?
A
- Pars Nervosa
- Infundibulum
Pars NERvosa in the NEUROhypophysis
20
Q
Describe Pars Distalis
A
Portion of the anterior lobe
Cords of epithelial cells interspersed with fenestrated capillaries
21
Q
Describe Pars Intermedia
A
Portion of the anterior lobe
Cells are basophilic corticotropes (produce MSH)
Surrounds a series of colloid-filled follicles that represent residual lumen of Rathke’s Pouch
22
Q
Describe Pars Tuberalis
A
Portion of the anterior lobe
Forms collar/sheath around the infundibulum
most cells basophilic gonatropic cells
23
Q
Describe Pars Nervosa
A
Portion of the posterior lobe
Neurosecretory axons and endings
24
Q
Describe the infundibulum
A
Portion of the posterior lobe
Contains neurosecreotry axons forming through the hypothalamo-hypophyseal tracts
25
How is release of hormones from the anterior pituitary gland regulated?
hormones of anterior pituitary gland are stimulated/repressed by the hormones released from the hypothalamus
Stimulated by 5 releasing hormones
Suppressed by 2 inhibiting hormones
Also inhibited through negative feedback loop
26
How do regulating hormones from the hypothalamus reach the anterior lobe?
Remember: anterior lobe's release/supression of hormones is regulated from the hormones released from the hypothalamus
These hormones reach the anterior lobe via hypothalama-hypophyseal portal system
27
Where are the neurosecretory neurons?
in the hypothalamus
28
What do the neurosecretory neurons in the hypothalamus synthesize?
the hypothalamic releasing and inhibitory hormones
this is synthesized in their cell bodies
29
After being synthesized in the neurosecretory neurons cell bodies in hypothalamus, hypothalamic hormones travel down _____ and exit via _____.
Hypothalamic hormones travel down the axons of the neurosecretory cells to the axon terminals where they exit via exocytosis
30
After exiting the neurosecretory cell axon terminal, hypothalamic hormones enter ____ at the ___ via ____
Enter the HYPOPHYSEAL PORTAL SYSTEM at the PRIMARY PLEXUS OF THE HYPOPHYSEAL PORTAL SYSTEM via DIFFUSION
31
What is the primary plexus of the hypophyseal portal system? What is it's distinguishing morphological feature?
This is how hypothalamic hormones diffuse into the hypophyseal portal system
they are fenestrated capillaries (because hormones ente here via DIFFUSION)
32
The hypothalamic hormones pass through the primary plexus of the hypophyseal portal system to the ___ and into the _____.
into the HYPOPHYSEAL PORTAL VEINS
and then into the SECONDARY PLEXUS OF THE HYPOPHYSEAL PORTAL SYSTEM
33
What is the secondary plexus of the hypophyseal portal system? What is it's distinguishing morphological characteristic?
The second set of fenestrated capillaries which hypothalamic hormones travel through
34
At the end of the secondary plexus of the hypophyseal portal system, where do the hypothalamic hormones end?
The secondary plexus of the hypophyseal portal system brings hypothalamic hormones DIRECTLY into the
PARS DISTALIS
35
There are 2 groups of secretory cells in the anterior lobe based on staining affinity. What are they?
1. Chromophils
| 2. Chromophobes
36
What is the difference between chromophils and chromophobes?
Where are they?
Pars Distalis (Anterior lobe)
CHROMOPHILS - affinity for staining. hormone stored in cytoplasm.
CHROMOPHOBES- weak stain. few or no secretory cells. clear cells. reserve/primitive cells. undifferentiated cells - can become chromophils
37
What is the % of chromophils vs chromophobes
50% and 50% of pars distalis
*remember chromophobes are undifferentiated and can become chromophils
38
What are the two types of chromophils in the pars distalis?
What is there % breakdown?
1. Basophils - 10%
affinity for basic dyes
2. Acidophils 40%
affinity for acidic dyes
39
How many types of basophils are present in pars distalis? What are they?
1. Gonadotropes (FSH and LH)
2. Corticotropes (ACTH)
3. Thryotropes (TSH)
40
How many types of acidphils are present in pars distalis? What are they?
1. Somatotropes (GH) - most abundant
| 2. Lactotropes (mammotropes, PRL)
41
hGh
- Full name?
- What cell secretes?
- What cell type?
Human Growth Hormone
Somatotropes
Acidphophil (chromophil)
42
TSH
- Full name?
- What cell secretes?
- What cell type?
Thyroid-Stimulating Hormone
Thyrotropes
Basophil (chromophil)
43
FSH
- Full name?
- What cell secretes?
- What cell type?
Follicle-Stimulating Hormone
Gonadotropes
basophil (chromophil)
44
LH
- Full name?
- What cell secretes?
- What cell type?
Luteinizing Hormone
Gonadotropes
Basophil (chromophil)
45
PRL
- Full name?
- What cell secretes?
- What cell type?
Prolactin
Lactotropes
Acidophil (chromophil)
46
ACTH
- Full name?
- What cell secretes?
- What cell type?
Adrenocorticotrophic Hormone
Corticotropes
Basophils (chromophils)
47
MSH
- Full name?
- What cell secretes?
- What cell type?
Melanocyte-Stimulating Hormone
Corticotropes
Basophils (chromophils)
48
What do somatotropes secrete?
hormone secreting hormone - acidophils
49
what do thyrotropes secrete?
thyroid-stimulating hormone - basophils
50
What do gonadotropes secrete?
follicle stimulating hormone - basophil
luteinizing hormone - basophil
51
What do lactotropes secrete?
prolactin - acidophil
52
What do corticotropes secrete?
adrenocorticotrophic hormone - basophils
Melanocyte-stimulating hormone - basophils
53
Which part of the pituitary gland is continuous with the infundibulum on a histology slide?
the pars nervosa
can tell by same cell type
54
Does the posterior lobe synthesize hormones? Are there secretory cells present?
Posterior lobe does not synthesize hormones
therefore there are no secretory cells present
55
What is actually found within the posterior lobe?
axon terminals of hypothalamic neurosecretory neurons
fibroblasts, mast cells and pituicytes
56
What are pituicytes?
cell type of posterior lobe
Type of glial cell resembling astrocyte; associates with fenestrated capillaries; has many branches; pigmented vesicle in cytoplasm; nuclei round/oval; most common cell type in posterior lobe
57
What is the most common cell type in the posterior lobe? What are the other cell types? What else is present?
Most common cell type = pituicytes
other cell types: fibroblasts, mast cells
other structures: axon terminals of hypothalamic neurosecretory neurons
58
What are the two hormones stored and released in the posterior lobe?
1. Oxytocin (OT)
| 2. Antidiuretic hormone (ADH) (vasopressin)
59
Where are the axons of the hypothalmic neurosecretory neurons of the hypothalamo-hypophyseal tract?
In the infundibulum
60
Where are the terminal boutons of the hypothalamic neurosecretory neurons of the hypothalamo-hypophyseal tract?
In the posterior lobe
61
Where are the hormones stored in the posterior lobe?
Herring bodies
| secretory vesicles in dilated portions of the axons near the terminals
62
What are Herring bodies? Where are they located?
Herring bodies are secretory vesicles where hormones are stored in the posterior lobe.
They are found in the dilated portions of the axons near terminal bodies.
63
What is Oxytocin's target tissue?
uterus and mammary glands
64
How is oxytocin secretion controlled?
neurosecretory cells of hypothalamus secrete OT in respones to uterine distention and stimulation of nipples
65
What is the principal action of oxytocin?
Stimulates control of smooth muscle cells of uterus during childbirth;
stimulates contraction of myoepithelial cells in mammary glands to cause milk ejection
66
What is ADH (vasopressin)'s target tissue?
Kidneys, Sudoriferous (sweat) glands, Arterioles
67
How is ADH (vasopressin) secretion controlled?
neurosecretory cells of hypothalamus secrete ADH in response to elevated blood osmotic pressure, dehydration, loss of blood volume, pain or stress, low blood osmotic pressure, high blood volume, and alcohol inhibit ADH secretion
68
What is ADH (vasopressin) principal action?
conserves body water by decreasing urine volume
decreases water loss through perspiration, raises blood pressure by constricting arterioles
69
What is the pineal gland/body and where is it located?
It is a neuroendocrine gland.
Located in diencephalon
70
What does the pineal gland/body do?
regulates daily body rythm; day and night cycle (circadian rythm)
71
Which endocrine gland regulates the circadian rhythm?
the pineal body
| neuroendocrine gland
72
Pineal gland/body major hormone production is _____
melatonin
73
What endocrine gland secretes mostly melatonin?
Pineal gland/body (because in charge of regulating circadian rhythm)
74
What are the two cell types in the pineal gland/body and % presence?
1. Pinealocytes (parenchymal cells) 95%
| 2. Interstitial (glial) cells 5%
75
Pineal gland/body has a characteristic presence of _______
How can you identify these on histo slide?
corpora arenacea (brain sand)
seen as giant purple circles on histology slide
76
Adrenal glands aka ____
Suprarenal gland
77
What structure is surrounding the adrenal gland?
capsule (just like kidney)
78
Two parts of the adrenal gland are ____ and ____
cortex and medulla
79
Describe the difference between the cortex and the medulla of an adrenal gland
Cortex - large, peripheral, just below capsule, makes up 80-90% of gland, steroid-secreting
Medulla- smaller, centrally located, catecholamine-secreting cells
80
What is the difference between production in cortex and medulla?
Cortex - produces steroir secreting cells
Medulla - produces catecholamine secreting cells
81
What are the subdivisions of cortex in the adrenal gland?
1. Zona glomerulosa
2. Zona Fasciulata
3. Zona Reticularis
82
Describe the zona glomerulosa (on histo slide)
outermost area of the adrenal cortex
appear rounded (ribbon-like)
acinar appearance but not long like acinus
83
Describe the zona fasciculata (on histo slide)
Middle area of the adrenal cortex between zona glomerulosa and zona reticularis
long columnar cells
lighter stained, foamy appearance to cytoplasm
thickest layer
84
Describe the zona reticularis (on histo slide)
Third and innermost zone of the adrenal cortex
Has many sinusoid vessels passing between the layers
Darker staining and has reticular-like or trabecular-like arrangement
85
Zona glomerulosa:
- What type of hormone secreted?
- Main hormone secreted?
- Main function?
Zona Glomerulosa
Type of hormones secreted: mineralocorticoid hormone
Main hormone secreted: aldosterone
Function: regulates Na, K and water; control of blood pressure
86
Zona Fasciculata:
- What type of hormone secreted?
- Main hormone secreted?
- Main function?
ZONA FASCICULATA
Type of hormone: glucocorticoid hormones
main hormone: cortisol
main function: regulates glucose and fatty acid metabolism; suppresses the immune system; provides reistance to stress
87
Zona reticularis
- What type of hormone secreted?
- Main hormone secreted?
- Main function?
ZONA RETICULARIS
Type of hormone secreted: androgen hormone
Main hormone secreted: DHEA (dehydroepiandrosterone) important for gonad development
Function: Assists in early growth of axillary and pubic hair in both sexes
88
Medulla of adrenal glands
- What type of hormone secreted?
- Main hormone secreted?
- Main function?
MEDULLA
Type of hormone secreted: cateocholamines
Main hormones secreted: epinephrine (adrenaline), and norepinephrine (NE) *noradrenaline)
Function: intesify sympathetic responses in other parts of the body
89
Are adrenal medulla sympathetic ganglion?
they are MODIFIED sympathetic ganglion
90
What is the adrenal medulla's embryologic origin?
neural crest cells
91
Does the adrenal medulla have axons pesent?
No and therefore do not release a neurotransmitter
92
What are chromaffin cells? Where are they?
Chromaffin cells are modified neurons that cluster around blood vessels and release hormones in the adrenal medulla
93
How are chromaffin cells controlled?
(modified neurons in adrenal medulla)
controlled by sympathetic preganglionic cells which allows for quick signaling to chromaffin cells to release hormones via exocytosis
94
What are the islets of langhan? Where are they?
The endocrine portion of the pancreas
aka pancreatic islets 100-200um in diameter
found throughout pancreas but most numerous in tail
95
What do islets of langerhan do?
synthesize and secrete hormones in the pancreas (mostly in the tail of the pancreas)
96
How do islets of langerhan stain? What are we comparing them to?
They stain pale compared to the exocrine portion of the pancreas (pancreatic acini)
97
What are the 4 principle cells of the islets of langerhan?
1. Beta or B cells
2. Alpha or A cells
3. Delta or D cells
4. F Cells
98
What do the 3 principle cells of the islets of langerhan produce?
1. Beta (B) Cells = insulin
2. Alpha (A) cells = glucagon
3. Delta (D) cells = somatostatin (identical to growth hormone-inhibiting hormone GHIH from hypothalamus)
4. F cells = pancreatic polypeptide
99
Insulin.
What does it do? What is it released from?
Released from Beta cells of islets of langerhan in pancreas
LOWERS BLOOD GLUCOSE LEVEL as it signals for an accelerated glucose transport into cells.
conversion of glucose into glycogen (glycogenesis)
100
What is glycogenesis? How is it stimulated?
Conversion of glucose to glycogen
Insulin stimulates it. Insulin produced by beta cells of islets of langerhan in pancreas.
101
Glucagon.
What does it do? What is it released from?
released by alpha cells in islets of langerhan of pancreas
RAISES BLOOD GLUCOSE LEVEL as it signals for acceleration of breakdown of glycogen to glucose in the liver (glycogenolysis)
this glucose then released into blood
102
What is glycogenolysis? What stimulates it?
breakdown of glycogen into glucose
stimulated by alpha cells of islets of langerhan of pancreas
103
What is the difference between insulin and glucagon?
insulin = glucogenesis (glucose into glycogen) LOWERS BLOOD GLUCOSE LEVEL
glucagon = glucogenolysis (glycogen into glucose) RAISES BLOOD GLUCOSE LEVELS
104
Somatostatin.
| What does it do? What is it released by?
Released by delta cells of islets of langerhan in pancreas
inhibits insulin and glucagon secretion
105
Where are F cells located in relation to where the rest of the islets of langerhan are located?
F cells located within head of pancreas (all others are in tail of pancreas)
106
Describe thyroid gland morphologically
3 parts: right lateral lobe
isthmus
left lateral lobe
fibrous capsule and septa, creating lobules
107
What does the thyroid gland contain?
thyroid follicles surrounded by follicular cells
108
Describe the epithelium of follicular cells and where they are in the thyroid gland
follicular cells surrounding thyroid follicles in thyroid gland
follicular cells are simple squamous to low columnar
109
What are thyroid follicles responsible for?
production of thyroid hormones
110
What are the two thyroid hormones?
1. Thryoxine (tetra-iodothyronine or t4) - 4 atoms of iodone
| 2. Tri-iodothyronine (t3) - 3 atoms of iodone
111
What are t3 and t4 important for?
growth, cell differentiation, control of basal metabolic rate and oxygen consumption of body cells
112
What are thyroid follicles filled with?
Colloid
which is gel-like mass predominantly composed of thyroglobulin
(thyroglobulin large iodinated glycoprotein which is teh inactive form of thyroid hormones)
113
What is thyroglobulin? Where is it located?
thyroglobulin = large iodinated glycoprotein; inactive form of thyroid hormone
thyroglobulin makes up the most of colloid which is found within thyroid follicles
114
How does thyrglobulin become thyroid hormones?
reminder: thyrglobulin is inactive form of thyroid hormone
when thyroid hormones need to be released, thyrglobulin is brough back into the follicular cells, modified, and released as thyroid hormones into fenestrated blood capillaries that surround follicles
115
What is TGB?
thyroglobulin
116
What are parafollicular cells? AKA ____
Aka C clls
may be part of follicular epithelium between follicles of thyroid gland
117
Where are C cells found?
C cells aka parafollicular cells
found between follicles of the thyroid gland
118
How do C cells compare to follicular cells in a histo slide?
C cells are larger and paler staining than follicular cells
119
What do C cells produce?
Calcitonin hormone
120
Calcitonin
| What releases it? What is it's impact?
C cells (parafollicular cells) of thyroid gland release calcitonin (CT)
CT decreases level of calcium in blood by encouraging calcium salts to be deposited in bone matrix (building of bone) and inhibits action of osteoclasts (cells that normally resorb or breakdown bone's extracellular matrix)
121
How is CT secretion regulated?
negative feedbcak systems control calcitonin secretion
high blood Ca levels stimulate secretion of CT
low blood Ca levels inhibit secretion of CT
122
How many parathyroid glands does a person half?
typically 4 (2 on each side)
Can have anywhere from 2-6
123
What are the 2 cell types located in the parathyroid gland?
1. Chief cells
| 2. Oxyphil Cells
124
Chief cells of parathyroid gland
- What do they produce?
- Describe their morphology, staining, etc.
Produce PTH (parathyroid hormone)
most numerous cell; small cell; round central nucleus; pale staining; slightly acidophilic cytoplasm
125
Oxyphil cells of the parathyroid gland
- What do they produce?
- Describe their morphology, staining, etc
Produce: unknown. Entire function unknown.
Larger cell; VERY acidophilic cytoplasm; more common with age; unknown function
126
What is the impact of PTH? What secretes PTH?
PTH = Parathyroid hormone secreted by chief cells of parathyroid gland
Impact: increases level of calcium in blood stimulation of osteoclasts to resorb bone which releases Ca into blood
also acts on kidneys to slow rate of Ca loss from blood into urine
127
What synthesizes oxytocin?
paraventricular nucleus
128
What synthesizes ADH?
ADH - vassopressin
supraoptic nucleus
129
What does supraoptic nucleus synthesize?
ADH/vasopressin
130
What does paraventricular nucleus synthesize?
oxytocin
