endocrine system- functional anatomy and physiology Flashcards
1
Q
what does the major endocrine system consist of?
A
The major endocrine system consists of the pituitary gland, thyroid, parathyroid, adrenal glands, pancreas, ovary and testes.
2
Q
define hormone
A
to excite
3
Q
define endocrine
A
(within/separate) glands ‘pour’ secretions into blood stream (thyroid, adrenal, beta cells of pancreas)
4
Q
define exocrine
A
outside) – glands ‘pour’ secretions through a duct to site of action (pancreas - amylase, lipase)
5
Q
what are the three types of hormone action?
A
endocrine
paracrine
autocrine
6
Q
describe endocrine hormone action
A
blood-borne, acting at distant sites
7
Q
describe paracrine hormone action
A
acting on adjacent cells
8
Q
describe autocrine hormone action
A
feedback on same cell that secreted hormone
9
Q
describe the structure of peptides
A
-Vary in length – TRH: 3 amino acids, Gonadotrophins: 180 amino acids
-Linear or ring structures
-Two chains and may bind to carbohydrates e.g LH,FSH
10
Q
where are peptides stored?
A
Stored in secretory granules, hydrophilic, water soluble
11
Q
how are peptides released?
A
Released in pulses or bursts
12
Q
how are peptides cleared?
A
Cleared by tissue or circulating enzymes
13
Q
how are water soluble hormones transported?
A
unbound
14
Q
how are fat soluble hormones transported?
A
protein- bound
15
Q
describe cell interaction with water soluble hormones
A
bind to surface receptor
16
Q
describe cell interaction with fat soluble hormones
A
diffuse into cell
17
Q
describe half life on water soluble hormones
A
short
18
Q
describe half life on fat soluble hormones
A
long
19
Q
describe clearance of water soluble hormones
A
fast
20
Q
describe clearance of fat soluble hormones
A
slow
21
Q
name some water soluble hormone examples
A
peptides
monoamines
22
Q
name some fat soluble hormone examples
A
Thyroid hormone, steroids
23
Q
where are steroids stored
A
synthesised on demand
24
Q
where are peptides/monoamines stored?
A
in vesicles
25
describe the synthesis stage of making peptide hormones
Synthesis: preprohormone -> prohormone
26
describe the packaging stage of making peptide hormones
Packaging: prohormone -> hormone
27
how are peptides stored and secreted as?
hormone
28
what are the steps of making a peptide hormone?
1. synthesis
2. packaging
4. storage
4. secretion
29
what do peptide hormones do?
-Surface receptor and secondary messenger activation
- Insulin receptor
30
what secretes amine?
medulla
31
what is the rate limiting step of amines?
the conversion to l-DOPA
32
describe amines
water soluble, stored in secretory granules, release pulsatile, rapid clearance,
33
what do amines bind to?
Bind to alpha and beta receptors or D1 and D2
34
when amines bind to alpha receptors what can occur?
vasoconstriction, dilated pupil, alertness, contraction of stomach, bowel, anal sphincter
35
when amines bind to beta receptors what can occur?
vasodilatation, increased heart rate, bronchial and visceral smooth muscle relaxation
36
what are amines used for ?
Adrenoceptor Activation and Secondary Messengers
Stimulate the sympathetic nervous system – fight-or-flight response
37
describe the solubility of thyroid hormones
Thyroid hormones are not water soluble; 99% is protein bound
38
describe the secretion of thyroid hormones
Only 20% of T3 in the circulation is secreted directly by thyroid
39
what do secretory cells do- thyroid hormones?
Secretory cells release thyroglobulin into colloid – acts as base for thyroid hormone synthesis
40
what done adding iodine to tyrosine do?
form iodothyrosines
41
how do you form iodothyrosines
Incorporation of iodine on tyrosine molecules
42
what does coagulation of iodothyrosines do?
gives rise to T3 and T4 and stored in colloid bound to thyroglobulin
43
what does TSH stimulate?
stimulates the movement of colloid into secretory cell, T4 and T3 cleaved from thyroglobulin
44
what makes up a follicle?
Secretory cells and colloid make up follicle
45
what are the 3 hormone receptor locations?
1. cell membranes- peptide
2. cytoplasm - steroid
3. nucleus - thyroid
46
describe the nuclear receptor family
oestrogen
thyroid hormone
vitamin d
47
describe the steroid receptor family
- glucocorticoids- cortisol
-mineralocorticoids- aldosterone
-androgens- testosterone
- progesterone
48
what are the steps of synthesis of thryoxine T4 and T3
49
What is an advantage of cell membrane receptor?
– cell selectivity
50
describe the solubility of vitamin D
fat soluble
51
how does vitamin d enter the cell?
Enters cells directly to nucleus to stimulate mRNA production
52
how is vitamin d transported?
Transported by Vitamin D binding protein
53
describe the structure of
Adrenocortical and gonadal steroids
95% protein bound
54
what does Adrenocortical and gonadal do after entering cell?
After entering the cell, it passes to nucleus to induce response
55
what does Adrenocortical and gonadal bind to?
Bind to a cytoplasmic receptor
56
what is Adrenocortical and gonadal steroids altered for?
Altered to active metabolite
57
how is Adrenocortical and gonadal steroids inactivated?
- In liver by reduction and oxidation, or conjugation to glucoronide and sulphate groups
58
how do steroid hormones enter cell?
Steroid hormone diffuse through plasma membrane and binds to receptor
59
what enters the nucleus with steroid hormones?
Receptor-hormone complex enters nucleus
60
what binds to GRE in steroid action?
Receptor-hormone complex binds to GRE
61
what does binding initiate in steroid action?
Binding initiates transcription of gene to mRNA
62
what directs protein synthesis?
mRNA directs protein synthesis
63
describe the steps of steroid action
Steroid hormone diffuse through plasma membrane and binds to receptor
Receptor-hormone complex enters nucleus
Receptor-hormone complex binds to GRE
Binding initiates transcription of gene to mRNA
mRNA directs protein synthesis
64
how are hormones secreted?
Basal secretion – continuously or pulsatile
65
what are inhibiting factors for hormone release?
dopamine inhibiting prolactin, sum of positive and negative effects (GHRH and somatostatin on GH)
66
what 5 things control hormone action?
1. hormone metabolism
2, hormone receptor induction
3. hormone receptor down regulation
4. synergism
5. antagonism
67
how does hormone metabolism control hormone action?
increased metabolism to reduce function
68
how does hormone receptor induction control hormone action?
– induction of LH receptors by FSH in follicle
69
how does hormone receptor down regulation control hormone action?
hormone secreted in large quantities cause down regulation of its target receptors
70
how does synergism control hormone action?
combined effects of two hormones amplified (glucagon with epinephrine)
71
how does antagonism control hormone action?
one hormone opposes other hormone (glucagon antagonizes insulin)
72
go over pirtuitary anatomy
73
what do hypothalamic neurone do
synthesize oxytocin or ADH.
74
where are oxytocin and ADH transported?
transported down the axons of the hypothalamic-hypophyseal tract to the posterior pituitary.
75
where are oxytocin and ADH stored?
in axon terminals in posterior pituitary.
76
when hypothalamic neurones are activate what happens?
activated, hormones released.
77
Control of vasopressin release and it’s actions
78
what does oxytocin do?
stimulates mammary glands
and labour contractions
79
what hormones are released by the anterior pituitary?
TSH- thyroid- thyrotrophs
ACTH- adrenal cortex- corticotrophs
FSH and LH- testes or ovaries- gonadotrophs
GH- entire Body- somatorophs
Prolactin- Mammary glands- lactotrophs
80
name some examples of pituitary dysfunction
Tumour mass effects
Hormone excess
Hormone deficiency
81
what test would you do if you had pituitary dysfunction?
Investigations
Hormonal tests
If hormonal tests
abnormal or tumour
mass effects perform
MRI pituitary
82
describe the hypothalamic-pituitary-thyroid axis
Hypothalamus -> TRH -> anterior pituitary -> TSH -> thyroid gland -> thyroid hormones
83
describe the function of thyroid hormone
* Accelerates food metabolism
* Increases protein synthesis
- Stimulation of carbohydrate metabolism
*Enhances fat metabolism
- Increase in ventilation rate
- Increase in cardiac output and heart rate
* Brain development during foetal life and postnatal development
*Growth rate accelerated
84
what is the half life of t4?
5 to 7 days
85
what is the half life of t3
1 day
86
what does the adrenal cortex produce?
steroid hormones
87
what does Renin-Angiotensin System do?
decrease blood volume and/ or blood pressure
increase potassium in blood
or vice versa
88
name the three types of steroid hormones?
Mineralocorticoids e.g. aldosterone
Glucocorticoids e.g. cortisol androgens
Androgens e.g. androstenedione and DHEA
89
what does the adrenal medulla produce?
epinephrine
norephinephrine
90
what is the short term response in stress with adrenal hormones?
* Heart rate increases
* Blood pressure increases
* Bronchioles dilate
* Liver converts glycogen to glucose and releases
glucose to blood
* Blood flow changes, reducing digestive system activity
and urine output
* Metabolic rate increases
91
what is the long term response in stress with adrenal hormones?
Kidneys retain
* Proteins and fats converted
sodium and water
to glucose or broken down
* Blood volume and
for energy
blood pressure
* Blood glucose increases
rise
Immune system
supressed
