Endocrinology Flashcards
(130 cards)
1
Q
7 hormone facts
A
More than one produced in one endocrine gland
More then one tissue secrets the same hormone
More than one target cell type for a signal hormone
A single target cell can be influenced by more than one hormone
Secretion varies over time and will be effected by changes in the environment
Hormones can be blood borne or neuronally driven
Some hormones are excreted from tissues that have other functions
2
Q
Synthesis and secretion post translational modification of peptide hormones
A
1) peptide cleavage
2) glycosylation
3) phosphorylation
4) sulfation
5) amidation
6) acetylation
7) subunit aggregation
3
Q
Describe hormone release feedback control
A
This is predominantly negative
But can also be positive
Ie) output counteracts input and is frequently seen in the trophic hormones
4
Q
Hormone release neuroendocrine reflexes
A
Combination of neural and hormonal processes
Not the same as neuromodulation
5
Q
Hormone release rhythms
A
Release of hormones is entrained to environmental cycles which vary in interval length and duration
Melatonin secretion peaks at night
Cortisol secretion has two predominant phases
6
Q
Explain carrier proteins with hormone delivery
A
Carrier proteins can be general or specific to the hormone in question dictated by binding affinity
Specific carries - corticosteroid binding globulin to corticosteroids thyroid hormone binding globulin and transthyretin to thyroid hormones
General carrier - albumin
7
Q
Hormone activation
A
Metabolism of the precursor or release from the carrier protein will activate the hormone that will then have a half life in the blood
8
Q
The length of time for hormone half life follows the general pattern
A
1) single amino acid derivatives = minutes
2) peptide hormones = mins to hours
3) steroid hormones = hours
9
Q
Hormone inactivation
A
Enzyme degradation
Hormone receptor complex endocytosis
Conjugation
10
Q
Endocrine dysfunction types
A
Hyposecretion
Hypersecretion
Target cell
11
Q
Describe hyposecretion of endocrine dysfunction
A
Primary or secondary usually the result of atrophy of the endocrine gland and normally treated through replacement therapy
12
Q
Describe hypersecretion of endocrine dysfunction
A
Primary or secondary usually the result of a benign tumour (adenoma) normally treated through inhibition or removal
13
Q
Describe target cell endocrine dysfunction
A
Lack of receptors or biomechanics machinery at the target cell
Ie) hyperinsulinemia
Target cell responsiveness is also altered naturally
14
Q
Response at target cell
A
Up and down regulation
Permissiveness
Synergism
Antagonism
15
Q
Up and down regulation response at target cells
A
Receptors at the target cell are themselves regulated in response to hormone levels influencing abundance and affinity
16
Q
Measurement of binding kinetics for hormone/receptor complexes relies heavily on the
A
Chemical law of mass action
17
Q
Do all hormone receptor complexes adhere to the law of mass action
A
Non-cooperative = law of mass action is upheld
Positively cooperative = ligand binding increases receptor affinity of vacant receptors
Negatively cooperative = ligand binding decreases receptor affinity of vacant receptors
18
Q
Permissiveness response at target cell
A
One hormone cannot fully exert its effect without the other being present
19
Q
Synergism response at target cell
A
The combined effect is greater then the sum of the parts
20
Q
Antagonism response at target cells
A
The actions of one hormone reduces the effectiveness of the second can be direct or indirect
21
Q
What are the two types of hormone receptors
A
Membrane bound
Nuclear receptors
22
Q
Membrane bound hormone receptors
A
Ligand gated
Enzyme linked
Guanylyl cyclase and G protein linked receptors
Second messenger system includes
- adenylate cyclase
- guanylate cyclase
- inositol phosphate and diacyl glycerol
23
Q
Nuclear receptors
A
Most lipophilic hormones act through nuclear receptors and many genes will have responsive elements
24
Q
Nomenclature of
Anterior pituitary
Posterior pituitary
A
Pars distalis
Adenohypophysis
Pars nervosa
Neurohypophysis
25
The hypothalamus and posterior pituitary form a
neuroendocine system with cell bodies based in the hypothalamus
26
Posterior pituitary hormones are synthesized in the
Hypothalamus
27
Cell bodies then extend down the ___ and terminate in the ____
Infundibulum and terminate in the posterior pituitary
28
Describe neurohypophysial peptides
Two nonapeptides = OT and AVP
Precursor peptides produced in the hypothalamus - neurophysins
Closely related but one can work within the other
29
AVP and OT neurophysins + proteolytic enzymes are packages in ___ and begun to migrate down the axon to the ___ where the nerve terminals are located
Secretory Granules
| Neurohypophysis
30
Vasopressin, arginine vasopressin, and antidiuretic hormone release and action
Release
- reduced ECFV which increases plasma osmolaitiy which increases osmorecpetor activity which increases vasopressin release
Action
- increases h2o reabsorption in renal tubules
- vasoconstriction of vascular smooth muscles
31
Oxytocin release and action
Release
- birth canal distension increases oxytocin release
- infant suckling increases oxytocin release
Action
- increases utrine muscle contraction during parturition
- increases milk ejection from breast
32
Describe behavioural aspects of OT
Increases maternal behaviour in rats but estrogens need to be present
Plasma OT levels increase during sexual arousal in both sexes
Act as neuromodulators in the brain to influence social recognition memory and affiliative behaviours such as paid bonding
33
Describe behavioural aspects of AVP
Stimulates release of ACTH that is synergistic with CRH
Seems to play a greater role in males rather then females in regard to social recognition and consolidation of social memory
Aggression courtship scent marking and learning
34
Adenohypophysial cells
Histological and cytological methods have provided definitive evidence on the cellular source for each hormone release from the adenohypophysis
35
Hypothalamic anterior pituitary axis
Hormones synthesized and release from the anterior pituitary are under control of the hypophysiotropic hormones that can be stimulatory or inhibitory
36
What are the hormones of the glycoprotein family
Follicle stimulating hormone
Leutinizing hormone
Thyroid stimulating hormone
Human chorionic gonadotropin
Each has a A and B subunit the amino acid sequence of the A subunit is similar but the B subunit varies
37
Explain pars intermedia
Many animals have an anatomically separate pars intermedia
The predominant endocrine product is alphaMSH
In humans this is also the case during development
As adults these cells are not anatomically distinct but still synthesize and secrete aMSH
38
Normal growth means
1) Protein, Fat, Cartilage synthesis
2) cell proliferation
3) bone lengthening
39
Normal growth is influenced by
1) generic resolve
2) diet and nutrient transfer
3) disease and stress
4) multiple layers of hormonal control
40
Growth rate
GH levels increase during puberty
In makes testicular androgens are v. Important and increase dramatically during puberty
Adrenal androgens also increase and may be more important in females
Testosterone and estrogen both ultimately put brakes on
41
Growth hormone (GH) production and inhibition
Production stimulated by GHRH
Inhibited by GHIH
42
What is the most abundant adenohypophysial hormone
Growth hormone
43
Spontaneous secretion of GH over a 24 hour period usually peaks when
In the first 90 mins of sleep
44
The somatomedin hypothesis
Growth hormone does not have a direct effect on growth of any given tissue but rather acts indirectly through somatomedins
45
Somatomedins hypothesis
| There are two main somatomedins
Insulin like growth factors 1 and 2
They are 70 and 67 amino acids respectively and share many similarities with insulin
IgF 2 is more abundant in adults
46
Circulating levels of IGF 1 increase massively during ___ but ____ increases moderately by comparison
Pubertal growth spurt
GH
47
The __ is the mature bone shaft with the ___ at either end
Diaphysis
Epiphysis
48
In a growing bone the ___ is separated from the ___ by the ___
Epiphysial
Diaphysis
Epiphysial plate
49
___ produce enzymes collagen and proteins to provide framework for hydroxyapatite crystals. They deposit new bone on the outer edges of old bone to increase width
Osteoblasts
50
Osteoblasts will ultimately turn into mature bone cells ___
Osteocytes
51
Bone length grow is regulated by cartilage cells ___ located in the epiphyseal plates
Chondrocytes
52
Thyroid hormones are
Involved in energy homeostasis
Hypothyroidism = reduced growth TH is largely permissive
53
Insulin is involved in
Carbohydrate metabolism
Deficiency can block growth and excess can promote growth potential cross reactivity with IGF receptors
54
Androgens and estrogens arrest
Long bone length increase by closure of the epiphyseal plate
55
Prolactin belongs to the ___ family and influenced
GH
Mammary gland growth as well as aspects of the immune system
56
Placental lactogen belongs to the __ family and influences
GH
Neonatal development maternal glucose and amino acid supply
Peaks around mid pregnancy until full term
57
Neurotrophic factors are
Nerve growth factors
58
Erythropoietin are
Red blood cell growth factor
59
Platelet derived growth factors are
Vascular injury repair but also involved in the development of artherosclerosis
60
Epidermal growth factors enhanced proliferation of
Epidermis
Gut lining
Pulmonary lining
61
Tumour derived growth factors angiogenesis
Fibroblast growth factors
| Transforming growth factors
62
Why regulate calcium
Calcium is perhaps the most tightly regulated ion in circulation
- 99% of the bodies calcium is calcified structures
- 0.9% is intracellular
- 0.1% exists in the ECF half is bound to proteins or negatively charged ions and the rest is free from Ca2
Cell-cell integrity of tight junctions
Cofactor for clotting blood
Required for structural form of bone and teeth
63
Neuromuscular excitability
Reduced calcium leads to tetanic muscle contraction and high levels lead to reduced muscular contraction
64
Stimulus secretion coupling (calcium importance)
Many cells willl require calcium to enter the cell to stimulate the secretion of a given substance
65
Regulation of calcium ____ impacts phosphate concentrations
ALWAYS
66
Bone remodelling requires deposition and resorption using
Osteocytes =
Osteoblasts =
Osteoblasts =
Osteocytes = mature bone cells
Osteoblasts = bone builders responsible for depositing the collagen matrix
Osteoclasts = bone breakers
67
Hormones involved in calcium regulation
Parathyroid hormone
Vitamin D3
Calcitonin
68
Describe parathyroid hormone
Negative relationship between plasma concentration and plasma (Ca2) that is extremely sensitive
69
Vitamin D3 (cholecalciferol) describe
Needs to be converted to 1,25-OH2)-vitamin D3 (calcritol)
70
Calcitonin is
The only hyocalcaemic hormone
71
Parathyroid hormone and bone
1) fast homeostatic regulation of Ca from bone fluid space
| 2) slower balancing of total body calcium from resorptive processes
72
What does parathyroid hormone do for the kidneys
PTH increases and decreases phosphate reabsorption
73
What does parathyroid hormone do for the intestine
Actions are indirect through stimulation of vitamin D3 production
74
Why is vitamin D considered a hormone
Because it can be produced in the skin from 7-dehydrocholesterol
75
Two important enzymatic steps that involve the sequential addition of hydroxyl groups
1) activation of 1alpha hydroxylase is the most important step and this enzyme is regulated by PTH
76
Target sites for vitamin D3
The gut is the best documented area of vitamin D3 action
Where both fast and slow components are initiated
77
Explain calcitonin
Not involved in day to day regulation but may be involved during the absorptive state and also during pregnancy
Calcitonin has both hypocalccaemic and hypophosphatemic effects
78
For the most part bone resorption and bone disposition balance each other out but
There are times when this is not the case
79
Osteoblasts are derived from ____
Osteoclasts are derived from___
Stromal cells in the bone marrow
Macrophages in the bone marrow
80
Osteoblasts and its precursor cells produce two main messengers __
RANKL (receptor activator of NFkB ligand)
Osteoprotegerin
81
Estradiol stimulates the production of
Osteoprotegerin
82
Osteoporosis is
Reduced bone mineral density
Prevalent in pre and post menopausal woman
Onset of osteoporosis and about 1% of bone mass is lost every year
83
Osteoporosis therapy
Exercise
Ca supplements
HRT
Calcitonin
SERMS and ANGELS
84
Tetraiodothyronine (T4) and triiodothyronine (T3) are both derived from _____ and synthesized in the ___ of the thyroid gland
Thyroglogulin
Follicular cells and the colloid of the thyroid gland
85
T4 and T3 are collectively referred to as the ___ hormones and are involved in the regulation of ____ and are key during ___
Thyroid hormones
Regulation of metabolic rate
Key during development
86
What are thyroid hormones basic ingredients
The amino acid tyrosine and the element iodine
Tyrosine can be made in the body whereas iodine is an essential component of our diet
87
Thyroid hormone deiodination
Deiodinases can have a strong preference for specific THs
Type 1 has a strong preference for reverse T3
Type 2 deiodinates only the outer ring
Type 3 deiodinates only the inner ring
These enzymes can be tissue specific
88
Actions of thyroid hormone
Calorigenic
TH is the most important regulator of basal metabolic rate
89
Actions of thyroid hormone
Sympathomimetic effect
Action is similar to the sympathetic nervous system
Increases target response to catecholamines
90
Actions of thyroid hormones
Cardiovascular
Largely as a result of the increase in catecholamine receptors and calorigenic effects
91
Actions of thyroid hormones
growth
Synergistic actions with both GH and IGFs
TH is essential for normal growth and neural development
92
Thyroid hormone abnormalities
This is one of the most common endocrine disorders and is very prevalent in young adult women
Includes both hypothyroidism and hyperthyroidism either of which are characterized by goiter
93
Goiter is
An over stimulation of the thyroid gland and not necessarily related to the capacity of the gland to synthesize and release TH
94
Exophthalmos is a thyroid hormone abnormality that is
A common feature of Graves' disease which is an autoimmune disease
95
Melatonin is
The primary hormone released from the pineal gland and is synthesized from the amino acid tryptophan
96
Melatonin is synthesized and released in a rhythmical fashion that is closely related to ____
Circadian rhythms
Scotophase = dark
Photophase = light
97
Darkness is a universal stimulus for the synthesis and release of ___ from the ___ suggesting a strong link between the pineal and the optic tract
Melatonin
Pineal gland
98
The melatonin link comes in the form of the _____ which is our major biological clock
Suprachiasmatic nucleus (SCN)
99
Our major biological clock is where the ____
Interaction between PER genes and CLOCK proteins cycle at a remarkably constant rate that shifts depending on light cues
100
Melatonin release peaks in humans usually __
In the middle of the night
101
___ involved in melatonin synthesis also follows a rhythm
Enzymes
102
___ follows cycles so there is a link between melatonin and ____ hormones and ___
Reproduction
Sex
Reproduction
103
Adrenal hormones
Mineralocorticoids
Glucocorticoids
Sex hormones
Epinephrine
Norepinephrine
104
What are the adrenal steroids released from the adrenal cortex
Mineralocorticoids = aldosterone
Glucocorticoids = cortisol
Sex hormones = dehydroepiandrosterone and androstenedione (androgens) and estrogens
105
Catecholamines released from the adrenal medulla
Epinephrine - about 80%
Norepinephrine - about 20%
106
Cholesterol as a precursor three main parent molecules
C21- pregnane
C19- androstane
C18- estrane
107
Mineralocorticoids:
Aldosterone acts on distal and collecting tubules of the ____ in the ___
Nephron
Kidney
108
Mineralocorticoids regulates ____ which has implications on the ___ and the ___ systems
Body fluid volume
Renal
Cardiovascular
109
Mineralocorticoids steroid is essential for life it promotes ___ retention and ___ excretion in the kidney
Na
K
110
Secretion of mineralocorticoids is regulated by the ____ system and also directly by circulating __ concentrations
Renin angiotensin system
K
111
Aldosterone regulation is largely independent of the ___
Pituitary gland
112
Hyperaldosteronism can be either ___ or ___ symptoms present as hypernatremia hypokalemia and usually hypertension
Primary (Conns syndrome)
Secondary
113
The adrenal gland produces small amounts of both male and female sex steroids as ____ in an ____
DHEA
Adrenal androgen
114
Why are estrogens considered female sec steroids and androgens considered male sex steroids
In males testosterone overpowers the actions of DHEA however as females otherwise lack androgens DHEA plays a role in the pubertal growth spurt hair growth and the female sex drive
115
Adrenogenital syndrome
Symptoms are dependent on sex and age of hyperactivity onset
Adult females - masculinity, fascial hair deepening of voice ect.
Newborn females - pseudohermaphroditism
Adult males - no effect
Pubertal males - precocious pseudopuberty
116
Glucocorticoids direct actions
Stimulates gluconeogenesis
- generation of glucose from non carbohydrate substrates (amino acids pyruvates and glycerol)
Inhibits glucose uptake by many peripheral tissues
Stimulates protein degradation in muscle
Stimulates lipolysis mobilising fatty acids as an alternative energy source
117
Glucocorticoids permissive actions
Vascular collapse during stressful events in the absence of glucocorticoids
118
Glucocorticoids anti-inflammatory and immunosuppressive
This anti inflammatory effects are seen following administration of supra physiologic or pharmacologic levels
Prevention of leucocytes infiltration into the wound site
Atrophy of lymphatic system
119
Cortisol hyper/hypo secretion issues
Cushing's syndrome (hyper)
Addison's disease (hypo)
120
Cushing's syndrome
Hypersecretion
Increased amounts of CRH or ACTH
Adrenal tumours
Ectopic ACTH release
Symptoms
- excess glucose, fat deposition in the face and abdomen thin legs and arms and facial hair excess
121
Addison's disease
Hyposecretion
General name for bilateral damage to the adrenals
Can also be primary or secondary in nature
Symptoms
- increased integument pigmentation, weakness, weight loss, hypotension, salt craving and hypoglycaemia
122
General adaptation to stress
1) primary alarm response
2) secondary resistance response
3) tertiary exhaustion response
123
Describe primary alarm response for the adaptation to stress
Catecholamine surge into the system
Increase BMR
Increase Blood flow to required organs
Hepatic glycogenolysis
124
Secondary resistance response to Stress
Described actions of cortisol on metabolism
Continued mobilisation of glucose for central organs
Continued breakdown of alternative energy stores (lipids and proteins)
125
Tertiary exhaustion response to stress
Muscle wasting, hyperglycaemia (diabetes)
Atrophy of the immune system gastric ulcers
Vascular derangements
126
The adrenal medulla essentially acts as an extension of the ____
Sympathetic nervous system
127
Catecholamine release from the adrenal medulla is largely under the control of the ___
SNS
128
Both catecholamines are stored in ____
Chromaffin granules
129
Epinephrine and norepinephrine are both the active Ligands in the ____ system and they will bind to one of the 4 ____ receptors (which are)
Adrenergic system
Adrenergic receptors
Alpha 1,2 beta 1,2
130
Describe epinephrine
Rapid mobilisation of the bodies energy reserves
Increase cardiac output and total peripheral resistance
Increase coronary and skeletal muscle arteriolar dilation
Reduce gut motility
Increases glycogenolysis in liver and muscle
Increased CNS alertness
Dilates pupils and flattens theblens
Increases sweating
