Comparative Anatomy and Microanatomy of the Endocrine Glands Flashcards
1
Q
What do endocrine organs do?
A
preserve homeostasis
they also secrete hormones directly to blood/lymph/tissue fluid
2
Q
Describe a characteristic of endocrine organs?
A
they are ductless organs
3
Q
neurohormonal system?
A
endocrine and nervous system are integrated
4
Q
where are endocrine organs derived from?
A
from the 3 germ layers
5
Q
where is the hypothalamus located in the brain?
A
at the ventral part of the brain
6
Q
what does the hypothalamus do?
A
it is the regulator of the endocrine and nervous system - maintains homeostasis
7
Q
what bodily functions does the hypothalamus regulate?
A
temp, thirst, hunger, sexual behaviour, blood volume etc. maintain homeostasis
8
Q
what does the hypothalamus coordinate?
A
coordinates the activity of the pituitary gland through the secretion of peptides and amines
9
Q
what are the two types of hormones produced by endocrine glands?
A
releasing and inhibitory
10
Q
where is the pituitary gland integrated?
A
with the hypothalamus (structurally and functionally)
11
Q
pituitary gland location?
A
suspended below the hypothalamus by a narrow stalk (infundibular and hypophysial stalk)
12
Q
Where does the pituitary gland lie within?
A
within bony cavity called the hypophysial fossa (sella turcica) of the sphenoid bone
13
Q
shape and size of pituitary gland?
A
small, oval gland
14
Q
where in the brain is the pituitary gland located?
A
between rostrally optic chiasm and the caudally mammillary bodies
15
Q
what is the pituitary gland controlled by?
A
by CNS and feedback from target organs
16
Q
Adenohypophysis?
A
the anterior lobe of the pituitary gland
17
Q
Neurohypophysis?
A
the posterior lobe of the pituitary gland
18
Q
How many parts is the Adenohypophysis made up from?
A
3 (sometimes 2)
19
Q
How many parts is the Neurohypophysis made up from?
A
3
20
Q
How is the Rathke’s pouch developed
A
during embryonic development, the roof of the mouth bulges upwards (invaginates) to form, structure known as Rathke’s pouch
21
Q
What is the Rathke’s pouch?
A
It is an ectodermal outpouching of the stomodeum - it is also known as the hypophyseal
22
Q
when does the Rathke’s pouch normally close?
A
normally closes in fetal development
23
Q
Acidophils?
A
cells that contain the polypeptide hormones - will stain red or organe
24
Q
Basophils?
A
cells that contain the glycoprotein hormones - will stain bluish colour
25
Chromophobes - cytoplasms?
have a cytoplasm that stains really poorly
26
what is the adenohypophysis (pars intermedia) closely associated with?
with pars nervosa
27
Describe the capillaries in the adenohypophysis - pars tuberalis?
they are fenestrated, to enable passage of hormones from the secretory cells into the bloodstream
28
what do the cells of the pars tuberalis form?
cells form folding sheets (folds) and occasional cysts
29
Describe the lumen of the Neurohypophysis?
has a lumen, that's continuous with the lumen of the brain's third ventricle
30
What does the production of peptides and amines - by the hypothalamus influence?
they influence the pituitary gland to produced tropic hormones
31
Give an example of how the production of peptides and amines - by the hypothalamus influence?
corticotropin which in turn influences the production of cortisol by peripheral target tissues
32
trope?
because they turn on endocrine glands or support
33
Where are neurohormones from the hypothalamus released to?
to the hypothalamic-pituitary portal system
34
what do neurohormones bind to?
bind to receptors on endocrine cells
35
what does the hypophysial portal system regulate?
regulate their hormonal secretion (releasing or inhibiting)
36
what two hormones does the hypothalamic - hypophysial tract secrete?
ADH and oxytocin
37
What happens to the hormones secreted by hypothalamic - hypophysial tract?
they are placed in vesicles and transported and stored - each terminal stores either vasopressin or oxytocin
38
pineal gland aka?
epiphysis cerebri
39
what cells does the pineal gland contain and what are these cells responsible for?
contain pinealocytes
astrocytes
responsible for secreting melatonin
40
how are pinealocytes arranged?
arranged like cords, follicles
41
what are corpora arenacea?
AKA - brain sand
human pineal gland contains characteristic, extracellular concretions called corpora arenacea
42
melatonin important for?
for regulating biological rhythms e.g. circadian rhythms and season effects on breeding, sleep etc. innate immune response
43
where is the master biological clock that serves as the pacemaker for circadian rhythms?
located in the hypothalamic suprachiasmatic nucleus
44
what does the rhythm of the hypothalamic suprachiasmatic nucleus control?
controls the rhythm of melatonin secretion by the pineal gland via a polysynaptic pathway
45
Describe the retiono-pineal pathway?
light enters retina
suprachiasmatic nuclei
paraventricular nuclei
intermediolateral cell column of the spinal cord
cervical ganglia
pineal gland
46
What are the central glyocytes?
support cells in CNS
47
what is the thyroid gland attached to?
attached to trachea on the right and left side just caudal to the cricoid cartilage
48
what tracheal rings does the thyroid gland span?
spanning the initial five to eight tracheal rings
49
what are the lobes of the thyroid gland connected by?
by an isthmus - in pigs they are fused
50
what is the thyroid gland derived from?
derived from pharyngeal endoderm
51
size of thyroid gland is variable depending on what?
depending on heredity, environmental and nutritional factors
52
location of thyroid gland varies with...
with species
53
what is each gland of the thyroid gland embedded in?
in deep cervical fascia and divided into lobules
54
what do the lobules of the thyroid gland consist of?
they consist of many units called thyroid follicles
55
what is colloid made up of?
of a glycoprotein called thyroglobulin
56
what is colloid?
it is an inactive precursor of T3 and T4
57
adrenal cortex?
makes up 80% of organ
58
location of adrenal gland?
cranial-medial
59
what is the adrenal cortex derived from?
mesoderm
60
how many parts make up the adrenal cortex?
3
61
What are the three parts of the adrenal cortex?
the Zona Glomerulosa
the Zona Fasciculata
the Zona Reticularis
62
What is adrenal medula?
it is a modified sympathetic ganglion
63
What is the adrenal medulla innervated by?
innervated by preganglionic sympathetic nerves
64
what are the cells of the adrenal medulla?
the chromaffin cells
65
What are the two functionally and histologically distinct components of the pancreas?
exocrine and endocrine
66
what does the endocrine pancreatic tissue consist of?
small, discrete clusters of cells called islets of langerhans (pancreatic islets)
67
what percentage of cells in the pancreas is made up of pancreatic islets?
1%
68
pancreas endocrine activity is not controlled by...?
pituitary hormones
69
describe the gland of the pancreas?
lobulated and encapsulated
70
structure of adrenal gland?
outer --> inner
capsule, zona glomerulosa (closer to outside, closer to kidney), zona fasciculata, zona reticularis, medulla (inner and outer region)
71
what does the zona glomerulosa secrete?
secretes mineralocorticoids
72
what does the zona fasciculata secrete?
glucocorticoids
73
what does the zona reticularis secrete?
secretes sex steroids or androgens; oestrogens
74
what hormones does the adrenal cortex produce?
adrenocorticoid hormones
75
how many regions of the adrenal cortex are there?
three distinct regions
76
what is the adrenal gland?
paired glands located craniomedially to the kidneys
77
what surrounds the adrenal gland?
a capsule
78
how is the adrenal gland organised?
into peripheral cortex and central medulla
79
Which artery/vein passes over the adrenal gland?
phrenicoabdominal a.&v.
80
what % of the adrenal gland is the 'cortex'?
80%
81
what is the parathyroid gland composed of?
it is composed of densely arranged cords of chief cells surrounded by a thin fibrous capsule
82
is the parathyroid gland paired?
usually there are two pairs (external and internal)
83
location of parathyroid gland?
they could be superficial or embedded to the thyroid gland
84
size of parathyroid gland?
only a few mm in diameter
85
location of parathyroid gland varies with what?
varies with species
86
what cell is responsible for synthesising, storing and secreting the parathyroid hormone?
chief cells of the parathyroid gland
87
what are chief cells also known as?
also called parathyroid or principal cells
88
what is the blood supply of the thyroid gland?
common carotid artery-thyroid artery
89
the right thyroid gland is close to what?
right gland is close to the common carotid artery, internal jugular vein, vagosympathetic trunk and tracheal duct
90
which nerve fibres does the thyroid gland receive?
both sympathetic and parasympathetic fibres
91
where are the sympathetic nerve fibres that the thyroid gland receives routed through?
routed through the cranial cervical ganglia
92
where are the parasympathetic nerve fibres that the thyroid gland receives routed through?
through the laryngeal branches of the vagus nerve
93
what two important nerves are close by to the thyroid gland?
the cranial and caudal laryngeal nerves
94
what are the follicles of the thyroid gland filled with?
filled with viscous protein rich fluid colloid
95
what are thyroid hormones synthesised in?
in colloid
96
what is colloid?
a substance that serves as an extracellular storage site
97
what cells are found within the walls of the thyroid follicles?
small Parafollicular cells
98
possible shaped of follicular cells?
follicular cells can be columnar, cuboidal, or squamous depending on their synthetic activity
99
what do follicle cells surround in the thyroid gland?
surround follicle cavity (which holds viscous colloid)
100
the follicular cells of the thyroid gland are the derivatives of what?
derivatives of the endoderm
101
what do the follicular cells of the thyroid gland secrete?
they secrete thyroid hormone
102
what do the lobules (that make up the thyroid gland) consist of?
many units called thyroid follicles
103
What is a vestigial eye?
many fish and amphibians have a median pineal eye and/or parietal/third eye
This is the pineal gland - it takes in information about light
104
in lower vertebrates, the pineal gland is sensitive to what?
it is directly photosensitive
105
pineal gland AKA?
Epiphysis cerebri
106
what is the pineal gland and where is it located?
part of the epithalamus and is located mid-brain
107
describe size and shape of pineal gland?
small organ and shaped like a pinecone
108
where is the pineal gland attached?
attached to the caudal end of the roof of the third ventricle directly before the rostral colliculi
109
which gland is the only gland to be directly influenced by the external environment via the retina?
the pineal gland
110
what hormone does the pineal gland secrete?
melatonin (derived from aa tryptophan)
111
how is neurohypophysis connected to hypothalamus?
by neural pathway
112
how is adenohypophysis connected to hypothalamus?
by vascular link
113
How does the neurohypophysis synthesise the hormones that it releases in to the blood?
releases the hormones into the blood that have been synthesised by the hypothalamus
114
How does the adenohypophysis synthesise the hormones that it releases in to the blood?
adenohypophysis itself synthesises the hormones that it releases into the blood
115
Why are the neurohormones of the neurohypophysis deposited directly into the capillaries?
because the neurohypophysis of the pituitary does not have a portal system
116
what does oxytocin do?
stimulates uterine contractions
117
What do ADH (anti-diuretic hormone) or Vasopressin do?
stimulates vasoconstriction and promotes fluid reabsorption by the kidneys; constricts vessels to raise blood pressure (arterioles)
118
where are oxytocine, ADH and vasopressin synthesised and release?
synthesised in the hypothalamus but released into the bloodstream in the pars nervosa
119
the hypothalamic - hypophysial tract secretes two neurohormones, what are they and how are they transported/stored?
oxytocin and ADH
they are placed in vesicles and transported + stored in terminals
each terminal stores either vasopressin or oxytocin
120
how are oxytocin and ADH released into the capillary bed?
they are conveyed along axons and released into neurohypophyseal capillary bed
121
What happens in the hypophysial portal system? 1st stage
1 - Neurohormones from the hypothalamus are released to the Hypothalamic-pituitary portal system
122
What happens in the hypophysial portal system? 2nd stage
Neurohormones bind to receptors on endocrine cells
123
What happens in the hypophysial portal system? 3rd stage
Regulate their hormonal secretion (releasing or inhibiting)
124
What is the hypophysial portal system?
blood vessels in the brain that connects the hypothalamus with the adenohypophysis
125
Where does the hypophysial portal system begin?
at the base of the hypothalamus
126
what happens to the arterial blood reaching the hypothalamus from the hypophysial portal system?
it branches to capillaries
127
What happens in the hypophysial portal system after the arterial blood reaching the hypothalamus branches to capillaries?
here, the venous blood joins and makes the small portal vein that passes through, stalk into the adenohypophysis
128
What happens in the hypophysial portal system after the portal vein stalks into the adenohypophysis?
here, they branch to anterior capillaries which in turn drain into the venous system
129
what are tropic hormones produced by - (the ones secreted by the pituitary gland)?
they are produced by neurosecretory cells in the several hypothalamic nuclei
130
what are most tropic hormones produced and secreted by?
by the ANTERIOR pituitary gland
131
Name two of the hormones produced by adenohypophysis?
GH - growth hormone
FSH - follicle stimulating hormone
132
haematology appearance of pars nervosa?
the pinkest - with some purple dots
133
haematology appearance of Rathke's pouch?
white line
134
nuclei of the hypothalamus?
neuron cell bodies clustered in the hypothalamus
135
where does the nuclei of the hypothalamus send axons to?
to the neurohypophysis
136
central gliocytes?
support cells
137
central gliocytes aka?
pituicytes-neuroglial cells
138
oxytocin and ADH =
vasopressin
139
herring bodies?
secretory vesicles along the axons
140
neurohypophysis has no?
no neuron cell bodies
141
describe the myelination of the axons of the hypothalamic neurons?
unmyelinated
142
components of the neurohypophysis?
median eminence
infundibular stalk
pars nervosa
143
what is the infundibular stalk?
nerve tract
144
where is the median eminence?
base of the hypothalamus (this is a part of the neurohypophysis
145
what is the pars nervosa?
bulk of the neurohypophysis
146
what does the pars tuberalis part of the adenohypophysis do?
provides scaffold for the capillary network of the hypophyseal portal system
147
what is the pars intermedia?
a thin zone of basophilic cells
148
what is the primary function of the pars intermedia?
it is colour change regulation
- via melanotrophs ( a-melanocyte stimulating hormone) [a-MSH]
149
what three cells are found within pars distalis?
acidophils, basophils and chromophobes
150
what cells are classed as basophils in the pars distalis of the adenohypophysis?
Thyrotrophs
Gonadotrophs
Corticotrophs
151
What hormone does a thyrotroph secrete?
thyroid stimulating hormone (TSH)
152
What hormones does a Gonadotroph secrete?
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
153
What hormone does a Corticotroph secrete?
Adrenocorticotropic hormone (ACTH)
154
what cells are classed as acidophils in the pars distalis of the adenohypophysis?
somatotrophs
lactotrophs
155
what hormones does a somatotroph secrete?
growth hormone (GH)
somatotropin
156
what hormone does a lactotroph secrete?
prolactin (PRL)
157
meaning of rudimentary?
undeveloped
158
Describe the presence of pars intermedia (of the adenohypophysis) in humans and birds?
rudimentary in humans and lacking in birds
159
What parts make up the adenohypophysis?
3 parts
Pars distalis
Pars intermedia
Pars tuberalis
160
which part of the adenohypophysis forms the stalk?
the pars tuberalis
161
How many sections make up the pituitary gland?
5
162
What sections make up the pituitary gland?
Adenohypophysis
Pars intermedia
Neurohypophysis
Hypophysial stalk
Recess of third ventricle
163
How many parts make up the pituitary gland median section?
3
164
What are the parts that make up the pituitary gland median section?
Adenohypophysis
Pars intermedia
Neurohypophysis
165
Which is the anterior lobe of the pituitary gland and which is the posterior lobe of the pituitary gland?
Anterior lobe: adenohypophysis
Posterior lobe: Neurohypophysis
166
What is the neurohypophysis?
it is he bulging of the diencephalon floor resulting in the outgrowth of the brain
it consists on nervous tissue from the hypothalamus
167
Where is the neurohypophysis derived from?
neural ectoderm
168
where is the adenohypophysis derived from?
oral ectoderm
169
What is the adenohypophysis?
an outgrowth of the pharynx (root of mouth) and it is glandular (hence 'adeno')
170
What does the nuclei of the hypothalamus consist of?
clusters of neurons
171
what does the nuclei of the hypothalamus do?
it sends axons to the posterior pituitary
secretes releasing hormones to the anterior pituitary
and intergrades and regulates vital bodily functions
