Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gut, metabolism and hormones > Growth and thyroid hormone 3 > Flashcards

Growth and thyroid hormone 3 Flashcards

1
Q

Other factors apart from growth hormone influence growth - what are these 4?

A

Genetic determination, an adequate diet, freedom from chronic disease and stressful environment, normal levels of growth-influencing hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does genetic determination influence growth ?

A

Genetic determination: of an individuals growth capacity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How does an adequate diet influence growth ?

A

An adequate diet, including enough protein and ample amino acids to accomplish protein synthesis necessary for growth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does freedom from chronic disease and stressful environment influence growth ?

A

Stunted growth from stress induced secretion of cortisol –over a prolonged period of time.
- Cortisol can promote protein breakdown, inhibiting growth of long bones and block the secretion of GH.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How do normal levels of growth-influencing hormones influence growth ?

A

In addition to GH, other hormones including thyroid hormone, insulin and the sex hormones play secondary roles in promoting growth.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q
  1. What does pineal gland release?
  2. Thyroid gland?
  3. Parathyroid gland?
  4. Adrenal glands?
  5. Testes?
  6. Ovaries?
  7. Pancreas?
A
  1. Melatonin
  2. Thryoxine, triiodothyonine, calcitonin
  3. PTH
  4. Cortex - cortisol and alodesterone and Medulla - adrenaline and noradrenaline
  5. Testosterone
  6. Estrogen and progesterone
  7. Glucagon, insulin and somatostatin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What hormones come from the hypothalamus?

A

Releasing and inhibiting hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What comes from the anterior and posterior lobes of the pituitary gland?

A

Anterior lobe: ACTH, TSH, FSH, LH, Prolactin, growth hormone
Posterior lobe: ADH and oxytocin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Major regulators of growth:

A

Growth hormone and somatomedins (IGFs - insulin growth factors)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Other growth influencing hormones?

A

Oestrogens/Testosterone, Insulin, Thyroid hormones, Calcitonin, PTH and Vitamin D

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Other growth factors? 4

A

Epidermal Growth Factor - polypeptide with mitogenic activity
Platelet Derived Growth Factor - stimulates fibroblasts and glial cell growth
Nerve Growth Factor - neuronal survival and synaptic out-growth
Fibroblast Growth Factor - stimulates bone cell proliferation and collagen synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Another name for growth hormone?

A

Somatotropin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What kind of hormone is somatotropin?
Molecular weight approx?
How much made per day?
Encoded by what chromosome?

A

peptide hormone 191 amino acid
mol wt approx. 20 kDa
500µg made per day (circulating 0-30 ng/ml,
t1/2 ~20min)
GH is encoded on chromosome 17

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Is the release of growth hormone (GH) continuous, if so/not why?

A

Release of GH is not continuous
Different factors are responsible for growth at different periods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Does GH play a role in fetal growth, if not which hormones do?

A

Fetal growth is promoted by placenta hormones
GH plays no role in fetal growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the postnatal growth spurt?

A

First 2 years of life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

During puberty growth spurt which group of hormones from what glands promote growth in male and female?

A

Male: Androgens (testes) promote growth
Female: Androgens (adrenal glands, less potent) promote growth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What are the 2 periods of rapid growth in children?

A

a postnatal growth spurt up to the age of 2 and a pubertal growth spurt during adolescence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What time does puberty begin at and before puberty is there sex differences?

A

Before puberty little sex differences in height or weight. Puberty begins at age 11 in girls and age 13 in boys

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

During puberty GH and androgen secretion is elevated what does this promote?
What does this do for boys and girls and which hormones are mainly involved?

A

They promote protein synthesis and bone growth
Testosterone – promotes sharp increase in height in boys
In females androgens from the adrenal cortex most likely involved in female growth spurt. There is a rise in oestrogen secretion during puberty but the role this female sex hormone may play is unclear.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do testosterone and oestrogen both do on bone?

A

testosterone and oestrogen both act on bone to halt its further growth so that full height is attained at the end of adolescence.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

GH is released via a pulsed release - from what gland?
Higher levels during the day/sleep?
When is secretion stimulated?
Is there any rhythm to this?
When does GH release surge?

A

Gh is released from anterior pituitary in several bursts
It is high in the morning before awakening and low during the day
Secretion is stimulated during deep sleep
Rhythm linked to sleep-wake not light/dark
Surges in first 2 hrs of sleep at night

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

GH release - the number/magnitude pulses depend on age when is it high/low/absent?

A

high in puberty, low in adults, absent at 50yr+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

There is age-related decrease in GH release what changes occur?

A

change in muscle:fat ratio and decreased bone density

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

GH is often sold as “anti-ageing” therapy but what may it actually do?

A

May actually speed ageing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What controls GH and where is it made?

A

GHRH - Growth hormone releasing hormone and somatostatin made by hypothalamic neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What kind of receptor is GHRH?
What does GHRH stimulate?
What are GH bursts initiated by?
What terminates this?

A

GHRH receptor is a 7 transmembrane domain G-protein coupled receptor
GHRH stimulates GH synthesis and secretion
GH bursts initiated by bursting secretion of GHRH
Terminated by somatostatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Injection of GH into animals causes? 6

A

─ increases glucose levels in blood
─ promotes protein synthesis
─ promotes lipolysis in adipocytes
─ promotes bone growth
─ results in erythropoesis
─ has anti-insulin activity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Long term metabolic effects of GH - carbohydrates? protein synthesis? lipids? growth?

A

Carbohydrates - increases glucose levels in blood
Proteins Synthesis - increases tissue amino acid uptake
Lipids (Lipolysis) - increases free fatty acids in blood
Stimulates Growth - stimulates IGF production

30
Q

GH releases IGF1: Insulin growth factor how - what does it stimulate?
What does it act on?
What does this acting on cause?

A

GH stimulates liver production of somatomedins (insulin-like growth factor; IGF-1)
Acts on bone & soft tissues to promote growth
Stimulates protein synthesis, cell division (of chondrocytes), lengthening, thickening of bones

31
Q

What are the metabolic effects of GH releasing IGF1?

A

Increases fatty acid levels in blood (by breakdown of fat)
Increases blood glucose levels (by decrease of glucose uptake by muscles)

SEE SLIDE 13 DIAGRAM

32
Q

Are IGFs related to insulin?
What organ does GH stimulate to make IGFs?

A

Structurally released
The liver

33
Q

Does IGF stimulate bone and soft tissue growth?
If so/not what does this stimulation do

A

Yes
Hyperplasia: cell proliferation
Hypertrophy: increasing the size of cell

34
Q

Does IGF stimulate apoptosis?

A

No it prevents apoptosis

35
Q

Give an example of disease associated with GH and how IGF can help:

A

Mice genetically lacking GH are dwarfed
IGF can overcome GH defects

36
Q

What causes pituitary gigantism - what is it called in adults and children?

A

GH excess caused by tumour cells of anterior pituitary
─ in children gigantism
─ in adults acromegaly

37
Q

What causes acromegaly?

A

GH hypersecretion after adolescence causes acromegaly
Benign tumors (adenomas) in pituitary gland produces excess GH

38
Q

Features of acromegaly?

A

Thickening of bones
Coarsened facial features
Soft tissue swelling (hands and feet)
Heart failure
Vision loss (compressed optic chiasm)

39
Q

What medication is there to reduce GH secretion/tumour?

A

Bromocriptine (DA receptor agonist), somatostatin, to stop GH production and GH receptor antagonists are emerging

40
Q

What is dwarfism due do?
How is it treated?
Is it hereditary how is this caused?
What is Laron dwarf?
What is African pygym?

A

GH deficiency - low GH
Treated by replacing with GH
It is hereditary of having low GHRH
Laron dwarf is when there’s a defective GH receptor
African Pygmy is when there’s a defective IGF1 receptor

41
Q

SLIDE 18 -> Feedback Loops of GH diagram

A
42
Q

There are metabolic effects of GH that are not related to growth such as increasing f.a. levels and blood glucose levels - how does this occur?

A
  • Increases fatty acid levels in the blood by enhancing breakdown of triglyceride fat stored in adipose tissue.
  • Increases blood glucose by decreasing glucose uptake by muscles and increasing glucose output by the liver– muscle use mobilised fatty acids as fuel instead of glucose.
43
Q

What is the overall metabolic effects of GH?

A

Mobilise fat stores as a major energy substrate while conserving glucose for glucose dependent tissues such as brain.

44
Q

Note: Brain can only use glucose as its metabolic fuel, yet the brain cannot store glycogen (stored glucose) to any extent.

This pattern is useful during prolonged fasting or other situations where the body’s energy needs exceed available glucose stores

A
45
Q

4 other hormones responsible for growth?

A

Thyroid hormone, Insulin, (Testosterone and oestrogens) which are androgens

46
Q

Is thyroid hormone essential for growth and responsible for promoting growth?
What does it play a permissive role in?
When do the actions of GH manifest?
What happens to hypothyroid children?
Does hypersecretion affect growth?

A

Thyroid hormone – essential for growth BUT not directly responsible for promoting growth.
Plays a permissive role in skeletal growth
The actions of GH only manifest when sufficient TH is present.
Hypothyroid children: Growth severely stunted.
Hypersecretion: does not affect growth.

47
Q

What is insulin in terms of growth?
What do insulin deficiencies do?
What does hyperinsulinism cause?

A

Insulin is a growth promoter and promotes protein synthesis.
Insulin deficiency – blocks growth
Hyperinsulinism – spurs excessive growth.

48
Q

Broad function of androgens?
Do they stimulate growth?
What about weight gain?
Is there any muscle mass increased or decreased?

A

Pubertal growth spurt, stimulate protein synthesis in many organs.
Stimulate linear growth
Promote weight gain
Increase muscle mass

49
Q

Which is the most potent androgen?

A

Testosterone

50
Q

Do androgens have an effect in growth without GH?

A

Androgens have virtually no effect on body growth in the absence of GH

51
Q

Where is the thyroid gland?
Where does it develop from?

A

Located on the front of upper part of trachea
Develops from epithelial outgrowth of tongue

52
Q

What are the major secretory cells in the thyroid gland?
How are they arranged?
What is the functional unit?
How do they appear?
What is colloid?

A

Major secretory cells are follicular cells
They are arranged in hollow spheres
The functional unit is a follicle
Follicles appear as rings consisting of a single layer of
follicular cells enclosing an inner lumen filled with
colloid
Colloid is a substance that serves as an extracellular storage site for TH.

53
Q

What is the major constituent of colloid?
How is this incorporated during their synthesis?

A

A large glycoprotein molecule known as thyroglobulin (Tg) – incorporated into TH during their synthesis.

54
Q

Types of thyroid hormones: 3

A

-> T3 (Triiodotyronine) (t1/2 ~1.5 days) in follicles
-> T4 (Thyroxine) (t1/2 ~7 days) in follicles
-> Calcitonin by C cells – role in Calcium metabolism not related to T3/T4

55
Q

Function of T3+T4?

A

Accelerate metabolism and increase carbohydrate, fat and protein turnover

56
Q

Structure of T3+T4?

A

They are tyrosine-based hormones
* T3 has 3 iodine atoms, T4 contains 4
* T3 more effective, but T4 more abundant

57
Q

Levels of T3+T4 -
Controlled by?
Transported where, bound to what?
Made by?
When is iodide absorbed?

A

Controlled by anterior pituitary TSH
Transported in blood, bound to thyroxinebinding globulin (TBG)
Made by follicular cells when iodide available
Iodide absorbed from blood to thyroid follicles

58
Q

Synthesis, storage and secretion of TH - 9 steps:

A
  1. Tyrosine containing Tg produced within the thyroid follicular cells by endoplasmic reticulum/Golgi complex is transported by exocytosis into the colloid.
  2. Iodide is carried by secondary active transport from the blood into the colloid by symporters in the basolateral membrane of the follicular cells.
  3. In the follicular cell, the iodide is oxidised to active form by TPO at the luminal membrane.
  4. The active iodide exists the cell through a luminal channel to enter the colloid.
  5. Catalysed by tPO, attachment of 1 iodide to tyrosine within the Tg molecule yields MIT. Attachment of 2 iodides to tyrosine yields DIT.
  6. Coupling of 1 MIT and 1 DIT yields T3. Coupling of 2 DITs yield T4.
  7. On appropriate stimulation, the thyroid follicular cells engulf a portion of Tg containing colloid by phagocytosis.
  8. Lysosomes attack the engulfed vesicle and split the iodinated products from Tg.
  9. T3+T4 diffuse into the blood (secretion). MIT and DIT are deiodinated, and the freed iodide is recycled for synthesising more hormone.
59
Q

Effects of thyroid gland? 6

A
  • Main determinant of basal metabolic rate
  • Influences synthesis and degradation of carbohydrate, fat and protein
  • Increases target cell responsiveness to catecholamines
  • Increases heart rate and force of contraction
  • Essential for normal growth
  • Plays crucial role in normal development of the nervous system
60
Q

SLIDE 28 FEEDBACK LOOPS OF THYROID HORMONE

A
61
Q

What is Goiter?
How much iodine in normal thyroid gland?
What happens in the disease?
What size can normal thyroid gland grow to during goiter?

A

Low iodine uptake
Normal: thyroid gland takes up 30% of
ingested iodide
Disease: dietary iodide insufficiency
─ no T3/T4 made
─ thyroid cell proliferation
─ iodide uptake increases
─ normal human thyroid gland of 25 g may grow to 250 g during goiter

62
Q

What is Hashimoto’s disease?

A

Autoimmune disease where autoantibodies destroy
thyroid follicular cells

63
Q

What is hypothyroidism?

A

Primary failure of the thyroid gland itself
Secondary to a deficit of TRH, TSH or both
Inadequate dietary supply of iodide

64
Q

What is crentinism?

A

Cretinism is a condition of severely stunted physical and mental growth due to untreated congenital deficiency of thyroid hormones

65
Q

What happens in crentinism hypothyrodism - infants?

A

Stunted growth
Lack of bone formation
Skeletal abnormalities
Severe mental retardation
Protruding tongue

66
Q

What is myxedema?

A

An extreme complication of hypothyroidism in which patients exhibit multiple organ abnormalities and progressive mental deterioration

67
Q

Myxedema is hypothyroidism developing in older child or in an adult what are the clinical features? 12

A
  • Generalised fatigue
  • Mental slugglishness
  • Slow speech
  • Cold intolerance
  • Overweight
  • Shortness of breath
  • Constipation
  • Decreased sweating
  • Cool and pale skin
  • Generalized edema
  • Enlargement of tongue
  • Deepened voice
68
Q

Symptoms of hyperthyroidism? 7

A

high metabolic rate, protruding eyes, hyperactivity, insomnia, heat sensitivity, weight loss, always hot

69
Q

What is disease of hyperthyroidism?
What is it

A

Grave’s disease - Autoimmune (TSH mimicked by
autoantibodies – also known as thyroid stimulating immunoglobulin (TSI))

70
Q

Treatments for hyperthyroidism? 4

A

Beta blockers help some symptoms
Anti-thyroid medications
Radioactive iodine treatment destroys overactive thyroid cells
Surgery thyroidectomy

71
Q

SEE DIAGRAM ON SLIDE 33

A

Gut, metabolism and hormones (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions