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CEP > Hormone Synthesis And Action > Flashcards

Hormone Synthesis And Action Flashcards

1
Q

Definition of endocrine system

A

A system of ductless glands and cells that secrete hormones
Regulates - metabolism, homeostasis and reproduction

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2
Q

List of endocrine glands

A

Pineal glands
Hypothalamus
Pituitary
Thyroid
Parathyroid
Thymus
Pancreas
Adrenal
Kidney
GIT
Ovaries/ testis

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3
Q

What are Endocrine Glands

A

Release secretions (hormones) into blood directly from cells - ductless glands

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4
Q

What are exocrine glands?

A

(Not part of endocrine system) release their secretions outside the body and may be ducted e.g. gut secretions, sweat glands

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5
Q

What are mixed glands?

A

Pancreas produces digestive juice + insulin, glucagon and somatostatin

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6
Q

What is a hormone?

A

Hormone is a substance secreted directly into the blood by specialised cells
Hormones are present in only minute concentrations in the blood and bind to specific receptors on target cells

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7
Q

What are the 2 major regulatory systems of the body

A

Nervous
Endocrine

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8
Q

Comparisons between nervous and endocrine systems

A

Few NT vs many hormones
Generally rapid vs generally slow
Generally short lived vs generally long lasting
Localised vs widespread

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9
Q

Three mechanisms of chemical signalling

A

Intracrine
Autocrine
Paracrine

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10
Q

What is intracrine signalling

A

Generated by a chemical acting within the same cell

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11
Q

What is autocrine signalling

A

Chemical or hormone secreted
And binds to autocrine receptors on the same cell

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12
Q

What is paracrine signalling

A

Chemical communication between neighbouring cells

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13
Q

What is the “classical” endocrine and neuroendocrine signalling mechanism

A

A chemical released by a specialised group of cells int circulation and acting on a distant target tissue

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14
Q

What is feedback control of hormonal release

A

Process by which body senses change and responds to it

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15
Q

What is negative feedback

A

Process by which body senses change and activates mechanism to reduce it
The final product of an endocrine cascade acts to inhibit the release of hormones higher up the cascade

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16
Q

What is positive feedback

A

Process by which body senses change and activates mechanism to amplify it

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17
Q

3 main groups of hormones?

A

Peptide hormones
Steroid hormones
Amine hormones

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18
Q

What is the most common hormone

A

Peptide hormone

19
Q

Features of peptide hormones

A

Made of amino acids
Hydrophilic
Preformed and stored in membrane bound vesicles ready for release by exocytosis

20
Q

How are peptide hormone synthesised?

A

Produced on RER as large precursor molecule - “preprohormone”
Matures into prohormone via cleavage of N terminal signal sequences
Bioactive hormone prod as result of enzymatic processing

21
Q

What are the subunits of pituitary glycoprotein hormones

A

Alpha subunit - genetic subunit for all hormones
Beta subunit - specific to each hormone

Released from anterior PG

22
Q

Some hormones secreted from anterior pituitary gland

A

Thyroid stimulating hormone TSH
Luteinising hormone LH
Follicle stimulating hormone FSH
Growth hormone GH
ACTH
Prolactin

23
Q

Precursor of steroid hormones

A

Cholesterol

24
Q

What is the rate limiting step in the production of steroid hormones

A

Pregnenolone
CYP11A

25
Q

Examples of steroid hormones

A

Adrenal cortex (glucocorticoid and mineral corticoids) and sex hormones (testosterone/ oestrogen)

26
Q

Features of steroid hormones?

A

Hydrophobic
Not stored - synthesised as required, then diffuse out of cell

27
Q

How are steroid hormones synthesised

A

Hydrolysis of esters and release of cholesterol
Cholesterol to pregnenolone in mitochondria (steroid hormones cannot be stored so stored as precursor)
Processing of pregnenolone in SER

28
Q

How is the movement of cholesterol to mitochondrion regulated

A

Regulated by steroid acute regulatory protein (StAR)
ACTH regulates StAR activity and processing of cholesterol

29
Q

The secretions of different zonas in the adrenal cortex

A

Zona glomerulosa - aldosterone
Zona fasciculata - cortisol
Zona reticularis - adrenal androgens

30
Q

How are enzymes involved in the synthesis of specific hormones

A

Specific tissue contains cells expressing enzymes leading to specific hormone synthesis

31
Q

What does increase in secretion reflect?

A

Reflects accelerated rates of synthesis

32
Q

How are steroid hormones eliminated

A

By inactivating metabolic transformations and excretion in urine or bile

33
Q

Features of thyroid hormones

A

Amine hormones
Small
Non polar
Hydrophobic
Soluble in plasma membranes

34
Q

Transportation of steroid & thyroid

A

Binding increases:
- solubility
- half life
Reservoir in blood
Specific binding proteins TBG and CBG
Or non specific binding proteins Albumin - loose binding

35
Q

Receptors of protein hormones

A

Cell surface receptors
Activate second messenger cascade and change cellular function

36
Q

What are the receptors of steroid hormones

A

Intracellular receptors
Cytoplasm or nuclear
Hormone-receptor complex binds to HRE

37
Q

Types of endocrine disorders

A

Hormones in excess
Hormone deficiency

38
Q

Causes and treatment of excess primary disorders

A

Hormones in excess:
Often caused by tumours/ exogenous intake of hormone
Treatment - surgical removal of gland

39
Q

Causes and treatment of insufficiency

A

Hormones in deficiency:
Primary - primary organ inadequate
Secondary - tropic hormone deficient/ autoimmune destruction

Treatment - replacement therapy
Orally absorbed, long half life
Injection - otherwise degraded in GIT

40
Q

What is the outcome of deficiency or excess of growth hormone

A

Deficiency: Dwarfism
Excess: Gigantism

41
Q

What is the outcome of deficiency or excess of ADH

A

Deficiency diabetes insipidus
Excess hypervalemia

42
Q

What is the outcome of deficiency or excess of insulin

A

Diabetes mellitus
Coma

43
Q

Examples of peptide hormones

A

GH
CRH corticotropins

CEP (12 decks)

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